ABA和NO在印度梨形孢提高玉米苗期抗旱性的作用

Effect of ABA and NO on Improving Drought Tolerance of Zea mays L. at Seedling Stage by Piriformospora indica

为明确脱落酸(ABA)和一氧化氮(NO)在印度梨形孢调控玉米耐旱性中的作用,本研究采用15%的聚乙二醇(PEG)对接种及未接种印度梨形孢的玉米幼苗进行模拟干旱胁迫,比较分析两者在受干旱胁迫后ABA含量、NO含量以及NO处理后程序性细胞死亡(PCD)相关基因表达水平的差异。分析表明:接种印度梨形孢能明显缓解PEG模拟干旱胁迫对玉米生长的抑制作用。在干旱条件下,印度梨形孢接种处理的玉米叶片中的ABA含量高于未接种处理玉米叶片。接种印度梨形孢能显著诱导玉米叶片中ABA合成关键基因ZEP的表达,与叶片中ABA含量的积累情况类似。在干旱胁迫条件下,接种印度梨形孢的玉米叶片中NO含量高于未接种处理的玉米叶片。在NO供体硝普钠(SNP)处理5 d后,ZEP基因的表达量在根和叶片中显著增加。在SNP处理3 d和5 d后,玉米叶片中抗病相关基因Rp1-D21上调表达,而在根中Rp1-D21基因的表达被抑制。接种印度梨形孢能诱导Rp1-D21基因在玉米根和叶中的表达。Bax-I基因在接种印度梨形孢的玉米叶片和根系中相较于未接种的植株更早且更剧烈地被诱导表达。研究表明,印度梨形孢通过调节ABA、NO以及程序性细胞死亡相关基因的表达来提高玉米的抗旱能力。

To illuminate the role of ABA and NO in the regulation of drought tolerance of maize by Piriformospora indica, this study used 15% PEG to simulate drought stress in maize seedlings inoculated and uninoculated with Piriformospora indica. The differences of ABA content, NO content and the expression level of programmed cell death（PCD） related genes after NO treatment were compared and analyzed. Results showed that the inoculation of P. indica could significantly alleviate the damage to maize caused by 15% PEG-6000 induced drought stress.Under drought stress, the ABA content in P. indica inoculated maize was higher than uninoculated maize. P. indica inoculation also induced the key gene ZEP that responsible for ABA biosynthesis which was consistent with the change of ABA content. The NO content in P. indica inoculated maize was higher than uninoculated maize after drought treatment. After the NO donor SNP treatment for 5 days, the expression of ZEP in leaves and root significantly increased. The expression level of pathogen resistance related gene Rp1-D21 was enhanced in maize leaves while it was inhabited in roots after SNP treatment for 3 d and 5 d. The inoculation of P. indica could induce the expression of Rp1-D21 gene in leaves and root of maize. The induction of Bax-I in leaves and root of P. indica inoculated maize was stronger than that in uninoculated maize. In conclusion, P. indica could improve the drought tolerance through regulating the expression of ABA, NO and genes related to programmed cell death.