Role of ACC-deaminase synthesizing and plant growth-promoting bacteria in reducing salt-stress in .

Unlabelled: Salinity is a significant concern in crop production, causing severe losses in agricultural yields. , also known as Holy Basil, is an important ancient medicinal plant used in the Indian traditional system of medicine. The present study explores the use of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-producing strains of plant-growth-promoting bacteria (PGPB) namely Str-8 (, Sd-6 (, Fd-2 (), Art-7 (, and Ldr-2 (, and (Th), possessing multi-functional properties like growth promotion, stress alleviation, and for enhancing yield under salt stress. The results showed that co-inoculation of Th and PGPBs enhanced plant height and fresh herb weight by 3.78-17.65% and 7.86-58.76%, respectively; highest being in Th + Fd-2 and Th + Art-7 compared to positive control plants. The doubly inoculated plants showed increased pigments, phenol, flavonoids, protein, sugar, relative water content, and nutrient uptake (Nitrogen and Phosphorous) as compared to monocultures and untreated positive control plants. In addition, co-inoculation in plants resulted in lower Na, MDA, HO, CAT, APX activities, and also lower ACC accumulation (49.75 to 72.38% compared to non-treated salt- stressed plant) in , which probably played a significant role in minimizing the deleterious effects of salinity. Finally, multifactorial analysis showed that co-inoculation of Th and PGPBs improved growth, its physiological activities, and alleviated salt stress compared to single inoculated and positive control plants. These microbial consortia were evaluated for the first time on  under salt stress. Therefore, the microbial consortia application could be employed to boost crop productivity in poor, marginalized and stressed agricultural fields.

Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-023-01328-2.