Table 1: Benefits of microbial interactions on plants under well-watered and drought stress conditions.

Biotic Factor	Interaction Type/benefit	References
Pseudomonas putida and soybean (G.max)	Mutualistic interaction between the bacterium P. putida and soybean (G. max) under drought and saline conditions. Secretion of gibberellins by the bacterium enhanced soybean growth	[73]
Rhizobium etli 12a3 and common bean (Phaseolus vulgaris)	Mutualistic interaction between R. etli 12a3 and common bean (P. vulgaris) under drought stress condition. The bacterium enhanced plant tolerant ability of the bean plant by causing increase in proline accumulation	[47]
Bradyrhizobium diazoefficiens andAeschynomene afraspera	Symbiotic interaction with plant under well-watered condition. The microorganism enhanced host plant growth by fixing atmospheric nitrogen	[2, 74]
Rhizobium spp. and soybean (G. max)	Symbiotic interaction with plant under well-watered condition. Rhizobium inoculation with AMF prevented red crown rot disease of soybean (G. max) during symbiotic interaction	[64]
AMF and host plant	Symbiotic relationship with the host. Host plant protection against herbivore attack through common mycelial network in well-watered soil. The AMF’s common mycelial network led to the production of volatile organic compounds that attract parasitoid wasps (herbivore enemies) that destroyed the herbivore	[75]
Bacillus licheniformis K11 and pepper plant	Mutualistic interaction between the bacterium B. licheniformis and pepper plant under drought stress conditions. Accumulation of drought stress proteins and RNA in the bacterial inoculated plants made them to survive better than the non-inoculated pepper plants	[76]
Rice and species of Burkholderia and Rhizopus	Symbiotic and pathogenic interaction with plant under well-watered condition. The fungus was unable to produce spores in the absence of the endosymbiont. The endosymbiont produces rhizoxin (the causative agent of seedling blight of rice) and phytotoxin. The fungus stimulates the endosymbiont growth	[77]
R. solani and S. elegans	Parasitic relationship with the host under well-watered condition. The toxins released by the parasite (S. elegans) caused changes in R. solani growth and metabolic process leading to down regulation in the biosynthesis of several antimicrobial substances by R. solani	[44]
Mycorrhizal fungus Glomus mosseae and soybean (G. max)	Mutualistic interaction between the fungus G. mosseae and soybean (G. max) under drought stress condition. The fungus protected the plant against premature nodule senescence induced by drought stress by inducing higher glutathione reductase (GR) activity in soybean root and nodules which may have contributed to decreased oxidative damage to biomolecules involved in early nodules senescence	[78]
Erysiphe pisi and Pisum sativum	Pathogenic interaction under well-watered condition. The fungus (E. pisi) upregulated the gene coding for invertase and decreased the starch content of the host plant (P. sativum)	[79]
Azospirillum sp. And wheat plant	Mutualistic interaction between Azospirillum sp. and wheat plant under drought condition. IAA improved wheat root development and uptake of nutrients and water under drought stress	[80]
Blumeria graminis and Pisum sativum	Pathogenic interaction. The fungus (B. graminis) caused change in sugar content and down-regulation of photosynthesis in the host plant (P. sativum). under well-watered condition ‘The depression in photosynthesis was not only due to cell death and the effective removal of green leaf area, but also to an alteration in host metabolism’	[81]
A consortium of Mesorhizobium ciceri (CR-30 and CR-39), Rhizobium phaseoli (MR-2), and Rhizobium leguminosarum (LR-30) and wheat plant	Mutualistic interaction between the bacterial consortium and wheat plant under drought stress condition. The wheat plant growth, drought tolerance index and biomass were improved by IAA produced by the bacterial consortium	[82]
Bacillus subtilis QST713	Amensalistic interaction under well-watered condition. The bacterium produced antibiotic (iturin A) that helps to control damping off disease caused by Botrytis cinerea and R. solani in host plants	[83]
A Consortium of AMF and Bacillus thuringiensis/Pseudomonas and Trifolium repens	Mutualistic interaction between the microbial species (fungi and bacteria) and the plant T. repens in a natural arid soil under drought conditions. AMF/bacterial inoculation significantly enhanced the plant growth by increasing plant’s nutrient uptake and relative water content	[84]
Pantoea agglomerans C9-1	Amensalistic interaction under well-watered condition. P. agglomerans produced herbicolin (antimicrobial substance) effective against Erwinia amylovora, the causative agent of fire blight in plants	[85]
A consortium of exotic Glomus intraradices, G. deserticola and G. mosseae and the plant Juniperus oxycederus	Mutualisic interaction between the exotic mycorrhizal fungal consortium and the plant Juniperus oxycederus under drought stress conditions. Mycorrhizal fungal consortium increased root and shoot nitrate reductase by 38 and 188% respectively with respect to the plant neither treated with composted sewage sludge (SS). ‘Both the plants inoculated with exotic AM fungi and the plants grown with composted SS developed additional mechanisms to avoid oxidative damage produced under water-shortage conditions’	[86]
Pseudomonas aeruginosa Migula 7NSK2 and tomato plants	Mutualistic/antagonistic interaction. The bacterium produced pyochelin siderophore that protect tomato plants from the parasitic oomycetes (Pythium spp.) under well-watered condition	[87]
Heteroconium chaetospira and Chinese cabbage	Mutualistic interaction between the fungus H. chaetospira and the host plant Chinese cabbage under well-watered condition. H. chaetospira was found to suppress club-root disease (caused by soil-borne protozoan Plasmodiophora brassicae) on Chinese cabbage and enhanced the aboveground plant biomass of the plant in non sterile soil. The hyphae of the fungus colonized the root tissues of the plant without causing any external effects on the plant	[88]
Azospirillum lipoferum and maize	Mutualistic interaction between the bacterium Azospirillum lipoferum and maize under drought condition. Gibberellins produced by the bacterium increased abscisic acid levels and alleviated drought stress	[89]