黑麦品种间耐铝差异性机制研究

Studies on the mechanisms responsible for rye cultivar differences in Al resistance

采用室内模拟方法,研究了铝对黑麦根系分泌有机酸的诱导作用及根尖磷对铝的固定作用。结果表明.在铝胁迫下冬牧品种(Win)相对根伸长率高于King品种。在铝胁迫下,经磷预处理的根尖铝和磷含量增加,且以Win品种根尖中的Al、P含量较高,说明根尖磷对铝的固定是黑麦耐铝的机制之一。另一方面,在铝胁迫下,两品种根系均分泌柠檬酸和苹果酸,且Win的分泌速率较高。有机酸的分泌随着铝处理浓度(10、30、50μmol/L)和时间(0.5、3、6、9、12 h)的增加而增加.但在低温(4℃)下柠檬酸分泌量显著减少。Al处理0.5 h后苹果酸已明显分泌。而柠檬酸的分泌在铝处理6 h后才明显增加。在铝处理前,进行缺磷预处理(3 d)不能增加有机酸的分泌,10/μmol/L的La^(3+)、cu^(2+)、Ni^(3+)也不能诱导根系分泌有机酸。说明铝诱导根系专一性分泌有机酸也是黑麦品种间耐铝性差异的机制之一。

Both aluminum （Al）-induced secretion of organic acids from roots and the immobilization of Al with phosphorus in roots were investigated to elucidate Al-resistant mechanisms in rye （Secale cereale L. cv. Win and King）. It was shown that root elongation rate after Al treatment （10, 30, 50 μmol/L） in Win was higher than that in King. Pretreatment with phosphate before Al treatment increased P and Al content in root tips, and Al/P in Win root tips was higher than that in King. These results suggested that the immobilization of Al with phosphorus in root tips was associated with Al resistance mechanism in rye. On the other hand, Al induced the secretion of citrate and malate from roots of both cultivars and, furthermore, the secretion rate was higher in Al-resistant Win than that in Al-sensitive King. The secretion of organic acids increased with increasing Al concentration （10, 30, 50 μmol/L） and periods （0.5, 3, 6, 9, 12 h）, while the secretion of citrate decreased significantly under low temperature （4℃）.The secretion of malate was detected as soon as 0.5 h after Al treatment, while apparent increase in the secretion of citrate could not be detected until 6 h after Al treatment. Phosphorus-deficiency pretreatment for 3 d before Al treatment could not increase the secretion of organic acids. Moreover, the treatment with La^3＋, Cu^2＋ or Ni2＋ （10μmol/L） failed to induce the secretion. All these results suggested that specific secretion of organic acids from roots was also a mechanism for rye cuhivar differences in Al resistance.