AUTHOR=Li Cong , Yu Hurong , Li Cheng , Zhao Tianlun , Dong Yating , Deng Xiaolei , Hu Jiahui , Zhang Yi , Zhang Fan , Daud M. K. , Chen Jinhong , Zhu Shuijin 

TITLE=QTL Mapping and Heterosis Analysis for Fiber Quality Traits Across Multiple Genetic Populations and Environments in Upland Cotton

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 9 - 2018

YEAR=2018

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2018.01364

DOI=10.3389/fpls.2018.01364

ISSN=1664-462X

ABSTRACT=An “immortalized F2” (IF2) and two reciprocal backcross (HSBCF1 and MARBCF1) populations were constructed to investigate the genetic bases of fiber quality traits in upland cotton across four different environments. A relatively high level of heterosis for micronaire (MIC) in IF2s, as well as fiber length (FL) and MIC in MARBCF1s was observed. A total of 167 quantitative trait loci (QTLs) was detected in the three related experimental populations and their corresponding mid-parental heterosis (MPH) datasets using the composite interval mapping (CIM) approach. Analysis of genetic effects of QTLs detected in different populations and their MPH datasets showed 16 (24.24%) partial dominance (PD) QTLs and 46 (69.70%) over-dominance (OD) QTLs were identified in an IF2 population; 89 (62.68%) additive QTLs, three (2.11%) PD QTLs, and 49 (34.51%) OD QTLs were detected in two BCF1 populations. Multi-environment analysis showed 48 and 56 main-QTLs (m-QTLs), and 132 and 182 epistasis-QTLs (e-QTLs), by inclusive composite interval mapping (ICIM) in IF2 and two BCF1 populations, respectively. Phenotypic variance explained by e-QTLs, except for MARBCF1s, was higher than that by m-QTLs. Thus, the over-dominant, partial dominant, and epistasis effects were the main causes of heterosis in the IF2 population, while the additive, over-dominant, and epistasis effects were the primary genetic basis of heterosis in the two BCF1 populations. Taken together, additive effect, partial dominance, over-dominance, and epistasis contributed to fiber quality heterosis in upland cotton, but over-dominance and epistasis were the most important factors.