ABSTRACT

Bacterial 1-aminocyclopropane-1-carboxylate (ACC) deaminase is a key factor for alleviating the plant ethylene biosynthesis, which is induced by stress. The ACC deaminase-improved strains of the rice endophytic Bradyrhizobium sp. SUTN9-2, SUTN9-2 (ACCDadap) and SUTN9-2:pMG103::acdRS, exhibit 1.4- and 8.9-fold higher ACC deaminase activity than the wild type, respectively (Sarapat S, Songwattana P, Longtonglang A, Umnajkitikorn K, Girdthai T, Tittabutr P, Boonkerd N, Teaumroong N. 2020. Effects of Increased 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase Activity in Bradyrhizobium sp. SUTN9-2 on Mung Bean Symbiosis under Water Deficit Conditions. Microbes Environ. 35). The effects of these on rice growth under water deficit conditions were evaluated. The bacterial inoculations reduced ethylene synthesis, leading to a reduction in membrane destruction and the chlorophyll content of rice. Furthermore, the bacterial inoculations improved the leaf relative water content, survival, recovery rates, and improved the crop yield in field conditions. Therefore, the water deficit tolerance of rice was improved by controlling ethylene biosynthesis by improving ACC deaminase activity with endophytic SUTN9-2. Moreover, the SUTN9-2 (ACCDadap) strain can be used as a bio-inoculant under field conditions to enhance rice growth, grain yield, and enhance drought tolerance.

摘要

细菌1-氨基环丙烷-1-羧酸酯（ACC）脱氨酶是缓解植物乙烯生物合成的关键因素，该合成是由于胁迫引起的。水稻内生Bradyrhizobium sp。的ACC脱氨酶改良菌株。SUTN9-2，SUTN9-2（ACCDadap）和SUTN9-2：pMG103 :: acdRS，分别比野生型具有1.4倍和8.9倍的ACC脱氨酶活性（Sarapat S，Songwattana P，Longtonglang A，Umnajkitikorn K，Girdhai T，Tittabutr P，Boonkerd N，Teaumroong N.2020。增加1-的影响在水分亏缺条件下，根瘤菌属植物SUTN9-2中的氨基环丙烷-1-羧酸（ACC）脱氨酶对绿豆共生的影响（微生物环境，35）。评估了这些对缺水条件下水稻生长的影响。细菌接种减少了乙烯的合成，从而导致大米的膜破坏和叶绿素含量降低。此外，细菌接种提高了田间条件下叶片的相对含水量，存活率，恢复率，并提高了作物产量。因此，通过利用内生SUTN9-2提高ACC脱氨酶活性来控制乙烯的生物合成，从而提高了水稻的水分亏缺耐受性。此外，SUTN9-2（ACCDadap）菌株可以在田间条件下用作生物接种剂，以增强水稻生长，提高谷物产量并增强抗旱性。