摘要
表观直链淀粉含量（Ａｐｐａｒｅｎｔａｍｙｌｏｓｅｃｏｎｔｅｎｔ，ＡＡＣ），是通过稻米直链淀粉和枝链淀粉的长链Ｂ与碘发生显色反应来测定的。决定米饭质地的不是直链淀粉的含量，而是枝链淀粉的长链Ｂ的含量及其性质。在多数品种中，稻米ＡＡＣ主要受控于蜡质基因（ｗｘ）座位上的不同等位基因。在该座位上，根据Ｗｘ蛋白的有无及特性，已发现ｗｘ，Ｗｘａ和Ｗｘｂ３个不同的等位基因；根据Ｗｘ基因ＤