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The article presents a study which assessed the genetic variability of cotton germplasm and land races using temperature induction response (TIR) to identify more sources for intrinsic tolerance and to identify the genotypes that combine temperature tolerance with tolerance of drought stresses. Topics include standardization of optimum induction temperature and challenging high temperature for cotton seedlings and percent mortality of cotton seedlings at different lethal temperatures.

Background: Cotton is an economically important crop. It is crucial to find an effective method to improve cotton yield, and one approach is to decrease the abscission of cotton bolls and buds. However, the lack of knowledge of the genetic and molecular mechanisms underlying cotton boll abscission traits has hindered genetic improvements. Results: Pearson's correlation analysis revealed a significant positive correlation between boll abscission rates 1 (AR1) and boll abscission rates 2 (AR2). A genome-wide association study was conducted on 145 loci that exhibited high polymorphism and were uniformly distributed across 26 chromosomes (pair). The study revealed 18, 46, and 62 markers that were significantly associated with boll abscission, fiber quality, and yield traits (P < 0.05), explaining 1.75%–7.13%, 1.16%–9.58%, and 1.40%–5.44% of the phenotypic variation, respectively. Notably, the marker MON_SHIN-1584b was associated with the cotton boll abscission trait, whereas MON_CGR5732a was associated with cotton boll abscission and fiber quality traits. Thirteen of the marker loci identified in this study had been previously reported. Based on phenotypic effects, six typical cultivars with elite alleles related to cotton boll abscission, fiber quality, and yield traits were identified. These cultivars hold great promise for widespread utilization in breeding programs. Conclusions: These results lay the foundation for understanding the molecular regulatory mechanism of cotton boll abscission and provide data for the future improvement of cotton breeding. [ABSTRACT FROM AUTHOR]

Cotton fiber is one of the main raw materials for the textile industry. In recent years, many cotton fiber quality QTL have been identified, but few were applied in breeding. In this study, a genome wide association study (GWAS) of fiber-quality traits in 265 upland cotton breeding intermediate lines (GhBreeding), combined with genome-wide selective sweep analysis (GSSA) and genomic selection (GS), revealed 25 QTL. Most of these QTL were ignored by only using GWAS. The CRISPR/Cas9 mutants of GhMYB_D13 had shorter fiber, which indicates the credibility of QTL to a certain extent. Then these QTL were verified in other cotton natural populations, 5 stable QTL were found having broad potential for application in breeding. Additionally, among these 5 stable QTL, superior genotypes of 4 showed an enrichment in most improved new varieties widely cultivated currently. These findings provide insights for how to identify more QTL through combined multiple genomic analysis to apply in breeding. [ABSTRACT FROM AUTHOR]

Abstract Background The approach of directly testing yarn quality to define fibre quality breeding objectives and progress the selection is attractive but difficult when considering the need for time and labour. The question remains whether yarn prediction tools from textile research can serve as an alternative. In this study, using a dataset from three seasons of field testing recombinant inbred line population, Cottonspec, a software developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) for predicting ring spun yarn quality from fibre properties measured by High Volume Instrument (HVI), was used to select improved fibre quality and lint yield in the population. The population was derived from an advanced generation inter-crossing of four CSIRO conventional commercial varieties. The Cottonspec program was able to provide an integrated index of the fibre qualities affecting yarn properties. That was compared with selection based on HVI-measured fibre properties, and two composite fibre quality variables, namely, fibre quality index (FQI), and premium and discount (PD) points. The latter represents the net points of fibre length, strength, and micronaire based on the Premiums and Discounts Schedule used in the market while modified by the inclusion of elongation. Results The population had large variations for lint yield, fibre properties, predicted yarn properties, and composite fibre quality values. Lint yield with all fibre quality traits was not correlated. When the selection was conducted first to keep those with improved fibre quality, and followed for high yields, a large proportion in the resultant populations was the same between selections based on Cottonspec predicted yarn quality and HVI-measured fibre properties. They both exceeded the selection based on FQI and PD points. Conclusions The population contained elite segregants with improved yield and fibre properties, and Cottonspec predicted yarn quality is useful to effectively capture these elites. There is a need to further develop yarn quality prediction tools through collaborative efforts with textile mills, to draw better connectedness between fibre and yarn quality. This connection will support the entire cotton value chain research and evolution.

The main purpose of this research is to compare the bio-morphological properties, fiber properties, technological quality indicators and net return levels of different cotton varieties, to include different varieties in hybridization and to use the obtained hybrids as a starting material in selection. The research was carried out in the experimental area of the Plant Protection and Technical Plants Scientific Research Institute in Samukh district in 2017-2020. Research material consisted of the local Ganja-110 cotton variety and some cotton varieties S-6524 (Uzbekistan), BA-440 (Turkey), Akala Beret (Israel), Selekt (Greece), Tashauz-68 (Turkmenistan) brought from cotton growing countries. The results of this research revealed that cotton varieties differ from each other in terms of raw cotton yield, this yield indicator was 4,380 kg/ha in Ganja-110 cotton variety against lower yields in the other varieties. The raw cotton mass of the Ganja-110 cotton variety was 6.3 g in a boll while it varied 5.2-6.0 g in a boll for the other different cotton varieties. It has been determined that the net return of other cotton varieties was also lower than Ganja-110 variety. It is recommended to use hybrids with enhanced heterosis effect obtained from crossbreeding between different cotton varieties. [ABSTRACT FROM AUTHOR]

The experiment was laid out in 2020 to compare the performance of thirty-seven F3 and F4 multi-parental bulk populations of cotton, including comparative cultivars, and to assess the heritability of traits studied. The differences within generations were significant for seed cotton yield, ginning outturn, fiber quality, and nep fragments. The mean fiber strength of the F4 generation showed significant performance compared with F3. The broad sense heritability was high for ginning out-turn, fiber length, and fiber strength. The normal distribution for F3 and F4 generations due to non-significant skewness and kurtosis values indicated that there were no epistatic effects on the heritability of traits studied. Eight F4 lines were selected for transfer to F5 generation according to optimization in terms of desired traits. [ABSTRACT FROM AUTHOR]

