Effects of Suillus Luteus on the root morphology and endogenous hormones of Pinus massoniana seedlings under drought stress

Abstract

Aims Ectomycorrhizal fungus (ECMF) may enhance plant drought resistance. However, there is limited information regarding the effects of ECMF on drought resistance in Pinus massoniana, a native species representing an afforestation pioneer tree in subtropical regions of China. Methods We conducted a pot experiment to assess the effects of Suillus luteus on the root morphology and endogenous hormones of masson pine under drought stress. Four water levels (normal water, light drought, moderate drought and severe drought) and three inoculation levels (non-ECMF-inoculated, inoculated with S12 and inoculated with S13) were compared using a factorial design. Root morphology and endogenous hormones were tested after 45 days of stress. Results The results showed that total root length, projection area, total root surface area, total root volume, root tip number, connection count, average number of first-order lateral roots and angle of first-order lateral root of the masson pine seedlings which inoculated S. luteus were significantly increased under drought stress. The light drought stress is beneficial to the root morphological development of masson pine. Compared with the non-inoculated seedlings, the concentrations of gibberellic acid (GA), zeatin riboside (ZR) and indole-3-acetic acid (IAA) were increased, while the concentration of abscisic acid (ABA) was significantly decreased. Moreover, root morphology was positively correlated with GA, IAA, and ZR, but negatively correlated with ABA. Conclusions S. luteus can promote the root growth and development of masson pine seedlings, notably by regulating the balance in concentration of endogenous hormones, thus improving the drought resistance ability of masson pine seedlings.