Wang Zhongyu, Cai Caiping, Yu Ziheng, Reyimu Yibadiguli, Han Xin, Lv Meng, Zhang Zihan, Li Weixi, Zhu Guozhong, Guo Wangzhen
State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization, Nanjing Agricultural University, Nanjing, 210095, China.
Engineering Research Center of Ministry of Education for Cotton Germplasm Enhancement and Application, Nanjing Agricultural University, Nanjing, 210095, China.
Theor Appl Genet. 2025 May 25;138(6):126. doi: 10.1007/s00122-025-04915-x.
A fiber micronaire QTL qMIC-A11 was fine-mapped, and the GDSL esterase/lipase gene GbGELP was identified as the causal gene of the QTL. GbGELP modulates cell elongation and cotton fiber development. Fine mapping and map-based cloning of fiber micronaire (MIC)-related quantitative trait loci (QTL) have not been reported to date. Here, we utilized a G. hirsutum (Gh) acc. TM-1-G. barbadense (Gb) acc. Hai7124 introgression line CSSL47, which exhibits a significant decrease in MIC compared to TM-1, to cross with TM-1 and develop the F and F secondary segregating populations. Further, a stable MIC QTL qMIC-A11 was simultaneously detected in the F and F populations and anchored within a 407 kb region. Among them, GB_A11G1593 encoding a GDSL esterase/lipase, exhibited substantially higher expression levels at fiber elongation period in CSSL47 compared to TM-1, which was temporally identified as the causal gene for qMIC-A11 and named as GbGELP. The heterologous expression of GbGELP in Arabidopsis showed increased root length, root cell length, rosette leaf growth, and trichome density. However, knockdown of GbGELP homologs in CSSL47 significantly decreased the fiber length. Further investigation found that there was an A/T single-nucleotide polymorphism variation (SNP) in the promoter of GELP orthologs between CSSL47 and TM-1, which results in a differential CATTAAATT/CATTTAATT HAHR1-box cis-acting element, a binding site for the homeodomain-leucine zipper IV (HD-ZIP IV). GbGELP was regulated by a HD-ZIP IV transcription factor GhHDG2 via binding to the CATTAAATT element in the GbGELP promoter, while GhGELP could be activated due to GhHDG2 unable to bind the CATTTAATT element in the GhGELP promoter. The fine-mapped MIC QTL qMIC-A11, along with the causal gene GbGELP, will be utilized to improve the fiber quality in cotton breeding.
一个纤维马克隆值QTL qMIC-A11被精细定位，并且GDSL酯酶/脂肪酶基因GbGELP被鉴定为该QTL的因果基因。GbGELP调节细胞伸长和棉花纤维发育。迄今为止，尚未有关于纤维马克隆值（MIC）相关数量性状基因座（QTL）的精细定位和基于图谱克隆的报道。在此，我们利用陆地棉（Gh）品种TM-1-海岛棉（Gb）品种海7124渐渗系CSSL47（与TM-1相比，其MIC显著降低）与TM-1杂交，构建了F和F次级分离群体。此外，在F和F群体中同时检测到一个稳定的MIC QTL qMIC-A11，并将其定位在一个407 kb的区域内。其中，编码GDSL酯酶/脂肪酶的GB_A11G1593在CSSL47纤维伸长时期的表达水平显著高于TM-1，在时间上被确定为qMIC-A11的因果基因，并命名为GbGELP。GbGELP在拟南芥中的异源表达显示根长度增加、根细胞长度增加、莲座叶生长和毛状体密度增加。然而，CSSL47中GbGELP同源基因的敲低显著降低了纤维长度。进一步研究发现，CSSL47和TM-1之间GELP直系同源基因启动子存在A/T单核苷酸多态性变异（SNP），这导致了一个不同的CATTAAATT/CATTTAATT HAHR1-box顺式作用元件，即同源域亮氨酸拉链IV（HD-ZIP IV）结合位点。GbGELP通过与GbGELP启动子中的CATTAAATT元件结合，受HD-ZIP IV转录因子GhHDG2调控，而由于GhHDG2无法结合GhGELP启动子中的CATTTAATT元件，GhGELP可被激活。精细定位的MIC QTL qMIC-A11及其因果基因GbGELP将用于棉花育种中改善纤维品质。
