Department of Environmental and Biological Chemistry, Chungbuk National University, Cheongju, Chungbuk, 28644, Republic of Korea.
Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, 51006, Tartu, Estonia.
Planta. 2019 Jun;249(6):1903-1919. doi: 10.1007/s00425-019-03139-w. Epub 2019 Mar 15.
Inoculation of endophytic Methylobacterium oryzae CBMB20 in salt-stressed rice plants improves photosynthesis and reduces stress volatile emissions due to mellowing of ethylene-dependent responses and activating vacuolar H-ATPase. The objective of this study was to analyze the impact of ACC (1-aminocyclopropane-1-carboxylate) deaminase-producing Methylobacterium oryzae CBMB20 in acclimation of plant to salt stress by controlling photosynthetic characteristics and volatile emission in salt-sensitive (IR29) and moderately salt-resistant (FL478) rice (Oryza sativa L.) cultivars. Saline levels of 50 mM and 100 mM NaCl with and without bacteria inoculation were applied, and the temporal changes in stress response and salinity resistance were assessed by monitoring photosynthetic characteristics, ACC accumulation, ACC oxidase activity (ACO), vacuolar H ATPase activity, and volatile organic compound (VOC) emissions. Salt stress considerably reduced photosynthetic rate, stomatal conductance, PSII efficiency and vacuolar H ATPase activity, but it increased ACC accumulation, ACO activity, green leaf volatiles, mono- and sesquiterpenes, and other stress volatiles. These responses were enhanced with increasing salt stress and time. However, rice cultivars treated with CBMB20 showed improved plant vacuolar H ATPase activity, photosynthetic characteristics and decreased ACC accumulation, ACO activity and VOC emission. The bacteria-dependent changes were greater in the IR29 cultivar. These results indicate that decreasing photosynthesis and vacuolar H ATPase activity rates and increasing VOC emission rates in response to high-salinity stress were effectively mitigated by M. oryzae CBMB20 inoculation.
内生甲基杆菌 CBMB20 接种可提高盐胁迫下水稻的光合作用并减少胁迫挥发性排放，这归因于乙烯依赖性反应的缓和和液泡 H+-ATP 酶的激活。本研究旨在通过控制 ACC（1-氨基环丙烷-1-羧酸）脱氨酶产生的甲基杆菌 CBMB20 在盐敏感（IR29）和中度耐盐（FL478）水稻（Oryza sativa L.）品种对盐胁迫的适应中的作用来分析其对光合作用特性和挥发性排放的影响。施加了 50 mM 和 100 mM NaCl 盐水水平以及有无细菌接种，通过监测光合作用特性、ACC 积累、ACC 氧化酶活性（ACO）、液泡 H+-ATP 酶活性和挥发性有机化合物（VOC）排放来评估胁迫响应和耐盐性的时间变化。盐胁迫显著降低了光合速率、气孔导度、PSII 效率和液泡 H+-ATP 酶活性，但增加了 ACC 积累、ACO 活性、绿叶挥发物、单萜和倍半萜以及其他胁迫挥发物。这些响应随着盐胁迫和时间的增加而增强。然而，用 CBMB20 处理的水稻品种表现出提高的植物液泡 H+-ATP 酶活性、光合作用特性和降低的 ACC 积累、ACO 活性和 VOC 排放。在 IR29 品种中，细菌依赖性变化更大。这些结果表明，通过接种甲基杆菌 CBMB20，有效减轻了高盐胁迫下光合作用和液泡 H+-ATP 酶活性的降低以及 VOC 排放率的增加。
