两种基因型龙葵对镉胁迫的生理响应及镉吸收差异

Difference of Cadmium Absorption and Physiological Responses to Cadmium Stress in Two Different Solanum Nigrum

采用盆栽试验,通过研究不同浓度镉(0、5、25、50、100μg·g-1)胁迫下红果龙葵和少花龙葵幼苗根、茎和叶的生物量变化、镉吸收量、镉转移率、镉富集系数和叶片抗氧化酶(SOD、POD)活性、叶片可溶性蛋白和游离脯氨酸含量等指标的变化,比较2种基因型龙葵富集镉的差异。结果表明,2种基因型龙葵富集重金属镉存在明显差异。与对照相比,在Cd胁迫浓度≥25μg·g-1时,2种龙葵的生物量显著下降(P<0.05),而少花龙葵的下降趋势较红果龙葵小;随着Cd胁迫浓度的增加,2种龙葵根、茎和叶的Cd吸收量显著上升(P<0.05),且根部Cd含量高于茎和叶,而少花龙葵的根、茎和叶中的Cd含量均高于红果龙葵,2种龙葵的镉转移率和富集系数除5μg·g-1Cd胁迫外,均小于1,且少花龙葵对镉转移率和镉富集系数均大于红果龙葵。2种龙葵叶片可溶性蛋白、游离脯氨酸含量以及抗氧化酶(SOD、POD)活性均表现为先上升后下降,均表现为少花龙葵上升幅度大而下降幅度较小。综合各项指标表明,2种龙葵均不是Cd的超积累植物,少花龙葵的耐Cd胁迫能力较红果龙葵强。

The influence of different cadmium concentrations（0, 5, 25, 50, 100 μg·g-1） on the biomass, Cd absorption, Cd transfer frequency, Cd bioaccumulation coeffieient, activity of antioxidant enzymes（SOD, POD ） and other physiological characteristics of two Solarium Nigrum varieties were studied to compare the difference of cadmium enrichment by a pot experiment. The results showed that two Solarium Nigrum varieties had obvious difference in Cd absorption. Compared with controls, the biomass of two varieties decreased significantly（P〈0.05 ） when Cd concentration ≥25μg ·g-1, and within the two viarieties, the biomass reduction of S. nigrum L. var. flavovirens S. Z exceeded that of S. photeinocarpum Nakamura. With the increasing Cd concentration, Cd absorption in root, stem and leaf of two varieties increased significantly （P〈0.05）, but Cd absorption in root was higher than that in stem and leaf, and Cd concentration by S. photeinocarpum Nakamura was higher than that by S. nigrum L. var.flavovirens S. Z. Only under 5μg·g-1 Cd stress were Cd transfer frequency and Cd bioaccmulation coeffieient of two varieties higher than 1, besides, Cd transfer frequency and Cd bioacemulation coeffieient in S. photeinocarpum Nakcanura were greater than in S. nigrum L. var. flavovirens S. Z.. With the increasing of Cd concentration, soluble protein, free Pro and activity of antioxidant en- zymes（SOD, POD） were significantly increased under lower Cd concentration and decreased under higher Cd concentration. Compared with controls, these physiological characteristics of S. photeinocarpum Nakamura displayed obvious rise and not obvious decline than that of S. nigrum L. var. flavovirens S. Z. In conclusion, two varieties were not the Cd hyperaccumulator and S. photeinocorpum Nakamura had a higher tolerance to cadmium stresses.