Plant-microbe interactions play a key role in alleviating the impacts of abiotic and biotic stresses on plant health and production. Gene specific NGS techniques can be employed to enable a better understanding of the factors influencing the diversity and dynamics of specific microbial functional groups. Climate change induced fluctuations in the amount and pattern of rainfall, across Australia and worldwide, exposing crops to multiple water stress conditions pose most difficult challenges facing agricultural sustainability and food security. Soil bacteria that produce 1-Aminocyclopropane-1-Carboxylic Acid (ACC) Deaminase have been shown to promote plant growth under abiotic stresses such as water stress by lowering stress ethylene levels through deamination of ACC. Using gene specific primers for the bacterial gene encoding ACC deaminase (acdS), we examined the diversity (NGS sequencing) and abundance (qPCR) of ACC deaminase positive bacteria in soils and plants from cropping fields in South and Western Australia and Central Himalaya Kumaun region, India.
A total of 25 genera mostly belonging to the phyla Proteobacteria and Actinobacteria accounted for the majority of acdS gene harbouring microbes in Australian and Indian soils and wheat roots. Bacteria belonging to the Comamonadaceae and Bradyrhizobiaceae families were the most abundant groups. However, significant differences were observed in the acdS community composition at the genus level e.g. Acidovorax, Variovorax, Bradyrhizobium, Ensifer and Methylibium. Also, significant differences were observed between wheat cultivars and water-stress conditions in both countries. Beta diversity analysis indicated significant variation in acdS-community composition between locations (South Australia, Western Australia and North India), plant type (wheat vs. perennial grasses) and varieties. Panicum coloratum L. cv. Bambatsi, a summer active perennial c4 grass, supported greater diversity (chao1 and Shannon indices) of acdS gene harbouring microbiome in roots. These results indicate that although edaphic and environmental factors are the major drivers of acdS community, a cultivar-based selection of specific genera may be occurring suggesting a variety-based response in terms of plant-acdS community interactions.