Background: The approach of directly testing yarn quality to define fibre quality breeding objectives and progress the selection is attractive but difficult when considering the need for time and labour. The question remains whether yarn prediction tools from textile research can serve as an alternative. In this study, using a dataset from three seasons of field testing recombinant inbred line population, Cottonspec, a software developed by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) for predicting ring spun yarn quality from fibre properties measured by High Volume Instrument (HVI), was used to select improved fibre quality and lint yield in the population. The population was derived from an advanced generation inter-crossing of four CSIRO conventional commercial varieties. The Cottonspec program was able to provide an integrated index of the fibre qualities affecting yarn properties. That was compared with selection based on HVI-measured fibre properties, and two composite fibre quality variables, namely, fibre quality index (FQI), and premium and discount (PD) points. The latter represents the net points of fibre length, strength, and micronaire based on the Premiums and Discounts Schedule used in the market while modified by the inclusion of elongation. Results: The population had large variations for lint yield, fibre properties, predicted yarn properties, and composite fibre quality values. Lint yield with all fibre quality traits was not correlated. When the selection was conducted first to keep those with improved fibre quality, and followed for high yields, a large proportion in the resultant populations was the same between selections based on Cottonspec predicted yarn quality and HVI-measured fibre properties. They both exceeded the selection based on FQI and PD points. Conclusions: The population contained elite segregants with improved yield and fibre properties, and Cottonspec predicted yarn quality is useful to effectively capture these elites. There is a need to further develop yarn quality prediction tools through collaborative efforts with textile mills, to draw better connectedness between fibre and yarn quality. This connection will support the entire cotton value chain research and evolution. [ABSTRACT FROM AUTHOR]

Low phosphorus (P) availability is a major problem for cotton production. Identification of low P tolerant and efficient genotypes would best address these problems. In this regard, thirty cotton genotypes were categorized for dry matter production and P use efficiency (PUE) under low and normal P conditions. The results showed that cotton genotypes displayed considerable variations in root morphology, dry matter production, photosynthesis, PUE, and antioxidant system in response to low and normal P conditions. Genotypes Jimian169, Zhongzhimian2, and Lumianyan16 produced more dry matter have high PUE and were considered strong low P tolerant and efficient, whereas genotypes DES926, TM‑1, and CCRI10 have low dry matter and PUE and were proved to be weak low P tolerant and inefficient. Based on various classification methods, genotypes Jimian169 and DES926 were considered strong and weak low P tolerant cotton genotypes, respectively. For most of the traits, the heritability was high, suggesting that selection under low P is more reliable than under the normal P condition. The use of the identified cotton genotypes and traits could improve cotton breeding activities and help to improve sustainable cotton production. [ABSTRACT FROM AUTHOR]

Cotton is widely distributed worldwide, and improving the quality of its fiber is one of the most important tasks in cotton breeding. Cotton fibers are primarily composed of cellulose, which is synthesized by CesA complexes (CSCs). However, the functions of CesA genes in cotton fiber development have not been comprehensively analysed. In this study, the cotton transcriptome and metabolome were used to investigate the function of CesA genes in fiber development. Finally, 321 metabolites were obtained, 84 of which were associated with the corresponding genes. Interestingly, a target gene named Gh_A08G144300, one of the CesA gene family members, was closely correlated with the development of cotton fibers. The target CesA gene Gh_A08G144300 was analysed to determine its specific function in cotton fiber development. High-level gene expression of Gh_A08G144300 was found at different fiber development stages by RNA-seq analysis, and the silencing of Gh_A08G144300 visibly inhibited the growth of cotton fibers, showing that it is critical for their growth. This study provides an important reference for research on the gene function of Gh_A08G144300 and the regulatory mechanism of fiber development in cotton. [ABSTRACT FROM AUTHOR]

Relationships between yield components and lint yield are complicated because of interrelationships among them. Traditionally, the exploration of these interrelationships was analyzed by path coefficients which requires a priori knowledge of the cause and effect relationships. Commonality analysis is a method of multiple regression to dissect the total effects of yield components to yield into direct effects and indirect effects. This study was designed to dissect relationships of yield components to yield based on commonality analysis and determine correlated selection responses of yield to selections of different yield components. Selections were made within 300 F3 plants in 2017 for the top seventy-five plants by LP and six within-boll yield components, lint weight per seed, seeds per boll, seed surface area, lint weight per fiber (LWF), lint weight per unit seed surface area, and lint number per unit seed surface area. F4 progenies were evaluated in field with two replicates in 2018. Direct coefficients of the seven single yield components ranged from 0.00 to 0.18 with LP as the largest contributor. Indirect coefficients of multiple components ranged from − 0.04 to 0.08. Five single yield components and five multiple yield components were chosen for selections based on their relatively large coefficients to yield. The correlated selection response (CR) of lint yield, 1684 kg ha−1, in F4 was significantly positive to selections by LP, but the CR of seed size and fiber length was negative to the selection by LP. The CR of lint yield, 1769 kg ha−1, to selections by multiple yield components of LP-LWF, had 5% increase compared with the selection by LP alone. There was no significant CR of seed size and fiber length to these selections. This study was a first application of commonality analysis in crop breeding and results provide evidence for its feasibility in exploration of interrelationships among yield components in breeding. [ABSTRACT FROM AUTHOR]

The growing worldwide population is driving up demand for cotton fibers, but production is hampered by unpredictable temperature rises caused by shifting climatic conditions. Numerous research based on breeding and genomics have been conducted to increase the production of cotton in environments with high and low-temperature stress. High temperature (HT) is a major environmental stressor with global consequences, influencing several aspects of cotton plant growth and metabolism. Heat stress-induced physiological and biochemical changes are research topics, and molecular techniques are used to improve cotton plants' heat tolerance. To preserve internal balance, heat stress activates various stress-responsive processes, including repairing damaged proteins and membranes, through various molecular networks. Recent research has investigated the diverse reactions of cotton cultivars to temperature stress, indicating that cotton plant adaptation mechanisms include the accumulation of sugars, proline, phenolics, flavonoids, and heat shock proteins. To overcome the obstacles caused by heat stress, it is crucial to develop and choose heat-tolerant cotton cultivars. Food security and sustainable agriculture depend on the application of genetic, agronomic, and, biotechnological methods to lessen the impacts of heat stress on cotton crops. Cotton producers and the textile industry both benefit from increased heat tolerance. Future studies should examine the developmental responses of cotton at different growth stages, emphasize the significance of breeding heat-tolerant cultivars, and assess the biochemical, physiological, and molecular pathways involved in seed germination under high temperatures. In a nutshell, a concentrated effort is required to raise cotton's heat tolerance due to the rising global temperatures and the rise in the frequency of extreme weather occurrences. Furthermore, emerging advances in sequencing technologies have made major progress toward successfully se sequencing the complex cotton genome. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) play essential roles in plant defense responses, although such roles have not been identified in cotton in response to the plant pathogenic fungus Verticillium dahliae. In this study, the functions of miR398b and its target genes in cotton-V. dahliae interaction were investigated. The transcript levels of miR398b were down-regulated by V. dahliae infection and miR398b overexpression in cotton made the plants more susceptible to V. dahliae. The results suggest that miR398b negatively regulates cotton resistance to V. dahliae. This may occur by miR398b repression of some CC-NBS-LRR genes via translational inhibition, interfering with defense responses and leading to cotton susceptibility to V. dahliae. Alternatively, miR398b may guide the cleavage of the mRNAs of GhCSD1, GhCSD2 and GhCCS, each of which functions in reactive oxygen species (ROS) regulation and homeostasis, thereby causing excessive ROS accumulation in miR398b-overexpressing plants in response to V. dahliae infection. This study suggests conserved and novel roles of miR398b in the cotton-V. dahliae interaction. These discoveries may be coupled with new strategies in cotton breeding programs to improve resistance to V. dahliae. [ABSTRACT FROM AUTHOR]

