The Characteristics Of Al-induced Organic Aicd Anions Secretion In Hydrangea Macrophylla And VALT Gene Expression Research

Nowadays, the toxicity of Aluminum is the main factor to limit plant grows, crop production and forest degradation in acid soil. In order to grow in the condition of Aluminum toxicity, the plant has develops series of aluminum tolerance mechanisms. Currently, it is considered that Al-induced of organic acids from roots is a main mechanism for some Al-tolerance plant. This study’s material is hydrangea. In order to compare the difference of the secretion of organic acids under different concentration aluminum, the study will use hydroponic experiment. The purpose is to understand the ability of anti Aluminum of hydrangea macrophylla, As well as various influence factors of hydrangeas organic acid secretion. On this basis, successfully clone plasma membrane-localized Al transporters genes vacuolar Al transporter VALT gene fragment of hydrangeas, studied the differentially expresses of various parts under aluminum situation. All the results are as follows:Hydrangeas under aluminum stress the secretion of organic acids is oxalate in this experiment. The root elongation of hydrangea cutting decease as the concentration of Aluminum increase after the cuttings immersing into0,50,100,200,400,600μmol·L-1AlCl3liquor, and the secretion of oxalic acid start increase at50μmol·L-1. At this concentration, the apical begin to be damaged. The amount of oxalate secreted from the segment of0-5mm from root apex is greater than other segment (5-10,10-15,15-20mm). This shows that the main part of the secretion of oxalic acid is0-5mm segment of the root.The secretion of oxalic acid of hydrangea is higher than the comparison under the condition of deficiency of phosphorus. At10days, the secretion of oxalic acid reaches a peak and thereafter begins to decline. This study results suggest that the secretion of oxalic acid is not a hydrangea-specific responses to aluminum stress. After0.5and2hours treatment, there is also a little quantity of secretion of oxalic acid, but do not have big change. But it has remarkable increase in the fourth hour. This shows that the secretion of oxalic acid of hydrangea under the abduction of Aluminum belong to the second mode.Anion channel inhibitors PG and protein synthesis inhibitors CHM basically inhibit the secretion of oxalic acid of hydrangea root system under the abduction of Aluminum. This shows that the oxalic acid of hydrangea root system need anion channel and protein synthesis to take part in.By the method of molecular biology system, this study successfully clone VALT gene fragment of hydrangea macrophylla. By semi-quantitative RT-PCR study show that, VALT gene can present both in the roots and leaves of hydrangea, but the express of the roots are higher than the leaves when under into each concentration Al stress. The present of VALT gene reach the max when the concentration of AICl3reach to400μmol·L-1.