Phytopathology. 2007 Sep;97(9):1083-93. doi: 10.1094/PHYTO-97-9-1083.
ABSTRACT The Lr34/Yr18 resistance gene provides durable, adult-plant, slow rusting resistance to leaf rust, yellow rust, and several other diseases of wheat. Flag leaves may exhibit spontaneous leaf tip necrosis and tips are more resistant than leaf bases. Despite the importance of this gene, the mechanism of resistance is unknown. Patterns of expression for 55,052 transcripts were examined by microarray analysis in mock-inoculated flag leaves of two pairs of wheat near isogenic lines for Lr34/Yr18 (Jupateco 73S/Jupateco 73R and Thatcher/Thatcher-Lr34). The Thatcher isolines were also examined for patterns of expression after inoculation with leaf rust. Mock-inoculated leaf tips of resistant plants showed up-regulation of 57 transcripts generally associated with ABA inducibility, osmotic stress, cold stress, and/or seed maturation. Several transcripts may be useful as expression markers for Lr34/Yr18. Five transcripts were also up-regulated in resistant leaf bases. The possible role of these transcripts in resistance is discussed. In mock-inoculated plants, pathogenesis-related (PR) proteins were not up-regulated in resistant flag leaves compared with that in susceptible flag leaves. In inoculated plants, the same set of PR proteins was up-regulated in both resistant and susceptible flag leaves. However, expression was often higher in resistant plants, suggesting a possible role for Lr34/Yr18 in priming of defense responses.
摘要 Lr34/Yr18 抗性基因提供了对叶锈病、条锈病和小麦其他几种病害的持久、成株期、慢锈性抗性。旗叶可能表现出自发的叶尖坏死，叶尖比叶基更具抗性。尽管该基因很重要，但抗性机制尚不清楚。通过微阵列分析，在两对携带 Lr34/Yr18 的近等基因系（Jupateco 73S/Jupateco 73R 和 Thatcher/Thatcher-Lr34）的模拟接种旗叶中，检查了 55052 个转录本的表达模式。还检查了 Thatcher 近等基因系在接种叶锈后的表达模式。在抗性植株的模拟接种叶尖中，57 个转录本通常与 ABA 诱导、渗透胁迫、冷胁迫和/或种子成熟相关，表现出上调。几个转录本可能可作为 Lr34/Yr18 的表达标记。在抗性叶基中也上调了 5 个转录本。讨论了这些转录本在抗性中的可能作用。在模拟接种的植株中，与感病旗叶相比，抗性旗叶中病程相关（PR）蛋白没有上调。在接种植株中，同一组 PR 蛋白在抗性和感病旗叶中均上调。然而，在抗性植株中表达通常更高，表明 Lr34/Yr18 可能在防御反应的启动中起作用。
