Plant–Actinobacteria Interactions for Biotic and Abiotic Stress Management in Crops

Environmental stresses are key constraints that reduce plant growth and development, which further leads to reduction in yield agricultural production. Interestingly, among the many beneficial soil microorganisms, plant-associated rhizosphere and endophytic actinobacteria constitute a high proportion of the microbial biomass in soil and can produce a wide range of secondary metabolites, which endorses plant growth by reducing the inhibitory effects of biotic stresses caused by phytopathogenic bacteria, fungi, nematodes, viruses, etc. In addition, recent reports highlight actinobacterial association for plant growth promotion by reducing ill effects of several abiotic stresses induced on crop plants by salinity, drought, heavy metals, and temperature. These stresses are considered the main source of yield reduction in many crops. Plant growth-promoting actinobacteria that are able to tolerate these extreme environments help plants to survive under above-stress condition through direct and indirect mechanisms. Endophytic and rhizosphere actinobacteria also play a role in increasing the accumulation of plant fitness factors such as relative water content, proline content, total sugar content, enhanced photosynthesis activity, catalyze activity, and antioxidant synthesis in plants, which improve their resistance to environmental stresses. This chapter particularly emphasizes the perceptions of biotic and abiotic stress ecosystems in plant-associated actinobacteria and the mechanism in acquiring the characteristic feature of adaptive responses and their application in biotic and abiotic stress management in different crop plants.