Applied Plant Pathology Laboratory, Department of Studies in Botany, University of Mysore, Manasagangotri, Mysuru, 570 006, Karnataka, India.
Department of Studies in Biotechnology, University of Mysore, Manasagangotri, Mysuru, 570 006, Karnataka, India.
Microbiol Res. 2021 Dec;253:126891. doi: 10.1016/j.micres.2021.126891. Epub 2021 Oct 9.
Rhizobacteria from pearl millet were screened to produce 1-aminocyclopropane-1-carboxylate (ACC) deaminase and to evaluate its role in alleviating drought stress. Amongst 96 isolates, 28 were positive for ACC deaminase production, with MMR04 offering maximum activity of 2196.23 nmol of α-ketobutyrate produced mg of protein h. The ACC deaminase producing rhizobacteria with multiple beneficial properties along with root colonization and non-pathogenic were selected [Bacillus amyloliquefaciens (MMR04), Bacillus subtilis (MMR18) and Stenotrophomonas maltophilia (MMR36)] to confirm the presence of ACC deaminase gene. A significant enhancement in seed germination (91.75%) and seedling vigor (1213.73) was noted upon seed treatment with MMR04 and hence further evaluated for its ability to induce drought stress. The seed treatment with MMR04 improved plant growth parameters and total chlorophyll and RWC in plants grown under severe drought stress (G5) conditions compared to control plants. In addition, MMR04 seed treatment enhanced proline, APX and SOD activity while decreased the MDA content up to 2.3 fold compared to untreated plants (G5). Gene expression studies revealed a significant decrease of 3.3 and 1.8 fold in the relative expression of drought-responsive (DREB-1E) and ethylene-responsive factor (ERF-1B) marker genes, respectively and an increase of 2.2 and 2.9 fold in the relative expression of APX1 and SOD1, respectively in MMR04 treated plants grown under G5 conditions over control. The results confirmed that ACC deaminase producing B. amyloliquefaciens MMR04 could defend the pearl millet plants against drought stress through an antioxidative system, thereby warranting its application in drought stress management.
从珍珠粟中筛选出根际细菌，以生产 1-氨基环丙烷-1-羧酸（ACC）脱氨酶，并评估其在缓解干旱胁迫中的作用。在 96 个分离株中，有 28 个分离株能够产生 ACC 脱氨酶，其中 MMR04 的最大活性为 2196.23 nmol α-酮丁酸产生 mg 蛋白 h。选择具有多种有益特性、根际定殖和非致病性的 ACC 脱氨酶产生根际细菌[解淀粉芽孢杆菌（MMR04）、枯草芽孢杆菌（MMR18）和嗜麦芽寡养单胞菌（MMR36）]来确认 ACC 脱氨酶基因的存在。用 MMR04 处理种子后，种子发芽率（91.75%）和幼苗活力（1213.73）显著提高，因此进一步评估了其诱导干旱胁迫的能力。与对照植物相比，用 MMR04 处理种子可改善植物在严重干旱胁迫（G5）条件下的生长参数和总叶绿素及 RWC。此外，与未处理植物（G5）相比，MMR04 种子处理可提高脯氨酸、APX 和 SOD 活性，同时将 MDA 含量降低至 2.3 倍。基因表达研究表明，在 G5 条件下生长的用 MMR04 处理的植物中，与干旱应答（DREB-1E）和乙烯应答因子（ERF-1B）标记基因的相对表达量分别显著降低了 3.3 倍和 1.8 倍，而 APX1 和 SOD1 的相对表达量分别增加了 2.2 倍和 2.9 倍。结果证实，ACC 脱氨酶产生菌解淀粉芽孢杆菌 MMR04 可以通过抗氧化系统来防御珍珠粟植物免受干旱胁迫，因此值得在干旱胁迫管理中应用。
