ACC deaminase-producing rhizosphere bacteria modulate plant responses to flooding

Flooding events are predicted to increase over the coming decades, calling for a better understanding of plant responses to submergence. Specific root-associated microbes alter plant hormonal balance, affecting plant growth and stress tolerance. We hypothesized that the presence of such microbes may modulate plant responses to submergence. We tested whether root-associated bacteria producing the enzyme ACC (1-aminocyclopropane-1-carboxylate) deaminase affect submergence responses in Rumex palustris, a flood tolerant riparian plant. Ethylene is a key plant hormone regulating flood–associated acclimations and ACC deaminase activity of bacteria may decrease ethylene levels in the plant. Rumex palustris plants were inoculated with Pseudomonas putida UW4 or an isogenic mutant lacking ACC deaminase, and subsequently exposed to complete submergence. Submergence triggered ethylene-mediated responses, including an increase in leaf elongation and shoot fresh weight. Flood responses, including p...未来数十年间，洪涝事件预计将呈愈发频发的趋势，这要求学界进一步深化对植物淹没响应机制的理解。特定的根关联微生物可重塑植物体内的激素平衡，进而调控植物生长与胁迫耐受性。我们提出假说：这类根关联微生物的存在，或可调控植物对淹没胁迫的响应。 本研究以耐洪涝的河岸植物沼生酸模（Rumex palustris）为实验材料，探究能够合成ACC（1-氨基环丙烷-1-羧酸）脱氨酶（ACC deaminase）的根相关细菌，是否会影响该植物的淹没响应。乙烯（Ethylene）是调控植物洪涝适应过程的关键植物激素，而细菌的ACC脱氨酶活性可降低植物体内的乙烯含量。我们将沼生酸模植株分别接种恶臭假单胞菌（Pseudomonas putida）UW4菌株，以及一株缺失ACC脱氨酶活性的等基因突变株，随后将其置于完全淹没环境中进行胁迫处理。 淹没胁迫触发了乙烯介导的植物响应，包括叶片伸长速率提升与地上部鲜重增加。洪涝响应包括……