ABSTRACT Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil microorganisms that colonize roots and stimulate plant growth. Some PGPR strains can directly regulate plant growth in the absence of physical contact with the plant, via volatile organic compounds (VOCs) emissions. Recently, we have described that Arabidopsis thaliana respond differentially to diacetyl, a VOC from Bacillus amyloliquefaciens strain GB03 (GB03), through integral modulation of the immune system and the phosphate-starvation response (PSR) system, resulting in either mutualism or immunity. Under phosphate deficient conditions, diacetyl enhances salicylic acid- and jasmonic acid-mediated immunity and consequently causes plant hyper-sensitivity to phosphate deficiency. Here, we show that application of exogenous gibberellin (GA) partially alleviates the deleterious effect caused by either B. amyloliquefaciens GB03 VOCs or diacetyl in Arabidopsis under phosphate deficient conditions, while DELLA quadruple mutant exposed to GB03 VOCs exhibits a partial reduction on the stress symptoms. Moreover, diacetyl appears to enhance DELLA protein accumulation and increase the expression of several GA deactivation-related genes. These findings suggest that the DELLA-mediated GA signaling pathway is involved in the bi-faceted role of GB03 VOCs in regulating plant growth.

中文翻译：

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细菌来源的双乙酰部分通过 DELLA 依赖性赤霉素信号通路增强拟南芥磷酸盐饥饿反应

摘要 植物生长促进根际细菌 (PGPR) 是天然存在的土壤微生物，它们定植于根部并刺激植物生长。一些 PGPR 菌株可以通过挥发性有机化合物 (VOC) 排放在与植物没有物理接触的情况下直接调节植物生长。最近，我们描述了拟南芥通过对免疫系统和磷酸盐饥饿反应 (PSR) 系统的整体调节，对双乙酰（一种来自解淀粉芽孢杆菌 GB03 (GB03) 的 VOC）有不同的反应，从而导致共生或免疫。在缺磷条件下，双乙酰增强水杨酸和茉莉酸介导的免疫，从而导致植物对缺磷的超敏反应。这里，我们表明，外源赤霉素 (GA) 的应用部分减轻了在磷酸盐缺乏条件下拟南芥中由解淀粉芽孢杆菌 GB03 VOC 或双乙酰引起的有害影响，而暴露于 GB03 VOC 的 DELLA 四重突变体表现出部分减轻应激症状。此外，双乙酰似乎增强了 DELLA 蛋白的积累并增加了几个 GA 失活相关基因的表达。这些发现表明，DELLA 介导的 GA 信号通路参与了 GB03 VOC 在调节植物生长中的双重作用。双乙酰似乎增强了 DELLA 蛋白的积累并增加了几个 GA 失活相关基因的表达。这些发现表明，DELLA 介导的 GA 信号通路参与了 GB03 VOC 在调节植物生长中的双重作用。双乙酰似乎增强了 DELLA 蛋白的积累并增加了几个 GA 失活相关基因的表达。这些发现表明，DELLA 介导的 GA 信号通路参与了 GB03 VOC 在调节植物生长中的双重作用。