Trichoderma aspereullm accc 30536 inoculation differently regulates the time-course expression of five indole-3-acetic acid amido synthetase genes and the levels of IAA, SA and JA in populus davidiana × P. alba var. pyramidalis

Some indole-3-acetic acid amido synthetases (GH3 proteins) were confirmed to catalyze the connection between IAA, SA or JA with amino acid to regulate hormone dynamic balances in promoting plant growth; they can also improve plants' resistance to stress through activating SA, JA and ethylene signaling pathways. Trichoderma spp. are widely-known beneficial biocontrol agents. However, the expression pattern of plant GH3 genes induced by Trichoderma remained unexplored. In this study, five GH3 genes in Populus davidiana × P. alba var. pyramidalis (named PodaGH3-1, PodaGH3-2, PodaGH3-5, PodaGH3-9 and PodaGH3-10) were cloned. Their characteristic analysis showed that the five PodaGH3s genes were highly conservative and closely related at the residues linked to ATP binding with IAA or JA, and their expression levels changed obviously under Trichoderma inoculation. Moreover, IAA, JA and SA contents showed a fluctuating yet increasing trend during the 72 hours when poplar seedling rhizosphere was colonized by Trichoderma. In summary, all the five PodaGH3s could be activated by the interaction between biotrophic Trichoderma and poplar seedlings. (author)