缺磷白羽扇豆根系分泌物收集方法的比较研究

Comparative studies on methods of collecting root exudates from phosphorus deficient white lupin

用高效液相色谱法研究了根系分泌物原位收集法和溶液培养收集法在分析缺磷白羽扇豆 (L upi-nus albus L .)幼苗根系分泌有机酸时的优劣性 ,同时分析了相应根组织、木质部伤流液和韧皮部汁液中有机酸的种类和数量。结果表明 :2种收集方法所获得的有机酸种类和数量并不完全相同。原位收集法能获得白羽扇豆不同根段分泌有机酸的状况 ,即排根主要分泌苹果酸、柠檬酸和反丁烯二酸 ,根尖主要分泌苹果酸、乳酸、反丁烯二酸 ,且所反映的有机酸分泌状况与相应根组织以及木质部伤流液中有机酸的种类和变化趋势基本一致。溶液培养收集法可获得白羽扇豆整个根系分泌有机酸的状况 ,在其根系收集液中含有酒石酸、苹果酸、乳酸、顺丁烯二酸、柠檬酸、反丁烯二酸 ,但该方法在根系分泌物的收集过程中不可避免地引入了去离子水对根系的胁迫作用 ,增加了微生物的污染环节。

The advantages of different root exudates collecting methods were investigated via analysis of HPLC.The seedlings of white lupin were cultured in the phosphorus deficient nutrient solution and the organic acids in the corresponding root tissue were also investigated when root exudates were collected in order to determine the real kinds and quantities of organic acids in the root exudates.The results showed the kinds and quantities of organic acids collected by the two methods were not identical.The methods of localized collection of root exudation can acquire the real kinds and quantities of organic acids excreted from the root and can determine the real site where the organic acids were excreted.The organic acids excreted from the proteoid were malic acid,citric acid and fumaric acid,and the root tips excreted malic acid,lactic acid and fumaric acid.The kinds and tendency of organic acids in the root exudates accord with those in the xylem exudation and corresponding root tissues.The method of bathing root system is advantageous to determine the total quantities of organic acids,which include tartaric acid,malic acid,lactic acid,maleic acid,citric acid,succinic acid,fumaric acid,but it can not avoid the stress of collecting solution and rhizosphere micro organism pollution.