转Xa23基因水稻的白叶枯病抗性及其遗传分析

在分离克隆抗白叶枯病基因Xa23研究中获得大量转基因水稻材料。为了系统研究转Xa23基因水稻的抗病稳定性和遗传模式, 本文通过逐株进行抗白叶枯病接种鉴定、PCR和Southern blot分子检测, 对一批转Xa23基因水稻植株进行了T₀代到T₂代的跟踪分析。结果表明, Xa23基因的整合和表达, 使感病受体品种牡丹江8号获得抗病性。由于Xa23基因插入受体基因组的位点不同, 同是单拷贝插入的转基因T₀代抗病植株, 其抗病程度有明显差异。T₀代植株的抗病程度, 可以准确、稳定地遗传到T₁代和T₂代。单拷贝转基因植株分离群体的抗感植株分离比接近3∶1, 表明转Xa23基因遵循孟德尔单基因遗传模式。已获得2个纯合的单拷贝转基因抗病株系, 它们的抗病程度稍有差别, 将用于外源基因插入位置效应分析和杂交稻抗病育种。

Genetic Analysis on Bacterial Blight Resistance of Xa23-Transgenic Rice

Transgenic rice plants were previously generated by Agrobacterium-mediated transformation during our research on molecular cloning of Xa23 gene, a bacterial blight (BB) resistance gene from the wild rice species Oryza rufipogon. To investigate the stability and inheritance of the transgene and its corresponding BB-resistance phenotype, more than 350 Xa23-trangenic rice plants from T₀, T₁, and T₂ generations were subjected to BB-pathogen inoculation, PCR and Southern blot analysis for the trans-gene. Results showed that, Xa23 gene was incorporated and expressed in the genome of the susceptible receptor rice variety Mu-danjiang 8 that acquired BB-resistance. Due to the difference of the transgene insertion sites, T₀ plants with single-copy insertion performed quite different degrees of resistance and their resistance was accurately and stably inherited to T₁ and T₂ generations. We also observed that the transgene in the single-copy insertion transgenic lines inherited following the Mendelian rules. Two homozygous, single-copy insertion transgenic lines with different resistance degrees have been obtained.