In 2021, Xinjiang's cotton output was 5.129 million t, accounting for 89. 50% of China's total. The autonomous region produces high-quality long-staple cotton, natural colored cotton, fine-staple cotton (upland cotton), organic cotton, etc. The southern Xinjiang cotton area is one of the three major long-staple cotton (island cotton) producing regions in the world. This paper introduced the history of cotton planting and breeding in Xinjiang from the aspects of cultural relics records, history of entering Xinjiang, historical achievements of breeding and breeding leaders. We studied the intellectual property protection of cotton breeding in the autonomous region from the aspects of biological genetic resources, invention patents, utility model patents and new plant varieties, analyzed the six main problems existing in cotton breeding and its intellectual property protection, and discussed the tactics for cotton breeding and its intellectual property protection in Xinjiang under the strategy of strengthening the country with intellectual property. Eight suggestions in response to the Xinjiang cotton incident were also put forward, including establishing a Xinjiang national cotton germplasm nursery, protecting biological genetic resources, and strengthening the protection of creative intellectual property rights in the field of breeding to escort technological innovation in the cotton seed industry. [ABSTRACT FROM AUTHOR]

Researchers have used quantitative genetics to map cotton fiber quality and agronomic performance loci, but many alleles may be population or environment-specific, limiting their usefulness in a pedigree selection, inbreeding-based system. Here, we utilized genotypic and phenotypic data on a panel of 80 important historical Upland cotton (Gossypium hirsutum L.) lines to investigate the potential for genomics-based selection within a cotton breeding program's relatively closed gene pool. We performed a genome-wide association study (GWAS) to identify alleles correlated to 20 fiber quality, seed composition, and yield traits and looked for a consistent detection of GWAS hits across 14 individual field trials. We also explored the potential for genomic prediction to capture genotypic variation for these quantitative traits and tested the incorporation of GWAS hits into the prediction model. Overall, we found that genomic selection programs for fiber quality can begin immediately, and the prediction ability for most other traits is lower but commensurate with heritability. Stably detected GWAS hits can improve prediction accuracy, although a significance threshold must be carefully chosen to include a marker as a fixed effect. We place these results in the context of modern public cotton line-breeding and highlight the need for a community-based approach to amass the data and expertise necessary to launch US public-sector cotton breeders into the genomics-based selection era. [ABSTRACT FROM AUTHOR]

The norm of reaction in qualitative aspect was studied in 31 Bulgarian and foreign cotton cultivars. The results of competitive variety trial carried out at the Field Crops Institute in town of Chirpan during the period 2016 - 2019 were used. The type of their dynamic regression (of their regression curve) and the structure of ecological environments in their dynamic rows were determined, on five traits, in order to characterize the reaction norm of the studied genotypes. It was found that the studied cultivars had in most cases another reaction norm differing considerably from that of the standard variety. The specificity of their reaction was manifested to a smaller extent in regard to its type and more strongly in the structure of ecological environments in their dynamic rows. As regards the individual traits, the reaction norm of cultivars was expressed to varying degrees, depending on their peculiarities. In terms of type of reaction, cultivars 791-169 (similar to the standard variety in 4 characters), Philipopolis, Kris, Darmi, Natalia and T-08 (similar in 3 characters) were the closest to the standard variety. Cultivars Boyana, Nelina, Colorit and C-9070, in which there was no similarity of traits with the standard variety, and other 13 cultivars, similar in only one trait, were the furthest from it. Cultivars from these two groups could be included in one selection program to create new genotypes with a convex type of reaction for most of the traits. The convex type of regression, with the exception of Helius variety, occurred in all cultivars and traits, which was a prerequisite for an effective selection of genotypes with high adaptive ability. With high adaptability and very valuable for the cotton breeding programs were found the cultivars: IPTP Veno and Tabladila-16, with a convex type of dynamic regression in four traits - seed cotton yield, boll weight, fiber ginning out turn and fiber length; Kris, Stoneville 112 and Dorina with a convex type of regression for three traits. [ABSTRACT FROM AUTHOR]

Enhancing genetic diversity to breed cotton (Gossypium hirsutum L.) for water‐limited production in the Texas High Plains is one objective of the Texas A&M AgriLife Research breeding program in Lubbock. CA 4008 (Reg. no. GP‐1099, PI 698821) was derived from TX 307 (PI 165390) and 07‐A‐05, an unreleased breeding line. TX 307, wild material of species Gossypium hirsutum, was used as a parent based on performance in hydroponic salinity characterization of 290 accessions conducted at Texas A&M AgriLife Research in Lubbock from 2006 to 2009. Performance testing for yield, fiber quality, and other agronomic properties was conducted at six site‐years from 2014 to 2017 with check cultivars 'FM 958' (PI 619096), a high‐yield and fiber quality regional standard, and 'DP 491' (PI 618609), which historically produced good yield and quality under water stress in the Texas High Plains. CA 4008 produced similar yield and fiber quality, lower lint percentage, and taller plants across site‐years compared with checks. CA 4008 was tested at 11 locations across the United States in the 2017 Regional Breeder Testing Network and showed low leaf defoliation under Verticillium wilt pressure. In previous studies, CA 4008 had less germination reduction under salinity than 27 of 31 Texas A&M AgriLife Research in Lubbock lines but equal to cultivar 'FM 989' (PI 603956). CA 4008 had less root dry weight reduction under salinity in hydroponic studies but equal to FM 989 in shoot and leaves dry weight reduction. CA 4008 is adapted to Texas High Plains stress conditions developed from a wild accession. [ABSTRACT FROM AUTHOR]

