拟南芥钙依赖蛋白激酶参与植物激素信号转导

在植物信号通路中,涉及到钙应答的蛋白激酶大多是钙依赖蛋白激酶。钙依赖蛋白激酶作为钙信号转导因子,参与了包括激素信号转导途径在内的很多传递过程。本工作在前人研究的基础上,对拟南芥AtCPK30基因的功能进行了深入的研究。RT-PCR分析结果表明:AtCPK30在植物根中的表达量很高,其在幼苗中的转录水平分别受ABA、IAA、2,4-D、GA_3和6-BA等激素的诱导调节。AtCPK30基因过表达的转基因株系幼苗的主根比野生型的长,同时发现转基因植株幼苗的根在缺钙的MS培养基上生长较野生型植株长,表明缺钙对转基因幼苗影响较小。用ABA、IAA、GA_3和BA处理时,转基因植株幼苗的根对激素更敏感。当野生型和转基因植株生长在含有生长素抑制剂NPA的MS培养基上时,NPA对转基因植株侧根的抑制比对野生型弱。GFP-CPK30融合蛋白的亚细胞定位研究结果表明:CPK30蛋白定位在细胞壁和细胞膜上。这些研究结果说明了AtCPK30作为钙信号转导因子,参与了多种激素调节植物根生长的过程。

A Calcium-dependent Protein Kinase Is Involved in Plant Hormone Signal Transduction in Arabidopsis

A number of signal pathways have been found through which abundant calcium-stimulated protein ki- nase activity in plant is associated with calcium-depen- dent protein kinases(CDPKs)which act as the calcium sensors mediating numerous responses,including hor- mone signaling.Basing on previous studies,we made additional functional analysis of the gene AtCPK30 en- coding a protein kinase in Arabidopsis.Results of semi- quantitative reverse transcription PCR(RT-PCR)analy- sis indicated that AtCPK30 was highly expressed in root and induced by ABA,IAA,2,4-D,GA_3and 6-BA treat- ment.The physiological roles of AtCPK30 were studied using a gain-of-function approach.Seedlings of AtCPK30 transgenic lines had longer primary roots than those plants of wild-type at the early stages.Interestingly,when these plants grew on MS lack of Ca~(2 )including wild-type and transgenic lines,the roots of transgenic line were more sensitive to calcium,lack of Ca~(2 )had less effect on roots of transgenic lines than those of wild-type.Treated with several plant hormones, such as ABA,IAA,GA_3and 6- BA,the roots of seedlings of transgenic line developed abnormally because they were more sensitive to hormones.Furthermore,NPA relatively less inhibited emergency of lateral roots of transgenic line than those of the wild-type.Green fluorescent protein-CPK30(GFP- CPK30)fusion protein studies revealed the localization of AtCPK30 to both cell wall and plasma membrane. These results suggest that AtCPK30 acts as the calcium sensor and involved in the hormone-signaling pathways.