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Evaluation of the genetic variability, heritability and genetic advance of traits is an essential task in any plant improvement program. Twenty maize genotypes were replicated twice in a randomized complete block design on a research plot of Prithu Technical College, Deukhuri Dang of Nepal from June 2017 to September 2017 to determine genetic variability, heritability, and genetic advance for different agronomic traits. Analysis of variance showed significant differences in the traits tassel length, ear height, days to fifty percent tasseling, days to fifty percent silking, kernels’ rows ear-1, kernels row-1 and grain yield. The highest GCV (31.53%) and PCV (39.20%) were recorded on grain yield. Grain yield and ear height recorded high heritability along with high genetic advance as a percent of mean (GAM). Tassel length and kernels row-1 showed high heritability integrated with moderate GAM and moderate heritability integrated with moderate GAM respectively. Further, grain yield showed a significant and positive correlation with plant height, tassel length, ear height, cob length, cob diameter, kernels’ rows ear-1, and kernels row-1. Thus the selection of ear height, tassel length and kernels row-1 is suggested as they performed better in terms of both heritability and GAM than other traits and they also recorded a significant and positive correlation with yield.

Strigolactones (SLs) are a recently identified class of phytohormones that regulate diverse developmental processes in land plants. However, the signaling mechanism of SLs in maize (Zea mays) remains largely unexplored. Here, we identified the maize gene DWARF 53 (ZmD53) and demonstrated that ZmD53 interacts with the SL receptors DWARF 14A/B (ZmD14A/B) in a rac-GR24-dependent manner. Transgenic maize plants expressing a gain-of-function mutant version of Zmd53 exhibited insensitivity to exogenous rac-GR24 treatment and a highly pleiotropic phenotype, including excess tillering and reduced tassel branching, indicating that ZmD53 functions as an authentic SL signaling repressor in maize. In addition, we showed that ZmD53 interacts with two homologous maize SPL transcription factors, UB3 and TSH4, and suppresses their transcriptional activation activity on TB1 to promote tillering. We also showed that UB2, UB3, and TSH4 can physically interact with each other and themselves, and that they can directly regulate the expression of TSH4, thus forming a positive feedback loop. Furthermore, we demonstrated that ZmD53 can repress the transcriptional activation activity of UB3 and TSH4 on their own promoters, thus decreasing tassel branch number. Our results reveal new insights into the integration of SL signaling and the miR156/SPL molecular module to coordinately regulate maize development.

The genome‐wide association studies (GWASs) are essential to determine the genetic bases of either ecological or economic phenotypic variation across individuals within populations of the model and nonmodel organisms. For this research question, the GWAS replication testing different parameters and models to validate the results' reproducibility is common. However, straightforward methodologies that manage both replication and tetraploid data are still missing. To solve this problem, we designed the MultiGWAS, a tool that does GWAS for diploid and tetraploid organisms by executing in parallel four software packages, two designed for polyploid data (GWASpoly and SHEsis) and two designed for diploid data (GAPIT and TASSEL). MultiGWAS has several advantages. It runs either in the command line or in a graphical interface; it manages different genotype formats, including VCF. Moreover, it allows control for population structure, relatedness, and several quality control checks on genotype data. Besides, MultiGWAS can test for additive and dominant gene action models, and, through a proprietary scoring function, select the best model to report its associations. Finally, it generates several reports that facilitate identifying false associations from both the significant and the best‐ranked association Single Nucleotide Polymorphisms (SNPs) among the four software packages. We tested MultiGWAS with public tetraploid potato data for tuber shape and several simulated data under both additive and dominant models. These tests demonstrated that MultiGWAS is better at detecting reliable associations than using each of the four software packages individually. Moreover, the parallel analysis of polyploid and diploid software that only offers MultiGWAS demonstrates its utility in understanding the best genetic model behind the SNP association in tetraploid organisms. Therefore, MultiGWAS probed to be an excellent alternative for wrapping GWAS replication in diploid and tetraploid organisms in a single analysis environment., The genome‐wide association studies (GWASs) are essential to determine the genetic bases of either ecological or economic phenotypic variation across individuals within populations of model and nonmodel organisms. Replication is a good practice to assess results, but straightforward methodologies that manage both replication and tetraploid data are still missing. To solve this problem, we designed the MultiGWAS, a tool that does GWAS for diploid and tetraploid organisms by executing in parallel four software packages, two for polyploid data (GWASpoly and SHEsis) and two for diploid data (GAPIT and TASSEL). MultiGWAS includes (1) the input and preprocessing of genomic data in different formats (including VCF files), (2) association analysis by running the GWAS software in parallel, (3) postprocessing and summarizing of their results, and (4) reporting using graphical and tabular views. MultiGWAS identifies both the highest scoring and shared associations between the four software packages, which helps users decide more intuitively on possible true or false associations. MultiGWAS can test for additive and dominant gene action models, and, through a proprietary scoring function, select the best model to report its associations. We tested MultiGWAS with public tetraploid potato data for tuber shape and several simulated data under both additive and dominant models. These tests demonstrated that MultiGWAS is better at detecting reliable associations than using each of the four software packages individually. ​

Bulk segregant analysis (BSA) is another method of identifying significant molecular markers linked to the target gene or region for specific traits. BSA is easier and less expensive than other methods; it does not require genetic map construction and needs fewer markers than the number needed to construct a genetic map for QTL mapping. The purpose of our study was to identify simple sequence repeat (SSR) markers linked with leaf- and seed-related traits in Perilla crop, and to allow the selection of better accessions in Perilla breeding programs with marker-assisted selection (MAS). The genotypes of the 25 SSR markers and phenotypic data for the eight qualitative traits were used to confirm significant marker-trait associations (SMTAs) using TASSEL software. To detect SSR markers associated with leaf color, the 16 individuals of the F3 population were divided into three bulk groups based on the colors of the surface and reverse sides of the leaf, respectively: six in the green/green group, five in the green/purple group and five in the purple/purple group. This study detected 18 significant marker-trait associations (SMTAs) involving 12 SSR markers associated with six agronomic traits. The SSR markers KNUPF15, KNUPF21, KNUPF29, and KNUPF60 were associated with leaf surface color, and KNUPF11, KNUPF15, KNUPF21, and KNUPF60 were associated with leaf reverse side color. In addition, five SSR markers were associated with seed-related traits. KNUPF11 and KNUPF29 were associated with seed coat color, while KNUPF29 was associated with seed size. KNUPF12, KNUPF16, and KNUPF42 were associated with seed hardness. To verify the selected significant SSR markers associated with leaf color and seed-related traits, a UPGMA dendrogram for 11 individuals in the F3 population, which formed two bulk groups consisting of 6 green/green and 5 purple/purple individuals, was constructed using six SSR marker-related LC and RLC traits. These results are very important for understanding the characteristics of Perilla leaves and seeds; they may also support opportunities to effectively preserve and utilize existing accessions and to allow Perilla breeders to improve crop quality by mean of MAS

Finger millet (Eleusine coracana(L.) Gaertn. subsp.coracana) is the most importantmillet in eastern Africa and perhaps the oldest domesticated cereal grain in Africa.One of the major factors limiting finger millet production is blast disease caused bythe fungusMagnaporthe grisea. Crop wild relatives and landraces present a poten-tial source of novel genes. This study investigated the response of cultivated and wildrelatives of finger millet to an isolate of blast disease from western Kenya. Previousgermplasm collections were purified through two generations of single-seed descentbefore screening alongside improved and farmer-preferred varieties (FPVs) under ascreen house across three seasons. Farmer-preferred varieties were identified throughparticipatory varietal selection (PVS). The plants were inoculated twice during eachgrowth period using hand-spraying method and data on disease incidence recorded atgrain-filling stage. Genotypic data was generated using diversity arrays technology(DArT) sequencing and data analysis done using Genstat 18.2 and TASSEL 5.2.58.We observed high heritability (81%), indicating that the variation observed was pre-dominantly genetic. Wild accessions were generally more resistant to the disease incomparison to the cultivated accessions. Preliminary genome-wide association study(GWAS) using general linear model with principal component analysis led to theidentification of 19 markers associated with blast disease that will be be developedinto assays for genotype quality control and trait introgression. Wild accessions andlandraces of finger millet present a good reservoir for novel genes that can be incor-porated into crop improvement programs.

