Lehrstuhl für Phytopathologie, Technische Universität München Emil-Ramann-Straße 2, D-85354 Freising-Weihenstephan, Germany.
Mol Plant Microbe Interact. 2017 Nov;30(11):906-918. doi: 10.1094/MPMI-04-17-0088-R. Epub 2017 Sep 11.
Plant RBOH (RESPIRATORY BURST OXIDASE HOMOLOGS)-type NADPH oxidases produce superoxide radical anions and have a function in developmental processes and in response to environmental challenges. Barley RBOHF2 has diverse reported functions in interaction with the biotrophic powdery mildew fungus Blumeria graminis f. sp. hordei. Here, we analyzed, in detail, plant leaf level- and age-specific susceptibility of stably RBOHF2-silenced barley plants. This revealed enhanced susceptibility to fungal penetration of young RBOHF2-silenced leaf tissue but strongly reduced susceptibility of older leaves when compared with controls. Loss of susceptibility in old RBOHF2-silenced leaves was associated with spontaneous leaf-tip necrosis and constitutively elevated levels of free and conjugated salicylic acid. Additionally, these leaves more strongly expressed pathogenesis-related genes, both constitutively and during interaction with B. graminis f. sp. hordei. Together, this supports the idea that barley RBOHF2 contributes to basal resistance to powdery mildew infection in young leaf tissue but is required to control leaf cell death, salicylic acid accumulation, and defense gene expression in older leaves, explaining leaf age-specific resistance of RBOHF2-silenced barley plants.
植物 RBOH（呼吸爆发氧化酶同源物）-型 NADPH 氧化酶产生超氧阴离子自由基，在发育过程和应对环境挑战中具有功能。大麦 RBOHF2 在与生物亲和性的禾本科白粉菌 Blumeria graminis f. sp. hordei 的相互作用中有多种报道的功能。在这里，我们详细分析了稳定沉默 RBOHF2 的大麦植物在叶片水平和年龄特异性上的易感性。结果表明，与对照相比，年轻的 RBOHF2 沉默叶片组织对真菌穿透的易感性增强，但衰老叶片的易感性显著降低。衰老的 RBOHF2 沉默叶片中易感性的丧失与自发的叶尖坏死和游离及结合水杨酸的水平升高有关。此外，这些叶片中与病程相关的基因表达水平更高，无论是在与 B. graminis f. sp. hordei 相互作用时还是在非诱导条件下。综上所述，这表明大麦 RBOHF2 有助于对年轻叶片组织中白粉病感染的基础抗性，但需要控制衰老叶片中的细胞死亡、水杨酸积累和防御基因表达，从而解释了 RBOHF2 沉默大麦植物的叶片年龄特异性抗性。
