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Maize rough dwarf disease (MRDD) is caused by a virus and seriously affects maize quality and yield worldwide. MRDD can be most effectively controlled with disease-resistant hybrids of corn. Here, MRDD-resistant (Qi319) and -susceptible (Ye478) parental inbred maize lines and their 314 recombinant inbred lines (RILs) that were derived from a cross between them were evaluated across three environments. A stable resistance QTL, qMrdd2, was identified and mapped using best linear unbiased prediction (BLUP) values to a 0.55-Mb region between the markers MK807 and MK811 on chromosome 2 (B73 RefGen_v3) and was found to explain 8.6 to 11.0% of the total phenotypic variance in MRDD resistance. We validated the effect of qMrdd2 using a chromosome segment substitution line (CSSL) that was derived from a cross between maize inbred Qi319 as the MRDD resistance donor and Ye478 as the recipient. Disease severity index of the CSSL haplotype II harboring qMrdd2 was significantly lower than that of the susceptible parent Ye478. Subsequently, we fine-mapped qMrdd2 to a 315-kb region flanked by the markers RD81 and RD87, thus testing recombinant-derived progeny using selfed backcrossed families. In this study, we identified a novel QTL for MRDD resistance by combining the RIL and CSSL populations, thus providing important genetic information that can be used for breeding MRDD-resistant varieties of maize.

Abiotic stress is the main factor that severely limits crop growth and yield. NAC (NAM, ATAF1/2 and CUC2) transcription factors play an important role in dealing with various abiotic stresses. Here, we discovered the ZmSNAC13 gene in drought-tolerant maize lines by RNA-seq analysis and verified its function in Arabidopsis thaliana. First, its gene structure showed that ZmSNAC13 had a typical NAC domain and a highly variable C-terminal. There were multiple cis-acting elements related to stress in its promoter region. Overexpression of ZmSNAC13 resulted in enhanced tolerances to drought and salt stresses in Arabidopsis, characterized by a reduction in the water loss rate, a sustained effective photosynthesis rate, and increased cell membrane stability in leaves under drought conditions. Transcriptome analysis showed that a large number of differentially expressed genes regulated by overexpression of ZmSNAC13 were identified, and the main drought tolerance regulatory pathways involved were the ABA pathway and MAPK cascade signaling pathway. Overexpression of ZmSNAC13 promoted the expression of genes, such as PYL9 and DREB3, thereby enhancing tolerance to adverse environments. Adaptability, while restraining genes expression such as WRKY53 and MPK3, facilitates regulation of senescence in Arabidopsis and improves plant responses to adversity. Therefore, ZmSNAC13 is promising gene of interest for use in transgenic breeding to improve abiotic stress tolerance in crops.

Genomic selection (GS) is an efficient way for trait improvement in crops. GS for kernel dehydration rate (KDR) has not been reported until now. The elite single-cross hybrid Zhengdan958 is the most widely planted hybrid in China, but has slow KDR and high grain moisture at harvest that seriously hamper mechanical harvesting efficiency. The present study aimed to determine whether GS is an effective strategy for improving KDR in an exotic × adapted population and to identify a lower-cost SNP panel and suitable statistical model for GS prediction. Here, the elite U.S. population BS13(S)C7 was crossed to inbred line Zheng58 to establish a training population that was then testcrossed to the inbred Chang7-2. Phenotypic traits including days to anthesis (DA), ear height (EH), water content of the ears (WC), KDR, and grain yield (GY) were measured in two locations during 2016 and 2017. We found that the rrBLUP model using 24,435 filtered SNPs with minimum call rate > 50% and minor allele frequency > 0.05 resulted in the highest prediction accuracy. Further, a subset of 5000 SNPs randomly selected from 24,435 high-quality SNPs provided a lower-cost SNP panel with sufficient prediction accuracy for GS. The breeding efficiency of GS compared with conventional selection varied from 0.28 to 0.66. Predicted genetic gains were − 0.15%, − 1.42%, − 0.64%, 1.89%, and 1.30% for DA, EH, WC, KDR, and GY, respectively, indicating that GS was adequate for improving KDR and other important traits, with advantages over pedigree breeding for both simple and complex traits in an exotic × adapted population.

