Phytopathology. 2003 Nov;93(11):1452-9. doi: 10.1094/PHYTO.2003.93.11.1452.
ABSTRACT The resistance gene Pi-ta protects rice crops against the fungal pathogen Magnaporthe grisea expressing the avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta, originally introgressed into japonica rice from indica origin, was previously isolated by positional cloning. In this study, we report the nucleotide sequence of a 5,113-base pair region containing a japonica susceptibility pi-ta allele, which has overall 99.6% nucleotide identity to the indica Pi-ta allele conferring resistance. The intron region shows the levels of sequence diversity that typically differentiate genes from indica and japonica rices, but the other gene regions show less diversity. Sequences of the Pi-ta allele from resistant cultivars Katy and Drew from the southern United States are identical to the resistance Pi-ta sequence. Sequences from susceptible cultivars El Paso 144 and Cica 9 from Latin America define a third susceptibility haplotype. This brings the total number of Pi-ta haplotypes identified to four, including the resistance allele and three susceptibility alleles. The Pi-ta locus shows low levels of DNA polymorphism compared with other analyzed R genes. Understanding the natural diversity at the Pi-ta locus is important for designing specific markers for incorporation of this R gene into rice-breeding programs.
摘要 Pi-ta 抗性基因以基因对基因的方式保护水稻作物免受表达无毒基因 AVR-Pita 的真菌病原体稻瘟病菌的侵害。Pi-ta 最初是从籼稻中导入到粳稻中的，之前已通过定位克隆进行了分离。本研究报告了一个包含 5113 个碱基对的区域的核苷酸序列，该区域包含一个粳稻感病 pi-ta 等位基因，与赋予抗性的籼稻 Pi-ta 等位基因总体上具有 99.6%的核苷酸同一性。内含子区域显示出通常区分籼稻和粳稻基因的序列多样性水平，但其他基因区域的多样性较低。来自美国南部的抗性品种 Katy 和 Drew 的 Pi-ta 等位基因序列与抗性 Pi-ta 序列相同。来自拉丁美洲的感病品种 El Paso 144 和 Cica 9 的序列定义了第三个感病单倍型。这使已鉴定的 Pi-ta 单倍型总数达到四个，包括抗性等位基因和三个感病等位基因。与其他分析的 R 基因相比，Pi-ta 基因座显示出低水平的 DNA 多态性。了解 Pi-ta 基因座的自然多样性对于设计将该 R 基因纳入水稻育种计划的特定标记非常重要。
