Effects of Aluminum on Stress Resistance Physiology and Root Tip Cell Ultrastructure of Mycorrhizal Seedlings of Pinus massoniana
[Objective]To provide theoretical basis for the application of ectomycorrhizal fungi in improving the aluminum tolerance of host plants and afforestation,we studied the changes of physiology,root tip cell ultrastructure and subcellular distribution of Al in mycorrhizal/non mycorrhizal seedlings of Pinus massoni-ana under different Al3+ levels.[Method]Semi annual mycorrhizal and non mycorrhizal P.massoniana seedlings were treated with 0,0.2,0.4 and 0.8 mmol·L-1 Al3+(AlCl3)respectively by sand culture and pot ir-rigation with aluminum.We analyzed the changes of antioxidant enzyme activity,MDA content and subcel-lular distribution of Al in roots,the distribution of ROS and MDA in roots,and the ultrastructure of root tips.[Results](1)With the increase of exogenous aluminum concentration,the activities of SOD,CAT,POD and the content of MDA in the roots of mycorrhizal/non mycorrhizal seedlings of masson pine showed an overall upward trend.At high aluminum level(0.8 mmol·L-1),the activities of antioxidant enzymes and the content of MDA were the highest,and the non mycorrhizal seedlings were more affected by aluminum.(2)With the increase of exogenous aluminum concentration,the aluminum content absorbed by root tips of P.massoniana increased significantly,and the aluminum content absorbed by mycorrhizal seedlings was sig-nificantly higher than that of non mycorrhizal seedlings.(3)From the cell ultrastructure and subcellular dis-tribution of Al,a large number of Al3+ first combined with the cell wall,and the intracellular Al3+ strongly combined with the biofilm,which strengthened the leakage of organelles and interfered with various regu-latory processes of nucleus and mitochondria.Because of the adsorption of aluminum by mycorrhiza,the content of aluminum ions in cells reduced,the structure of subcellular organelles was protected,the basic function of cells was maintained,and the toxicity of aluminum was alleviated.[Conclusion]The antioxid-ant enzyme activity and MDA content of root of P.massoniana are increased by aluminum treatment,and aluminum with 0.4 mmol·L-1 produces obvious aluminum toxicity symptoms.Mycorrhizal fungi can reduce aluminum toxicity and improve plant aluminum tolerance by absorbing more aluminum,which is probably an important external resistance mechanism of root seedlings mycorrhiza of P.massoniana.
mycorrhizaPinus massoniana Lamb.aluminum toleranceantioxidant enzymecell ultrastructuresubcellular distribution
万方数据
维普
