Cotton fiber strength is mainly determined during the secondary cell wall (SCW) thickening stage. In 24―25 days post anthesis (DPA) of SCW thickening stage, cDNA-amplified fragment length polymorphism (AFLP) was carried out to construct fiber transcriptome groups. Based on these groups, cotton fiber strength candidate genes were detected by composite interval mapping (CIM) through quantitative trait locus (QTL) scanning. The mapping population was the interspecific backcross BC1 of Gossypium hirsutum × G. barbadense. One hundred and fifteen BC1 plants were used for group construction with 102 qualified absence/presence polymorphic transcript-derived fragments (TDFs) from G. barbadense, and 78 TDFs were assigned into eight transcriptome groups that gave a total length of 462.63 centimorgans (cM). Two significant QTLs, FS1 and FS2, were detected and explained 16.08% and 15.87% of fiber strength variance, respectively. Of the six TDFs co-segregating with FS1 and FS2, except one encoding an unknown protein, five targeted putative phosphatidylinositol kinase, trehalose-6 phosphate synthase, MADS transcription factor, cellulose synthase-like protein and phenylalanine ammonia lyase, respectively. These functional genes were involved in plant cell wall morphogenesis or cellulose synthesis metabolism processes, and were considered as the candidate genes controlling cotton fiber strength.
LIU HengWeiWANG XingFenPAN YuXinSHI RuiFengZHANG GuiYinMA ZhiYing
利用ClustalX等软件对公共数据库现有的393753条棉花EST序列分析,得到349815条非冗余EST序列,借助自主开发的SSRmine软件共发掘SSR位点11372个,分布于10507条EST中,EST-SSR的频率是3%,平均相隔21kb出现一个SSR。在2～6bp的重复基元中,三核苷酸和六核苷酸分别占34.1%、40.6%,二、三、四、五和六核苷酸基序分别以AG/CT、AAG/CTT、AAAT/ATTT、AAAAG/CTTTT和AAAAAG/CTTTTT的类型最多。利用去冗余的且在亚洲棉、陆地棉、海岛棉中没有被开发过的410条EST序列设计开发了200对非冗余性SSR引物,利用自主开发的SSRD软件通过SSR引物序列下载、预处理、Blastn、提取相似性分值≥81%的引物编号、提取引物冗余对、冗余引物写成一行6个步骤去除来源于自身部分同源序列以及与CMD释放的不同棉种相似性SSR引物,得到了非相似性引物,定名为CRIXXX(CRI即Cotton Research Institute)。并分别选用棉花12个种的代表性材料对其中100对进行引物功效评价,包括多态信息含量(polymorphism information content,PIC)及引物通用性研究。结果显示,从自主开发的100对SSR引物筛选出56对均能在12份材料间扩增出稳定明显的条带,其中多态性引物35对,多态率占35%。引物的PIC变幅为0.097～0.888,平均为0.482;1对海岛棉EST-SSR引物在12份材料间的通用性为100%,25对亚洲棉引物通用性为81%,74对陆地棉引物通用性为80.1%。
Plant hormones play important roles in cotton fiber growth and development.However,the interaction of phytohormones is largely unknown in fiber cells up to now.DELLA proteins are critical component in GA （gibberellic acid） signal transduction,which are also regulated by other phytohormones,such as auxin and ethylene.To understand the regulation of DELLA genes in cotton fiber growth and development,we cloned four DELLA genes from upland cotton fibers （Gossypium hirsutum L.）,named GhGAI1,GhGAI2,GhGAI3,and GhGAI4.Alignment of the four predicted proteins with other reported DELLA proteins in various species displayed that they shared conserved domains and high homology.Expression profiles of the four GhGAIs in various tissues and organs as well as cotton fibers in different stages displayed that GhGAI1 has higher transcriptional levels than other GhGAIs in all detected samples.Furthermore,the expression level of GhGAI1 was significantly reduced in 0 dpa （day post anthesis） ovules by addition of IAA and epi-BL,and exogenous epi-BL decreased GhGAI1 level in 7 dpa fiber.Similarly,the levels of the other three GhGAIs in 0 dpa ovules and 7 dpa fibers were also regulated by applied phytohormones.In addition,the levels of GhGAI1 were higher in Xuzhou142 fl mutant （fuzzless-lintless） than in FL （Gossypium hirsutum vs.Xuzhou 142） from-1 to 3 dpa ovules,suggesting that GhGAI1 engaged in cotton fiber cell initiation.These results indicated that DELLA genes are involved in the process of fiber cell initiation and elongation regulated by different phytohormones.
HU Ming-yu LUO Ming XIAO Yue-hua LI Xian-bi TAN Kun-ling HOU Lei DONG Jing LI De-mou SONG Shui-qing ZHAO Juan ZANG Zhen-le LI Bao-li PEI Yan
