细胞分裂素类物质对镉胁迫下玉米幼苗生长和抗氧化酶活性及脯氨酸含量的影响

采用水培试验,研究了镉胁迫下喷施细胞分裂素类物质6-苄氨基嘌呤(6-BA)和激动素(KT)对玉米幼苗生长、叶片叶绿素含量、脯氨酸含量、植株镉含量和活性氧清除酶活性的影响.结果表明,与单纯镉胁迫相比,喷施6-BA和KT提高了玉米幼苗的生物量、根和地上部镉含量、叶绿素和脯氨酸含量,降低了叶片丙二醛(MDA)含量,促进了叶片过氧化物酶(POD)和过氧化氢酶(CAT)活性的升高,但对超氧化物歧化酶(SOD)活性的影响不明显.说明细胞分裂素类物质6-BA和KT可缓解镉胁迫对玉米幼苗的伤害,其机制可能与细胞分裂素物质能维持叶绿素稳定、刺激细胞内H2O2清除酶类活性及促进脯氨酸积累有关.当6-BA浓度在0～20mg·L-1之间时,其对玉米幼苗镉胁迫的缓解效应随喷施浓度的提高而增强,而KT的最适喷施浓度为70mg·L-1.

Effect of exogenous cytokinins on growth,activities of antioxidative enzymes and proline content in corn seedlings (Zea Mays L.) under cadmium stress

The effects of spraying two cytokinins, 6-benzylaminopurine (6-BA) and kinetin (KT), on the growth, the contents of chlorophyll and proline and cadmium, as well as the activities of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in the leaves of corn seedlings under cadmium stress were studied by solution culture experiments. The results showed that spraying 6-BA and KT increased the biomass and the contents of chlorophyll, proline and cadmium, while it decreased the content of malondialdehyde (MDA) in corn leaves. The treatments also promoted the increase of the enzyme activities of CAT and POD, while they did not significantly influence the activities of SOD in corn leaves. The results suggest that exogenous cytokinins could alleviate the toxicity of cadmium to corn seedlings by keeping the stability of chlorophyll, enhancing the H2O2 scavenging systems through accumulating more proline, and improving the activities of POD and CAT in plants. The alleviation effects increased with the increase of spraying concentrations from 0 to 20 mg·L-1 for 6-BA, while the optimal alleviation effect was obtained at a concentration of 70 mg·L-1 for KT.