Maintaining sufficient water transport during flowering is essential for proper organ growth, fertilization, and yield. Water deficits that coincide with flowering result in leaf wilting, necrosis, tassel browning, and sterility, a stress condition known as “tassel blasting.” We identified a mutant, necrotic upper tips1 (nut1), that mimics tassel blasting and drought stress and reveals the genetic mechanisms underlying these processes. The nut1 phenotype is evident only after the floral transition, and the mutants have difficulty moving water as shown by dye uptake and movement assays. These defects are correlated with reduced protoxylem vessel thickness that indirectly affects metaxylem cell wall integrity and function in the mutant. nut1 is caused by an Ac transposon insertion into the coding region of a unique NAC transcription factor within the VND clade of Arabidopsis. NUT1 localizes to the developing protoxylem of root, stem, and leaf sheath, but not metaxylem, and its expression is induced by flowering. NUT1 downstream target genes function in cell wall biosynthesis, apoptosis, and maintenance of xylem cell wall thickness and strength. These results show that maintaining protoxylem vessel integrity during periods of high water movement requires the expression of specialized, dynamically regulated transcription factors within the vasculature.

Summary The Zea Mays BIG GRAIN 1 HOMOLOG 1 (ZM‐BG1H1) was ectopically expressed in maize. Elite commercial hybrid germplasm was yield tested in diverse field environment locations representing commercial models. Yield was measured in 101 tests across all 4 events, 26 locations over 2 years, for an average yield gain of 355 kg/ha (5.65 bu/ac) above control, with 83% tests broadly showing yield gains (range +2272 kg/ha to −1240 kg/ha), with seven tests gaining more than one metric ton per hectare. Plant and ear height were slightly elevated, and ear and tassel flowering time were delayed one day, but ASI was unchanged, and these traits did not correlate to yield gain. ZM‐BG1H1 overexpression is associated with increased ear kernel row number and total ear kernel number and mass, but individual kernels trended slightly smaller and less dense. The ZM‐BG1H1 protein is detected in the plasma membrane like rice OS‐BG1. Five predominant native ZM‐BG1H1 alleles exhibit little structural and expression variation compared to the large increased expression conferred by these ectopic alleles.

Isolated microspore culture systems have been designed in maize by several groups, mainly from the late 1980s to early 2000s. However, even with optimized protocols, microspore embryogenesis induction has remained very dependent on the genotype in maize, with elite germplasm generally displaying no response or very low response. Yet, these last few years, significant progress has been accomplished in understanding and controlling microspore embryogenesis induction in model dicot and monocot species. This knowledge may be transferred to maize, and isolated microspore culture may gain new interest in this crop, at least for embryogenesis research. The methods we hereby present in detail permit the purification of 3-12 × 105 viable microspores per maize tassel, at the favorable stage for microspore embryogenesis. When cultured in appropriate liquid media, microspores from responsive genotypes give rise to androgenic embryos, which can then be regenerated into fertile doubled haploid plants.

Maize (Zea mays L.) is a monoecious grass plant in which mature male and female florets form the tassel and ear, respectively. Maize is often used as a model plant to study flower development. Several maize tassel seed mutants, such as the recessive mutants tasselseed1 (ts1) and tasselseed2 (ts2), exhibit a reversal in sex determination, which leads to the generation of seeds in tassels. The phenotype of the dominant mutant, Tasselseed5 (Ts5), is similar to that of ts2. Here, we positionally cloned the underlying gene of Ts5 and characterized its function. We show that the GRMZM2G177668 gene is overexpressed in Ts5. This gene encodes a cytochrome C oxidase, which catalyzes the transformation of jasmonoyl-L-isoleucine (JA-Ile) to 12OH-JA-Ile during jasmonic acid catabolism. Consistent with this finding, no JA-Ile peak was detected in Ts5 tassels during the sex determination period, unlike in the wild type. Transgenic maize plants overexpressing GRMZM2G177668 exhibited a tassel-seed phenotype similar to that of Ts5. These results indicate that the JA-Ile peak in tassels is critical for sex determination and that the Ts5 mutant phenotype results from the disruption of this peak in tassels during sex determination.

The glume is an organ of the maize spikelet and plays important roles in anther and kernel development. Vestigial glume1 (Vg1) is a classic mutant associated with ligule and glume development. Here we report the phenotypic characterization, fine mapping, and candidate gene analysis of the Vg1 mutant. Vg1 is a semi-dominant and pleiotropic gene, and also affects plant height, ear height, and tassel length. Vg1 ligule degeneration begins at the first leaf, and the Vg1 tassel and ear can be distinguished from those of wild-type plants when their lengths reach respectively 55 mm and 51 mm. Using a BC3 mapping population of 11,445 plants, we delimited the Vg1 functional site to an interval of 7.4 kb, flanked by the markers InDelLM and CRM6. A putative cyclopropane fatty-acid synthase gene (ZmCPA-FAS1) was hypothesized to underlie the mutant phenotype. We detected a Helitron insertion in the sixth intron of ZmCPA-FAS1. Its presence caused abnormal alternative splicing of ZmCPA-FAS1 that conferred new characteristics on the Vg1 mutant. These findings are a basis for further discovery of the molecular mechanism underlying glume development and a potential guide for maize breeding of small-glume varieties, especially sweet corn breeding. Keywords: Vestigial glume1, Fine mapping, Candidate gene analysis, ZmCPA-FAS1, Glume development

In this research, the relationships among the 31 microsatellite markers with charcoal rot disease resistance related indices in 130 different soybean cultivars and lines were evaluated using association analysis based on the general linear model (GLM) and the mixed linear model (MLM) by the Structure and Tassel software. The results of microsatellite markers showed that the genetic structure of the studied population has three subpopulations (K=3) which the results of bar plat also confirmed it. In association analysis based on GLM and MLM models, 31 and 35 loci showed significant relationships with the evaluated traits, respectively, and confirmed considerable variation of the studied traits. The identified markers related to some of the studied traits were the same which can probably be due to pleiotropic effects or tight linkage among the genomic regions controlling these traits. Some of these relationships were including, the relationship between Sat_252 marker with amount of charcoal rot disease, Satt359, Satt190 and Sat_169 markers with number of microsclerota in stem, amount of charcoal rot disease and severity of charcoal rot disease, Sat_416 marker with number of microsclerota in stem and amount of charcoal rot disease and the Satt460 marker with number of microsclerota in stem and severity of charcoal rot disease. The results of this research and the linked microsatellite markers with the charcoal rot disease-related characteristics can be used to identify the suitable parents and to improve the soybean population in future breeding programs.

