外源Ca^2＋对水杨酸诱导番茄抗灰霉病的增效机制

Synergistion mechanism of exogenous Ca^(2+) to SA-induced resistance to Botrytis cinerea in tomato

探讨了外源Ca2+对水杨酸(SA)诱导番茄抗灰霉病的增效机制.以番茄灰霉病敏感型品种‘L402’幼苗为材料,分别进行H2O(对照)、SA、SA+Ca和SA+EGTA(Ca2+螯合剂)处理,期间(1~5 d)分析各处理植株叶片活性氧(ROS)含量,苯丙氨酸解氨酶、几丁质酶和β-1,3-葡聚糖酶活性,以及病程相关蛋白编码基因PR1、PR2和PR3表达水平的变化,并调查处理3 d后灰霉病情指数.结果表明:与对照(病情指数为74.8)相比,SA、SA+Ca和SA+EGTA处理的植株叶片灰霉病的病情指数分别为46.9、38.5和70.3;SA处理明显提高叶片ROS含量以及苯丙氨酸解氨酶、几丁质酶和β-1,3-葡聚糖酶活性,这些参数在SA+Ca处理的植株中被进一步提高,但在SA+EGTA处理的植株中则被降低;SA处理明显提高了PR1、PR2a和PR3b的表达水平,Ca2+进一步加强了这一效果,而EGTA则起抑制作用.SA或SA+Ca处理期间的PR2b和PR3a表达较未处理的对照上调了1~2倍,而PR1、PR2a和PR3b上调了2~5倍.表明Ca2+对SA诱导番茄抗灰霉病具有增效作用,其机理至少与Ca2+和SA协同作用促进ROS形成有关,而ROS作为信号分子增加植株抗病相关酶活性以及PR1、PR2a和PR3b等防卫基因的表达.

In this study,we investigated the effect of exogenous calcium and salicylic acid（ SA） on Botrytis cinerea resistance in tomato seedlings. We treated a tomato strain susceptible to Botrytis cinerea with foliar spraying of water,SA,SA＋Ca Cl2 and SA＋EGTA（ Ca^2＋chelating agent） for one to five days. During the treatment,leaves were collected to analyze the reactive oxygen species（ ROS）content,phenylalanine ammonia lyase（ PAL） activity,chintase and β-1,3-glucanase levels,and the expression of pathogenesis related protein 1,2,3（ PR1,PR2,PR3）. Three days after infection,the disease index was 74.8 in control plants,and 46.9,38.5 and 70.3 in SA,SA＋Ca and SA＋EGTA treated plants,respectively. SA treatment significantly increased ROS leaf accumulation,and activities of PAL,chintase and β-1,3-glucanase. These values were further enhanced in SA ＋ Ca treated plants,but decreased in SA＋EGTA treated plants. Application of SA significantly increased the expression levels of PR1,PR2 a and PR3 b,which were further elevated by the combination treatment with Ca^2＋. These effects were counteracted by the combination treatment of SA and EGTA.The transcription levels of PR2 b and PR3 a were up-regulated by 1-2 folds,and PR1,2a and 3b by2-5 folds in SA- and SA＋Ca-treated plants relative to control. These data suggested that application of Ca^2＋could synergistically increase SA-induced resistance to B. cinerea. The resistance was associated with ROS accumulation,therefore the increase in resistance might be through ROS ability to increase the activity of defense-related enzymes and expression levels of PR1,PR2 a and PR3 b.