Endophytic Bacillus strains enhance pearl millet growth and nutrient uptake under low-P

Abstract

Bacterial endophytes are considered to have a beneficial effect on host plants, improving their growth by different mechanisms. The objective of this study was to investigate the capacity of four endophytic Bacillus strains to solubilize iron phosphate (Fe-P), produce siderophores and indole-acetic acid (IAA) in vitro, and to evaluate their plant growth promotion ability in greenhouse conditions by inoculation into pearl millet cultivated in a P-deficient soils without P fertilization, with Araxá rock phosphate or soluble triple superphosphate. All strains solubilized Fe-P and three of them produced carboxylate-type siderophores and high levels of IAA in the presence of tryptophan. Positive effect of inoculation of some of these strains on shoot and root dry weight and the N P K content of plants cultivated in soil with no P fertilization might result from the synergistic combination of multiple plant growth promoting (PGP) traits. Specifically, while B1923 enhanced shoot and root dry weight and root N P content of plants cultivated with no P added, B2084 and B2088 strains showed positive performance on biomass production and accumulation of N P K in the shoot, indicating that they have higher potential to be microbial biofertilizer candidates for commercial applications in the absence of fertilization.

Effect of Plant Growth Promoting Bacteria on the Growth of Wheat Seedlings Subjected to Phosphate Starvation

“…That may be a consequence of an IAA response related to increased root branching and more efficient nutrient uptake by the plant. Moreover, some authors suggest a direct effect of IAA-producing bacteria on shoot growth [42][43][44].…”

Plant growth promoting and antifungal activity in endophytic Bacillus strains from pearl millet (Pennisetum glaucum)

“…Emerging research evidences clearly pointed out the significance of microbiota dwelling inside the pearl millet host in offering stress tolerance as well as assistance in enhancing the survival and fitness attributes under unfavorable conditions [3,8]. So far, a wide range of bacterial species from Bacillus, Agrobacterium, Burkholderia, Azospirillum, Enterobacter, Rhizobium, Pseudomonas, and Azotobacter genera have been documented as an excellent growth-promoting endophytes in different types of crops [8][9][10][11][12][13][14][15]. Unfortunately, limited reports are available on the plant growth promoting and antifungal activity in endophytic strains of Bacillus species from pearl millet.…”

Culturable Stress-Tolerant Plant Growth-Promoting Bacterial Endophytes Associated with Adhatoda vasica

“…isolated from Eucalyptus leaves and stems have shown growthpromoting effects on Eucalyptus plantlets under controlled environment (Paz et al 2012). Recently, endophytic Bacillus strains isolated from sap, roots, and leaves of maize plants have been reported to enhance the growth and nutrient uptake of pearl millet (Ribeiro et al 2018).…”

“…Microorganisms have huge potential offering an alternative to the use of inorganic fertilizers and chemical pesticides. Most of the research related to plant growth-promoting potential of microorganisms is focused on rhizobacteria; however, there is an increasing interest in the huge potential offered by endophytic bacteria for plant growth promotion (Ribeiro et al 2018). Endophytic microorganisms produce plant growthpromoting metabolites including phytohormones, enzymes like ACC deaminase, organic acids aiding in phosphate solubilization, siderophores, cellulases, and chitinases (Vyas and Kaur 2017).…”