Abstract:
Plant growth-promoting rhizobacteria (PGPR) benefit plants through a variety of
mechanisms, including I the production of secondary metabolites such asantibiotics, cyanide,
and hormone-like substances; (ii) siderophores production; (iii) resistance to soilborne root
pathogens; (iv) phosphate solubilization; and (v) di-nitrogen fixation.
IAA, a common byproduct of L-tryptophan metabolism, translocated carbohydrates during its
synthesis and regulates important physiological processes such as cell growth, tissue
differentiation, and tactic responses in its naturally occurring form (Etesami and Beattie,
2018). It has also been reported that IAA promotes cell elongation, flowering, and fruiting
through increased osmosis and protein synthesis, while delaying abscission (Zhao et al.,
2018). IAA is produced by a variety of microorganisms, but it also serves as a growth factor
for bacteria.Many bacteria have been found to produce IAA. It is even assumed that more
than 80% of rhizosphere bacteria can synthesis IAA (Patten and Glick 1996; Khalid et al.
2004). Plant-microbe interactions occur through chemical communications in the rhizosphere, and a
three-part interaction mechanism has been noticed between plants, pathogenic microbes, and
plant-beneficial microbes. However, full knowledge on rhizosphere communications between
plants and microbes, tripartite interactions, and the biochemical impact of these interactions
on the plant metabolome is limited and poorly understood. Furthermore, the molecular and
biological processes causing PGPR impacts on induced systemic resistance (ISR) and
priming in plants remain unknown. (Mashabela MD, Piater LA, Dubery IA, Tugizimana F,
Mhlongo MI 2022).