Cotton breeding in Bulgaria is mainly aimed at improving the earliness, productivity and fiber quality of modern varieties. The creation of new genetic diversity is one of the basic prerequisites for the success of breeding programs. The aim of the study was to evaluate cotton lines obtained by intraspecific and remote hybridization combined with backcross technology, with a view to their most effective usage in selection. Twenty-three lines were included in competitive variety trials conducted during the 2014-2017 period. The averaged results showed that lines 550, 639, 641, obtained by remote hybridization, appeared to be very promising. These three lines were distinguished by the best combination of productivity, fiber length and fiber lint percentage, and by these three indicators they exceeded the standard variety Chirpan-539. A new cotton variety Aida (No. 457) was approved, which in seed cotton yield and fiber yield, and technological fiber properties surpassed the standard varieties Chirpan-539 for earliness and productivity and Avangard-264 for fiber quality. The candidate variety 535 continued the state variety testing. Two new candidate cotton varieties No. 550 and No. 553 were released. In the state variety testing the three candidate varieties confirmed their qualities. The obtained lines, distinguished by one trait or by a complex of qualities, enriched the gene pool of Bulgarian cotton. [ABSTRACT FROM AUTHOR]

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Raw fiber properties are important in determining the value of cotton (Gossypium hirsutum L.). They determine the type and quality of cotton products that can be produced, making them important to textile processors and farmers, and are critical traits of interest for breeders. Improvement of fiber quality is an established objective for the Texas A&M AgriLife Research cotton breeding program in Lubbock, TX. CA 4009 (Reg. no. GP‐1086, PI 695389) and CA 4010 (Reg. no. GP‐1087, PI 695390) originated from crosses made in 2012. Three years of multilocation replicated performance testing were conducted. CA 4009 and CA 4010 produced longer fiber with higher length uniformity and elongation than all commercial cultivar checks, and fiber strength was greater than two checks. Yield was not significantly different from the checks for either line. CA 4009 and CA 4010 were evaluated in the 2018 Regional Breeders Testing Network (RBTN) field trials, and both lines maintained fiber quality across locations. Fiber length, length uniformity, and strength were higher than the checks. CA 4009 and CA 4010 had less short fiber content than all checks. The RBTN provides quality scores, and both CA 4009 and CA 4010 scored higher than all checks and other RBTN entries. These germplasm lines have a fiber quality package that may be valuable for improving multiple fiber properties that address market demands and textile industry requirements. Core Ideas: CA 4009 and CA 4010 cotton have improved fiber length, length uniformity, and elongation.Yield for CA 4009 and CA 4010 was not significantly different from commercial checks.Fiber packages and quality scores suggest potential yarn quality greater than commercial checks. [ABSTRACT FROM AUTHOR]

Researchers have used quantitative genetics to map cotton fiber quality and agronomic performance loci, but many alleles may be population or environment-specific, limiting their usefulness in a pedigree selection, inbreeding-based system. Here, we utilized genotypic and phenotypic data on a panel of 80 important historical Upland cotton (Gossypium hirsutum L.) lines to investigate the potential for genomics-based selection within a cotton breeding program’s relatively closed gene pool. We performed a genome-wide association study (GWAS) to identify alleles correlated to 20 fiber quality, seed composition, and yield traits and looked for a consistent detection of GWAS hits across 14 individual field trials. We also explored the potential for genomic prediction to capture genotypic variation for these quantitative traits and tested the incorporation of GWAS hits into the prediction model. Overall, we found that genomic selection programs for fiber quality can begin immediately, and the prediction ability for most other traits is lower but commensurate with heritability. Stably detected GWAS hits can improve prediction accuracy, although a significance threshold must be carefully chosen to include a marker as a fixed effect. We place these results in the context of modern public cotton line-breeding and highlight the need for a community-based approach to amass the data and expertise necessary to launch US public-sector cotton breeders into the genomics-based selection era.

Background: Cotton breeding programs mainly focus on improving cotton fibers, but less attention has been paid by breeders to cottonseed oil improvement. Breeding cottonseed for oil content has mainly depended on phenotypic information used to select varieties with high seed oil content. The purpose of this study was to evaluate some cotton genotypes regarding their oil content and other characters related to fiber yield, in order to select genotypes with high oil content and acceptable levels of the other characters. Seventeen different genotypes of cotton were used in this study. A two-year experiment was carried out at Sids Agricultural Research Station, Beni Suef, Egypt, during 2017 and 2018, using a randomized complete block design with six replications. Seed cotton yield, lint cotton yield, boll weight, seed index, embryo index, oil % and embryo oil index characters were recorded. Results: The analysis of variance results showed highly significant differences among the genotypes for all the studied traits except boll weight in season 2017. The overall cotton embryo oil % ranged from 33.40 to 40.28 among the genotypes, while the overall cotton embryo oil index ranged from 1.79 to 2.47. Maximum cotton embryo oil % was noted by the genotypes 15 [{(G83 × G80) × G89} × Australian] and 8 [(G 91 × G90) × (G 85 × G 83)], while maximum cotton embryo oil index was noted by the genotype 13 [(G 91 × G 90) × G80]. The results showed positive correlations between seed cotton yield and lint cotton yield, seed index and embryo index, seed index and embryo index oil %, embryo index and embryo index oil %, and oil % and embryo index oil %. Conclusions: It could be concluded that using seed or embryo oil percentages as criteria for differentiating genotypes according to their oil content is misleading and the best efficient measure is using the seed or embryo oil indices because they depend on weight basis. Also, Genotypes 13, 15 and 8 were the best genotypes regarding oil % and they could be used in breeding programs for cotton oil improvement. [ABSTRACT FROM AUTHOR]

The growth and instability in area, production and yield of cotton in Maharashtra was assessed before and after introduction of Bt cotton varieties. The study aims to know the growth behavior of cotton production over the years. The contribution of area and productivity towards cotton production was measured by decomposing the cotton production series. The method proposed by Minhas and Vidhyanathan and reframed by Sharma was employed. The compound growth rate was estimated on the basis of fit using non-linear model i.e. exponential. The fitted equation was estimated using marquardt algorithms. Cuddy-Della Valle instability index was employed to estimate the instability in area, production and yield of cotton. The analysis was carried out using SAS macro available on IASRI web site with the help of SAS 9.3 software. Results revealed that, area, production and productivity of cotton were increased significantly after the introduction of Bt hybrids technology. The enhancement in productivity of cotton after the adoption of Bt hybrids technology by farmers was associated with the moderate instability. The productivity of cotton was moderately fluctuating from one year to another year. These fluctuations were also seen in cotton production. Bt cotton hybrids improved the yield and production and in some extent were also responsible for area expansion but the yield and production performance of cotton after the introduction of Bt was not stable. Enhancement in yield was the major factor responsible for improvement in cotton production in Maharashtra state compared to area. [ABSTRACT FROM AUTHOR]

