水稻穗萌抗性与OsVP1基因启动子序列及其表达水平的关系

Relation of Pre-harvest Sprouting Resistance in Rice to the Promoter Sequence and Expression of Gene OsVP1

以易穗萌的冈46B、穗萌抗性好的桂R106和深97B3个品种为材料,比较研究了穗萌抗性不同的水稻品种新鲜种子胚中OsVP1基因的表达水平及OsVP1基因的启动子序列差异。结果表明,在开花受粉后不同时间的新鲜种子胚中,桂R106和深97B中OsVP1及受其调控的下游基因OsEM的表达水平均高于冈46B;且与冈46B相比,桂R106和深97B中OsVP1基因的表达对ABA更敏感。比较3个品种的OsVP1基因启动子序列,发现易穗萌的冈46B仅有一种启动子序列,而抗穗萌的桂R106和深97B有2种类型启动子序列,其中一种与冈46B的一样,另一种与冈46B中OsVP1启动子序列相比有3处碱基差异,推断桂R106和深97B中可能存在至少2个OsVP1基因拷贝。这可能是桂R106和深97B中OsVP1基因表达水平高于冈46B,进而导致其对穗萌的抗性强于冈46B的主要原因。

The expression levels and the variance in promoter sequences of the OsVP1 gene in fresh seed embryos of rice varieties with different levels of resistance to pre-harvest sprouting（ PHS） were comparatively studied using three varieties including Gang 46B（ a PHS-susceptible variety）,Gui R106 and Shen 97B（ two anti-PHS varieties） as the materials. The results indicated that in fresh seed embryos at different days after pollination,the OsVP1 gene and its regulated downstream gene Os EM had a higher expression level in Gui R106 and Shen 97 B than in Gang 46B; in addition,the expression of OsVP1 was more sensitive to ABA in Gui R106 and Shen 97 B than in Gang 46 B. Comparison of promoter sequences of the OsVP1 gene in three varieties revealed that the PHS-susceptible variety Gang 46 B had only one promoter sequence while the anti-PHS varieties Gui R106 and Shen 97 B had two. One of them was identical to that in Gang 46 B,but the other was different at three loci from that in Gang 46 B,inferring that there existed at least two copies of the OsVP1 gene in Gui R106 and Shen 97 B. This could be the major reason why the OsVP1 gene had a higher expression level and led to a better resistance to pre-harvest sprouting in Gui R106 and Shen 97 B than in Gang 46 B.