褪黑素对水稻镉积累及其化学结合形态的影响

Effects of exogenous melatonin on accumulation and chemical form of Cd in rice

研究了添加外源褪黑素对水稻幼苗中Cd积累以及水稻体内Cd化学形态分布的影响结果表明:Cd胁迫显著降低水稻幼苗地上部和根部的生物量,并且显著降低水稻叶片的叶绿素含量.适宜的外源褪黑素添加能明显提高Cd胁迫下水稻的地上部和根部生物量,降低水稻地上部和根部Cd含量.当Cd胁迫浓度为5μmol·L^(-1)时,添加20μmol·L^(-1)褪黑素使水稻地上部和根部Cd含量分别比对照处理降低48.4%和16.9%,添加100μmol·L^(-1)褪黑素水稻地上部和根部Cd含量分别降低67.5%和47.9%.添加外源褪黑素也显著降低了水稻体内Cd的转运效率.当Cd胁迫浓度为20μmol·L^(-1)时,添加20和100μmol·L^(-1)褪黑素使水稻Cd的转运效率分别比对照降低24.4%和46.8%.通过逐步提取法对水稻幼苗Cd的化学结合形态进行分析发现,添加外源褪黑素使水稻体内氯化钠提取态Cd的比例提高,而水溶态Cd、乙醇提取态Cd的比例明显降低,说明添加褪黑素可促进水稻体内移动性较强的Cd形态向移动性较弱的Cd形态转移,从而降低水稻对Cd的吸收和转运.

Effects of exogenous melatonin on accumulation and chemical form of Cd in rice seed- lings were investigated. The results showed that Cd stress significantly decreased the biomass of shoots and roots, and the chlorophyll content in rice leaves. The addition of exogenous melatonin could remarkably increase the biomass of rice and significantly decreased Cd content in the shoots and roots. At Cd concentration of 5 μ mol · L-1 , addition of 20 μ mol ·L-1 exogenous melatonincould decrease Cd content in rice shoots and roots by 48.4% and 16.9% respectively, compared with the control. When the concentration of exogenous melatonin rose to 100 μmol · L-1, Cd content in rice shoots and roots decreased by 67.5% and 47.9% respectively. Furthermore, the addition of exogenous melatonin obviously decreased the Cd-transloeation efficiency of rice seedlings. When the Cd concentration was 20 μmol · L-1 , addition of 20 and 100 μmol · L-1 exogenous melatonin could decrease the Cd-translocation efficiency by 24.4% and 46.8% respectively. The chemical form of Cd in rice seedlings was analyzed by using sequential extraction. The results showed that exogenous me- latonin addition increased the proportion of NaCl-extraetable Cd, while decreased the proportion of ethanol-extractable Cd and water-extractable Cd in rice seedlings. It was suggested that the addition of exogenous melatonin could promote the transfer of Cd from strong to weak mobility form, thereby reducing the uptake and transport of Cd in rice seedlings.