This study was carried out at Aydin Adnan Menderes University, Agriculture Faculty Field Crops Experiment fields under drip irrigation system to investigate the response of cotton hybrid populations to water stress in F8 generations in accordance with Augmented randomized complete block design. Each lines and five control varieties (Gloria, Flash, DP332, Candia and Claudia) were planted one row and 12 m long under irrigated (%100: full irrigation) and water stress (%50: deficit irrigation) conditions. The result of the study revealed that in F8 generation; Carmen x Nazilli-503 (line no: 1), DPL-90 x Tamcot-22 (line no: 10), BA-308 x Carmen (line no: 38), DPL-90 x Tamcot-22 (line no: 66) and ST-373 x DPL-90 (line no: 72) cotton advanced lines exhibited the highest seed cotton yield and fiber quality. As for under deficit water stress condition Nazilli-503 x Tamcot-22 (line no: 6), ST-373 x Carmen (line no: 23), BA-308 x Nazilli-503 (line no: 47), BA-308 x Carmen (line no: 72), and Ş-2000 x Tamcot-22 (line no: 90) were found to be drought resistant or tolerant hybrid populations. In order to register new cotton varieties with high yield and fiber quality suitable for full and limited irrigation conditions, selected cotton lines will be tested for variety yield tests. [ABSTRACT FROM AUTHOR]

Key message: Background-independent (BI) and stably expressed (SE) quantitative trait loci (QTLs) were identified using two sets of introgression lines across multiple environments. Genetic background more greatly affected fiber quality traits than environmental factors. Sixty-one SE-QTLs, including two BI-QTLs, were novel and 48 SE-QTLs, including seven BI-QTLs, were previously reported. Cotton fiber quality traits are controlled by QTLs and are susceptible to environmental influence. Fiber quality improvement is an essential goal in cotton breeding but is hindered by limited knowledge of the genetic basis of fiber quality traits. In this study, two sets of introgression lines of Gossypium hirsutum × G. barbadense were used to dissect the QTL stability of three fiber quality traits (fiber length, strength and micronaire) across environments using 551 simple sequence repeat markers selected from our high-density genetic map. A total of 76 and 120 QTLs were detected in the CCRI36 and CCRI45 backgrounds, respectively. Nine BI-QTLs were found, and 78 (41.71%) of the detected QTLs were reported previously. Thirty-nine and 79 QTLs were SE-QTLs in at least two environments in the CCRI36 and CCRI45 backgrounds, respectively. Forty-eight SE-QTLs, including seven BI-QTLs, were confirmed in previous reports, and 61 SE-QTLs, including two BI-QTLs, were considered novel. These results indicate that genetic background more strongly impacts on fiber quality traits than environmental factors. Twenty-three clusters with BI- and/or SE-QTLs were identified, 19 of which harbored favorable alleles from G. barbadense for two or three fiber quality traits. This study is the first report using two sets of introgression lines to identify fiber quality QTLs across environments in cotton, providing insights into the effect of genetic backgrounds and environments on the QTL expression of fiber quality and important information for the genetic basis underlying fiber quality traits toward QTL cloning and molecular breeding. [ABSTRACT FROM AUTHOR]

Background: The low genetic diversity of Upland cotton limits the potential for genetic improvement. Making full use of the genetic resources of Sea-island cotton will facilitate genetic improvement of widely cultivated Upland cotton varieties. The chromosome segments substitution lines (CSSLs) provide an ideal strategy for mapping quantitative trait loci (QTL) in interspecific hybridization. Results: In this study, a CSSL population was developed by PCR-based markers assisted selection (MAS), derived from the crossing and backcrossing of Gossypium hirsutum (Gh) and G. barbadense (Gb), firstly. Then, by whole genome re-sequencing, 11,653,661 high-quality single nucleotide polymorphisms (SNPs) were identified which ultimately constructed 1211 recombination chromosome introgression segments from Gb. The sequencing-based physical map provided more accurate introgressions than the PCR-based markers. By exploiting CSSLs with mutant morphological traits, the genes responding for leaf shape and fuzz-less mutation in the Gb were identified. Based on a high-resolution recombination bin map to uncover genetic loci determining the phenotypic variance between Gh and Gb, 64 QTLs were identified for 14 agronomic traits with an interval length of 158 kb to 27 Mb. Surprisingly, multiple alleles of Gb showed extremely high value in enhancing cottonseed oil content (SOC). Conclusions: This study provides guidance for studying interspecific inheritance, especially breeding researchers, for future studies using the traditional PCR-based molecular markers and high-throughput re-sequencing technology in the study of CSSLs. Available resources include candidate position for controlling cotton quality and quantitative traits, and excellent breeding materials. Collectively, our results provide insights into the genetic effects of Gb alleles on the Gh, and provide guidance for the utilization of Gb alleles in interspecific breeding. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium spp.) is the most important natural fiber crop worldwide. The diversity of Gossypium species also provides an ideal model for investigating evolution and domestication of polyploids. However, the huge and complex cotton genome hinders genomic research. Technical advances in high-throughput sequencing and bioinformatics analysis have now largely overcome these obstacles, bringing about a new era of cotton genomics. Here, we review recent progress in Gossypium genomics based on whole genome sequencing, resequencing, and comparative genomics, which have provided insights about the genomic basis of fiber biogenesis and the landscape of cotton functional genomics. We address current challenges and present multidisciplinary genomics-enabled breeding strategies covering the breadth of high fiber yield, quality, and environmental resilience for future cotton breeding programs. Cotton is an important natural fiber crop cultivated worldwide that also provides an ideal model for investigating evolution and domestication of polyploids Combinations of the latest technologies, such as optical mapping, high-throughput chromosome conformation capture (Hi-C), and Pacific Biosciences (PacBio) long-reads, have been used to generate multiple high-quality reference genomes of diploid and allotetraploid cotton. Comparative population genomics illuminated the genetic history of cotton domestication and identified the genomic variation determining fiber yield, quality, and stress resistance. [ABSTRACT FROM AUTHOR]

Cotton is an important crop that has made significant gains in production over the last century. Emerging pests such as the reniform nematode have threatened cotton production. The rare African diploid species Gossypium longicalyx is a wild species that has been used as an important source of reniform nematode immunity. While mapping and breeding efforts have made some strides in transferring this immunity to the cultivated polyploid species, the complexities of interploidal transfer combined with substantial linkage drag have inhibited progress in this area. Moreover, this species shares its most recent common ancestor with the cultivated A-genome diploid cottons, thereby providing insight into the evolution of long, spinnable fiber. Here we report a newly generated de novo genome assembly of G. longicalyx. This high-quality genome leveraged a combination of PacBio long-read technology, Hi-C chromatin conformation capture, and BioNano optical mapping to achieve a chromosome level assembly. The utility of the G. longicalyx genome for understanding reniform immunity and fiber evolution is discussed. [ABSTRACT FROM AUTHOR]

