Gupta Anmol, Rai Smita, Bano Ambreen, Sharma Swati, Kumar Manoj, Binsuwaidan Reem, Suhail Khan Mohammad, Upadhyay Tarun Kumar, Alshammari Nawaf, Saeed Mohd, Pathak Neelam
IIRC-3, Plant-Microbe Interaction and Molecular Immunology Laboratory, Department of Biosciences, Faculty of Science, Integral University, Lucknow 226026, India.
CSIR-National Botanical Research Institute, Rana Pratap Marg, Lucknow 226001, India.
Plants (Basel). 2022 Dec 7;11(24):3419. doi: 10.3390/plants11243419.
Salinity-induced ethylene production and reactive oxygen species (ROS) inhibit agricultural productivity. The plant synthesizes ethylene directly from aminocyclopropane-1-carboxylic acid (ACC). By using ACC as a nitrogen source, bacteria with ACC deaminase (ACCD) inhibit the overproduction of ethylene, thereby maintaining the ROS. The present study investigated the ACCD activity of previously identified rhizobacterial strains in Dworkin and Foster (DF) minimal salt media supplemented with 5 mM ACC (as N-source). Bacterial isolates GKP KS2_7 (Pseudomonas aeruginosa) and MBD 133 (Bacillus subtilis) could degrade ACC into α-ketobutyrate, exhibiting ACCD activity producing more than ~257 nmol of α-ketobutyrate mg protein−1 h−1, and were evaluated for other plant growth-promoting (PGP) traits including indole acetic acid production (>63 µg/mL), phosphate solubilization (>86 µg mL−1), siderophore (>20%) ammonia and exopolysaccharide production. Furthermore, Fourier Transform Infrared analysis also demonstrated α-ketobutyrate liberation from ACC deamination in DF minimal salt media, thereby confirming the ACCD activity. These isolates also showed enhanced tolerance to salinity stress of 3% w/v NaCl in vitro, in addition to facilitating multifarious PGP activities. Seed bacterization by these ACCD-producing bacterial isolates (GKP KS2_7 and MBD 133) revealed a significant decline in stress-stimulated ethylene levels and its associated growth inhibition during seedling germination. They also mitigated the negative effects of salt stress and increased the root-shoot length, fresh and dry weight of root and shoot, root-shoot biomass, total sugar, protein, reducing sugar, chlorophyll content, and antioxidants enzymes in Pisum sativum. As a result, these strains (GKP KS2_7 and MBD 133) might be applied as biofertilizers to counteract the negative effects of soil salinity.
盐分诱导的乙烯生成和活性氧（ROS）会抑制农业生产力。植物直接从1-氨基环丙烷-1-羧酸（ACC）合成乙烯。通过将ACC用作氮源，具有ACC脱氨酶（ACCD）的细菌可抑制乙烯的过量生成，从而维持ROS水平。本研究调查了先前鉴定的根际细菌菌株在补充有5 mM ACC（作为氮源）的德沃金和福斯特（DF）基本盐培养基中的ACCD活性。细菌分离株GKP KS2_7（铜绿假单胞菌）和MBD 133（枯草芽孢杆菌）可将ACC降解为α-酮丁酸，表现出ACCD活性，每毫克蛋白质每小时产生超过约257 nmol的α-酮丁酸，并对其他促进植物生长（PGP）特性进行了评估，包括吲哚乙酸生成（>63 µg/mL）、磷溶解（>86 µg mL−1）、铁载体（>20%）、氨和胞外多糖生成。此外，傅里叶变换红外分析还证明了在DF基本盐培养基中ACC脱氨产生α-酮丁酸，从而证实了ACCD活性。这些分离株除了促进多种PGP活性外，在体外对3% w/v NaCl的盐胁迫也表现出增强的耐受性。用这些产生ACCD的细菌分离株（GKP KS2_7和MBD 133）对种子进行接种处理后发现，在种子萌发过程中，胁迫刺激的乙烯水平及其相关的生长抑制显著下降。它们还减轻了盐胁迫的负面影响，增加了豌豆的根长和茎长、根和茎的鲜重和干重、根和茎生物量、总糖、蛋白质、还原糖、叶绿素含量以及抗氧化酶。因此，这些菌株（GKP KS2_7和MBD 133）可作为生物肥料来抵消土壤盐分的负面影响。
