Table 1. Plant growth-promoting mechanims exhibited by Plant Probiotic Bacteria in several crops.

Plant growth promotion (PGP) traits	PGP Rhizobacteria (genus level)	Crop type	References
Nitrogen fixation	Azoarcus	rice	[21]
	Azorhizobium	wheat	[22]
	Azospirillum	several cereals, sugarcane, bean, soybean	[23]–[27]
	Azotobacter	several cereals, lineseed, tobacco, sunflower, tea, coffee, coconut tree, beetroot, tomato	[28],[29],[30]
	Bacillus	rice	[31],[32]
	Brevundimonas	wheat	[33]
	Burkholderia	rice	[34],[35]
	Enterobacteriales	maize, wheat, sugarcane	[33],[36],[37]
	Frankia	Alnus	[38]
	Gluconacetobacter	sugarcane	[39]
	Herbaspirillum	sugarcane, bean, rice, sorghum, maize	[40],[41],[42]
	Paenibacillus	rice, canola	[31],[43]
	Pseudomonas	rice	[32]
	Rhizobium and related genera	leguminous plants	[44]
Phytohormone biosynthesis (auxins, gibberelings, cytokynins, ethylene and ACC desaminase synthesis)	Azobacter	cucumber	[45]
	Bacillus	potato, cucumber, oriental thuja, pepper, rice	[33],[46]–[49]
	Enterobacteriales	sugarcane, wheat, pepper, soybean	[33],[37],[50],[51]
	Hartmannibacter	summer barley	[52]
	Paenibacillus	lodgepole pine, rice, barley, wheat	[31],[53],[54]
	Phyllobacterium	Arabidopsis	[7],[55]
	Pseudomonas	wheat, mung bean	[56],[57]
	Rhizobium and related genera	pepper, tomato, lettuce, carrot, strawberries, carnation, chickpea, mung bean, hop clover	[6],[57]–[63]
	Sphinogomonas	tomato, soybean	[51],[64]
	Streptomyces	indian lilac, cocoa	[65],[66]
Phosphate solubilization	Bacillus	rice	[31]
	Burkholderia	rice	[67]
	Enterobacteriales	wheat	[33]
	Herbaspirillum	rice	[67]
	Paenibacillus	rice	[31]
	Phyllobacterium	strawberries	[7]
	Rhizobium and related genera	pepper, tomato, lettuce, carrot, strawberries, carnation, chickpea	[6],[58],[60],[61],[62]
	Streptomyces	wheat	[68]
Potassium solubilization	Bacillus	wheat, maize Sudan grass, eggplants, pepper, cucumber, cotton, rape, groundnut	[69]–[74]
	Enterobacteriales	tobacco	[74],[75]
	Frauteria	tobacco	[76]
	Microbacterium	tobacco	[75]
	Paenibacillus	black pepper	[74]
	Pseudomonas	tobacco, tea	[77]
Siderophore production	Bacillus	maize, pepper, rice	[31],[78]
	Chryseobacterium	tomato	[79]
	Enterobacteriales	wheat	[33]
	Micrococcus	maize, canola	[80]
	Phyllobacterium	strawberries	[7]
	Pseudomonas	potato, maize	[78]
	Rhizobium and related genera	pepper, tomato, lettuce, carrot, strawberries, carnation, chickpea	[6],[58],[60],[61],[62]
	Stenotrophomonas	maize, canola	[80]
	Streptomyces	indian lilac, cocoa	[65],[66]
Biocontrolers (production of plant cell wall degrading enzymes, induced disease suppression, resistance to stresses…)	Bacillus	maize, peanut, Chinese cabbage, cucumber, tomato, lettuce, banana, berries, pepper, cucumber, mint	[81]–[84]
	Enterobacteriales	tomato, wheat, apple tree	[33],[85],[86],[87]
	Mycobacterium	maize	[81]
	Paenibacillus	tomato, pepper, barley, wheat	[54],[88],[89]
	Pseudomonas	cotton, maize, pidgeon pea, wheat, rice, cucumber, tomato	[31],[81],[84],[90],[91],[92]
	Rhizobium and related genera	peanut, pidgeon pea	[82],[91]
	Streptomyces	cocoa, wheat	[66],[68]