Data_Sheet_1_Anthocyanins from Malus spp. inhibit the activity of Gymnosporangium yamadae by downregulating the expression of WSC, RLM1, and PMA1.pdf

Malus plants are frequently devastated by the apple rust caused by Gymnosporangium yamadae Miyabe. When rust occurs, most Malus spp. and cultivars produce yellow spots, which are more severe, whereas a few cultivars accumulate anthocyanins around rust spots, forming red spots that inhibit the expansion of the affected area and might confer rust resistance. Inoculation experiments showed that Malus spp. with red spots had a significantly lower rust severity. Compared with M. micromalus, M. ‘Profusion’, with red spots, accumulated more anthocyanins. Anthocyanins exhibited concentration-dependent antifungal activity against G. yamadae by inhibiting teliospores germination. Morphological observations and the leakage of teliospores intracellular contents evidenced that anthocyanins destroyed cell integrity. Transcriptome data of anthocyanins-treated teliospores showed that differentially expressed genes were enriched in cell wall and membrane metabolism-related pathways. Obvious cell atrophy in periodical cells and aeciospores was observed at the rust spots of M. ‘Profusion’. Moreover, WSC, RLM1, and PMA1 in the cell wall and membrane metabolic pathways were progressively downregulated with increasing anthocyanins content, both in the in vitro treatment and in Malus spp. Our results suggest that anthocyanins play an anti-rust role by downregulating the expression of WSC, RLM1, and PMA1 to destroy the cell integrity of G. yamadae.

苹果属（Malus）植物常受山田胶锈菌（Gymnosporangium yamadae Miyabe）引发的苹果锈病（apple rust）为害。锈病发生时，多数苹果属物种及栽培品种会产生黄色病斑，且病情通常较为严重；而少数栽培品种可在锈病病斑周围积累花青素（anthocyanins），形成红色病斑，此类病斑能够抑制染病区域的扩张，或可赋予植株锈病抗性。接种试验结果显示，带有红色病斑的苹果属材料锈病病情显著更轻。与山荆子（M. micromalus）相比，带红色病斑的苹果属‘普罗菲申’（M. 'Profusion'）品种积累的花青素含量更高。花青素对山田胶锈菌展现出浓度依赖性抗真菌活性，可通过抑制其冬孢子（teliospores）萌发发挥作用。形态学观察与冬孢子胞内内容物渗漏实验均证实，花青素能够破坏山田胶锈菌的细胞完整性。对经花青素处理的冬孢子进行转录组（transcriptome）分析发现，其中的差异表达基因（differentially expressed genes）显著富集于细胞壁及细胞膜代谢相关通路。在‘普罗菲申’苹果的锈病病斑处，可观察到周期性细胞与锈孢子（aeciospores）出现明显的细胞萎缩现象。此外，无论在体外处理体系还是苹果属植物体内，细胞壁与细胞膜代谢通路中的WSC、RLM1及PMA1基因的表达量均随花青素含量升高呈逐步下调趋势。本研究结果表明，花青素可通过下调WSC、RLM1及PMA1基因的表达，破坏山田胶锈菌的细胞完整性，从而发挥抗锈病作用。