State Key Laboratory of Agrobiotechnology and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China.
J Integr Plant Biol. 2012 May;54(5):321-9. doi: 10.1111/j.1744-7909.2012.01112.x. Epub 2012 Apr 13.
rhm1 is a major recessive disease resistance locus for Southern corn leaf blight (SCLB). To further narrow down its genetic position, F(2) population and BC(1) F(1) population derived from the cross between resistant (H95(rhm) ) and susceptible parents (H95) of maize (Zea mays) were constructed. Using newly developed markers, rhm1 was initially delimited within an interval of 2.5 Mb, and then finally mapped to a 8.56 kb interval between InDel marker IDP961-503 and simple sequence repeat (SSR) marker A194149-1. Three polymorphic markers IDP961-504, IDP B2-3 and A194149-2 were shown to be co-segregated with the rhm1 locus. Sequence analysis of the 8.56 kb DNA fragment revealed that it contained only one putative gene with a predicted amino acid sequence identical to lysine histidine transporter 1 (LHT1). Comparative sequence analysis indicated that the LHT1 in H95(rhm) harbors a 354 bp insertion in its third exon as compared with that of susceptible alleles in B73, H95 and Mo17. The 354 bp insertion resulted in a truncation of the predicted protein of candidate resistance allele (LHT1-H95(rhm) ). Our results strongly suggest LHT1 as the candidate gene for rhm1 against SCLB. The tightly linked molecular markers developed in this study can be directly used for molecular breeding of resistance to Southern corn leaf blight in maize.
rhm1 是玉米南方叶斑病（SCLB）的一个主要隐性抗病基因位点。为了进一步缩小其遗传位置，构建了来自玉米抗性（H95(rhm)）和亲本感病（H95）杂交的 F2 群体和 BC1F1 群体。利用新开发的标记，rhm1 最初被限定在 2.5 Mb 的区间内，然后最终映射到 InDel 标记 IDP961-503 和简单重复序列（SSR）标记 A194149-1 之间的 8.56 kb 区间内。三个多态性标记 IDP961-504、IDP B2-3 和 A194149-2 与 rhm1 位点共分离。该 8.56 kb DNA 片段的序列分析表明，它仅包含一个假定基因，其预测的氨基酸序列与赖氨酸组氨酸转运蛋白 1（LHT1）完全相同。比较序列分析表明，与 B73、H95 和 Mo17 的感病等位基因相比，H95(rhm) 中的 LHT1 在其第三外显子中含有 354 bp 的插入。354 bp 的插入导致候选抗性等位基因（LHT1-H95(rhm)）的预测蛋白截短。我们的研究结果强烈表明 LHT1 是 SCLB 的候选基因。本研究中开发的紧密连锁的分子标记可直接用于玉米南方叶斑病抗性的分子育种。
