摘 要

 

棉花作为一种常见的作物，在全球多地区的气候都适宜种植外，纺织技术的发展让民众对于棉花的需求日益增加。衣被民生，利莫赖大，然而棉花上的“癌症”——黄萎病，正严重阻碍着植棉业的发展。培育并推广抗黄萎病的棉花新品种是目前作物育种上的头等大事。

 

本课题组前期创制了一套以中棉所36为受体和轮回亲本，海1为供体亲本的陆海渐渗系群体，在此基础上评价出一个抗黄萎病稳定的材料MBI9626。将其作为研究对象，与中棉所36杂交后连续自交两代，依次得到F2、F2:3和F2:4群体，测定表型性状；以覆盖棉花26条染色体的2292个SSR（Simple sequence repeat）标记先后对亲本和F2群体进行多态性检测和基因型检测；寻找表型与基因型的对应关系，挖掘与MBI9626纤维产量、品质和黄萎病抗性相关的QTL（Quantitative trait loci）。

 

鉴别出16个与纤维产量相关的QTL，包括7个与铃重相关，9个与衣分相关，可解释2.25%-6.14%的表型变异率，其中多年多环境稳定QTL 6个。

 

鉴别出12个与纤维品质相关的QTL，包括上半部平均长度3个，断裂比强度4个，马克隆值4个，整齐度1个，可解释2.49%-12.30%的表型变异率，其中多年多环境稳定QTL 2个。

 

鉴别出10个与黄萎病抗性相关的QTL，包括发病率6个和病情指数4个，可解释3.32%-10.00%的表型变异率，其中多年多环境稳定QTL 7个。

 

关键词：棉花黄萎病，染色体片段渐渗系，QTL，精细定位，候选基因鉴定41

 

Abstract

 

As a common crop, cotton is suitable for planting in many regions of the world.The development of textile technology makes people's demand for cotton increase day by day.However, the "cancer" of cotton -- Verticillium wilt,is seriously hindering the development of cotton planting industry.

 

In the early stage, our research group constructed a set of chromosome segment substitution lines with CCRI36 as the recurrent parent and Hai1 as the donor parent. On this basis, MBI9626 with stable disease resistance was evaluated.After crossing with CCRI36 for two successive generations, F2,F2:3 and F2:4 populations were obtained, and the phenotypic data were determined. 2292 SSR markers covering 26 chromosomes of cotton were used todetect polymorphism and genotype of parents and F2 populations. The corresponding relationship between phenotype and genotype was searched,and QTLs related to fiber yield, fiber quality and Verticillium wilt resistance of MBI9626 were dug.

 

1.Sixteen QTLs related to fiber yield were detected,including 7 QTLs related to boll weight and 9 QTLs related to lint percent, with phenotypic contribution rates ranging from 2.25%-6.14%, including 6 QTLs with multi-year environmental stability.

 

2.Twelve QTLs were detected for fiber quality, including 3 for upper half mean length,4 for fiber strength, 4 QTLs related to Micronaire, and 1 QTLs related to fiber uniformity. Phenotypic contribution rates ranged from 2.49%-12.30%, including 2 QTLs for multi-year environmental stability.

 

3.Ten QTLs related to Verticillium wilt resistance were detected,including 6 for disease incidence and 4 for disease index, and the phenotypic contribution rate ranged from 3.32% to 9.99%, including 7 QTLs for multi-year environmental stability.

 

4.qVW-5-1 can be identified in two environments,which coincide with the interval of qVW-C5-2 in low generation populations (BC1S1 and BC2F1, accounting for 13.59% maximum phenotypic variation) and qVW-Chr05-2 in 300high generation populations (BC5F3:5, accounting for 5.43% maximum phenotypic variation) of the same chromosome segment substitution lines.qVW-5-1 was used as the target loci for fine mapping.

 

To narrow qVW-5-1 interval, the regions were first blast with the genome sequence of Upland cotton.After the tandem repeats were found,new markers were designed, and a total of 9 polymorphic primers were obtained.

 

At the same time, the markers at both ends of qVW-5-1 were used toscreen the recombinant individual plants containing the target fragment, and the secondary large isolation population was constructed. qVW-5-1 was eventually targeted between markers 130 and 238,with a physical distance of 95Kb and containing nine genes (GH_A05G0220-GH_A05G0228).

 

On the other hand, in order to better understand the molecular mechanism of Verticillium wilt resistance in cotton,transcriptome sequencing was performed on the root tissues (0, 7 and 15 days) of MBI9626 infected by V991 and its parents, Hai1 and CCRI36, and 8453 differentially expressed genes were screened in total. The differentially expressed genes contained in the most significant Temporal expression patterns were enriched by GO,and were mainly clustered intosubgroups related to metabolic processes, cell processes, single biological processes and biological regulation, cell membrane, cell membrane part, cell and cell part, linkage and catalytic activity. KEGG annotation results showed that the differentially expressed genes were most associated with plant hormone signal transduction pathways and secondary metabolism.

 

Finally, the transcriptome sequencing results were correlated with the fine mapping resultsof qVW-5-1, and 7 out of the 9 genes in the fine mapping region were differently expressed. Based on the expression level,annotation information and theprogress of biological research at home and abroad, we believe that GH_A05G0221, GH_A05G0223, GH_A05G0225 and GH_A05G0226 may be involved in the defense process of Verticillium wilt in cotton. Further experiments are needed to prove the gene's function.

 

Key words: Cotton Verticillium wilt, Chromosome segment substitution lines,Quantitative trait locus, Fine mapping, Candidate gene identification

 

ne mapping region were differently expressed.Based on the expression level,annotation information and theprogress of biological research at home and abroad, we believe that GH_A05G0221, GH_A05G0223, GH_A05G0225 and GH_A05G0226 may be involved in the defense process of Verticillium wilt in cotton. Further experiments are needed to prove the gene's function.

 

Key words: Cotton Verticillium wilt, Chromosome segment substitution lines,Quantitative trait locus, Fine mapping, Candidate gene identification