两种海棠秋季叶色变化的生理机制研究

摘要

The autumn leaves of Malus ‘Royalty’ and Malus ‘Guanghui’ were used to study the changes of the leaf color,and the content of chlorophyⅡ,anthocyanin,soluble sugar and PAL activity were measured,in order to explore the relationship between the leaf color change of Malus and endogenous substances in autumn.The results showed that,the leaf color of Malus ‘Royalty’ rendered purple red in growth stages,but changed to green in autumn.The leaf color of Malus ‘Guanghui’ turned from green to red as the temperature rised,then changed to green when the temperature decreased.The analysis of these mensuration results showed that,the leaf color of Malus ‘Royalty’ and Malus ‘Guanghui’ was closely related to the ratio of pigments.When the ratio of anthocyanin to chlorophyⅡ dropped to 14,the leaf color of Malus ‘Royalty’turned from red to green,so the color expression of leaves of Malus ‘Royalty’ was on account of anthocyanin degradation and chlorophy Ⅱ accumulation.The color expression of leaves of Malus ‘Guanghui’ was determined by anthocyanin content and carotenoids content,the leaf color of Malus ‘Guanghui’ turned from green to red when the ratios of anthocyanin to chlorophy Ⅱ increased to three and carotenoids accumulated.Soluble sugar offered material and energy for the synthesis of anthocyanin.PAL activity was closely related to the synthesis of pigments,but it might not be the key enzyme.%以王族海棠(Malus‘ Royalty’)和光辉海棠(Malus‘Guanghui’)秋季(8～10月)成熟叶片为试验材料,观察其叶色变化,并对其叶绿素、花色素苷、可溶性糖含量及苯丙氨酸解氨酶(PAL)活性进行测定,以期揭示两种海棠叶片色泽、内色素变化与其内源物质的相关关系.结果表明,王族海棠叶片虽生育期呈现紫红色,但秋季却出现“返绿”现象;光辉海棠则随着温度升高,叶片由绿色转变为红色,温度降低,红色退去,叶片呈现绿色.上述指标测定结果显示,两种海棠叶色表现均与叶片内色素的比例密切相关.王族海棠叶片内当花色素苷与叶绿素含量比值降至14时,其叶色由紫红色转变为绿色,其叶色变化主要是由花色素苷降解而叶绿素的积累引起的;光辉海棠成熟叶片的叶色变化则是由花色素苷和类胡萝卜素的含量共同决定的,花色素苷与叶绿素含量比值升至3、类胡萝卜素大量积累时,其叶色由绿色转变为橙红色.可溶性糖为花色素苷的合成提供原料和能源,PAL活性和叶片内色素的合成有必然联系,但不是惟一决定色素合成的调控酶.