Synergistic effect of phytohormone-producing ectomycorrhizal fungus Suillus luteus and fertilizer GGR6 on Pinus massoniana growth

Suillus luteus is an edible ectomycorrhizal fungus (EMF). The S. luteus strain LS88 secretes many phytohormones, including salicylic acid (SA) and indole-3-carboxylic acid (ICA). LS88 was inoculated to the tree Pinus massoniana and treated with the amino acid fertilizer GGR6. Plant growth parameters, plant enzyme activities, chlorophyll contents, and element contents were analyzed. Our results show that GGR6 may help the development of S. luteus-P. massoniana ectomycorrhiza. Moreover, LS88 and GGR6 synergistically affect P. massoniana growth and element uptake. Phytohormone detection on the roots of LS88-inoculated P. massoniana seedlings showed that LS88 could significantly increase the ICA content within a week. The SA content in the roots in the inoculated group seedlings increased slightly, but the salicylic acid 2-O-β-glucoside (SAG) content decreased. Therefore, we speculate GGR6 may enhance the growth-promoting effect of EMF on plants, and LS88 affects P. massoniana growth through secreting phytohormones.