棉花李氏突变体（Li1)重要候选基因GhAS1的克隆与功能解析

MYB transcription factors are the key factors in the plant trichome development signal transduction pathway which are also play an important regulatory role during the growth and development of cotton fiber. Based on the fine mapping of a cotton ligon lintless mutant, a gene named GhAS1 which is highly cosegregated to the trait of the curly leaves and lint fiberless was cloned. This gene is an encoding MYB domain transcription factor which its high expression level was verified in leaves, ovules and fibers by RT-PCR. BLAST results reveal that it has high degree of sequence homology to Arabidopsis AS1 gene and so far there are no reports related to this gene's cloning and functional anlysis in cotton. We consider it is a new gene.This project intends to compare the sequence and expression differences of the GhAS1 between the two near-isogenic lines Li-1 widetype and Li-1 mutant in order to study the molecular bases of the Li-1 mutant phenotype. The identification of the GhAS1's function will be further verified by plant overexpression and RNAi experiments. The promoter region of GhAS1 will also be cloned and fused to GUS reporter gene to study gene's spatial and temporal expression patterns and to filter the specific motifs or sections which are responsible for fiber development. By using BiFC method and Transcriptome Deep Sequencing Tech we plan to obtain GhAS1 interaction proteins and identify GhAS1 target genes. Through the above analysis this project expect to elucidate the signal transduction functions of GhAS1 on the mechanism of cotton leaf and fiber growth and development.

MYB转录因子是植物表皮毛发育信号转导的关键因子，在棉纤维的生长发育过程中起重要作用。本项目通过研究棉花短绒及叶片卷曲突变体Li1，应用图位克隆对控制其变异性状的基因进行精细定位后发现和叶片及纤维发育相关的重要基因GhAS1与变异性状共分离。该基因为编码MYB结构域的转录因子，在棉花叶片，胚珠，纤维中均表达。由于迄今未见任何GhAS1在棉花中克隆及功能研究的报道，因此本项目拟比较Li1自交后代近等基因系两种表型（Li1正常，Li1突变）间GhAS1基因的序列和表达差异，在此基础上进一步通过转基因技术研究GhAS1的功能；克隆其启动子并研究该基因的时空表达模式和筛选纤维特异性表达的作用元件；同时利用BiFC技术研究与GhAS1相互作用的蛋白和应用表达谱深度测序技术分析GhAS1的靶基因。通过对GhAS1功能和信号转导通路的分析阐明GhAS1在棉花叶片和纤维生长、发育过程中的作用机制。

棉花为世界上重要的经济作物, 棉纤维是由棉花胚珠外表皮单个表皮细胞分化而来的, 可作为研究单细胞毛状体的发育，细胞的伸长或成熟、细胞壁和纤维素合成机理的模式材料. 棉花Li-1突变体为显性突变，该突变体的表型为茎秆扭曲，叶片卷曲以及种子表皮无长绒。本项目通过研究棉花短绒及叶片卷曲突变体 Li1，应用图位克隆对控制其变异性状的基因进行精细定位后发现和叶片及纤维发育相关的重要基因GhAS1与变异性状共分离。因此本项目比较了 Li1自交后代近等基因系两种表型（Li1正常，Li1突变）间的表达差异，在此基础上进一步通过转基因技术研究 GhAS1 的功能；应用表达谱深度测序技术分析 GhAS1的靶基因。通过对 GhAS1 功能和信号转导通路的分析阐明 GhAS1 在棉花叶片和纤维生长、发育过程中的作用机制。