Abstract：
Barley cultivation is adversely affected by high-temperature stress, which may modulate plant defense responses to pathogens such as barley powdery mildew (Blumeria graminis f. sp. hordei, Bgh). Earlier research focused mainly on the influence of short-term heat stress (heat shock) of barley on Bgh infection. In this study, our aim was to investigate the effects of both short- and long-term heat stress (35 °C from 30 s to 5 days) on Bgh infection in the barley cultivar Ingrid and its near-isogenic lines containing different powdery mildew resistance genes (Mla12, Mlg, and mlo5) by analyzing symptom severity and Bgh biomass with RT-qPCR. The expression of selected barley defense genes (BAX inhibitor-1, Pathogenesis- related protein-1b, Respiratory burst oxidase homologue F2, and Heat shock protein 90-1) was also monitored in plants previously exposed to heat stress followed by inoculation with Bgh. We demonstrated that pre-exposure to short- and long-term heat stress negatively affects the resistance of all resistant lines manifested by the appearance of powdery mildew symptoms and increased Bgh biomass. Furthermore, prolonged heat stress (48 and 120 h) enhanced both Bgh symptoms and biomass in susceptible wild-type Ingrid. Heat stress suppressed and delayed early defense gene activation in resistant lines, which is a possible reason why resistant barley became partially susceptible to Bgh.
摘要：
大麦栽培受到高温胁迫的不利影响,可以调节植物对病原体的防御反应，例如大麦白粉病（Blumeriagraminisf.sp.hordei,Bgh）。早期的研究主要集中在大麦的短期热应激（热休克）对Bgh感染的影响上。在这项研究中,我们的目的是研究短期和长期热胁迫（35°C，30s至5天）对大麦品种Ingrid及其含有不同白粉病抗性基因的近等基因系的Bgh感染的影响（Mla12，Mlg，和mlo5）通过RT-qPCR分析症状严重程度和Bgh生物量。选择的大麦防御基因的表达（BAX抑制剂-1，致病基因相关蛋白-1b，还在先前暴露于热胁迫的植物中监测了呼吸爆发氧化酶同源物F2和热休克蛋白90-1），然后接种了Bgh。我们证明，暴露于短期和长期热应激对所有抗性系的抗性产生负面影响，表现为出现白粉病症状和增加的Bgh生物量。此外，长时间的热应激（48和120小时）增强了易感野生型Ingrid的Bgh症状和生物量。热应激抑制和延迟抗性系中的早期防御基因激活，这是抗性大麦对Bgh部分易感的可能原因。
