Rhizobacterial Strain Bacillus megaterium BOFC15 Induces Cellular Polyamine Changes that Improve Plant Growth and Drought Resistance

Abstract

Plant-growth-promoting rhizobacteria can improve plant growth, development, and stress adaptation. However, the underlying mechanisms are still largely unclear. We investigated the effects of Bacillus megaterium BOFC15 on Arabidopsis plants. BOFC15 produced and secreted spermidine (Spd), a type of polyamine (PA) that plays an important role in plant growth. Moreover, BOFC15 induced changes in the cellular PAs of plants that promoted an increase of free Spd and spermine levels. However, these effects were remarkably abolished by the addition of dicyclohexylamine (DCHA), a Spd biosynthetic inhibitor. Additionally, the inoculation with BOFC15 remarkably increased plant biomass, improved root system architecture, and augmented photosynthetic capacity. Inoculated plants also displayed stronger ability to tolerate drought stress than non-inoculated (control) plants. Abscisic acid (ABA) content was notably higher in the inoculated plants than in the control plants under drought stress and polyethylene glycol (PEG)-induced stress conditions. However, the BOFC15-induced ABA synthesis was markedly inhibited by DCHA. Thus, microbial Spd participated in the modulation of the ABA levels. The Spd-producing BOFC15 improved plant drought tolerance, which was associated with altered cellular ABA levels and activated adaptive responses.

The extreme plant‐growth‐promoting properties ofPantoea phytobeneficialisMSR2 revealed by functional and genomic analysis

“…phytobeneficialis MSR2 contains multiple genes involved in the biosynthesis and transport of polyamines such as putrescine, spermidine, 1,3‐diaminopropane, as well as genes involved in the biosynthesis and catabolism of GABA (Table S14). Polyamines and GABA play an important role in plant–microbe interactions and plant growth promotion activities of plant‐associated bacteria (Xie et al ., ; Bown and Shelp, ; Zhou et al ., ).…”

“…Polyamines and GABA play an important role in plantmicrobe interactions and plant growth promotion activities of plant-associated bacteria (Xie et al, 2014;Bown and Shelp, 2016;Zhou et al, 2016).…”

Exogenous Melatonin Improves Plant Iron Deficiency Tolerance via Increased Accumulation of Polyamine-Mediated Nitric Oxide

“…It has previously been reported that polyamine can stimulate the biosynthesis of NO in Arabidopsis roots [35]. Furthermore, interruption of NO release has been shown to inhibit certain effects of polyamine on plants [36,50], indicating that NO acts as a downstream transducer of polyamine-mediated signaling pathways. Intriguingly, overproduction of NO can provoke toxic effects in plants [51].…”

Rhizosphere pseudomonads as probiotics improving plant health

“…Other microbial products, such as trehalose and polyamines, could also be important to both microbe and root cell survival. Secretion of the polyamine spermidine by a PGPR Bacillus isolate is instrumental in the induction of drought tolerance in the plant host (Zhou et al, 2017). Although a role in drought tolerance awaits investigation, polyamine synthesis by P. chlororaphis O6 is linked to its biocontrol potential (Park et al, 2017).…”