Abstract:
Drought stress adversely inhibits plant growth and causes yield loss worldwide. Beneficial Trichoderma species have recently been shown to improve drought resistance in different plant species, whereas the underlying mechanisms of Trichoderma-induced drought resistance of host plants remain largely elusive. Herein, the effects of a Trichderoma harzianum isolate on maize's responses to drought stress were investigated. Inoculation with T. harzianum significantly promoted the growth and enhanced drought tolerance of maize plants. The whole genome expression profiles of the Trichoderma-inoculated plants were examined by RNA-sequencing, showing that several differentially expressed genes were positively associated with the process of ethanol-acetic acid metabolism. Compared with non-inoculated (control) plants, colonization of maize plant by T. harzianum exhibited the increased abscisic acid (ABA) levels. Drought stress induced a further increase of ABA content in the plants, while the levels of ABA were markedly higher in the inoculated plants than the controls. Virus-mediated silencing of ZmADH1 or ZmALDH12, which was involved in the ethanol-acetic acid metabolic pathways, largely weakened the Trichoderma-induced effects in the drought-treated plants, such as lower leaf relative water content (RWC) and higher reactive oxygen species (ROS) levels. Collectively, our results suggested that the Trichoderma-induced changes of ethanol-acetic acid metabolic pathways played a vital role in regulation of maize adaptation to drought stress.
Keywords:
Abscisic acid
,
Drought stress
,
Trichderoma harzianum
,
Ethanolacetic acid metabolism