Background and aims

Microbial volatile organic compounds (mVOCs) play crucial roles in plant growth regulation and induce systemic resistance. Rhodopseudomonas palustris strain PS3 exhibits significant plant growth-promoting effects on various plants. This study aimed to elucidate the roles and mechanisms by which R. palustris mVOCs promote the growth of Arabidopsis thaliana and Chinese cabbage, and to explore their potential for biocontrol in Chinese cabbage.

Methods

Arabidopsis thaliana Col-0 and Chinese cabbage were cultivated to evaluate the plant growth-promoting traits and biocontrol activities of R. palustris mVOCs in both sterilized soil and natural soil. The compositions of mVOCs from PS3 and YSC3 strains were determined via GC‒MS, and the transcript levels in the plants and fungus were examined via RT‒qPCR.

Results

PS3 mVOCs remarkably promoted A. thaliana growth, increasing fresh weight, root length, and lateral root numbers, while YSC3 mVOCs only increased the number of lateral roots. The most effective PS3 mVOCs were identified as nonadecane, hexadecane, and ethyl acetate, and nonadecane showed superior effects. PS3 mVOCs activated the expression of auxin-responsive genes (SAUR38 and EXP14) in A. thaliana. Additionally, treating Chinese cabbage with PS3 mVOCs not only promoted its growth but also helped suppress leaf spot disease caused by Alternaria alternata.

Conclusions

These findings suggest that PS3 mVOCs promote plant growth by influencing auxin-responsive genes to stimulate root development. It also inhibits fungal pathogens by suppressing melanin synthesis, reducing foliar diseases in leafy vegetables. These results suggest that PS3 mVOCs could serve as an effective biostimulant and biocontrol agent for improving crop health in sustainable agriculture.

中文翻译：

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红假单胞菌衍生的微生物挥发性有机化合物对植物生长和生物防治的有益影响

 背景和目标

微生物挥发性有机化合物 （mVOCs） 在植物生长调节和诱导系统性耐药性中起着至关重要的作用。Rhodopseudomonas palustris 菌株 PS3 对各种植物表现出显着的植物生长促进作用。本研究旨在阐明 R. palustris mVOCs 促进拟南芥和大白菜生长的作用和机制，并探讨它们在大白菜中生物防治的潜力。

 方法

拟南芥以 Col-0 和大白菜为原料，评价 R. palustris mVOCs 在无菌土壤和天然土壤中的植物促生长特性和生防活性。通过 GC\u2012MS 测定 PS3 和 YSC3 菌株中 mVOCs 的组成，并通过 RT\u2012qPCR 检测植物和真菌中的转录水平。

 结果

PS3 mVOCs显著促进了拟南芥的生长，增加了鲜重、根长和侧根数，而YSC3 mVOCs仅增加了侧根数。最有效的 PS3 mVOCs 被鉴定为壬十烷、十六烷和乙酸乙酯，壬十烷表现出优异的效果。PS3 mVOCs 激活拟南芥生长素反应基因 （SAUR38 和 EXP14） 的表达。此外，用 PS3 mVOCs 处理大白菜不仅促进了其生长，还有助于抑制由链格孢菌引起的叶斑病。

 结论

这些发现表明，PS3 mVOCs 通过影响生长素响应基因刺激根系发育来促进植物生长。它还通过抑制黑色素合成来抑制真菌病原体，减少叶菜中的叶面病害。这些结果表明，PS3 mVOCs 可以作为一种有效的生物刺激剂和生物防治剂，以改善可持续农业中的作物健康。