Zhu Qian-Hao, Stiller Warwick, Moncuquet Philippe, Gordon Stuart, Yuan Yuman, Barnes Scott, Wilson Iain
Black Mountain Laboratories, CSIRO Agriculture and Food, Canberra, Australian Capital Territory 2601, Australia.
CSIRO Agriculture and Food, Narrabri, NSW 2390, Australia.
G3 (Bethesda). 2021 Mar 10;11(1):1-14. doi: 10.1093/g3journal/jkaa042.
Fiber mutants are unique and valuable resources for understanding the genetic and molecular mechanisms controlling initiation and development of cotton fibers that are extremely elongated single epidermal cells protruding from the seed coat of cottonseeds. In this study, we reported a new fuzzless-tufted cotton mutant (Gossypium hirsutum) and showed that fuzzless-tufted near-isogenic lines (NILs) had similar agronomic traits and a higher ginning efficiency compared to their recurrent parents with normal fuzzy seeds. Genetic analysis revealed that the mutant phenotype is determined by a single incomplete dominant locus, designated N5. The mutation was fine mapped to an approximately 250-kb interval containing 33 annotated genes using a combination of bulked segregant sequencing, SNP chip genotyping, and fine mapping. Comparative transcriptomic analysis using 0-6 days post-anthesis (dpa) ovules from NILs segregating for the phenotypes of fuzzless-tufted (mutant) and normal fuzzy cottonseeds (wild-type) uncovered candidate genes responsible for the mutant phenotype. It also revealed that the flanking region of the N5 locus is enriched with differentially expressed genes (DEGs) between the mutant and wild-type. Several of those DEGs are members of the gene families with demonstrated roles in cell initiation and elongation, such as calcium-dependent protein kinase and expansin. The transcriptome landscape of the mutant was significantly reprogrammed in the 6 dpa ovules and, to a less extent, in the 0 dpa ovules, but not in the 2 and 4 dpa ovules. At both 0 and 6 dpa, the reprogrammed mutant transcriptome was mainly associated with cell wall modifications and transmembrane transportation, while transcription factor activity was significantly altered in the 6 dpa mutant ovules. These results imply a similar molecular basis for initiation of lint and fuzz fibers despite certain differences.
纤维突变体是用于理解控制棉纤维起始和发育的遗传和分子机制的独特且有价值的资源，棉纤维是从棉籽种皮突出的极长的单个表皮细胞。在本研究中，我们报道了一种新的无毛簇生棉突变体（陆地棉），并表明无毛簇生近等基因系（NILs）与其具有正常有绒毛种子的轮回亲本相比，具有相似的农艺性状和更高的轧花效率。遗传分析表明，突变表型由一个单一的不完全显性位点决定，命名为N5。通过混合分组分离测序、SNP芯片基因分型和精细定位相结合的方法，将该突变定位到一个约250 kb的区间，该区间包含33个注释基因。使用来自分离无毛簇生（突变体）和正常有绒毛棉籽（野生型）表型的NILs的开花后0 - 6天（dpa）胚珠进行比较转录组分析，发现了导致突变表型的候选基因。还揭示了N5位点的侧翼区域富含突变体和野生型之间的差异表达基因（DEGs）。其中一些DEGs是在细胞起始和伸长中具有已证明作用的基因家族成员，如钙依赖蛋白激酶和扩展蛋白。突变体的转录组图谱在6 dpa胚珠中显著重编程，在0 dpa胚珠中重编程程度较小，但在2 dpa和4 dpa胚珠中没有重编程。在0 dpa和6 dpa时，重编程的突变体转录组主要与细胞壁修饰和跨膜运输相关，而转录因子活性在6 dpa突变体胚珠中显著改变。这些结果表明，尽管存在某些差异，但皮棉纤维和绒毛纤维起始的分子基础相似。