The tassel architecture of maize (Zea mays L.), which plays an important role in F1 hybrid seed production and yield performance, is genetically controlled by quantitative trait loci (QTLs). Here, we constructed a high-density SNP-based genetic map using an F2 population containing 148 individuals. This genetic map included 7613 SNPs whose average genetic distance was 0.19 cM. On account of the F2 population, we detected 14 QTLs responsible for tassel branch number (TBN), tassel weight (TW), central spike length (CSL), and meristem length (ML); eight of these QTLs demonstrated a relatively high level of phenotypic variation explanation (PVE) (PVE ≥ 10%), at a high level of significance. qTW-2 was a major QTL (LOD = 10.11 and PVE = 28.82%), and this QTL and qTBN-2 shared the same region, indicating a possible pleiotropic effect. An F2:3 population was developed to further verify QTLs in the F2 population. Finally, qTBN-5, qTW-2 and qCSL_N-10 were detected reproducibly. To help screen potential candidate genes, we chose 12 genes within the regions of qTBN-5, qML-6, qCSL_N-7 and qTW-2 and that were possibly involved in tassel morphogenesis according to Gene Ontology (GO) annotation analysis and performed quantitative real-time polymerase chain reaction (qRT-PCR). The expression of eight of the 12 genes was significantly (P

Crop yield is of a quantitative nature. Two complementary approaches linkage mapping and genome-wide association study (GWAS) have been employed for the identification of loci influencing maize yield. In previous research, we meta-analyzed QTL for maize yield. Here, we tried to integrate meta-QTL and GWAS analyses to dissect candidate genes for maize yield. A total of seven candidate genes were detected by both meta-QTL and two independent GWAS analyses. Functional annotation indicated that some candidate genes were responsible for the maintenance and differentiation of maize inflorescence meristem that directly affect yield productivity. In addition, well-characterized genes for maize yield-related traits, including SBP-box family member unbranched3 (ub3) for maize ear row number, zea floricaula/leafy1 (zfl1) for maize inflorescence architecture and reproductive transition were detected by the integrated meta-QTL and GWAS analyses. Expression analysis showed that some candidate genes were preferentially expressed in maize rapidly proliferated tissues, including shoot apex, tassel, and ear primordia, which influence maize inflorescence architecture and yield performance. Some candidate genes were hypothesized to be selected during maize domestication and improvement. Results presented here will not only facilitate the cloning of yield-related genes, and provide guidance in breeding of plants with high-yield productivity.

Association mapping has proven to be a powerful approach for dissecting the genetic basis of complex traits. In this study, QTLs controlling flag leaf characteristics under drought stress were detected in a set of 148 modern spring barley cultivars using AM analysis. Flag leaf length (FLL), flag leaf width (FLW), relative water content (RWC), chlorophyll content, and maximum quantum efficiency of PSII (Fv/Fm) which are important in photosynthetic rate, were evaluated under normal irrigation and drought stress conditions at grain filling stage. Population structure was estimated using Structure 2.3 and linkage disequilibrium (LD) was estimated by the ‘Full Matrix LD’ using Tassel 5.0 . Significant marker/trait associations were investigated based on K-Q matrix using Tassel 3.0 . The analysis of population structure divided the cultivars into two sub-groups. Significant LD values (P < 0.01) between polymorphic sites with regions of high and low LD were observed. A total of 84 significant putative genomic regions were identified, which delineated into 37 QTLs under two water treatments. Two stable QTLs on 2H and 3H were detected for FLL in drought stress treatment. A QTL for FLL were detected on 2H in normal treatment, which alone explained around 11% of phenotypic variance of FLL. This QTL was also associated with the expression of FLW and explained around 7.5% of phenotypic variance. The results suggest that major loci are located on chromosomes 2H, 3H, 4H and 5H involved in the development of flag leaf characteristics and could be used as selection criteria in barley breeding for drought tolerance.

MADS-box family proteins play an important role in grain formation and flower development; however, the molecular mechanisms by which transcription factors regulate the starch metabolism pathway are unclear in maize. Here, we report a transcription factor, ZmMADS1a, that controls starch biosynthesis in maize (Zea mays L.). We demonstrate the expression of ZmMADS1a in tassel, silk, and endosperm, and show that the protein is localized to the cell nucleus. Compared with the control, seeds of overexpressing ZmMADS1a increased starch content (especially amylose content), had smaller starch granules and altered chemical structure. Meanwhile, overexpression of ZmMADS1a resulted in increases in the contents of soluble sugars and reducing sugars in maize. ZmMADS1a plays a positive regulatory role in the starch biosynthesis pathway by up-regulating several starch biosynthesis related genes. We also show that ZmMADS1a has a similar adjustment mechanism of starch biosynthesis in rice. Collectively, our study suggests that ZmMADS1a functions as a positive regulator of starch biosynthesis by regulating the expression of key starch metabolism genes during seed development.

High temperature (HT) stress during flowering severely threatens crop grain yield, however, little is known about the underlying mechanisms in maize. A HT sensitive maize hybrid was subjected to 32/22 ℃ (maximum/minimum temperature, control), 36/26 ℃, and 40/30 ℃ for 14 consecutive days bracketing flowering (trial 1) and for seven days prior to flowering (trial 2). Maize grain yield did not decrease in the 36/26 ℃ treatment during trial 1 compared to the control treatment, but reduced by 73.6% in the 40/30 ℃ treatment as a result of reduced kernel number rather than kernel weight. High temperature stress advanced tasseling and pollen shedding, extended the anthesis-silking interval, and reduced the number and viability of pollen shed, but had no effects on silking. The shortened duration of pollen shedding was a result of the accelerated flowering speed of the tassel inflorescence. Leaf assimilate can be transferred to the tassel, but cannot be converted into starch in the HT stressed pollen. The damaged pollen morphology and the interrupted sugar to starch physiological process explained the reduced pollen viability. Starch granule number and size in the pollen decreased with the increased temperature. Thus, male organ growth is more sensitive to HT than female organs. Understanding the underlying mechanisms has implications for selecting or breeding HT tolerant maize.

THICK TASSEL DWARF1 (TD1) is a critical gene that negatively modulates meristem size during maize inflorescence development and may also regulate ear-related traits. In the present study, the whole genomic DNA sequences and the promoter regions of TD1 were analyzed in 165 diverse maize inbred lines. Polymorphism analysis identified 39 SNPs and five InDels in the genic region of TD1 and allowed 23 haplotypes to be classified. Among these sites, eight SNPs and one InDel were significantly associated with kernel number (KN) (p < 0.05), seven SNPs and one InDel were significantly associated with kernel number per row (KNPR) (p < 0.05), and three SNPs were significantly associated with kernel row number (KRN) (p < 0.05). In addition, 21 SNPs and 14 InDels were identified in the promoter regions of TD1, and two SNPs and seven InDels of these sites were found to be significantly associated with KRN (p < 0.05). The results denote that Hap_7 was the favorable haplotype for both KN and KNPR, and Hap_2 was the elite haplotype for KRN. These favorable haplotypes could be utilized in molecular marker-assisted selection (MAS) to improve KN, KNPR, or KRN, and thereby further increase grain yield in maize breeding programs.

High yield and efficient use of nitrogen is one of the major target for maize breeding worldwide. Both yield potential and nitrogen use efficiency (NUE) of maize is lower in China compared to that in the US. In this study, we analyzed the change of the plant traits related to high yield and NUE of maize cultivars registered and planted in China and US during the past 40 decades. Compared to the cultivar released in the US, Chinese cultivar are less tolerant to high planting density, higher ratio of ear height to plant height, low grain filling rate, more stay-green and longer growth period. We suggest an ideal plant architecture of maize for high yield and NUE. To achieve high yield and high NUE under intensive production conditions (medium and high nitrogen input, high density planting), an ideotype plant architecture is proposed which includes compact plant architecture, low ratio of ear height to plant height (around 0.36–0.38, close to the golden rate.), medium ear, small tassel, medium root size, one-layer brace root, half stay-green, efficient N remobilization, fast grain filling rate etc. The parameters can be utilized to guide future breeding.

