植物磺肽激素(Phytosulfokine, PSK)是新发现的一种能促进细胞分裂和分化的植物激素。水稻中该基因家族共有7个成员, 迄今为止PSK基因在水稻体内的功能和调控机制仍不清楚。文章首先利用生物信息学手段对OsPSK家族基因进行了结构比较和进化分析, 依据对水稻和拟南芥中PSK基因家族成员的分析认为: PSK祖先基因形成两个PSK基因的发生要早于单、双子叶植物的分化; 其中OsPSK1与其余的OsPSK2-OsPSK7进化自不同的祖先基因。对PSK家族成员在不同组织的表达分析发现不同基因具有不同的表达模式。文章通过基因枪转化的方法获得了水稻OsPSK3转基因系。文章着重研究了OsPSK3过量表达对水稻植株生长的影响。结果表明: 在转基因阳性株系中OsPSK3的表达量提高了约40%; 且OsPSK3ox-1有明显优于对照的营养性状, 表现在幼苗期产生更多的须根和根毛; 在各生长阶段直至结穗期与对照相比表现出更高的株高; 尤其在叶片叶绿素含量上, 转基因系较对照提高了2.3倍。
Phytosulfokine (PSK) is a newly discovered plant hormone, which can promote cell division and induce cell differentiation. It has 7 members in rice genome. So far, how the OsPSK functions and regulates in vivo is remaining unclear. In this study, we first did structural comparison and phylogenetic analysis of the 7-OsPSK-gene family via bioinformatics. Based on the phylogenetic analysis of the PSK genes in rice and Arabidopsis, we draw the conclusion that the formation of two paralogous PSK genes from the ancestral one was earlier than the monocotyledon-dicotyledon divergence; in addition, OsPSK1 and the rest OsPSK2-OsPSK7 stemmed from two different ancestors. Interrogating expression profiles of each OsPSK family member in different tissues showed different genes with different expression patterns. By means of the method of particle bombardment, we developed an OsPSK3 transgenic line, and further put much effort on studying rice growth under OsPSK3 overexpression background. It showed that the OsPSK3 overexpression line, OsPSK3ox increased OsPSK3 expression about 40% over the wild type, and presented obvious growth vigor with more fibrous roots and more root hairs at seedling stage. Plant height of OsPSK3ox-1 was higher from seedling to the full ripe stage. Notably in chloro-phyll content of leaves, OsPSK3ox plants increased 2.3 times over that of the wild type.
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