Pseudomonas putida Facilitates Pearl Millet Growth in Cold Environments and Alleviates Drought Stress by Modulating Phytohormone, Antioxidant, and Secondary Metabolite Pathways

Abstract

Pearl millet (Pennisetum glaucum (L.) R. Br.), a vital C4 Panicoid millet crop, predominantly thrives in rainfed regions subject to various abiotic stresses, notably drought and cold stress, limiting its growth potential and yield. As climate change exacerbates water scarcity, understanding methods to mitigate drought's adverse effects becomes crucial. However, particular bacteria flourishing in the rhizosphere, demonstrating resilience to drought and skilled at nurturing plant health, are recognized for their ability to enhance growth under various abiotic stresses. The current study demonstrated the varying effects of Pseudomonas putida MTCC5279 (RA) on mitigating drought stress under low-temperature field conditions for the pearl millet genotypes PRLT2/89–33 (drought-tolerant) and H77/833–2 (drought-resistant). Plants of both genotypes are grown till panicle emergence and subjected to drought stress at the start of January where temperature also drops in field conditions. The compound effect of drought with low temperature severely affects the inflorescence of both the genotypes but RA-inoculated PRLT2/89–33 plants have better performance than their respective control and drought plants as well compared to H77/833–2 genotypes. Abiotic stresses markedly influenced growth metrics, osmolyte buildup, MDA levels, and the capability to scavenge reactive oxygen species (ROS), all of which saw positive modulation following the application of RA in PRLT2/89–33. To our knowledge, this study represents the first comprehensive examination of P. putida-mediated plant growth enhancement in pearl millet under the combined effects of abiotic stresses.