Better Together -International Partnerships Can Solve Threats to Cotton Production
Speaker: Dr. Jodi Scheffler. Research Geneticist Plants. USDA-ARS. Stoneville, Mississippi, United States
When the seed breaks, when the fibre sticks… Some contaminants of cotton
Speakers: Dr Bruno Bachelier. Assistant Unit Director, Cotton Supply Chain Correspondent, CIRAD France. & Dr Jean-Paul Gourlot. Co-leader of the Cotton Sector Group, CIRAD, France.
[Background] Micronaire is a comprehensive index reflecting the fineness and maturity of cotton fiber. Micronaire is one of the important internal quality indicators of the cotton fiber and is closely related to the value of the cotton fiber. Understanding the genetic basis of micronaire is required for the genetic improvement of the trait. However, the genetic architecture of micronaire at the genomic level is unclear. The present genome-wide association study (GWAS) aimed to identify the genetic mechanism of the micronaire trait in 83 representative upland cotton lines grown in multiple environments.
[Results] GWAS of micronaire used 83 upland cotton accessions assayed by a Cotton 63 K Illumina Infinium single nucleotide polymorphism (SNP) array. A total of 11 quantitative trait loci (QTLs) for micronaire were detected on 10 chromosomes. These 11 QTLs included 27 identified genes with specific expression patterns. A novel QTL, qFM-A12–1, included 12 significant SNPs, and GhFLA9 was identified as a candidate gene based on haplotype block analysis and on strong and direct linkage disequilibrium between the significantly related SNPs and gene. GhFLA9 was expressed at a high level during secondary wall thickening at 20∼25 days post-anthesis. The expression level of GhFLA9 was significantly higher in the low micronaire line (Msco-12) than that in the high micronaire line (Chuangyou-9).
[Conclusion] This study provides a genetic reference for genetic improvement of cotton fiber micronaire and a foundation for verification of the functions of GhFLA9.
[Title] Genome-wide association study of micronaire using a natural population of representative upland cotton (Gossypium hirsutum L.)
[Authors] SONG Jikun, PEI Wenfeng, MA Jianjiang, YANG Shuxian, JIA Bing, BIAN Yingying, XIN Yue, WU Luyao, ZANG Xinshan, QU Yanying, ZHANG Jinfa, WU Man & YU Jiwen
Journal of Cotton Research 2021, 4: 14
[Background] In order to uncover the mechanism of significantly reduced insect resistance at the late developmental stage in cotton (Gossypium hirsutum L.), the relationship between boll setting rate under different planting densities and Bacillus thuringiensis (Bt) insecticidal concentrations in the boll wall were investigated in the present study. Two studies were arranged at Yangzhou, China during the 2017–2018 cotton growth seasons. Five planting densities (15 000, 25 000, 45 000, 60 000 and 75 000 plants per hectare) and the flower-removal treatment were imposed separately on Bt cotton cultivar Sikang3 to arrange different boll setting rates, and the boll setting rates and Bt toxin content were compared.
[Results] Higher boll setting rate together with lower Bt toxin contents in boll wall was observed under low planting density, whereas lower boll setting rate and higher Bt toxin contents were found under high planting density. Also, higher Bt protein concentration was associated with higher soluble protein content, glutamic-pyruvic transaminase (GPT), and glutamic oxaloacetate transaminase (GOT) activities, but lower amino acid content, and protease and peptidase activities. It was further confirmed that a higher boll setting rate with lower Bt protein content under flower-removal.
[Conclusion] This study demonstrated that the insecticidal efficacy of boll walls was significantly impacted by boll formation. Reduced protein synthesis and enhanced protein degradation were related to the reduced Bt toxin concentration.
[Title] Increasing plant density increases Bt toxin concentration of boll wall in cotton by decreasing boll setting speed
[Authors] ZHOU Mingyuan, CHEN Chen, TAMBEL Leila I. M., CHEN Yuan, ZHANG Xiang, CHEN Yuan & CHEN Dehua
Journal of Cotton Research 2021, 4: 12
[Background] Soil salt stress seriously restricts the yield and quality of cotton worldwide. To investigate the molecular mechanism of cotton response to salt stress, a main cultivated variety Gossypium hirsutum L. acc. Xinluzhong 54 was used to perform transcriptome and proteome integrated analysis.
[Results] Through transcriptome analysis in cotton leaves under salt stress for 0 h (T0), 3 h (T3) and 12 h (T12), we identified 8 436, 11 628 and 6 311 differentially expressed genes (DEGs) in T3 vs. T0, T12 vs. T0 and T12 vs. T3, respectively. A total of 459 differentially expressed proteins (DEPs) were identified by proteomic analysis, of which 273, 99 and 260 DEPs were identified in T3 vs. T0, T12 vs. T0 and T12 vs. T3, respectively. Metabolic pathways, biosynthesis of secondary metabolites, photosynthesis and plant hormone signal transduction were enriched among the identified DEGs or DEPs. Detail analysis of the DEGs or DEPs revealed that complex signaling pathways, such as abscisic acid (ABA) and jasmonic acid (JA) signaling, calcium signaling, mitogen-activated protein kinase (MAPK) signaling cascade, transcription factors, activation of antioxidant and ion transporters, were participated in regulating salt response in cotton.
[Conclusion] Our research not only contributed to understand the mechanism of cotton response to salt stress, but also identified nine candidate genes, which might be useful for molecular breeding to improve salt-tolerance in cotton.
[Title] Integrated transcriptome and proteome analysis reveals complex regulatory mechanism of cotton in response to salt stress
[Authors] CHEN Lin, SUN Heng, KONG Jie, XU Haijiang & YANG Xiyan
Journal of Cotton Research 2021, 4: 11
[Background] Cotton fiber yield is a complex trait, which can be influenced by multiple agronomic traits. Unravelling the genetic basis of cotton fiber yield-related traits contributes to genetic improvement of cotton.
[Results] In this study, 503 upland cotton varieties covering the four breeding stages (BS1–BS4, 1911–2011) in China were used for association mapping and domestication analysis. One hundred and forty SSR markers significantly associated with ten fiber yield-related traits were identified, among which, 29 markers showed an increasing trend contribution to cotton yield-related traits from BS1 to BS4, and 26 markers showed decreased trend effect. Four favorable alleles of 9 major loci (R2 ≥ 3) were strongly selected during the breeding stages, and the candidate genes of the four strongly selected alleles were predicated according to the gene function annotation and tissue expression data.
[Conclusion] The study not only uncovers the genetic basis of 10 cotton yield-related traits but also provides genetic evidence for cotton improvement during the cotton breeding process in China.
[Title] Association mapping and domestication analysis to dissect genetic improvement process of upland cotton yield-related traits in China
[Authors] GUO Chunping, PAN Zhenyuan, YOU Chunyuan, ZHOU Xiaofeng, HUANG Cong, SHEN Chao, ZHAO Ruihai, YANG Qingyong, ZHU Longfu, SHAHZAD Raheel, MENG Fande, LIN Zhongxu & NIE Xinhui
Journal of Cotton Research 2021, 4: 10