Combating mineral deficiencies has been a major challenge for agricultural scientists world over. Lack of calcium in diets could be overcome through biofortifying food crops especially cereals. Finger millet (Eleusine coracana) grains are highly rich in calcium, therefore in the present study this phenotypic trait was explored using association study on a natural population of finger millet. A total of 238 accessions of finger millet were analysed using 85 simple sequence repeats (SSR) markers. SSR profiles generated 160 alleles and 20 primer pairs which were polymorphic across the population with 0.14 to 0.78 polymorphic information content. Grain Calcium content (GCC) varied from 72 to 452 mg/100g seed. Two accessions, GPHCPB45 (452.8 mg) and GPHCPB 439.8 mg) each from Northern India and exotic areas were found with highest GCC. Association analysis through the general linear model in TASSEL software detected two markers UGEP78 and UGEP60 in significant association (P less than 0.001) to calcium content. The molecular marks, UGEP60 can be a potential marker with phenotypic variance amounting to 13.8%. However, the mixed linear model did not detect any significant associations probably because of low polymorphism within the finger millet collection considered in this study. Identification of two accessions with higher calcium content may be useful in finger millet improvement.

The fungus Pyrenophora teres causing disease symptoms similar to P. tritici-repentis was recently detected on wheat in Argentina. After confirmation by molecular studies the pathogen was identified as P. teres f. maculata, part of a complex of leaf spots that affect wheat and other cereal crops. The objective of this work was to characterize the virulence and identify QTL conferring resistance to two isolates of P. teres f. maculata (Ptm) in a collection of 110 spring wheat genotypes previously assembled for association mapping and genotyped with 2836 DArT markers. Two isolates of Ptm (PT2047 and PT2050) were used in field experiments. To find marker-trait associations (MTAs) a mixed linear model implemented in TASSEL 5.1 software was used. Considerable phenotypic variation in disease severity was observed at the seedling and adult stages, and some accessions were resistant to both isolates over 2 years. Twelve MTAs identified with nine markers were significantly associated with resistance. The nine markers were distributed over seven chromosomal regions on 6 of the 21 wheat chromosomes. These QTL were novel since this is the first study to identify genomic regions associated with resistance to Ptm in wheat. Wheat genotypes with moderate to high levels of resistance to P. teres f. maculata were identified and will be useful in breeding programs., Facultad de Ciencias Agrarias y Forestales

The objective of this study was to assess the nutrient contents and in vitro true digestibility (IVTD) of parts of the corn plant. The corn used in the study was P2088, a variety that is grown widely in Turkey. It had matured and was harvested 140 days after planting. Four replicate plants were separated into nine parts, namely lower stalk, central stalk, upper stalk, corn ear stalk, corn ear shuck, kernels, corn cob, leaf, tassel, plus the entire plant. The samples were dried and ground for analysis. Nutritional values were determined in the laboratory and in vitro digestibility was assessed. Significant differences in nutrient content were observed among parts of the corn plant. The highest crude protein (CP) content was found in the leaf (12.41%), followed by the grain (12.37%). Dry matter (DM) varied from 91.25% to 96.07%. The highest ether extract (EE) was in the grain (2.84%), and the upper stalk contained the least EE (0.29%). The parts also differed in their contents of crude cellulose (CS) and crude ash (CA) (P

Introduction: Quality characteristics including grain protein content, gluten, falling number, and SDS sedimentation volume are important contributors to the grain yield and quality of the wheat. To identify the markers associated with such traits, this study run in two separated experiments: under-field and in laboratory. Materials and Methods: One hundred wheat genotypes were evaluated in an alpha lattice design with two replications. Association mapping using Structure and Tassel software was carried out using 102 SSR markers: 66 unlinked and 36 quantitative trait loci (QTL)-linked SSR markers. Correction for population structure was performed using genome-wide SSR markers so that genotypes were divided into six subpopulations. Results: Thoroughly, 34 SSR markers linked with the above-mentioned traits were identified, twelve of them being QTL-linked markers. These markers were already mapped on the wheat chromosomes in previous studies containing known QTLs controlling kernel traits of the wheat. Our results confirmed 5, 3, 2, and 2 QTLs respectively for the grain protein, gluten, falling number, and SDS sedimentation volume which were previously tagged on the wheat chromosomes. Additionally, 3 QTLs were identified for the grain protein on the chromosomes 2A, 5A, 5D, and 7B. Whereas, 6 QTLs for gluten were detected on chromosomes 1A, 2D, 5A, 5B, 6B, and 7B; four QTLs were located on the chromosomes 2D, 5A, 5B, 5D, and 7D for falling number; and finally nine QTLs were found for SDS sedimentation volume on the chromosomes 1A, 1B, 2B, 3A, 3B, 4B, 6A, 6B, 7A, and 7B. Conclusions: The results of this study indicated that association mapping is a useful method for detecting and complementing QTL information; thus, this information can be used for further wheat improvement based on a molecular marker.

Low light is a type of abiotic stress that seriously affects plant growth and production efficiency. We investigated the response mechanisms of summer maize to low light by measuring the changes in endogenous hormones in the grains and during grain filling in summer maize at different light intensities to provide a theoretical basis for the production and management of summer maize under light stress. We applied different light treatments in a field experiment as follows: S, shading from tassel stage (VT) to maturity stage (R6); CK, natural lighting in the field; and L, increasing light from VT to R6. The shading level was 60%, and the maximum illumination intensity of the increasing light treatment on cloudy days was 1600–1800 μmol m−2 s−1. Compared with the control, shading significantly increased the grain abscisic acid (ABA) content at 5–20 days after pollination and decreased the indole acetic acid (IAA), zeatin riboside (ZR), and gibberellin (GA) contents (P

A total of fifty inbred lines of sweet corn were evaluated for eight quantitative characters at the Millet Breeding Station, Department of Millets, Tamil Nadu Agricultural University, Coimbatore during kharif 2014 to study the genetic diversity using multivariate (D square) analysis. The fifty inbreds categorized in to ten distinct clusters. The intra-cluster distances in all the ten clusters was low, indicating that the genotypes within the same cluster were closely related. The highest inter-cluster distance was observed between cluster I and cluster X and the lowest between the cluster II and III. The cluster VII and cluster X contained the highest (24) and lowest (1) number of genotypes, respectively. Cluster VI showed the highest mean values for kernel yield and all the yield contributing traits. Cob girth and number of tassel branches expressed maximum contribution towards total divergence among different characters. Development of hybrids utilizing these genotypes has the chance to obtain higher heterosis with high performing crosses.

Tassel, the male reproductive organs in maize, its development is adversely affected by drought during tasseling. To determine drought tolerance mechanisms of tassel differentiation at transcriptome level, RNA-Seq was performed using RNA of early developing tassel from 10 maize inbred lines under well-watered (control) and drought-stressed conditions, respectively. Results showed that the most active pathway for drought stress in maize were related to metabolic regulation at RNA level. And some genes, encoding enzymes involved in carbohydrate and lipid metabolism, were significantly down-regulated in drought-stressed plants. While, the transcription factors and genes, encoding catabolic or degradative enzymes, were over-expressed in maize early developing tassels under drought-stressed conditions, and among them, the transcripts of genes encoding exon-junction complexes involved in ‘RNA transcript’ and ‘mRNA surveillance’ pathways were significantly affected by drought stress. In addition, many other genes related to drought stress showed transcriptional changes at the later period of stress.

