小麦腺苷二磷酸葡萄糖焦磷酸化酶同工酶类型及时空表达分析

以9个小麦品种为材料,采用非变性聚丙烯酰胺凝胶电泳(Native-PAGE)和SDS聚丙烯酰胺凝胶电泳(SDS-PAGE)鉴定ADP-葡萄糖焦磷酸化酶(AGP)同工酶类型、表达数量及亚基组成,分析AGP同工酶空间分布特点和器官表达特异性。结果表明:(1)小麦植株中共表达6种AGP同工酶,即AGPp、AGPs、AGPe1、AGPe2、AGPe3和AGPe4。(2)AGPp分布在种皮中,AGPs分布在种皮与叶片中,而AGPe1、AGPe2、AGPe3和AGPe4专一在胚乳中表达;在小麦籽粒灌浆过程中,AGPe1首先表达,AGPe2和AGPe3紧随其后,AGPe4最后表达。(3)AGP各同工酶均由大、小2个亚基组成,小亚基分子量为50kD左右,大亚基分子量在51~54kD之间。(4)AGP同工酶空间分布具有器官特异性,并在籽粒发育进程中顺序表达;AGPe3、AGPe1和AGPe2是占主导地位的AGP同工酶,且可能是决定AGP总酶活性的主效应酶,在灌浆后期籽粒淀粉合成中起关键作用。

Isozyme Forms and Temporal and Spatial Expression Profile of ADP-glucose Pyrophosphorylase in Developing Wheat Grain

In order to elucidate the enzyme mechanism of starch biosynthesis in wheat endosperm and provide theoretical basis to enhancing wheat yield,we identified the isozyme forms,organ localization and subunits constitution of AGP in nine wheat cultivars from different provenances by using native polyacrylamide gel electrophoresis (Native-PAGE) and SDS polyacrylamide gel electrophoresis (SDS-PAGE).Results of the present study showed that:(1)There are six AGP isozymes in wheat,ie,AGPp,AGPs,AGPe1,AGPe2,AGPe3 and AGPe4.(2)AGPs localized in leaf and seed coat of wheat,but AGPp was solely in seed coat.AGPe1,AGPe2,AGPe3 and AGPe4 were exclusively present in wheat endosperm.AGPe1 expressed first,following by the AGPe2 and AGPe3.The AGPe4 expressed last.(3)Every AGP isozyme of endosperm was all composed of both large and small subunits.The molecular size of large and small one were approximately 51~54 kD and 50 kD,respectively.(4)Spatial localization of the AGP isozymes manifests organ specificity.AGP isozymes of endosperm exhibit rich genetic polymorphism,and expresse according to different developing periods of grain.AGPe3,AGPe1 and AGPe2 could be the key isozymes of AGP,and be a very important determinant for total AGP activity,play an major role in starch biosynthesis in late filling period of wheat grain.