Summary: Fine mapping QTLs and identifying candidate genes for cotton fibre‐quality and yield traits would be beneficial to cotton breeding. Here, we constructed a high‐density genetic map by specific‐locus amplified fragment sequencing (SLAF‐seq) to identify QTLs associated with fibre‐quality and yield traits using 239 recombinant inbred lines (RILs), which was developed from LMY22 (a high‐yield Gossypium hirsutumL. cultivar) × LY343 (a superior fibre‐quality germplasm with G. barbadenseL. introgressions). The genetic map spanned 3426.57 cM, including 3556 SLAF‐based SNPs and 199 SSR marker loci. A total of 104 QTLs, including 67 QTLs for fibre quality and 37 QTLs for yield traits, were identified with phenotypic data collected from 7 environments. Among these, 66 QTLs were co‐located in 19 QTL clusters on 12 chromosomes, and 24 QTLs were detected in three or more environments and determined to be stable. We also investigated the genomic components of LY343 and their contributions to fibre‐related traits by deep sequencing the whole genome of LY343, and we found that genomic components from G. hirsutum races (which entered LY343 via its G. barbadense parent) contributed more favourable alleles than those from G. barbadense. We further identified six putative candidate genes for stable QTLs, including Gh_A03G1147 (GhPEL6), Gh_D07G1598 (GhCSLC6) and Gh_D13G1921 (GhTBL5) for fibre‐length QTLs and Gh_D03G0919 (GhCOBL4), Gh_D09G1659 (GhMYB4) and Gh_D09G1690 (GhMYB85) for lint‐percentage QTLs. Our results provide comprehensive insight into the genetic basis of the formation of fibre‐related traits and would be helpful for cloning fibre‐development‐related genes as well as for marker‐assisted genetic improvement in cotton. [ABSTRACT FROM AUTHOR]

Copyright of Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Genetic diversity is the base of biological polymorphism and also the basic part of biological diversity. Significant role is played by genetic diversity and paternity of germplasm in cotton breeding. Genetic diversity in representative sets of advanced cotton genotypes was studied at molecular level employing polymorphic simple sequence repeats. Of seventy-two advanced cotton genotypes, thirty microsatellites primer pairs were studied, 29 showed to be polymorphic. DNA markers amplified fragments of 100 to 300 bp in size. The polymorphism information contents ranged between 0.76 and 0.99. Cluster analysis clearly grouped the 72 genotypes into seven groups A, B, C, D, E, F, G based on Nei's coefficient similarity matrix. Group B was found to be the most genetically distinct group when compared to other groups. However, group B had most of the candidates of under observed genotypes. This study exposed two major clusters of cotton cultivars and recognized the cotton genotypes which were genetically different. These results can be used as reference and baseline information to other researchers/breeders. The resolution to the genetic associations of these cotton accessions could be improved by increasing the number of more mapped markers. [ABSTRACT FROM AUTHOR]

The root-knot nematode, Meloidogyne incognita, is one of the most important parasites that cause economic losses in the cotton crop. Plant genetic resistance is the most desirable strategy to control this pathogen. Sources of resistance in cotton have been known for several years but only a few resistant commercial varieties have been released. Cotton breeding lines were developed using marker-assisted selection in early generation plants to introgress root-knot resistance genes from two different sources: M-315 or CIR1348. Phenotyping was carried out in greenhouse conditions to validate the molecular markers associated with the resistance genes in the breeding lines and confirmed by genotyping. The markers targeting QTLs from M-315 resistance source were highly efficient in the selection of plants resistant to M. incognita, with all plants expressing a reproduction factor inferior to 0.08. CIR1348 resistance source markers were also very efficient in selecting resistance; however, some segregation events revealed the need for fine mapping of the resistance QTLs. To clarify the resistance mechanisms, present in the germplasm derived from the M-315 resistance source, the resistant line CNPA 17-26 B2RF (triple cross [BRS 368RF × M-315] × [BRS 430B2RF]) was chosen for histopathological characterization of plant-nematode interaction and compared with the susceptible FiberMax 966 (FM 966). The second-stage juveniles (J2) penetrated equally in both genotypes. In the histopathological study, a strong blue fluorescence was visualized in the tissues around the nematode (hypersensitivity reaction, HR), mainly at the beginning (from 2 to 6 DAI) in the cortex and central cylinder of the resistant plant, indicating accumulation of phenolic compounds in the roots. At 9 DAI, giant cells in the early stage of subdivision next to nematodes were observed in the central cylinder of the resistant plant, and phenolic compounds were also shown around the nematode. At 12–40 DAI these initial cells were completely degraded with the presence of phenolics involving the nematodes and initial giant cells. No fully developed giant cells or mature females were observed, only fourth-stage juveniles (J4s), and males were frequently visualized at 34 DAI. This resistance mechanism characterizes near-immunity, and so no enlarged females and no egg production were observed. In susceptible control, it was possible to visualize feeding sites well developed from 6 to 30 DAI. Females reached maturity at 26 DAI, and eggs were observed at 30 DAI. Our results suggested that the resistance (near-immunity) of the line CNPA 17-26 B2RF was related to early (2–12 DAI) defense responses that totally prevented nematode reproduction. [ABSTRACT FROM AUTHOR]

