Quantitative expression analysis of rice bacterial blight resistant candidate genes of xa7 by real-time fluorescent quantitative PCR | 水稻白叶枯病抗性基因Xa7候选基因的实时荧光定量表达分析

Chinese. 摘　　要：水稻白叶枯病抗性基因Xa7精细定位的区域包括三个与抗性相关的候选基因。为研究这三个候选基因在水稻抗性反应中的作用,本研究利用水稻白叶枯黄单胞菌SCB4-1（Ⅳ型菌）接种分别在20℃、26℃和32℃条件下栽培的感病品种IR24及其含有Xa7基因的近等基因系IRBB7,采集接种前0d（对照）,及接种后0.5d、1d、2d、3d、4d、5d和6d的叶片,通过实时荧光定量PCR技术,研究在不同温度条件下Xa7三个候选基因（CG-XA7-1、CG-XA7-2、CG-XA7-3）在IRBB7和IR24中的表达情况。研究结果表明,在20℃条件下,CG-XA7-1和CG-XA7-2在IRBB7的表达量比IR24的低,CG-XA7-3的个别时间点在IRBB7的表达量比IR24的高,但并不显著;在26℃和32℃条件下,三个候选基因在IRBB7的表达量比IR24的高。对于抗病品种IRBB7,三个候选基因在26℃时的相对表达量比在20℃和32℃的高;对于感病品种IR24,三个候选基因在20℃时的相对表达量比在26℃和32℃的高。根据白叶枯病的发生适宜气温为25～30℃,而20℃以下和33℃以上该病发生受抑制的特点,测试的三个候选基因的表达量与水稻白叶枯病抗性有较高的相关性,可能在白叶枯病抗性反应中发挥一定的作用。

English. The rice bacterial blight resistant gene of Xa7 was previously mapped at the 118.5 kb regions which contained three candidate disease resistant genes.To understand the potential function of those genes during the defense responses against bacterial blight,the susceptible variety IR24 and its near isogenic line IRBB7 which containing Xa7 gene,respectively cultivated in the condition of 20 ℃,26 ℃ and 32 ℃,were inoculated with an Xanthomonas oryzae pv.oryzae（Xoo） isolate SCB4-1（Chinese race Ⅳ）.Leaf samples were collected at 0,0.5 d,1 d,2 d,3 d,4 d,5 d and 6 days after inoculation,The expressions of three candidate genes（CG-XA7-1,CG-XA7-2 and CG-XA7-3） were analyzed by real-time fluorescent quantitative PCR technique.The results showed that,the expression levels of CG-XA7-1 and CG-XA7-2 were higher in susceptible variety IR24 than in resistant variety IRBB7 under the condition of 20 ℃,while the expression levels of CG-XA7-3 in IR24 were lower than that in IRBB7 under the condition of 26 ℃ and 32 ℃.For the IRBB7,the expressions of three Xa7 candidate genes under in the condition of 26 ℃ were much higher than those under 20 ℃ and 32 ℃,As for the IR24,the expressions of three Xa7 candidate genes under the condition of 20 ℃ were much higher than those in 26 ℃ and 32 ℃.In particular,the rice bacterial blight disease usually occurred epidemically at the temperature of 25～30 ℃,and was suppressed under the condition of below the 20 ℃ and above the 33 ℃.These results indicated that three tested candidate resistant genes might involved in the defense responses against bacterial blight.