The establishment of inflorescence architecture is critical for the reproduction of flowering plant species. The maize plant generates two types of inflorescences, the tassel and the ear, and their architectures have a large effect on grain yield and yield-related traits that are genetically controlled by quantitative trait loci (QTLs). Since ear and tassel architecture are deeply affected by the activity of inflorescence meristems, key QTLs and genes regulating meristematic activity have important impacts on inflorescence development and show great potential for optimizing grain yield. Isolation of yield trait-related QTLs is challenging, but these QTLs have direct application in maize breeding. Additionally, characterization and functional dissection of QTLs can provide genetic and molecular knowledge of quantitative variation in inflorescence architecture. In this review, we summarize currently identified QTLs responsible for the establishment of ear and tassel architecture and discuss the potential genetic control of four ear-related and four tassel-related traits. In recent years, several inflorescence architecture-related QTLs have been characterized at the gene level. We review the mechanisms of these characterized QTLs.

Background Plant Architecture Related Traits (PATs) are of great importance for maize breeding, and mainly controlled by minor effect quantitative trait loci (QTLs). However, cloning or even fine-mapping of minor effect QTLs is very difficult in maize. Theoretically, large population and high density genetic map can be helpful for increasing QTL mapping resolution and accuracy, but such a possibility have not been actually tested. Results Here, we employed a genotyping-by-sequencing (GBS) strategy to construct a linkage map with 16,769 marker bins for 1021 recombinant inbred lines (RILs). Accurately mapping of well studied genes P1, pl1 and r1 underlying silk color demonstrated the map quality. After QTL analysis, a total of 51 loci were mapped for six PATs. Although all of them belong to minor effect alleles, the lengths of the QTL intervals, with a minimum and median of 1.03 and 3.40 Mb respectively, were remarkably reduced as compared with previous reports using smaller size of population or small number of markers. Several genes with known function in maize were shown to be overlapping with or close neighboring to these QTL peaks, including na1, td1, d3 for plant height, ra1 for tassel branch number, and zfl2 for tassel length. To further confirm our mapping results, a plant height QTL, qPH1a, was verified by an introgression lines (ILs). Conclusions We demonstrated a method for high resolution mapping of minor effect QTLs in maize, and the resulted comprehensive QTLs for PATs are valuable for maize molecular breeding in the future. Electronic supplementary material The online version of this article (10.1186/s12870-018-1233-5) contains supplementary material, which is available to authorized users.

The rising demand for popcorn necessitates improving the popping quality with higher yield of popcorn cultivars. Towards this direction several Quantitative Traits Loci (QTLs) for popping traits have been identified. However, identification of accurate and consistent QTLs across different genetic backgrounds and environments is necessary to effectively utilize the identified QTLs in marker-assisted breeding. In the current study, 99 QTLs related to popping traits reported in 8 different studies were assembled and projected on the reference map "Genetic 2005" using BioMercator v4.2 to identify metaQTLs with consistent QTLs. Total ten metaQTLs were identified on chromosome 1 (7 metaQTLs) and 6 (3 metaQTLs) with physical distance ranging between 0.43 and 12.75 Mb, respectively. Four identified metaQTLs, viz., mQTL1_1, mQTL1_5, mQTL1_7 and mQTL6_2 harboured 5–8 QTL clusters with moderately high R2 value. The clustered QTLs were from two or more experiments. Based on the expression pattern in endosperm and pericarp tissues, a total of 229 genes were selected. Nineteen of these genes are involved in carbohydrate metabolism. Of the 19 genes specifically involved in carbohydrate metabolism, 11 of them were in these regions, implying the importance of these clustered QTLs. MetaQTL1_1 at bin location 1.01 coincided with the reported QTLs related to various agronomic traits like stalk diameter, tassel length, leaf area and plant height. The identified metaQTLs can be further explored for fine mapping and candidate gene identification, which can be validated by loss or gain of function. Identified metaQTLs can be used for introgression of popping traits towards enhancing the popping ability.

High temperature adversely affects the plant physiological processes: limits plant growth and reduction in grain yield. Heat stress is often encountered to spring sowing of maize in spring season. Twenty maize inbred lines were studied for days to 50 % anthesis and silking, anthesis–silking interval, leaf firing, tassel blast, SPAD reading and leaf senescence, plant and ear height, leaf area index, ear per plant, cob length and diameter, number of kernel/ear, number of kernel row/ear, number of kernel row, silk receptivity, shelling percentage, thousand kernel weight and grain yield in alpha lattice design at National Maize Research Program at Rampur, Chitwan,Nepal with the objective to identify superior heat stress tolerant lines. Analysis of variance showed significant difference for all the traits. Result of multivariable analysis revealed that twenty inbred lines formed four clusters. The resistance inbred lines and susceptible inbred lines formed different clusters. The members of cluster 4 were found to be tolerant to heat stress due to they had lowest value of tassel blast, leaf firing, and leaf area index with highest value of cob diameter and length, ear per plant, number of kernel row/ear, number of kernel/ear, number of kernel row, shelling percentage, silk receptivity and grain yield whereas as members of cluster 1were found most susceptible due to they had longer anthesis silking interval, with maximum tassel blast and leaf firing along with no grain yield under heat stress condition. From this study inbred lines RL-140, RML-76, RML-91 and RML-40 were found most tolerant to heat stress. These inbred lines belonging to superior cluster could be considered very useful in developing heat tolerant variety and other breeding activities.

The maize tassel represents an indeterminate male inflorescence. The number of primordia that a given inflorescence meristem produces is related to its determinacy, i.e., capacity for continued meristem activity. Transcription factors (TFs) controlling determinacy in tassel axillary meristems are well studied in maize, and small RNAs are known to influence tassel development by repressing targets, including tassel-related TFs. As core components of the RNA-inducible silence complex (RISC), Argonaute (AGO) proteins are required for small RNA-mediated repression. Here, we characterized the biological function of AGO18b, a tassel-enriched AGO. The abundance of AGO18b transcripts gradually increased during tassel development from inception to gametogenesis and were enriched in the inflorescence meristem and axillary meristems of the tassel. Repressing AGO18b expression resulted in more spikelets, which contributed to a longer central spike of the tassel. Additionally, the transcripts of several HD-ZIP III TFs that were canonical targets of microRNA166 (miR166) accumulated in the AGO18b-repressed lines. We propose that AGO18b is a negative regulator of the determinacy of inflorescence and axillary meristems, and that it acts by interacting with the miR166-HD-ZIP III TF regulatory pathway.

Key message An easy and highly reproducible nondestructive method named the Leaf Collar Method is described to identify and characterize the different stages of pollen development in maize. Abstract In plants, many cellular events such as meiosis, asymmetric cell division, cell cycle regulation, cell fate determination, nucleus movement, vacuole formation, chromatin condensation and epigenetic modifications take place during pollen development. In maize, pollen development occurs in tassels that are confined within the internal stalk of the plant. Hence, identification of the different pollen developmental stages as a tool to investigate above biological processes is impossible without dissecting the entire plant. Therefore, an efficient and reproducible method is necessary to isolate homogeneous cell populations at individual stages throughout pollen development without destroying the plant. Here, we describe a method to identify the various stages of pollen development in maize. Using the Leaf Collar Method in the maize inbreed line B73, we have determined the duration of each stage from pollen mother cells before meiosis to mature tricellular pollen. Anther and tassel size as well as percentage of pollen stages were correlated with vegetative stages, which are easily recognized. The identification of stage-specific genes indicates the reproducibility of the method. In summary, we present an easy and highly reproducible nondestructive method to identify and characterize the different stages of pollen development in maize. This method now opens the way for many subsequent physiological, morphological and molecular analyses to study, for instance, transcriptomics, metabolomics, DNA methylation and chromatin patterns during normal and stressful conditions throughout pollen development in one of the economically most important grass species. Electronic supplementary material The online version of this article (10.1007/s00497-017-0311-4) contains supplementary material, which is available to authorized users.

