‘黄金梨’缺铁黄化叶片受GA_(3)诱导复绿的机理研究

Studies on the Regreening Mechanism of the Iron-deficiency Chlorosis Leaves induced by GA_(3)in‘Whangkeumbae’(Pyrus pyrifolia Nakai)

以‘黄金梨’缺铁黄化植株与正常植株为试材,于生长期黄化植株叶面喷施50、100、200和400 mg·L^(-1) GA_(3)溶液,测定叶片中Fe、GA_(3)、GA_(4)、IAA和JA含量,对叶绿体进行了电镜显微结构观察,并运用荧光定量PCR技术分析了Fe代谢与GA信号转导相关基因的表达量。结果表明,外源GA_(3)处理后9 d,黄化叶均有不同程度复绿,叶脉复绿明显,叶身部分复绿,其中400 mg·L^(-1) GA_(3)处理后12 d黄化叶复绿最明显。处理后9和12 d缺铁黄化叶片Fe含量显著高于清水处理对照。外源GA_(3)能诱导黄化叶片内FER1、FER2、FER3、FRO2、IRT1和FD1的表达,其中12 d各处理FER2和IRT1基因的表达量分别是对照10倍和40倍以上,说明外源GA_(3)促进了叶片内铁的贮藏、还原与转运相关基因的表达。外源GA_(3)处理显著提高了叶片中内源GA_(3)和GA_(4)含量,迅速诱导GID11和GID13基因的表达,其中50 mg·L^(-1) GA_(3)处理,GID11表达量在3 d是对照的76.45倍。400 mg·L^(-1) GA_(3)处理后12 d的叶片类囊体基粒片层较黄化叶片清晰,断裂片层少。试验结果初步揭示了GA_(3)诱导‘黄金梨’黄化叶复绿的机理。

In order to reveal the regreening effect and physiological mechanism of the iron-deficiency chlorosis leaves induced by GA_(3),the iron-deficiency chlorosis and normal plants of‘Whangkeumbae’(Pyrus pyrifolia Nakai)were used as the experiment materials,and GA_(3) solutions of 50,100,200 and 400 mg·L^(-1) was sprayed on chlorosis leaves during the growth period.The contents of Fe,GA_(3),GA_(4),IAA and JA in leaves were determined,the chloroplast ultrastructure was observed and photographed under an electron microscope,and the expression levels of genes related to Fe metabolism or GA signal transduction were analyzed by fluorescence quantitative PCR.The results showed that on the 9th day after treatment with exogenous GA_(3),the chlorosis leaves showed different degrees of regreening,with obvious vein regreening and partial body regreening.On the 12th day of treatment with 400 mg·L^(-1) GA_(3),the regreening of chlorosis leaves were the most obvious.The Fe content in regreening leaves were significantly higher than that in control with water on the 9th and 12th day after GA_(3) treatment.Exogenous GA_(3) could induce the expressions of FER1,FER2,FER3,FRO2,IRT1 and FD1 in chlorosis leaves.On the 12th day,the expression levels of FER2 and IRT1 in each treatment were more than 10 and 40 times higher than that in the control group,indicating that exogenous GA_(3) promoted the expression of genes related to iron storage,reduction and transport in leaves.Exogenous GA_(3) treatment significantly increased the contents of endogenous GA_(3) and GA_(4) in leaves and rapidly induced the expression of GID11 and GID13.Among them,the expression level of GID11 was 76.45 times higher than that of the control group on the 3rd day after the treatment with 50 mg·L^(-1) GA_(3).On the 12th day after treatment with 400 mg·L^(-1) GA_(3),the thylakoid granule lamellae in leaves were clearer than that of chlorosis leaves,with fewer fractured lamellae.The results preliminarily revealed regreening mechanism of chlorosis leaves induced by GA_(3) in‘Whangkeumbae’.