Arbuscular mycorrhiza enhances drought tolerance of tomato plants by regulating the 14-3-3 genes in the ABA signaling pathway

Arbuscular mycorrhizal (AM) fungi can substantially contribute to plant water uptake and drought tolerance. However, few studies examined whether AM symbiosis regulates the key functional genes in plant signaling under drought stress. The objective of present study was to investigate the influence of AM symbiosis on the expression of 14-3-3 genes (key genes in ABA signaling pathway) and plant adaptation to water deficit. The ABA-deficient tomato (Solanum lycopersicum) mutant notabilis (not) and its wild-type (wt) were cultivated with or without AM fungus Rhizophagus intraradices under well-watered or drought-stressed conditions. Plant phosphorus (P) concentration, transpiration rate (Tr), water use efficiency (WUE) and expression of 14-3-3 genes (TFT1-TFT12) were determined. The results indicated that mycorrhizal inoculation significantly increased shoot P concentrations of wt plants regardless of water regimes, and increased root P concentrations of the two genotypes under well-watered conditions. AM significantly up-regulated the expression of TFT2 and TFT3 in wt plants under drought stress. The decreased Tr led to increase of WUE and enhanced drought tolerance of wt plants. For not plants, AM significantly up-regulated the expression of TFT5, TFT7, TFT9 and TFT10 under drought stress, which subsequently altered the response of Tr to drought and prevented the decrease in WUE. The study supported that AM symbiosis could modulate the stomatal behavior and maintain WUE to improve plant drought tolerance possibly through regulation of the 14-3-3 genes in the ABA signaling pathway.