水稻单拷贝Xa21近等转基因系的培育与抗性分析

植物转基因的表达在一定程度上受其所在宿主基因组整合位置的影响 ,通常称为转基因位置效应。利用农杆菌介导法将抗白叶枯病基因Xa21转入水稻品种明恢 63,获得带有不同转基因拷贝数的转化体。对转化体连续自交 ,并对转基因整合位点进行鉴定和筛选 ,获得了明恢63遗传背景下整合在不同染色体位点的单拷贝Xa21转基因纯合系。这些转基因系除一个单拷贝转基因整合位点外 ,在基因组水平上是等同的 ,构成了近等转基因系。经分子杂交和遗传定位验证 ,共获得明恢63遗传背景下的6个近等转基因系。对这些近等转基因系进行抗白叶枯病分析,显示出几乎相同的高抗水平。这表明整合位点对Xa21的抗性没有影响 ,不存在转基因位置效应.

Breeding and Resistance Analysis of Near Iso-transgenic Lines with a Single Copy of the Transgene Xa21 in Rice

Plant transgene expression is affected by the integration sites in host genome to some degree, which is generally termed as "transgene position effects". The bacterial blight resistance gene Xa21 was previously transferred into a rice variety, Minghui63, through Agrobacterium-mediated transformation, and transformants with different transgene copy numbers were obtained. Through self-pollination of transgenic plants, identification and selection of transgene integration sites for several generations, homozygous transgenic lines with only one copy of the transgene Xa21 located at different chromosome positions were obtained on the Minghui63 genetic background. These transgenic lines were almost identical on their genome except for their different transgene locus and could be regarded as near iso-transgenic (NIT) lines. Six NIT lines were obtained and verified through Southern hybridization and genetic mapping of the transgene. These NIT lines displayed almost the same resistance level to bacterial blight, indicating that the integration sites did not affect the resistance expression of Xa21, and there were no position effects for the transgene.