FIGURE 1.

The effects of microbial volatiles on plant abiotic stress tolerance. VOCs can modulate Arabidopsis sodium homeostasis via tissue-specific regulation of HKT1 and possibly also via the SOS pathway. Accumulation of H₂O₂ and nitric oxide is involved in the VOC-induced drought tolerance in plants. Accumulation of choline synthesized by VOC-induced PEAMT and other osmo-protectants may be a common mechanism for increasing osmotic protection in salt- or drought-stressed plants. VOCs also trigger the expression of FIT1, FRO2, and IRT1 to facilitate iron uptake and plant growth. Under conditions of sulfur starvation, plants directly take up and assimilate the S-containing compounds (e.g., dimethyl disulfide) emitted from some PGPR. See text for details.