中文摘要：

【目的】研究油菜素类固醇物质（BRs）在棉花纤维生长发育过程中的作用。【方法】通过棉花EST序列的筛选和整合，从陆地棉徐州142纤维中克隆了一个BRs合成酶基因GhDWF1。【结果】其cDNA序列全长1849bp，包含一个1692bp的开放阅读框，推导编码563个氨基酸，与水稻、玉米、豌豆、番茄和拟南芥的BRs合成酶DWARF1/DIMINUTO有较高的同源性，具有该类蛋白的典型结构。GhDWF1基因在开花当天的胚珠和纤维中表达最强，在根、幼茎和纤维发育的各个时期表达较高。与徐州142野生型相比，无绒无絮突变体胚珠中表达量较低。【结论】暗示GhDWF1基因的表达与棉花纤维的生长发育有密切关系。

英文摘要：

[Objective] Brassinosteroids （BRs） are an important class of plant steroidal hormones that are essential in a wide variety of physiological processes. The present study determines the effects of BRs on development of cotton fibers. [Method] Through screening cotton EST data base and the candidated ESTs, a key gene （GhDWF1） involved in the upstream biosynthetic pathway of B Rs has been cloned from developing fibers of upland cotton （Gossypium hirsutum L.） cv. XuZhou 142. [ Result ]The full length of the cloned cDNA is 1 849 bp, including a 37 bp 5＇-untranslated region, an ORF of 1 692 bp and a 120 bp 3＇-untranslated region. The cDNA encodes a polypeptide of 563 amino acid residues with a predicted molecular mass of 65 kD. The deduced amino acid sequence has high homology with the BR biosynthetic enzyme, DWARF1/DIMINUTO, from rice, maize, pea, tomato and Arabidopsis. Furthermore, the typical conserved structure, such as the transmembrane domain, the FAD-dependent oxidase domain and FAD-binding site, is present in GhDWF1 protein. Southern blot indicated the GhDWF1 gene is a single copy in upland cotton genome. RT-PCR analysis revealed that the highest level of GhDWF1 expression was detected in 0DPA （Day Post Anthesis） ovule （with fibers）, while the lowest level was observed in cotyledon. The GhDWF1 gene was expressed highly in roots, young stems and fibers. Moreover, the expression level was higher in ovules （with fibers） of wildtype （Xuzhou142） than in ovules of fuzzless-lintless mutant at the same developmental stages （0DPA and 4DPA）. Results suggest that the GhDWF1 gene plays a crucial role in fiber development.