Douchkov Dimitar, Lueck Stefanie, Hensel Goetz, Kumlehn Jochen, Rajaraman Jeyaraman, Johrde Annika, Doblin Monika S, Beahan Cherie T, Kopischke Michaela, Fuchs René, Lipka Volker, Niks Rients E, Bulone Vincent, Chowdhury Jamil, Little Alan, Burton Rachel A, Bacic Antony, Fincher Geoffrey B, Schweizer Patrick
Leibniz Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK) Gatersleben, Corrensstrasse 3, Stadt Seeland, 06466, Germany.
ARC Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Parkville, Vic., 3010, Australia.
New Phytol. 2016 Oct;212(2):421-33. doi: 10.1111/nph.14065. Epub 2016 Jun 28.
Cell walls and cellular turgor pressure shape and suspend the bodies of all vascular plants. In response to attack by fungal and oomycete pathogens, which usually breach their host's cell walls by mechanical force or by secreting lytic enzymes, plants often form local cell wall appositions (papillae) as an important first line of defence. The involvement of cell wall biosynthetic enzymes in the formation of these papillae is still poorly understood, especially in cereal crops. To investigate the role in plant defence of a candidate gene from barley (Hordeum vulgare) encoding cellulose synthase-like D2 (HvCslD2), we generated transgenic barley plants in which HvCslD2 was silenced through RNA interference (RNAi). The transgenic plants showed no growth defects but their papillae were more successfully penetrated by host-adapted, virulent as well as avirulent nonhost isolates of the powdery mildew fungus Blumeria graminis. Papilla penetration was associated with lower contents of cellulose in epidermal cell walls and increased digestion by fungal cell wall degrading enzymes. The results suggest that HvCslD2-mediated cell wall changes in the epidermal layer represent an important defence reaction both for nonhost and for quantitative host resistance against nonadapted wheat and host-adapted barley powdery mildew pathogens, respectively.
细胞壁和细胞膨压塑造并支撑着所有维管植物的形态。在应对真菌和卵菌病原体的攻击时，这些病原体通常通过机械力或分泌裂解酶来破坏宿主的细胞壁，植物往往会形成局部细胞壁附着体（乳突）作为重要的第一道防线。细胞壁生物合成酶在这些乳突形成过程中的作用仍知之甚少，尤其是在谷类作物中。为了研究大麦（Hordeum vulgare）中一个编码类纤维素合酶D2（HvCslD2）的候选基因在植物防御中的作用，我们通过RNA干扰（RNAi）使HvCslD2沉默，从而培育出转基因大麦植株。这些转基因植株没有生长缺陷，但白粉菌Blumeria graminis的宿主适应性、毒性和无毒非宿主分离株更成功地穿透了它们的乳突。乳突穿透与表皮细胞壁中纤维素含量降低以及真菌细胞壁降解酶的消化作用增强有关。结果表明，HvCslD2介导的表皮层细胞壁变化分别代表了非宿主以及对非适应性小麦和宿主适应性大麦白粉病病原体的数量性宿主抗性的重要防御反应。