Background Starch biosynthesis in endosperm is a key process influencing grain yield and quality in maize. Although a number of starch biosynthetic genes have been well characterized, the mechanisms by which the expression of these genes is regulated, especially in regard to microRNAs (miRNAs), remain largely unclear. Results Sequence data for small RNAs, degradome, and transcriptome of maize endosperm at 15 and 25 d after pollination (DAP) from inbred lines Mo17 and Ji419, which exhibit distinct starch content and starch granule structure, revealed the mediation of starch biosynthetic pathways by miRNAs. Transcriptome analysis of these two lines indicated that 33 of 40 starch biosynthetic genes were differentially expressed, of which 12 were up-regulated in Ji419 at 15 DAP, one was up-regulated in Ji419 at 25 DAP, 14 were up-regulated in Ji419 at both 15 and 25 DAP, one was down-regulated in Ji419 at 15 DAP, two were down-regulated in Ji419 at 25 DAP, and three were up-regulated in Ji419 at 15 DAP and down-regulated in Ji419 at 25 DAP, compared with Mo17. Through combined analyses of small RNA and degradome sequences, 22 differentially expressed miRNAs were identified, including 14 known and eight previously unknown miRNAs that could target 35 genes. Furthermore, a complex co-expression regulatory network was constructed, in which 19 miRNAs could modulate starch biosynthesis in endosperm by tuning the expression of 19 target genes. Moreover, the potential operation of four miRNA-mediated pathways involving transcription factors, miR169a-NF-YA1-GBSSI/SSIIIa and miR169o-GATA9-SSIIIa/SBEIIb, was validated via analyses of expression pattern, transient transformation assays, and transactivation assays. Conclusion Our results suggest that miRNAs play a critical role in starch biosynthesis in endosperm, and that miRNA-mediated networks could modulate starch biosynthesis in this tissue. These results have provided important insights into the molecular mechanism of starch biosynthesis in developing maize endosperm. Electronic supplementary material The online version of this article (10.1186/s12864-019-5945-1) contains supplementary material, which is available to authorized users.

Maize rough dwarf disease (MRDD) is caused by a virus and seriously affects maize quality and yield worldwide. MRDD can be most effectively controlled with disease-resistant hybrids of corn. Here, MRDD-resistant (Qi319) and -susceptible (Ye478) parental inbred maize lines and their 314 recombinant inbred lines (RILs) that were derived from a cross between them were evaluated across three environments. A stable resistance QTL

The estimation of state of charge (SOC) is a key issue to ensure the safe operation of Li-ion battery packs, which have been widely utilized in electric vehicles. In this paper, two neural networks including BP neural network and fuzzy neural network are introduced to achieve the accurate SOC estimation for Li-ion batteries. Firstly, the traditional Thevenin model is selected as Li-ion batteries model, which is mainly used to obtain the datasets for the training and test of the neural networks. Then, BP neural network is adopted to estimate SOC, and the empirical formula for parameter selection of BP neural network is also analyzed in detail. Moreover, fuzzy neural network model is developed for SOC estimation. Finally, the simulation results show that the proposed fuzzy neural network model obtains a better estimation performance compared to BP neural network model.

This study presents a phase-sequence adaption method and mode prediction control for active power filter. Firstly, discrete mathematical model of active power filter is constructed. Secondly, model predictive control is developed to cope with the delay issue. The optimized switching states can be chosen to enhance the control capability. In addition, phase-sequence adaption scheme is presented to compensate the fault of negative sequence. Simulation results based on MATLAB/Simulation validate the performance of the proposed strategies for active power filter.

The central goal of maize (Zea mays L.) breeding is to increase the frequencies of favorable alleles in germplasm. Two broad-based composites Cpop.15 and Cpop.16 were subjected to five cycles of modified mass selection (MMS) to increase grain yield, lodging resistance, early maturing and short plant height. We evaluated the direct responses of Cpop.15 and Cpop.16 by analyzing per se performance of the two original populations and that of each resulting population after five cycles of MMS (a total of 12 entries) for days to silking (DS), plant height (PH), ear height (EH), stalk lodging (SL), and grain yield (GY) in four environments. Also, we evaluated trends in general and specific combining ability (GCA and SCA) for these traits in the testcrosses of the above 12 entries with three tester lines (for a total of 36 entries) that represent Chinese heterotic groups. Cpop.15 and Cpop.16 responded significantly to selection for DS, PH, and EH, while SL and GY showed no significant changes. GCA estimates in both populations were improved significantly for DS, PH, EH and GY, but not for DS and GY in Cpop.15, suggesting an increase in the frequency of favorable additive alleles with each cycle of selection for these traits. Promising hybrids could be easily generated by crossing inbred lines developed from later cycles of selection in Cpop.15 and Cpop.16 to Sipingtou germplasm. Our results indicate that MMS effectively improved the performance of both populations per se and testcrosses, taking the best advantage of both GCA and SCA.

