拟南芥突变体sus40-1D的遗传分析与候选基因鉴定

Genetic Analysis and Identification of Candidate Genes for a Mutant(sus40-1D)in Arabidopsis thaliana

植物器官的大小调控是一个重要的生物学过程,直接影响农作物产量。目前对于植物器官大小调控的研究集中在转录调控、激素信号通路及蛋白质合成与修饰等多个水平和途径,但具体的分子机制并不是很清晰。李云海实验室前期研究发现了一个器官大小的关键调控基因UBIQUITIN SPECIFIC PROTEASE 15(UBP15)/SUPPRESSOR2 OF DA1(SOD2)。sod2-1突变体由于UBP15基因缺失导致器官变小。UBP15作为DA1的底物,其蛋白稳定性受DA1的调节,但其下游通路并不清楚。为了进一步了解UBP15调控器官大小的分子机制,通过EMS诱变筛选分离得到了sod2-1的抑制突变体sus40-1D。sus40-1D sod2-1突变体与sod2-1植株相比,子叶、花瓣和种子面积显著增大。遗传分析表明sus40-1D为显性突变。基因组重测序及连锁分析鉴定出2个与sus40-1D紧密连锁的候选基因:At1g05820和At1g08470。At1g05820的突变发生在内含子区域,而At1g08470的突变发生在外显子区。本研究发现了一个调控器官大小的突变体sus40-1D,对该突变体的进一步研究将有助于解析植物器官大小的调控机制。

Regulation of organ size is an important developmental process,and organ size is also a yield trait.Several seed size pathways have been described,including transcription regulation,hormone signal pathway,protein synthesis and modification,but the genetic and molecular mechanisms of seed size control still limited.In the previous study,we identified UBIQUITIN SPECIFIC PROTEASE 15(UBP15)/SUPPRESSOR2 OF DA1(SOD2)as a key regulator of plant organ size.Mutation smaller or sod2-1 mutant,which contains mutation in UBP15,causes small organs.The peptidase DA1 can cleave UBP15 to control organ growth,but downstream targets of the DA1-UBP pathway remain unclear.To understand the molecular mechanisms of UBP15 in organ size,we isolated a suppressor of sod2-1(sus40-1D).The sus40-1D sod2-1 mutant produced large cotyledons,petals and seeds compared with the sod2-1 mutant.Genetic analyses showed that sus40-1D was a dominant mutation.Using Mutmap analysis,we identified two candidate genes At1g05820 and At1g08470.The mutation in At1g05820 occurred in the intronic region,and the mutation in At1g08470 happened in the exonic region.This study identified a sus40-1D mutant with altered organ size.These findings would help to further reveal the mechanisms of organ size control in plants.