钙磷对酸铝胁迫后紫花苜蓿-根瘤菌体系结瘤固氮的修复效应

本试验采用水培法,以三得利紫花苜蓿和耐酸苜蓿根瘤菌91522为材料,探讨了酸铝胁迫处理苜蓿幼苗1周后,施加Ca²⁺、P对紫花苜蓿-根瘤菌结瘤固氮性能和群体感应的修复/恢复作用。结果表明,酸铝毒害后,Ca²⁺对紫花苜蓿-根瘤菌结瘤过程有显著的修复效应,根瘤菌群体感应、根瘤固氮酶活性显著提高;4 μmol/L P素营养与Ca²⁺存在交互效应,导致苜蓿现瘤时间较未经修复的处理提前14 d,苜蓿结瘤总数提高了247.09%,结瘤率达到90%,根毛变形率由3.33%提高到28.89%。Ca²⁺对结瘤动力学曲线的修复作用主要表现为从开始结瘤起同期结瘤数显著提高。P素对结瘤数影响在Ca²⁺ 5 mmol/L条件下较显著;Ca²⁺对固氮酶活性有显著提高作用,而且5 mmol/L效果优于10 mmol/L,4 μmol/L P素可以进一步提高固氮酶活性。初步认为,补充Ca²⁺和4 μmol/L P可以促进根瘤菌在酸铝胁迫条件下群体感应物的分泌、改善苜蓿根毛对结瘤信号的感知和变形,修复酸铝对苜蓿和根瘤菌的毒害,恢复和提高固氮性能。

Reparations of Ca2+ and P on N-fixation of alfalfa-rhizobia after acid aluminum stress

In this paper, we used alfalfa and acid tolerate alfalfa rhizobium stain, Sinorhizobium meliloti 91522, as materials in water culture to study the effect of calcium and phosphorus on quorum sensing (QS) and N-fixation of alfalfa-rhizobia after acid aluminum stress. The research showed that calcium and phosphorus could repair the symbiosis nodular process of alfalfa-rhizobia after suffering from acid and Al toxicity; comparing with the control treatment, which is no Ca²⁺ and P treatment, under the conditions of 10 mmol/L Ca²⁺ and 4 μmol/L P, the nodulation time was 14 days earlier, nodular number had increased by 247.09%, the nodular ratio achieved to 90%, hair deformation rate of Medicago sativa increased from 3.33% to 28.89%. When 10 mmol/L Ca²⁺ and 4 μmol/L P were added, the nitrogenase activity improved significantly, and Ca²⁺could enhance the QS of S. meliloti significantly as well, hence promoting alfalfa to perceive the nodular signal. Preliminary tests proved that Ca²⁺ and P could recover the symbiosis nodular process and nitrogenase activity after alfalfa suffered from acidity and Al toxicity.