College of Horticulture, Northwest A&F University, Xianyang 712100, China.
Int J Mol Sci. 2021 Nov 15;22(22):12328. doi: 10.3390/ijms222212328.
Allicin compositions in garlic are used widely as fungicides in modern agriculture, in which diallyl disulfide (DADS) is a major compound. Downy mildew, caused by (), is one of the most destructive diseases and causes severe yield losses in cucumbers. To explore the potential mechanism of DADS-induced cucumber resistance to downy mildew, cucumber seedlings were treated with DADS and then inoculated with at a 10-day interval. Symptom observation showed that DADS significantly induced cucumber resistance to downy mildew. Furthermore, both lignin and HO were significantly increased by DADS treatment to responding infection. Simultaneously, the enzyme activities of peroxidase (POD) in DADS-treated seedlings were significantly promoted. Meanwhile, both the auxin (IAA) and salicylic acid (SA) contents were increased, and their related differentially expressed genes (DEGs) were up-regulated when treated with DADS. Transcriptome profiling showed that many DEGs were involved in the biological processes of defense responses, in which DEGs on the pathways of 'phenylpropanoid biosynthesis', 'phenylalanine metabolism', 'MAPK signaling', and 'plant hormone signal transduction' were significantly up-regulated in DADS-treated cucumbers uninoculated with the pathogen. Based on the results of several physiological indices and transcriptomes, a potential molecular mechanism of DADS-induced cucumber resistance to downy mildew was proposed and discussed. The results of this study might give new insight into the exploration of the induced resistance mechanism of cucumber to downy mildew and provide useful information for the subsequent mining of resistance genes in cucumber.
大蒜中的大蒜素成分被广泛用作现代农业中的杀菌剂，其中二烯丙基二硫醚（DADS）是主要化合物。由 引起的霜霉病是最具破坏性的疾病之一，会导致黄瓜严重减产。为了探索 DADS 诱导黄瓜抗霜霉病的潜在机制，用 DADS 处理黄瓜幼苗，然后每隔 10 天用 接种。症状观察表明，DADS 显著诱导黄瓜抗霜霉病。此外，DADS 处理显著增加了木质素和 HO 的含量，以应对 感染。同时，DADS 处理的幼苗中的过氧化物酶（POD）的酶活性也显著提高。同时，用 DADS 处理后，生长素（IAA）和水杨酸（SA）的含量增加，其相关差异表达基因（DEGs）上调。转录组分析表明，许多 DEGs 参与了防御反应的生物学过程，其中在未接种病原体的 DADS 处理的黄瓜中，与 '苯丙烷生物合成'、'苯丙氨酸代谢'、'MAPK 信号'和 '植物激素信号转导'途径相关的 DEGs 显著上调。基于几个生理指标和转录组的结果，提出并讨论了 DADS 诱导黄瓜抗霜霉病的潜在分子机制。本研究结果可能为探索黄瓜对霜霉病的诱导抗性机制提供新的思路，并为后续黄瓜抗性基因的挖掘提供有用信息。
