拟南芥中两个可能的SDD1新等位基因的鉴定与分析

SDD1是气孔发育过程中的关键调控基因, 编码一个类枯草杆菌(Bacillus subtilis)蛋白酶的丝氨酸蛋白酶。从EMS诱变的拟南芥(Arabidopsis thaliana)中筛选到2株类似sdd1-1的气孔密度突变体, 即e281和g204。其气孔密度和指数均比野生型增加约1.5倍, 气孔成簇。遗传分析和基因测序证实它们是2个不同的SDD1新等位基因, 其突变分别导致了底物结合位点N区域和催化三联体之一——S区域的氨基酸变化, 分别为S变成T及S变为F。形态学和生理学研究表明, SDD1基因不同位点发生突变可导致不同的生物学效应; 而且SDD1等位基因间存在拮抗作用, 其可能属于基因转应作用中的负效应。

Identification and Genetic Analysis of Two Putative SDD1 Alleles in Arabidopsis

SDD1 is a crucial gene regulating stomatal development and encodes a subtilisin-like serine protease. Screening an ethyl methane sulfonate (EMS)-mutagenized population of Arabidopsis thaliana, we isolated two mutants (e281 and g204) with altered stomatal characteristics. The two mutants showed about a 1.5-fold increase in stomatal density and index and formed a clustered stomata similar to the sdd1-1 mutant, but the internal leaf architecture was not altered. Genetic analysis and sequencing results confirmed that e281 and g204 are two novel SDD1 alleles. The mutation results in amino acid changes in the N domain for the substrate binding site and in one of the S domains for the catalytic triad, respectively. Moreover, morphological and physiological data indicate that mutation of different sites within the SDD1 gene lead to different phenotypes. The antagonism among SDD1 alleles can be a negative effect of the gene transvection.