The use of genomic selection (GS) has stimulated a new way to utilize molecular markers in breeding for complex traits in the absence of phenotypic data. GS can potentially decrease breeding cycle by selecting the progeny in the early stages. The objective of this study was to experimentally evaluate the potential value of genomic selection in Upland cotton breeding. Six fiber quality traits were obtained in 3 years of replicated field trials in Starkville, MS. Genotyping-by-sequencing-based genotyping was performed using 550 recombinant inbred lines of the multi-parent advanced generation inter-cross population, and 6292 molecular markers were used for the GS analysis. Several methods were compared including genomic BLUP (GBLUP), ridge regression BLUP (rrBLUP), BayesB, Bayesian LASSO, and reproducing kernel hilbert spaces (RKHS). The average heritability (h2) ranged from 0.38 to 0.88 for all tested traits across the 3 years evaluated. BayesB predicted the highest accuracies among the five GS methods tested. The prediction ability (PA) and prediction accuracy (PACC) varied widely across 3 years for all tested traits and the highest PA and PACC were 0.65, and 0.69, respectively, in 2010 for fiber elongation. Marker density and training population size appeared to be very important factors for PA and PACC in GS. Results indicated that BayesB-based GS method could predict genomic estimated breeding value efficiently in Upland cotton fiber quality attributes and has great potential utility in breeding by reducing cost and time. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fiber quality and yield are important traits of cotton. Quantitative trait locus (QTL) mapping is a prerequisite for marker-assisted selection (MAS) in cotton breeding. To identify QTLs for fiber quality and yield traits, 4 backcross-generation populations (BC1F1, BC1S1, BC2F1, and BC3F0) were developed from an interspecific cross between CCRI36 (Gossypium hirsutum L.) and Hai1 (G. barbadense L.). A total of 153 QTLs for fiber quality and yield traits were identified based on data from the BC1F1, BC1S1, BC2F1 and BC3F0 populations in the field and from the BC2F1 population in an artificial disease nursery using a high-density genetic linkage map with 2292 marker loci covering 5115.16 centimorgans (cM) from the BC1F1 population. These QTLs were located on 24 chromosomes, and each could explain 4.98–19.80% of the observed phenotypic variations. Among the 153 QTLs, 30 were consistent with those identified previously. Specifically, 23 QTLs were stably detected in 2 or 3 environments or generations, 6 of which were consistent with those identified previously and the other 17 of which were stable and novel. Ten QTL clusters for different traits were found and 9 of them were novel, which explained the significant correlations among some phenotypic traits in the populations. The results including these stable or consensus QTLs provide valuable information for marker-assisted selection (MAS) in cotton breeding and will help better understand the genetic basis of fiber quality and yield traits, which can then be used in QTL cloning. [ABSTRACT FROM AUTHOR]

The phosphatidy ethanolamine-binding proteins (PEBP) play an important role in controlling flower development and phase change. Here, a total of 61 PEBP genes were identified, in which 20, 21, 10, and 10 were from tetraploid Gossypium hirsutum (AD1) and G. barbadense (AD2), and diploid G. raimondii (D5) and G. arboreum (A2), respectively. In G. hirsutum , 20 identified PEBP genes were unevenly distributed on 12 chromosomes. The identified PEBP genes were classified into four groups (TFL1, MFT, FT and FT-like). Among those, FT-like group are unique to cotton. The majority of PEBP genes had similar intron/exon distribution, whereas the divergence of PEBP genes suggests the possibility of functional diversification. The expression of PEBP genes varied among different tissues. This study brings new insights into the integrated genome-wide identification of PEBP genes in cotton and provides a foundation for breeding cotton cultivars with early maturation. • A total of 61 PEBP genes were identified in cotton. • PEBP genes are expressed differently among different tissues. • PEBP genes are expressed differently during cotton fiber development. • Three pairs of duplications existed during cotton evolution. [ABSTRACT FROM AUTHOR]

Hybrid lethality forms a reproductive barrier that has been found in many eukaryotes. Most cases follow the Bateson–Dobzhansky–Muller genetic incompatibility model and involve two or more loci. In this study, we demonstrate that a coiled-coil nucleotide-binding site leucine-rich repeat (CC-NBS-LRR) gene is the causal gene underlying the Le 4 locus for interspecific hybrid lethality between Gossypium barbadense and G. hirsutum (cotton). Silencing this CC-NBS-LRR gene can restore F1 plants from a lethal to a normal phenotype. A total of 11 099 genes were differentially expressed between the leaves of normal and lethal F1 plants, of which genes related to autoimmune responses were highly enriched. Genes related to ATP-binding and ATPase were up-regulated before the lethal syndrome appeared; this may result in the conversion of Le 4 into an active state and hence trigger immune signals in the absence of biotic/abiotic stress. We discuss our results in relation to the evolution and domestication of Sea Island cottons and the molecular mechanisms of hybrid lethality associated with autoimmune responses. Our findings provide new insights into reproductive isolation and may benefit cotton breeding. [ABSTRACT FROM AUTHOR]

Breeders are aware of the phenomenon that in a hybridization programmes, certain crosses pass-on more favorable genes towards the progenies than others. Thus, identification of potential parents and hybrids remained main concern to cotton breeders for improving various yield and fibre traits in cotton breeding programmes. The present studies were carried-out to estimate the general and specific combining ability estimates and heterotic effects for different characters from line x tester crosses developed from six lines viz., Sindh-1, Sadori, CRIS-134, Chandi-95, Haridost and IR-1524 crossed with three testers i.e. NIA-ufaq, Sohni and Shahbaz. The experiment was laid-out in a Randomized Complete Block Design with four replications during 2016. The degrees of freedom for hybrids were split into lines, testers and line x tester interaction. The mean squares owing to lines and testers were significant for majority of the traits, however the general combining ability of lines for 1st sympodial node number while general combining ability of testers only boll weight was non-significant. Similarly, the mean square for line x tester interaction which designate specific combining ability were also significant for all traits except staple length, G.O.T. % and seed index. Among the lines, Chandi-95, IR-1524 and from testers Shahbaz expressed higher GCA effects especially for seed cotton yield, thus, proved as good general combiners and suitable parents for hybridization and selection of desirable plants from segregating populations. For SCA effects, F1 hybrids like Sadori x Shahbaz, Haridost x NIA-ufaq and Sindh-1 x Shahbaz demonstrated as best specific combiners, therefore’ these proved promising hybrids. The high heterotic effects were expressed by the hybrids Sadori x Shahbaz for bolls per plant, boll weight and seed cotton yield plant-1 and IR-1524 x NIA-ufaq for staple length thus, these hybrids with dominant and over dominant genes could be potential hybrids for the exploitation of heterosis breeding in cotton. [ABSTRACT FROM AUTHOR]

Cotton, the leading natural fiber, is cultivated worldwide, but its production is seriously threatened by pathogens. Accordingly, the selection of resistant cultivars has become a key priority of cotton breeding programs. In this study, a spontaneous mutant with red coloration (S156) and a control cultivar (S78) were used as experimental materials for a comparative analysis. Metabolomic analysis revealed the enrichment of flavonoids in S156 leaves compared with S78 leaves, and transcriptomic analysis revealed the upregulated expression of flavonoid biosynthesis genes in S156 leaves relative to S78 leaves. In addition, the red mutant showed a significantly increase in resistance to Verticillium dahliae , a fungal pathogen that poses a major threat to cotton production. The pathogen invasion process was suppressed in the red cotton cultivar. This study reveals the mechanism underlying the red coloration of S156 cotton and indicates the great potential of red cotton in pathogen- and insect-resistant breeding of cotton. • A spontaneous cotton mutant exhibited red coloration of its vegetative organs was newly discovered in the fields. • Comparative metabolomics analysis shows that the red mutant S156 accumulates more flavonoids compared to control variety S78. • The red coloration of the S156 cultivar may be attributed to the increased anthocyanin production. • The expression of related genes in flavonoid biosynthesis pathways was upregulated in S156 compared to S78. • The red mutant S156 shows enhanced disease resistance and antifungal activities to relative to S78. [ABSTRACT FROM AUTHOR]

