过表达大豆类受体蛋白激酶基因RLPK2促进转基因拟南芥叶片的衰老

Over expressionn of soybean receptor-like protein kinase RLPK2 gene from Glycine max promotes transgenic Arabidopsis thaliana leaf senescence

大豆RLPK2基因(GenBank登录号:AY687391)是一个编码N-末端富含亮氨酸重复序列的类受体蛋白激酶基因。为分析大豆RLPK2基因的功能,该研究以野生型拟南芥和大豆RLPK2基因过表达拟南芥植株为材料,通过农杆菌介导法转化野生型拟南芥,构建了大豆RLPK2基因过表达载体,分析了叶片衰老过程中叶绿素荧光参数、抗氧化酶活性及衰老相关基因表达量的变化。结果表明:(1)无论是野生型还是转基因拟南芥,随着叶片衰老进程的进行,光系统Ⅱ(PSⅡ)的最大光化学效率(F_(v)/F_(m))、PSⅡ实际光化学效率(Φ_(PSⅡ))、光化学淬灭系数(qP)和光合电子传递速率(ETR)均呈下降趋势,但后者下降趋势更明显;(2)激发压(1-qP)在叶片衰老前期的变化较为平稳,后期则急剧增加,且转基因型比野生型拟南芥增加更明显;(3)在叶片衰老的各个时期,转基因拟南芥叶片丙二醛(MDA)含量均显著高于野生型,而超氧化物岐化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均显著低于野生型;(4)实时荧光定量PCR检测结果表明,RLPK2转基因拟南芥中衰老标志基因ATSAG12,衰老关键转录因子ATNAP、ATWRKY6和叶绿素降解关键酶编码基因ATACD1表达量显著上调。综上认为,大豆类受体蛋白激酶基因RLPK2参与调控植物叶片衰老进程,其表达对叶片衰老具有促进作用。

Soybean RLPK2 gene(GenBank accession No.AY687391)is a receptor-like protein kinase gene that encodes a leucine-rich repeat(LRR)receptor kinase-type protein encoded with a N-terminal.In order to further analyze the function of the soybean RLPK2 gene,the overexpression vector of the RLPK2 gene was constructed via agrobacterium-mediated transformation of Arabidopsis thaliana.In this study,wild-type(WT)and transgenic A.thaliana plants were used as materials,and the variations in chlorophyll fluorescence parameters and the activities of antioxidant enzymes as well as the expression levels of senescence-associated genes in the aging process of leaves were investigated.The results were as follows:(1)Both WT and transgenic plants tended to decrease the efficiency of primary conversion of light energy of photosystemⅡ(PSⅡ)(F_(v)/F_(m)),actual photochemical efficiency of PSⅡ(Φ_(PSⅡ)),photochemical quenching coefficient(qP)and electron transport rate(ETR)while the latter showed a more obvious decreasing pattern as aging progressed.(2)The PSⅡexcitation pressure(estimated as 1-qP)was relatively stable in the early stage of leaf senescence,and increased sharply in the later stage of leaf senescence,while the transgenic plants showed a more obvious increasing trend.(3)At different leaf senescence stages,the malondialdehyde(MDA)content was significantly higher in transgenic plants than that in WT,while the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were significantly lower in transgenic plants than those in WT.(4)Additionally,the real-time quantitative RT-PCR showed that the expression levels of aging marker gene ATSAG12,critical senescence-associated transcription factors ATNAP,ATWRKY6 and chlorophyll degradation key enzyme-encoding gene ATACD1 increased in transgenic plants.In summary,transgenic A.thaliana exhibited faster leaf senescence compared with WT,and the expression of the soybean receptor-like protein kinase RLPK2 gene played an important role in promoting leaf senescence.