This is the first report on association analysis of salt tolerance and identification of SNP markers associated with salt tolerance in cowpea. Cowpea (Vigna unguiculata (L.) Walp) is one of the most important cultivated legumes in Africa. The worldwide annual production in cowpea dry seed is 5.4 million metric tons. However, cowpea is unfavorably affected by salinity stress at germination and seedling stages, which is exacerbated by the effects of climate change. The lack of knowledge on the genetic underlying salt tolerance in cowpea limits the establishment of a breeding strategy for developing salt-tolerant cowpea cultivars. The objectives of this study were to conduct association mapping for salt tolerance at germination and seedling stages and to identify SNP markers associated with salt tolerance in cowpea. We analyzed the salt tolerance index of 116 and 155 cowpea accessions at germination and seedling stages, respectively. A total of 1049 SNPs postulated from genotyping-by-sequencing were used for association analysis. Population structure was inferred using Structure 2.3.4; K optimal was determined using Structure Harvester. TASSEL 5, GAPIT, and FarmCPU involving three models such as single marker regression, general linear model, and mixed linear model were used for the association study. Substantial variation in salt tolerance index for germination rate, plant height reduction, fresh and dry shoot biomass reduction, foliar leaf injury, and inhibition of the first trifoliate leaf was observed. The cowpea accessions were structured into two subpopulations. Three SNPs, Scaffold87490_622, Scaffold87490_630, and C35017374_128 were highly associated with salt tolerance at germination stage. Seven SNPs, Scaffold93827_270, Scaffold68489_600, Scaffold87490_633, Scaffold87490_640, Scaffold82042_3387, C35069468_1916, and Scaffold93942_1089 were found to be associated with salt tolerance at seedling stage. The SNP markers were consistent across the three models and could be used as a tool to select salt-tolerant lines for breeding improved cowpea tolerance to salinity.

The negative effects of heat stress on maize growth and reproduction is often expressed in terms of significant yield penalty. Germplasm selection based on yield potential along with heat stress adaptive secondary traits, and establishing their interaction under stress helps in identifying suitable heat tolerant genotypes. To dissect intricate nature of heat stress tolerance, two field trials were conducted during spring 2014 and 2015 under natural heat stress conditions. Planting was adjusted to expose reproductive and grain filling period to high temperature regimes during May month in Hyderabad, India. Correlation analysis between grain yield under stress and secondary traits observed in two year experiments indicated that the traits such as - leaf firing (LF) (r = −0.34** and 0.06), tassel blast (TB) (r = −0.18 and −0.25), tassel sterility (TS) (r = −0.08 and −0.38*), anthesis-silking interval (ASI) (r = −0.24* and −0.02) and senescence (SEN) (r = −0.27** and −0.34*) were negatively correlated, while pollen shedding duration (PSD) (r = 0.33** and 0.4*), seed set percentage (SSP_OP) (r = 0.76** and 0.58**) and chlorophyll content (CHL) (r = 0.55** and 0.41*) were positively associated with grain yield under stress in 2014 and 2015, respectively. An ASI of 2–4 days and PSD of 2–4 days were found advantageous to grain yield under heat stress. Stigma receptivity was less affected under heat stress when compared to pollen viability, yet stigma initiation was delayed under heat stress, which resulted in prolonged ASI. Overall effect of heat stress was expressed in terms of SSP_OP, which explained yield variation by 78.5 and 57.8% for experiment 1 and 2, respectively. Thus, traits that are indicative of reproductive success under heat stress (ASI, TB, TS, pollen viability, stigma receptivity and SSP_OP) and other morpho-physiological traits (LF, SEN and CHL) may be used along with grain yield in index selection of suitable germplasm for heat stress tolerance.

Phenotypic measurements and images of crops grown under controlled-environment conditions can be analyzed to compare plant growth and other phenotypes from diverse varieties. Those demonstrating the most favorable phenotypic traits can then be used for crop improvement strategies. This article details a protocol for image-based root and shoot phenotyping of plants grown in the greenhouse to compare traits among different varieties. Diverse maize lines were grown in the greenhouse in large 8-gallon treepots in a clay granule substrate. Replicates of each line were harvested at 4 weeks, 6 weeks, and 8 weeks after planting to capture developmental information. Whole-plant phenotypes include biomass accumulation, ontogeny, architecture, and photosynthetic efficiency of leaves. Image analysis was used to measure leaf surface area and tassel size and to extract shape variance information from complex 3D root architectures. Notably, this framework is extensible to any number of above- or below-ground phenotypes, both morphological and physiological. © 2017 by John Wiley & Sons, Inc. Keywords: whole-plant; phenotypes; image-based analysis; shoots; roots

Summary Application of nitrogen fertilizer in the past 50 years has resulted in significant increases in crop yields. However, loss of nitrogen from crop fields has been associated with negative impacts on the environment. Developing maize hybrids with improved nitrogen use efficiency is a cost‐effective strategy for increasing yield sustainably. We report that a dominant male‐sterile mutant Ms44 encodes a lipid transfer protein which is expressed specifically in the tapetum. A single amino acid change from alanine to threonine at the signal peptide cleavage site of the Ms44 protein abolished protein processing and impeded the secretion of protein from tapetal cells into the locule, resulting in dominant male sterility. While the total nitrogen (N) content in plants was not changed, Ms44 male‐sterile plants reduced tassel growth and improved ear growth by partitioning more nitrogen to the ear, resulting in a 9.6% increase in kernel number. Hybrids carrying the Ms44 allele demonstrated a 4%–8.5% yield advantage when N is limiting, 1.7% yield advantage under drought and 0.9% yield advantage under optimal growth conditions relative to the yield of wild type. Furthermore, we have developed an Ms44 maintainer line for fertility restoration, male‐sterile inbred seed increase and hybrid seed production. This study reveals that protein secretion from the tapetum into the locule is critical for pollen development and demonstrates that a reduction in competition between tassel and ear by male sterility improves grain yield under low‐nitrogen conditions in maize.

To inform possibility of conducting marker assisted breeding of promiscuous soybean varieties, this study used 92 F2 lines from biparental cross to identify QTLs associated with promiscuous nodulation in soybean. GBS; genotyping by sequencing platform was used to generate SNPs through the pipeline 2 in TASSEL 5.0, Bowtie2 version 2.2.8 for tag alignment, Beagle version 4.1 to impute missing SNPs and R-QTL package in R for QTL identification. Four nodulation traits were assessedviznumber of nodules (NN), percent of effective nodules (NE), fresh weight and dry weight of nodules (NFW and NDW). Two QTLs were identified on chromosomes 10 and 13. Both QTLs were associated with NN, only QTL13 was associated NE and only QTL10 was associated with nodule ‘weights. It was observed that NN, NFW and NDW shared QTL10 and NN and NE share QTL13 allowing hypothetize on the existence of pleiotropic genes in those those two regions. Over dominance effect was observed for QTL10 and non additive effect for QTL13. The paper recommend investigations be pursued to validate those QTLs and set foundation for marker assisted selection of promiscuous soybean varieties. Also these findings could serve as starting point for gene cloning to better understand nodulation trait in soybean.

