番茄Sl_OASTL/LCD基因的克隆与表达及其对侧根生长的作用

硫化氢（H2S）是植物中最新发现的一种气体信号分子,高等植物中内源H2S主要由L-型半胱氨酸脱巯基酶（LCD）和D-型半胱氨酸脱巯基酶（DCD）两类蛋白产生。我们的前期研究结果表明外源H2S能够促进植物侧根发育。为了研究内源H2S的产生机制及H2S与一氧化氮（NO）在调控侧根发育中的作用,本实验以番茄幼苗为材料,克隆了编码H2S合成酶基因Sl_OASTL/LCD;研究抑制内源H2S对NO诱导侧根发育的影响;并研究了NO对Sl_OASTL/LCD表达的影响。结果显示：（1）番茄根中存在3个O-乙酰丝氨酸（硫醇）裂解酶基因（Sl_OASTL1、Sl_OASTL2、Sl_OASTL3）。比对和结构分析显示,Sl_OASTL1为编码H2S合成酶基因LCD,所以将Sl_OASTL1命名为Sl_OASTL/LCD;启动子区域分析显示,Sl_OASTL/LCD基因上游含有多个响应NO和植物激素信号的保守基序。（2）与对照相比,内源H2S合成酶抑制剂DL-炔丙基甘氨酸（PAG）和内源H2S清除剂亚牛磺酸（HT）处理均能抑制侧根生长。（3）外源NO供体硝普钠（SNP）显著诱导侧根生长。（4）PAG和HT处理均能够抑制NO对侧根生长的诱导作用。（5）RT-PCR分析显示,SNP处理能够显著诱导幼苗根中Sl_OASTL/LCD的表达。上述结果表明,NO可能通过调控Sl_OASTL/LCD的表达产生内源H2S诱导番茄幼苗侧根发育。

Cloning and Expression Analysis of SI_OASTL/LCD on Promoting Lateral Root Formation in Tomato （Solanum lycopersicum）

Hydrogen sulfide （H2S） is a novel gaseous signaling molecule. Previous study suggested that endogenous HES is synthesized by L-cysteine desulfhydrase （LCD） and D-cysteine desulfhydrase （DCD） in plants. We suggested that exogenous H2S could promote the growth of tomato （Solanum lycopersicum） lateral root in another research. In order to investigate the origin of endogenous H2S and the role of it in NO-modulated lateral root formation, the full-length sequence of HzS-producing gene SI_OASTL/LCD has been cloned from tomato （S. lycopersicum） root. The effect of prohibiting endogenous H2S generation in nitric oxide （NO）- induced lateral root formation in tomato （S. lycopersicum） seedling have been investigated, as well as the effect of NO on the expression of SI_OASTL/LCD. The main results are as follows. （1） Three O-acetylserine（thiol） lyase genes （SI_OASTL1, SI_OASTL2, and SI_OASTL3） have been cloned from tomato （S. lycopersicum） root. The alignment and structural analysis suggested that SI_OASTL1 might code for a H2S biosynthesis enzyme, which was designated as SI_OASTL/LCD. And there are many conserved NO- and hormone-responsive cis- elements by analyzing the promoter region of SI_OASTL/LCD. （2） Compared to the control, the growth of lateral root could be significantly inhibited under the treatment DL-propargylglycine （PAG） （a HzS biosynthesis inhibitor） and hypotaurine （HT） （a H2S scavenger）, respectively. （3） Exogenous NO donor sodium nitroprus~1d~i （SNP） could significantly induce the formation of lateral root. （4） PAG and HT could block the stimulating effect of NO on lateral root formation. （5） Treatment with SNP could stimulate the expression of SI_OASTL/ LCD in tomato （S. lycopersicum） root by RT-PCR analysis. These results suggested that NO promoted the growth of tomato （S. lycopersicum） lateral root by inducing endogenous H2S.