Seed bio-priming with ACC deaminase-producing bacterial strains alleviates impact of drought stress in Soybean (Glycine max (L.) Merr.)

Abstract

This study investigated the efficacy of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing rhizobacterial strains isolated from soybean rhizosphere to alleviate the negative impact of drought stress in soybean. Twenty rhizobacterial strains were isolated from disease-resistant soybeans, and only four isolates displayed ACC deaminase activity (more than 500 nmol of ketobutyrate mg protein−1 h−1). These strains also exhibited a variety of plant growth-promoting (PGP) traits, such as ammonia production, indole acetic acid concentration (>35 g mL−1), hydrogen cyanide (HCN) production, and solubilization of inorganic calcium orthophosphate (>70 μg mL−1). Based on 16S rDNA gene sequencing, the bacterial isolates (AKAD 1-2, AKAD 1-3, AKAD 3-1, and AKAD 3-7) were identified as Pantoea agglomerans (MH304295), Bacillus subtilis (MH304311), Bacillus cereus (MH333217), and Bacillus licheniformis (MH304284), respectively. .Seed bio-priming with these rhizobacteria improvedin vivodrought tolerance, mitigated drought stress and increased shoot length (16–68.6%), root length (40–108%), proline content (14.87–42.69%), sugar content (11.36–67.3%), and protein content (11.77–45%). The potential enzymatic activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) also increased by 35.87%, 26.63%, and 15.15%, respectively, in drought-stressed plants. The results support the efficacy of these isolates as effective bio-stimulants for improving crop performance in drought-affected agricultural fields. Thus, the present work opens new avenues for harnessing the potential of rhizobacterial bio-stimulants to address the challenges posed by drought stress in soybean cultivation, thereby advancing sustainable agricultural strategies for future food security.