Potato is one of the most important food crops all over the world. Breeding activities for this crop are mainly aimed to improve the quality and yield of tuber. However, genetic architecture of various traits contributing to the quality and yield of potato are not yet completely understood. Genome wide association studies provides a broader way to identify the genomic regions associated with various traits. Panels of 237 tetraploid potato genotypes from different countries were grown for two consecutive years 2016 and 2017 at experimental research area of Potato research center Niğde, Turkey. A genome wide association study using SolCAP 12K array was performed for various morpho-agronomic traits. Structure algorithm and neighborhood joining analysis clearly divided all genotypes into 4 clusters on the basis of their origin. For the marker trait association, Mixed Linear Model in TASSEL was performed and 36 genomic regions were found for the traits under study. The mean r(2) value was found to be 0.92 and mean significant LD was 47.5% in the populations. LD patterns reflected the breeding history of potato. The findings of present study provide a framework which could be useful for future potato breeding programs to enhance the production and to reduce the challenges in the coming years to feed world’s population. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12298-020-00785-3) contains supplementary material, which is available to authorized users.

Floral morphology is shaped by factors that modulate floral meristem activity and size, and the identity, number and arrangement of the lateral organs they form. We report the maize CRABS CLAW co-orthologs drooping leaf1 (drl1) and drl2 are required for development of ear and tassel florets. Pistillate florets of drl1 ears are sterile with unfused carpels that fail to enclose an expanded nucellus-like structure. Staminate florets of drl1 tassels have extra stamens and fertile anthers. Natural variation and transposon alleles of drl2 enhance drl1 mutant phenotypes by reducing floral meristem (FM) determinacy. The drl paralogs are co-expressed in lateral floral primordia, but not within the FM. drl expression together with the more indeterminate mutant FMs suggest that the drl genes regulate FM activity and impose meristem determinacy non-cell autonomously from differentiating cells in lateral floral organs. We used gene regulatory network inference, genetic interaction and expression analyses to suggest DRL1 and ZEA AGAMOUS1 target each other and a common set of downstream genes that function during floret development, thus defining a regulatory module that fine-tunes floret patterning and FM determinacy.

Regular corn cells have nuclei with 20 chromosomes. Ten of these are derived from the egg cell and ten from the sperm nucleus that fertilizes the egg. Corn cross-pollinates when silks protruding from the ear shoot capture pollen grains from the tassel which germinate on the silk and then releases two sperms, each bearing 10 chromosomes. The nucleus of one sperm fuses with the egg to form the zygote (2n = 20 chromosomes), whereas the other with one of the two polar nuclei, which then fuses with the other polar nucleus, forms a primary endosperm nucleus with 3n cells. The corn kernel is a single fruit constituted by the embryo, endosperm, aleurone, and pericarp. The pericarp is the transformed ovary wall, whereas the single-layered aleurone is part of the endosperm containing 3n cells. The starchy endosperm makes up the greater part of the kernel and the embryo and is actually a dormant young corn plant constituted by the plumule and primary root and the scutellum rich in nutrients necessary for germination. The pedicel serves as the attachment point of the kernel to the cob. The main strategies used to generate new varieties and hybrids are mass selection, random selfed lines, recurrent selection, and single cross and modified single-cross hybridization. Corn kernels can be altered by genetic means to give modifications in quantity and type of starch, protein, oil, and other aspects such as pericarp thickness or kernel hardness. Because of these strategies, many specialty corns have been generated like white, waxy, high-amylose, quality protein, high oil, popcorn, and sweet corns. Certified or registered seed production requires special attention in order to keep the pedigree and assure viability. Seeds are carefully harvested, dried, shelled, cleaned/sized, and treated with pesticides before marketing.

In the present study, Zea mays tassel which is a zero-value agricultural waste was used to produce a low-cost activated carbon using phosphoric acid as the activating agent. The prepared Z. mays tassel activated carbon (ZMTAC) was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The adsorbent was applied for adsorption of an emerging contaminant, metformin hydrochloride (MH) from pharmaceutical effluent. The effects of solution pH, contact time, adsorbent dosage, and initial MH concentration and their interactions were investigated using a response surface methodology following a central composite experimental design (CCD). The optimum experimental conditions were as follows: pH 9.5, contact time 67.50 min, dosage 0.5750 g, and MH concentration 152.50 mg/L. The isotherm data followed Langmuir isotherm model (R2 = 0.979; sum of square deviation, SSD = 0.321). The saturation adsorption capacity of ZMTAC was 44.84 mg/g at 20 °C. MH adsorption process followed pseudo-second-order kinetics (higher R2 and smaller SSD values). The thermodynamic properties obtained showed that the adsorption process was feasible, endothermic and spontaneous. Consequently, the study demonstrated that Z. mays tassel is a potential precursor for preparation of adsorbents for the removal of the MH from pharmaceutical effluent.

The determining process of pistil fate are central to maize sex determination, mainly regulated by a genetic network in which the sex-determining genes SILKLESS 1 , TASSEL SEED 1 , TASSEL SEED 2 and the paramutagenic locus Required to maintain repression 6 play pivotal roles. Maize silks, which emerge from the ear shoot and derived from the pistil, are the functional stigmas of female flowers and play a pivotal role in pollination. Previous studies on sex-related mutants have revealed that sex-determining genes and phytohormones play an important role in the regulation of flower organogenesis. The processes determining pistil fate are central to flower development, where a silk identified gene SILKLESS 1 (SK1) is required to protect pistil primordia from a cell death signal produced by two commonly known genes, TASSEL SEED 1 (TS1) and TASSEL SEED 2 (TS2). In this review, maize flower developmental process is presented together with a focus on important sex-determining mutants and hormonal signaling affecting pistil development. The role of sex-determining genes, microRNAs, phytohormones, and the paramutagenic locus Required to maintain repression 6 (Rmr6), in forming a regulatory network that determines pistil fate, is discussed. Cloning SK1 and clarifying its function were crucial in understanding the regulation network of sex determination. The signaling mechanisms of phytohormones in sex determination are also an important research focus.

The summer soybeans (Glycine max (L.) Merr.) in Hebei Province, China, which have adapted to different environments, show extraordinarily rich genetic diversity and extensive species variation. The objectives of this study were to analyze the population structure of summer soybean using simple sequence repeat (SSR) markers and to identify the SSR markers associated with specific traits. A set of 135 SSR markers was used to analyze 50 soybean cultivars, of which 47 cultivars were from 10 breeding institutions in Hebei Province and three cultivars were introductions from the United States. Software tools, the TASSEL, DARwin, and STRUCTURE, were used to analyze linkage disequilibrium (LD) and genetic structure. In addition, an association analysis between the molecular markers and the phenotypic values of 15 agronomic and quality traits was performed. The yield-related agronomic traits included plant height, bottom pod height, effective branch number, number of nodes on main stem, pod number per plan...

Medium and small seed companies require information on maize parental seed production to make rational choices on what germplasm to introduce into their seed and breeding pipelines. The objective of this study was to generate public data on the appropriate hybrid seed production information of five female lines (T21, T26, T28, T33 and T38) and one line (T10) as a male hybrid parent. The effect of female and male sowing date and sowing density on hybrid seed production characteristics including flowering time, flowering duration, distance between tassel and stigmas and effective seed yield was determined. Recommendations to stagger male and female sowing to achieve flowering synchrony for the hybrid parents were complemented with data of seedling growth stages. The results were similar for T21, T26, T28, and T38, sowing the female and T10 on a row proportion of 4 females:1 male, and on a second date, when the coleoptiles of the female plants are halfway to emerge, sowing the missing male row to complete the 4:2 ratio. T33 is a late flowering line, therefore it is desirable to sow T33 first and T10 five days later, or when the T33 coleoptile begins to emerge. Plant densities did not cause differences in most plant characteristics. Line T21 showed good female parental traits. While this study provides a knowledge framework for seed production technology for these single cross hybrids, data specific to seed production regions need to be generated by seed companies to define the best regimes for hybrid production.

