Data from: 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 post-submergence ethylene production, were reduced in plants inoculated with ACC deaminase-producing wild type bacteria, as compared to plants inoculated with the ACC deaminase negative mutant. Synthesis. We demonstrate that root-associated bacteria can alter plant response to environmental stress by altering plant hormonal balance. Plant-microbes interactions may thus be an overseen driver of plant life history strategies that should be taken into account when assessing plant ecological adaptations such as abiotic stress resistance.预计未来数十年洪涝事件将愈发频发，这要求学界更深入地理解植物对淹水（submergence）的响应机制。特定的根际微生物可通过调控植物激素平衡，影响植物生长与抗逆性。我们据此提出假说：这类根际微生物的存在，可调节植物对淹水的响应。 本研究针对产ACC（1-氨基环丙烷-1-羧酸）脱氨酶的根际细菌，是否会影响耐洪涝河岸植物沼生酸模（Rumex palustris）的淹水响应展开测试。乙烯是调控植物洪涝适应的关键植物激素，而细菌的ACC脱氨酶活性可降低植物体内的乙烯水平。实验中，我们将沼生酸模植株分别接种恶臭假单胞菌UW4（Pseudomonas putida UW4）以及一株缺失ACC脱氨酶的同基因缺失突变体，随后将所有植株置于完全淹水环境中。 淹水会触发乙烯介导的响应，包括叶片伸长与地上部鲜重的增加。与接种ACC脱氨酶阴性突变体的植株相比，接种产ACC脱氨酶野生型细菌的植株，其洪涝响应（包括淹水后乙烯生成量）显著降低。 综合分析表明：根际细菌可通过调控植物激素平衡，改变植物对环境胁迫的响应。由此可见，植物-微生物互作可能是调控植物生活史策略的一类被忽视的驱动因子，在评估植物生态适应性（如非生物抗逆性）时，需将其纳入考量范围。