玉米苗期耐镉胁迫的基因型差异

Genotypic Differences of Cadmium Tolerance at Maize Seedling Stages

为了确定适宜的玉米耐镉(Cd)基因型筛选指标,采用营养液培养的方法系统评价12个不同基因型玉米苗期耐Cd胁迫的基因型差异。结果表明,Cd胁迫下不同基因型玉米生长及抗氧化系统的活性等指标存在显著的品种间差异。主成分分析表明,植物株高、地上部干物质质量、根部干物质质量、根叶比、叶片SPAD值、叶片POD、CAT活性及叶片MDA质量摩尔浓度的耐Cd指数在3个主成分中占较大比重。相关性分析表明,地上部干物质质量和叶片SPAD值的耐Cd指数除分别与叶中SOD活性和根叶比的耐Cd指数未达显著相关外,与其他指标耐Cd指数的相关性均达到显著或极显著水平;同时,不同玉米品种间地上部植株干物质质量和叶片SPAD值耐Cd指数的变异系数均大于15%。因此,植株地上部干质量和叶片SPAD值的耐Cd指数适合作为耐Cd基因型筛选的指标。12个品种通过聚类分析分为3类:Cd敏感型、中间型、Cd耐受型。

The hydroponic experiment was conducted to evaluate the genotypic differences of 12 maize cultivars to cadmium （Cd） tolerance at seedling stage, in order to achieve suitable Cd tolerance genotype in maize. Two Cd levels of 100 mg/ L and 0 mg/L were designed. Under Cd treatments, the differences on growth and physiological traits such as activities of antioxidant system among different maize were significant. Principle component analysis indicated that the tolerance indexes of plant height, shoot dry mass, root dry mass, the ratio of root/shoot dry mass, the SPAD of leaves, the activities of POD and CAT in leaves and MDA molality in leaves had more proportion. Correlation analysis showed that the tolerance index of shoot dry mass was significantly correlated to the other toler ance index except the activity of SOD in leaves, and the tolerance index of SPAD of leaves was significantly correlated to the other tolerance index except the ratio of root/shoot dry mass. The differentiation of the tolerance index of shoot dry mass and SPAD of leaves between different maize cultivars were distinct （CV 〉 15%）. Therefore, the tolerance index of shoot dry mass and SPAD of leaves could be adopted as screening indexes. The 12 maize cultivars were classified as three types by cluster analysis of Cd sensitivity type, mean type and Cd tolerate type.