AM真菌对枳吸收磷和分泌磷酸酶的影响

Effects of arbuscular mycorrhizal fungi on phosphorous uptake and phosphatase release in trifoliate orange seedlings

研究0.1mmol/L P和1mmol/L P下接种丛枝菌根(AM)真菌Funneliformis mosseae对沙培枳Poncirus trifoliata实生苗P吸收、转运和分泌磷酸酶的影响。结果显示,在0.1mmol/L P和1mmol/L P下,接种AM真菌都增加了枳地上部和地下部干重、一级侧根和二级侧根数,但1mmol/L P下接种AM真菌显著降低了枳主根长。与不接种AM真菌相比,1mmol/L P下接种AM真菌显著降低了枳叶片酸性磷酸酶活性,但显著增加了根系酸性磷酸酶活性及根系分泌酸性磷酸酶基因Pt PAP1的表达水平。接种AM真菌显著增加了0.1mmol/L P和1mmol/L P下叶片磷含量,根系磷含量仅在1mmol/L P下接种AM真菌后显著增加。在0.1mmol/L P和1mmol/L P下接种AM真菌显著降低了枳叶片(PtPAP1和PtPAP3)和根系(PtPAP3)分泌磷酸酶基因以及叶片磷转运蛋白基因(PtaPT5和PtaPT6)的表达水平,显著增加了枳根系PtaPT3、PtaPT5和PtaPT6的表达量。因此,推断接种AM真菌能刺激枳侧根数增多和酸性磷酸酶分泌,增强磷转运蛋白基因的表达,从而改善枳对磷养分的吸收。

The effects of arbuscular mycorrhizal fungi（AMF）（Funneliformis mosseae） on phosphorus uptake and transportation and release of phosphatases of trifoliate orange（Poncirus trifoliata） seedling in sand culture were analyzed. The results showed that AM fungal inoculation significantly increased shoot and root dry weight and numbers of first-and second-order lateral root under 0.1mmol/L P and 1mmol/L P concentration. Mycorrhizal inoculation markedly decreased taproot length in 1mmol/L P. Compared with non-AMF treatment, AMF treatment dramatically decreased leaf acid phosphatase activity, but increased root acid phosphatase activity and relative expression of root acid phosphatase gene Pt PAP1 under 1mmol/L P condition. Inoculation with AMF notably increased leaf P content under two different P concentration and root P content under 1mmol/L P concentration. Under 0.1mmol/L and 1mmol/L of P concentration, inoculation with AM fungus significantly decreased the relative expression of leaf（PtPAP1, PtPAP3） and root（PtPAP3） acid phosphatase genes and leaf P transporter gene（PtaPT5, PtaPT6）, but markedly increased the relative expression of root P transporter gene（PtaPT3, PtaPT5, PtaPT6）. Therefore, we concluded that mycorrhizal inoculation stimulated the lateral root development and acid phosphatase secretion, in company with enhanced expression of P transport gene, thus, collectively improved P absorption in trifoliate orange seedlings.