Screening For Al Resistence Cultivars And The Role Of Plasma Membrane H~+-ATPase In Plant Aluminum Resistance

Aluminum is the major restriction factor of plant in acid soils. Most of the soil are acid soil in Zhejiang Province, and soil acidification become more and more severe. In the first part of this research we collect 187 local crop cultivars of various species which are cultured in low soil pH areas, according to the data of soil pH in Zhengjiang. In order to evaluate the Al tolerant character of these cultivars, the measurements of relative root elongation (RRE) was taken. We identified relatively more tolerant cultivars in Azuki bean, maize and wheat etc. Some cultivars of wheat, azuki bean and buckwheat were interestingly found to have great variance (>30%) of RRE in certain aluminum concentration. This indicates it is possible to find some crop resources with high aluminum resistance in local culticars. A library of the local crop cultivars was established in this research and it will provide ideal materials for future studies and saving gene recourses.Al-induced oxalate secretion is one of the major Al resistance mechanisms, but it is still controversial that whether plasma membrane H+-ATPase is in volved in the process. The second part of this paper focus on tomato, which can rapidly secrete oxalate in response to Al. the plasma membrane. We studied the oxalate secretion, and the H+-ATPase activity pattern under Al treatment. The correlation between PM H+-ATPase activity and Al-induced oxalate secretion was found to be not significant according to time and dose dependent Al treatment. Exposure to the PM H+-ATPase inhibitor VA do not influence oxalate secretion, but PG which reduced the Al-induced oxalate secretion, have no effect on PM H+-ATPase activity. Exposure to La confirms that Al is more likely to enhance oxalate secretion rather than high PM H+-ATPase activity. A comparative study on Hezuo903 (relatively sensitive) and Micro-tom (relatively toleran) provide direct evidence to show only Al-induced oxalate secretion but not PM H+-ATPase is correlated with Al tolerant variance between two cultivars. And at last a RT-PCR results is given and shows the expression pattern of 3 PM H+-ATPase gene regulates by Al in transcriptional level.