Effects of Exogenous Easily Extractable Glomalin-related Soil Protein on Drought Resistance of Idesia Polycarpa under Drought Stress
Research on glomalin-related soil protein (GRSP) have focused on soil aggregation and fungal physiology, while it is not clear whether exogenous GRSP could impact on drought tolerance of plants. The proposed study was carried out to evaluate the effect of exogenous easily extractable glomalin-related soil protein (EE-GRSP) on drought resistance of idesia polycarpa under drought stress. Half-strength EE-GRSP (0.007 mg protein/mL) was weekly applied into rhizosphere of potted idesia exposed to well-watered (WW) and drought stress (DS). Compared with the control with citrate buffer, the exogenous EE-GRSP could significantly increase the plant height, stem diameter, leaf number, and fresh weight of idesia seedlings. Under normal water conditions, the total root length, projected area, volume, root tip number, branch number and bifurcation number of exogenous EE-GRSP were higher than control group. The study indicated that exogenous EE-GRSP significantly improved the leaf photosynthetic rate, transpiration rate and stomatal conductance and intercellular CO2 concentration, while significantly reduced the relative water content and leaf temperature of seedling leaves under drought stress. Moreover, exogenous EE-GRSP significantly improved the content of water-stable aggregates and the stability of aggregates in rhizosphere of idesia seedling, increased the endogenous hormone content both in the leaves and roots under drought stress.