小偃54和小偃81高温抗条锈性及其与几丁质酶基因表达的关系

High Temperature Resistance to Stripe Rust of Xiaoyan 54 and Xiaoyan 81 and Its Correlation with the Expression of Chitinase Gene

为了探明小麦高温抗条锈性的遗传机理,以小麦条锈菌流行小种对小麦品种小偃54和小偃81进行了苗期接种鉴定,并采用RT-PCR方法从小偃54中克隆了几丁质酶基因Chi1编码区全长cDNA序列Chi1xy,利用半定量PCR技术比较分析了常温(14±1℃)和高温(21±1℃)处理下条锈菌侵染的小偃54几丁质酶基因Chi1xy的表达谱。结果表明,小偃54和小偃81均具有明显的高温抗条锈性。常温处理下,Chi1xy的表达没有明显变化,始终维持在较低水平。而高温处理下,Chi1xy的表达在处理后的前72 h变化不明显,96 h开始升高,并在144 h达到表达高峰,直到192 h仍维持较高的表达水平。两种温度处理下Chi1xy的表达谱差异显著,说明小偃54对条锈病的高温抗条锈性可能与几丁质酶基因Chi1xy的表达水平相关。这是首次发现几丁质酶和高温抗条锈性有关。

Stripe rust,caused by Puccinia striiformis f.sp.tritici,is one of the most serious wheat diseases worldwide.The most effective and economical method for controlling stripe rust is to breed and grow resistant varieties.However,single wheat variety is planted widely and stripe rust race variation occurs in high frequency,resulting in resistance of variety to stripe rust breakdown.Recently,high temperature-induced resistance to stripe rust attracts more and more attention due to its durable,non-race specific and all stage resistance.The aims of the present study are to evaluate the high temperature-induced resistance to stripe rust in common wheat varieties Xiaoyan 54 and Xiaoyan 81,and to investigate the correlation between high temperature-induced resistance and the expression of the chitinase gene.To evaluate the high temperature-induced resistance of Xiaoyan 54 and Xiaoyan 81 to stripe rust,seedlings from these two varieties were inoculated with two prevailing races of stripe rust,CY30 and CY31,and then the seedlings were separated to two groups and grew at high and normal temperature conditions,respectively.The resistance test results demonstrated that Xiaoyan54 and Xiaoyan81 both possessed apparent high temperature-induced resistance to stripe rust,suggesting that these two cultivars have high potential values in resistance breeding. To investigate the correlation between high temperature-induced resistance and the expression of chitinase,we isolated the coding region of chitinase gene Chi1 from Xiaoyan 54 by RT-PCR,named temporarily as Chi1xy.We further analyzed the expression profiles of Chi1xy in Xiaoyan54 seedlings infected with CY30 and grew under high（21±1℃） and normal（14±1℃） temperature conditions,respectively,by semi-quantitative RT-PCR.The expression profiles showed that,in normal temperature condition,the expression of the Chi1xy was kept at low level,similar to the control（non-inoculated seedlings） throughout the experimental period（up to 192 hours after treatment）.Whereas in high temperature condition,the expression of the Chi1xy was kept at low level till 72 h,similar to normal temperature treatment,but the expression level of Chi1xy was up-regulated remarkably during 96 to 192 h,and showed an expression peak at 144 h after high temperature treatment.This notable difference of the expression profiles between two temperature treatments suggested that expression level of the Chi1xy was correlated with high temperature-induced resistance to stripe rust in Xiaoyan 54. In this study,the correlation between high temperature-induced resistance to stripe rust and chitinase gene expression was reported in common wheat.Our data provided a new clue for further investigation on the genetic mechanism of high temperature-induced resistance to stripe rust in wheat.