陆地棉背景下海岛棉第18染色体片段置换系的培育及相关农艺性状QTL定位

Sub18是以陆地棉遗传标准系TM-1为背景, 含海岛棉3-79第18染色体的置换系材料。本研究以TM-1为受体亲本, 置换系Sub18为供体亲本, 借助分子标记辅助选择技术培育了一套以TM-1为背景, 含海岛棉3-79第18染色体不同长度片段的置换系。这套置换系由45个株系构成, 共78个置换片段。其中27个株系导入单片段, 占总株系的60%; 9个株系导入2个片段, 占20%; 9个株系导入3个及以上片段, 占20%。导入片段总长度为467.6 cM, 约为该染色体遗传长度的4倍, 每个株系内被替换的染色体片段长度不完全相同, 平均遗传长度为5.99 cM, 最短的为0.9 cM, 最长的20.35 cM。其中13个株系表现开放花蕾性状, 涉及的最短导入片段长5.05 cM。对TM-1、Sub18以及培育的45个导入系进行农艺性状调查和QTL联合定位分析, 鉴定出纤维强度(qFS-C18-1)、整齐度(qFU-C18-1)、马克隆值(qFMi-C18-1)、成熟度(qFMa-C18-1)、皮棉重(qLW-C18-1)、籽指 (qSI-C18-1)和衣分 (qLP-C18-1) 7个加性QTL和5个上位性效应QTL。研究结果为进一步精细定位目标QTL、克隆QTL以及重要性状分子设计育种奠定了基础。

Development of Gossypium barbadense Chromosome 18 Segment Substitution Lines in the Genetic Standard Line TM-1 of Gossypium hirsutum and Mapping of QTLs Related to Agronomic Traits

Substitution line 18 (Sub18) has the background of genetic standard line of G. hirsutum acc. TM-1 with the 18th chromosome of G. barbadense accession 3-79. In the study, a set of G. barbadense accession 3-79 chromosome 18 segment substitution lines (CSSL18) were developed via molecular marker-assisted selection (MAS), with TM-1 as a recipient parent and Sub18 as a donor. The developed CSSLs consisted of 45 lines and 78 introgressed segments in total. Of them, 27 were introgressed with single segment, accounting for 60% of the total lines; 9 were introgressed with two segments, accounting for 20%; and 9 were introgressed with three or more segments, accounting for 20%. The total length of introgression segments was 467.6 cM, which is 4 times of the genetic length of the chromosome 18. The substituted segment length varied in each line, ranging from the shortest of 0.9 cM to the longest of 20.35 cM, with an average length of 5.99 cM. Further, the opening bud trait was detected in 13 substitution lines, with the shortest introgressed segment of 5.05 cM. Using TM-1, Sub18 and 45 substituted lines as materials, we investigated agronomic traits and carried out QTL tagging by joint positioning analysis. Seven additive effect QTLs for fiber strength (qFS-C18-1), uniformity (qFU-C18-1), micronaire (qFMi-C18-1), maturity (qFMa-C18-1), lint weight (qLW-C18-1), seed index (qSI-C18-1), and lint percentage (qLP-C18-1) and five epistatic effect QTLs were identified, respectively. The results will lay a foundation for the fine mapping and cloning of target QTLs, and the molecular breeding by design for pyramiding multi-traits in cotton.