During the process of maize seed production, in order to ensure the genetic purity of parental forms of hybrid maize, an important work performed is the removal of male inflorescences from plants on mother rows. Hand detasseling has high precision but is labor-intensive. Mechanical detasseling offers the possibility to cover large acreages in a short period of time, but the number of leaves removed has a varying influence on plant performance and seed yield. The aim of this study was to simulate three types of damages on plants similar to those induced through mechanical detasseling and to assess the effects for five inbred lines during the course of three years. Results show that when tassels alone were removed, the average seed yield decreased an average of 4&ndash, 21%. When two leaves were removed with the tassel, yield decreased an average of 22&ndash, 31%, while when plants were cut above the main ear, seed yield decreased an average of 31&ndash, 66%. Environmental conditions influenced seed yield, especially high temperatures during flowering. Yield response to tassel and leaves removal varied between the inbred lines. Genotype controls maize ear and kernel characters, while environmental factors exercise a strong influence on seed yield, due to the succession of years with contrasting weather conditions in a key phenophase. Within the trend of full mechanization in agriculture, identification of inbred lines that cope better with plant damage can assist in optimizing seed production.

Kernel number is one of the critical components of maize yield and is sensitive to environment variation around tasseling when the tassel, stem and ear grow simultaneously. Similar to other areas in the world, the North China Plain faced reduced irradiance during the maize growing season, especially the critical window for determinating actual kernel number. Shade stress that occurs between 15 days pre-silking and 15 days post-silking significantly reduces kernel number and grain yield. In the present experiment, detasseling was conducted under 70% and 97% shade treatments to mitigate the environment stress at the 14-leaf (V14) and tasseling (VT) stages, respectively. Shading treatments significantly reduced kernel number per plant, especially when shading occurred at VT stage. Tassel removal did not relieve kernel losses under 97% shade, but detasseling did dramatically reverse the kernel losses under 70% shade. Removing tassel sink at V14 and VT promoted assimilates being apportioned to ear sink under 70% shade stress, thus encouraging more carbohydrates to be made available for ear growth. Consequently, detassseling increased soluble sugar concentration in the ear section, shortened anthesis-tasseling interval, accelerated ear growth, offering a method to improve kernel number under shade stress.

The maize leaf angle and tassel size have close relationships with grain yield. These traits had undergone a strong selection and great morphological changes during domestication and improvement. To understand the genetic architecture of these morphological traits, an F2:3 population was developed using the cross of Lv28 by H082183, the latter having more erect leaves and small tassels. Using a modified hidden Markov model (HMM), the genetic map covering 1495.79 cM was obtained from 1965 bin markers. QTL mapping identified six leaf angle QTL, seven tassel branch number QTL, and ten tassel dry weight QTL, including three large-effect QTL (R2 > 10%) qLA1_2, qLA2, and qTBN8. The inflorescence development gene tasselseed2 (ts2) and zea floricaula leafy2 (zfl2) were co-located in the interval of qTW1 and qTW2_1. Seven genes in qLA1_2 showed evidence of selection during maize improvement, including two protein kinase genes (GRMZM2G138475 and GRMZM2G114093) and two trehalose-phosphatase genes (GRMZM2G347280 and GRMZM2G008226). Interestingly, the significant SNPs associated with tassel branch number and the selection region in qTBN8 were consistent at 5′ non-coding region of GRMZM5G873917. And the nucleotide diversity analysis revealed that the 5′ regulatory region of GRMZM5G873917 was under strong selection. These results provide insights into genetic architectures of maize morphological traits and alleles which have potentials in maize breeding.

Genomic selection (GS) is the one of the new method for molecular marker-assisted selection (MAS) that can improve selection efficiency and thereby accelerate selective breeding progress. In the present study, we used the exotic germplasm LK1 to improve the shelling percentage of Qi319 by GS. Genome-wide marker effects for each trait were estimated based on the performance of the testcross and SNP data for F2 progenies in the training population. The accuracy of genomic predictions was estimated as the correlation between marker-predicted genotypic values and phenotypic values of the testcrosses for each trait in the validation population. Our study result indicated that selection response for shell percentage was 33.7%, which is greater than those for grain yield, kernel number per ear, or grain moisture at harvest. Selection response for tassel branch number and weight per 100 kernels was greater than 60%. The Higher trait heritability resulted in better prediction efficiency; Prediction accuracy increased with the training population size; Prediction efficiency did not differ significantly between SNP densities of 1000 bp and 55,000 bp. The results of the present research project will provide a basis for genome-wide selection technology in maize breeding, and lay the groundwork for the application of GS to germplasms that are useful in China.

Floret units in cereals produce grain, directly impacting yield. Here we report mutations in the maizeCRABS CLAW(CRC) co-orthologsdrooping leaf1(drl1) anddrl2alter the development of ear and tassel florets. Pistillate florets ofdrl1ears appear sterile and display ectopic unfused carpels that fail to enclose an expanded nucellus. Staminate florets ofdrl1tassels have extra stamens and retain fertile anthers. Natural variation and transposon alleles ofdrl2enhancedrl1floret phenotypes by reducing floral meristem (FM) determinacy. Thedrlparalogs are co-expressed in lateral floral organ primordia, but not within the FM. Together, the expression patterns and indeterminate mutant FMs suggest that thedrlgenes regulate FM activity and impose meristem determinacy by a non-cell autonomous signal. Genetic interaction analyses ofdrlmutants with maize floral mutants indicate that thedrlgenes are required throughout floret development, illustrating their importance for proper floret patterning in maize.

SNPs identify prospective genes related to response to Colletotrichum sublineola (anthracnose) in the sorghum association panel lines. Sorghum association panel (SAP) lines were scored over several years for response to Colletotrichum sublineola, the causal agent of the disease anthracnose. Known resistant and susceptible lines were included each year to verify successful inoculation. Over 79,000 single-nucleotide polymorphic (SNP) loci from a publicly available genotype by sequencing dataset available for the SAP lines were used with TASSEL association mapping software to identify chromosomal locations associated with differences in disease response. When the top-scoring SNPs were mapped to the published sorghum genome, in each case, the nearest annotated gene has precedence for a role in host defense.

Maize (Zea mays ssp. mays) is an agronomically important crop and also a classical genetic model for studying the regulation of plant architecture formation, which is a critical determinant of grain yield. Since the 1930s, increasing planting density has been a major contributing factor to the >7-fold increase in maize grain yield per unit land area in the USA, which is accompanied by breeding and utilization of cultivars characterized by high-density-tolerant plant architecture, including decreased ear height, lodging resistance, more upright leaves, reduced tassel branch number, and reduced anthesis-silking interval (ASI). Recent studies demonstrated that phytochrome-mediated red/far-red light signaling pathway and the miR156/SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE (SPL) regulatory module co-ordinately regulate the shade avoidance response and diverse aspects of plant architecture in responding to shading in Arabidopsis. The maize genome contains 30 ZmSPL genes, and 18 of them are predicted as direct targets of zma-miR156s. Accumulating evidence indicates that ZmSPL genes play important roles in regulating maize flowering time, plant/ear height, tilling, leaf angle, tassel and ear architecture, and grain size and shape. Finally, we discuss ways to exploit maize SPL genes and downstream targets for improving maize plant architecture tailored for high-density planting.