Abstract

Leaf rust caused by Puccinia hordei is a major disease of barley and is best managed by deploying effective resistance genes. The effect of post-inoculation temperature [18 ± 2°C (low), 22 ± 2°C (mid), or 26 ± 2°C (high)] on the expression of a selection of known all stage resistance (ASR) Rph genes and their interaction in combination with the adult plant resistance (APR) gene Rph20 were investigated in barley. Rph1.a and Rph2.b expressed best at higher temperatures whereas Rph4.d lost its effectiveness at higher temperatures when tested with pathotype (pt) 200 P− (avirulent on these genes). The expression of the genes Rph3.c, Rph5.e, Rph6.f, Rph12 (9.z), Rph13.x and Rph15.ad was not affected by post-inoculation temperature. The interaction between Rph14.ab and pt 5457 P+ gave the lowest infection type at low post-inoculation temperature. Among a selection of lines carrying Rph20 (‘Flagship’), Rph23 (‘Yerong’) and Rph24 (‘ND24260ʹ), higher levels of resistance were observed in seedlings of ‘Flagship’ (Rph20) at lower temperatures, while seedlings of ‘Yerong’ (Rph23) and ‘ND24260ʹ (Rph24) showed high infection types at all three temperatures with pt 5457 P+. When RphASR genes were combined with the APR gene Rph20 an enhanced level of seedling resistance was observed in the six combinations: Rph1.a+Rph20, Rph2.b+Rph20, Rph4.d+Rph20, Rph9.i+Rph20, Rph5.e+Rph20 and Rph15.ad+Rph20. Seedlings carrying the Rph5.e+Rph20 combination remained resistant when challenged with the Rph5.e-virulent pt 220 P+ + Rph13, suggesting a residual effect of Rph5.e when present in combination with Rph20. This is the first study to demonstrate that several ASR Rph genes interact with the APR gene Rph20 in an additive manner, emphasizing the importance of deploying genes in combination rather than individually to achieve durable resistance.

摘要

引起叶锈病小麦大麦是大麦的主要疾病，并且最好通过部署有效的抗性基因进行管理。接种后温度 [18 ± 2°C（低）、22 ± 2°C（中）或 26 ± 2°C（高）] 对一系列已知全阶段抗性 (ASR) 表达的影响在大麦中研究了Rph基因及其与成株抗性 (APR) 基因Rph20 的相互作用。Rph1.a和Rph2.b在较高温度下表达最好，而Rph4.d在用病理型 (pt) 200 P−（对这些基因无毒）进行测试时在较高温度下失去其效力。Rph3.c、Rph5.e基因的表达, Rph6.f , Rph12 (9.z) , Rph13.x和Rph15.ad不受接种后温度的影响。Rph14.ab和 pt 5457 P+之间的相互作用在低接种后温度下产生最低的感染类型。在选择携带Rph20 ('Flagship')、Rph23 (' Yerong ') 和Rph24 ('ND24260ʹ) 的品系中，在较低温度下在'Flagship' ( Rph20 ) 的幼苗中观察到更高水平的抗性，而' Yerong ' ' ( Rph23 ) 和 'ND24260ʹ ( Rph24 ) 在所有三个温度下都显示出高感染类型，pt 5457 P+。当RphASR 基因与 APR 基因Rph20结合，在六种组合中观察到幼苗抗性水平增强：Rph1.a + Rph20、Rph2.b + Rph20、Rph4.d + Rph20、Rph9.i + Rph20、Rph5.e + Rph20和Rph15.ad + Rph20。携带幼苗Rph5.e + Rph20当与挑战组合保持耐Rph5.e -virulent PT 220 P + + Rph13，提示的残留效果Rph5.e当与Rph20结合使用时。这是第一项证明几个 ASR Rph基因以加性方式与 APR 基因Rph20相互作用的研究，强调了将基因组合而不是单独部署以实现持久抗性的重要性。