不同耐铬性青菜中Cr6+的亚细胞分布及其耐性机理

摘要

为探明青菜对Cr6+的吸收及其耐性机理,选取2个不同耐铬(Cr)性青菜品种‘美加华'(Cr耐性品种)和‘三月慢’(Cr敏感品种)进行水培试验,比较0、10、50和100 μmol·L-1 Cr6+处理下青菜地上部和根系Cr含量、Cr的亚细胞分布、非蛋白巯基(NPT)、植物螯合肽(PCs)和抗氧化酶活性的差异.结果表明:(1)2个青菜品种地上部Cr含量显著小于根系的含量,且‘美加华’根系Cr含量、Cr的根系滞留率、地上部和根系细胞壁中Cr含量与总Cr含量的比值均显著大于‘三月慢’,而其可溶性Cr含量与总Cr含量的比值显著小于‘三月慢’.(2)Cr6+处理显著增加了青菜地上部NPT和PCs的含量,且‘美加华’增加的幅度显著高于‘三月慢’.(3)低浓度的Cr6+ (10μmol·L-1)能够提高青菜SOD、POD和CAT的活性,且‘美加华’的增幅大于‘三月慢’;而高浓度的Cr6+ (100 μmol·L-1)显著降低了SOD、POD和CAT的活性,且‘美加华’的降幅小于‘三月慢,.研究认为,在Cr6+胁迫条件下,与青菜品种‘三月慢’相比品种‘美加华’能将更多的Cr分布于根和细胞壁中,减少了跨膜进入细胞内的Cr,并且具有较高的抗氧化酶活性和PCs含量,从而表现出更强的耐Cr6+性.%In order to elucidate absorption,distribution and tolerance mechanisms of Brassica chinensis L.to chromium (Cr6+) stress,we grew two Brassica cultivars;‘Meijiahua'(Cr6+-stress tolerant) and ‘Sanyueman'(Cr6+-stress sensitive) hydroponically in Hoagland 0,10,50 and 100 μmol · L-1 Cr6+.The differencesin Cr absorbed contents and subcellular distribution,non-proteinthiol,phytochelatins(PCs) and antioxidant enzyme activities in shoots and roots were studied.The results were as follows:(1) the contents of Cr in shoots were significantly lower than those in the roots in both cultivars.The Cr root contents,Cr retention rate and the ratio of wall-bounded Cr to total Cr in shoots and roots of ‘Meijiahua'were significantly higher than those in ‘Sanyueman',but the ratio of water soluble Cr to total Cr was opposite.(2) Cr6+ treatments at all concentrations significantly increased the concentrations of non-protein thiol and phytochelatins (PCs) in shoots of both cultivars,but the increment in ‘Meijiahua'was significantly higher than that in ‘Sanyueman'.(3) Under low concentration of Cr6+ (10 μmol · L-1),the activities of SOD,POD and CAT were significantly increased,but the extent of increase was significantly higher in ‘Meijiahua'than that in ‘Sanyueman'.The activities of SOD,POD and CAT were significantly downregulated under high concentration of Cr6+ (100 μmol · L-1),but the magnitude of downregulation in ‘Meijiahua'was significantly lower than that in ‘Sanyueman'.These results indicated that under Cr6+ stress,as compared to ‘Sanyueman',more Cr was distributed in cell walls in shoot and root in ‘Meijiahua'to inhibit the transmembrane Cr to intracellular flow.Moreover,it has higher antioxidant enzyme activities and PCs content,so it showed a stronger tolerance to Cr6+.