Cotton is an agriculturally important crop. Because of its importance, a genome sequence of a diploid cotton species (Gossypium raimondii, D-genome) was first assembled using Sanger sequencing data in 2012. Improvements to DNA sequencing technology have improved accuracy and correctness of assembled genome sequences. Here we report a new de novo genome assembly of G. raimondii and its close relative G. turneri. The two genomes were assembled to a chromosome level using PacBio long-read technology, HiC, and Bionano optical mapping. This report corrects some minor assembly errors found in the Sanger assembly of G. raimondii. We also compare the genome sequences of these two species for gene composition, repetitive element composition, and collinearity. Most of the identified structural rearrangements between these two species are due to intra-chromosomal inversions. More inversions were found in the G. turneri genome sequence than the G. raimondii genome sequence. These findings and updates to the D-genome sequence will improve accuracy and translation of genomics to cotton breeding and genetics. [ABSTRACT FROM AUTHOR]

Cotton spinning mills need high-quality fibers to maintain their manufacturing efficiency. Machinery throughput is increasing and it could translate into more processes with higher breaking stress. Consequently, more fibers are susceptible to breaking or damage. To face this problem, breeders must develop new varieties whose fibers can better withstand this mechanical stress. The main tool utilized in cotton breeding programs is the High Volume Instrument (HVI), which reports in a short time measurements such as micronaire, length, color, and strength. This instrument can also determine fiber elongation, but there is no current correction method for it. Both elongation and strength factor into the work-to-break of fibers, which plays a direct role in fiber breakage and spinning performance. The objective of this work was to develop cotton elongation standards, devise a correction procedure for HVI lines, evaluate measurement stability, and validate these results with a set of independent samples. Two commercial bales, one with low and one with high HVI elongation, were identified as potential elongation standards. The potential standards were produced and evaluated. After validation, they were used to correct HVI lines against Stelometer (STrength-ELOngation-METER) measurements. An independent set of samples was tested on corrected HVIs to confirm the effectiveness of the elongation corrected measurements. The HVI data were at least as good as the Stelometer data, with increased data acquisition speed and precision. This research can help cotton breeders to improve fiber elongation and strength at the same time, resulting in better fibers for yarn spinning. [ABSTRACT FROM AUTHOR]

In its natural state, cotton (Gossypium spp.) is a perennial that flowers only under short‐day conditions. Early selection efforts eliminated this photoperiod requirement, allowing cotton cultivation to shift predominantly to annual growth under long summer daylengths throughout the world. Photoperiod sensitivity persists in many wild cottons and remains a major barrier to the introgression of beneficial alleles into elite breeding material. Identification of the variation and genetic factors underlying photoperiod response in cotton is needed to fully harness the genetic diversity of wild cotton and broaden the cultivated germplasm pool. Genetic variants, especially loss‐of‐function mutations in dominant genes conferring photoperiod sensitivity, would be highly valuable in this regard. After mutagenizing pima cotton (G. barbadense L.) seeds heterozygous for the major photoperiod response gene Gb_Ppd1 with γ rays, we identified plants no longer sensitive to photoperiod. Genetic analysis of BC1F1 plants derived from backcrossing the mutants with their photoperiod‐insensitive parent confirmed the loss‐of‐function mutations were allelic with Gb_Ppd1. Characterization of the mutants with molecular markers confirmed that all but one were deletions of Gb_Ppd1. Further, genotyping localized Gb_Ppd1 to a 12‐Mb region on chromosome D10. The newly identified genomic region and loss‐of‐function mutants may help assist with the identification and functional validation of candidate genes for photoperiod response in cotton, facilitating the valuable introgression of genetic diversity into cotton breeding programs. [ABSTRACT FROM AUTHOR]

Commercial varieties of upland cotton (Gossypium hirsutum) have undergone extensive breeding for agronomic traits, such as fiber quality, disease resistance, and yield. Cotton breeding programs have widely used Chinese upland cotton source germplasm (CUCSG) with excellent agronomic traits. A better understanding of the genetic diversity and genomic characteristics of these accessions could accelerate the identification of desirable alleles. Here, we analyzed 10,522 high‐quality single‐nucleotide polymorphisms (SNP) with the CottonSNP63K microarray in 137 cotton accessions (including 12 hybrids of upland cotton). These data were used to investigate the genetic diversity, population structure, and genomic characteristics of each population and the contribution of these loci to heterosis. Three subgroups were identified, in agreement with their known pedigrees, geographical distributions, and times since introduction. For each group, we identified lineage‐specific genomic divergence regions, which potentially harbor key alleles that determine the characteristics of each group, such as early maturity‐related loci. Investigation of the distribution of heterozygous loci, among 12 commercial cotton hybrids, revealed a potential role for these regions in heterosis. Our study provides insight into the population structure of upland cotton germplasm. Furthermore, the overlap between lineage‐specific regions and heterozygous loci, in the high‐yield hybrids, suggests a role for these regions in cotton heterosis. [ABSTRACT FROM AUTHOR]

[Objective]Gossypium mustelinum-based introgressed lines(ILs)were used to detect QTLs associated with lint percentage based on the construction of molecular genetic maps. It was expected that the QTLs for the improvement of upland cotton in Gmustelinum will be used to serve the molecular breeding of cotton yield. [Method]In this study, a G. hirsutum line PD94042 was used as the recipient parent and Gmustelinum as the donor parent, and the advanced-backcross population was constructed using the Upland cotton as the recurrent parent. By planting ILs and extracting DNA for SSR markers, a genetic linkage map of molecular markers was constructed. Win QTL Cart 2.5 software was used to combine the phenotypic data of the field with the genotype data and map QTLs of lint percentage. [Result]Based on the genetic maps of G. mustelinum introgression lines, totally 21 lint percentage QTLs were successfully detected. The phenotypic variation ranged from 19.3% to 42%. Among them, a main-effect QTL qLP-3 was detected in both environments, and Gmustelinum alleles increased lint percentage, which may be of great importance in mark-assisted selection. [Conclusion]Using the genetic map of Gmustelinum introgression line populations, 21 lint percentage-related QTLs were successfully identified, which provided informatioin for molecular marker-assisted breeding of cotton lint percentage, laying the foundation for further fine mapping of QTL. [ABSTRACT FROM AUTHOR]