ACC Deaminase Producing Plant Growth Promoting Bacteria: Mechanisms, Stress Mitigation and Prospects for Sustainable Agriculture.

ACC deaminase producing plant growth promoting bacteria have emerged as an effective biological solution to alleviate ethylene inhibition in plants exposed to stress. Central to stress mitigation, 1-aminocyclopropane-1-carboxylate (ACC) deaminase (AcdS) cleaves ACC to α-ketobutyrate and ammonia lowering stress-ethylene and sustaining growth. This review emphasis on advances in the structure, function, regulation of ACC deaminase and enzymatic control of ACC under diverse environmental conditions. It provides an insight of how ACC is released by roots, transported in the rhizosphere and taken up by beneficial bacteria. The AcdS activity influences auxin-ethylene balance to support better root growth and stress tolerance. ACC deaminase-producing PGPB belonging to genera such as Enterobacter, Bacillus, Pseudomonas, Lysinibacillus, Methylobacterium, Achromobacter, and Halobacillus have been widely reported to alleviate abiotic stresses including salinity, drought, temperature extremes, and heavy metal toxicity in major crops like wheat, rice, maize, and tomato. Future prospects include enhancing AcdS efficiency and stability through advanced molecular approaches and developing robust bioformulations for scalable field distribution in stress-resilient agriculture. The present review integrates structural, mechanistic and translational insights to guide scalable deployment of ACC deaminase producing PGPB for stress management.