Background: Maize rough dwarf disease (MRDD) is a disease caused by a virus that seriously affects maize yield and quality worldwide. Rice black streaked dwarf virus (RBSDV) in the Fijivirus genus in the Reoviridae family causes MRDD in maize. Typical MRDD symptoms of include severe dwarfing of plants, shortening of internodes. MRDD resistance is a complex trait that is quantitatively inherited and is controlled by several quantitative trait loci (QTL). MRDD is most efficiently controlled by the cultivation of disease-resistant corn hybrids. Results: Disease resistance in the MRDD-resistant Qi319 and -susceptible Ye478 parental inbred lines and the 314 recombinant inbred lines (RILs) that were derived from a cross between them was evaluated across three environments. A stable resistance QTL, qMrdd2 , which explained 8.64 to 11.02% of the total phenotypic variance in MRDD resistance, was identified repeatedly and was mapped using BLUP values to a 0.55-Mb region between the markers MK807 and MK811 on chromosome 2. We validated the effect of qMrdd2 using a chromosome segment substitution line population that were derived from a cross between maize inbred Qi319 as the resistance donor and Ye478 as the recipient. The disease-severity index (DSI) of CSSL haplotype II harboring qMrdd2 was significantly lower than the DSI of susceptible parent Ye478 ( P < 0.05). Mapping results using CSSLs were consistent with localization interval determined using RILs. The qMrdd2 locus acted with an additive effect but no significant dominant gene action in conferring MRDD resistance. We fine-mapped qMrdd2 locus into a 315-kb region flanked by the markers RD81 and RD87 by testing recombinant-derived progeny using selfed backcrossed families. Conclusions: qMrdd2 is a recently discovered QTL from Qi319 for resistance to MRDD with an additive effect but no significant dominant gene action for MRDD resistance. qMrdd2 was fine-mapped to a 315-kb interval on maize chromosome 2. Introgression of the MRDD resistance allele at the qMrdd2 locus of CSSL haplotype 2 using linked markers umc1824 and bnlg125 will be useful for maize breeding to reduce yield losses caused by MRDD. Keywords: Maize, Maize rough dwarf disease, QTL, Fine-mapping, RIL；CSSL.

Foxtail millet (FM) [Setaria italica (L.) Beauv.] is a grain and forage crop well adapted to nutrient-poor soils. To date little is known how FM adapts to low nitrogen (LN) at the morphological, physiological, and molecular levels. Using the FM variety Yugu1, we found that LN led to lower chlorophyll contents and N concentrations, and higher root/shoot and C/N ratios and N utilization efficiencies under hydroponic culture. Importantly, enhanced biomass accumulation in the root under LN was in contrast to a smaller root system, as indicated by significant decreases in total root length; crown root number and length; and lateral root number, length, and density. Enhanced carbon allocation toward the root was rather for significant increases in average diameter of the LN root, potentially favorable for wider xylem vessels or other anatomical alterations facilitating nutrient transport. Lower levels of IAA and CKs were consistent with a smaller root system and higher levels of GA may promote root thickening under LN. Further, up-regulation of SiNRT1.1, SiNRT2.1, and SiNAR2.1 expression and nitrate influx in the root and that of SiNRT1.11 and SiNRT1.12 expression in the shoot probably favored nitrate uptake and remobilization as a whole. Lastly, more soluble proteins accumulated in the N-deficient root likely as a result of increases of N utilization efficiencies. Such “excessive” protein-N was possibly available for shoot delivery. Thus, FM may preferentially transport carbon toward the root facilitating root thickening/nutrient transport and allocate N toward the shoot maximizing photosynthesis/carbon fixation as a primary adaptive strategy to N limitation.

ZD958 was the most low-N-efficient line among five maize and two teosinte lines. Zea parviglumis and Zea diploperennis were insensitive to N limitation. Maize and teosinte genetically and evolutionarily diverged in gene regulation. GDH2, ASN2, and T4 were consistently down-regulated across seven lines. Maternal asymmetric inheritance and heterosis vigor made ZD958 low-N-efficient. Nitrogen (N) deficiency remains a serious limiting factor for maize production in many developing countries. It is particularly important to better understand how hybrid maize responds to N limitation. ZD958, a dominant high-yield hybrid in North China, was comparatively analyzed with four other maize and two teosinte lines at physiological and transcriptional levels. ZD958 was the most low-N-efficient line among five maize and two teosinte lines due to its largest biomass accumulation at a lowest N concentration under N limitation; while Zea parviglumis and Zea diploperennis had large root systems and were insensitive to N limitation. In anti-parallel with down-regulation of N metabolic genes in the ZD958 root, carbon allocation towards the root was enhanced for the significant increase in the root length. Variations in expression patterns of ten genes mediating N uptake, transport, and metabolism indicated large genetic and evolutionary divergence among seven lines under N limitation. Notably, GDH2, ASN2, and VAAT5 were consistently down-regulated under N limitation across these maize and teosinte lines, suggesting essential evolutionary conservation of gene regulation in response to N limitation and providing molecular markers for N nutritional diagnosis. Asymmetric inheritance, mostly from its maternal donor Z58, and heterosis vigor made ZD958 low-N-efficient at the seedling stage. The superior traits in crown roots in ZD958 may be derived from its paternal donor Chang7-2. Thus, Z58, Chang7-2, and two wild maize lines (Z. parviglumis and Z. diploperennis) provide valuable germplasms for N-efficient and large-root maize breeding.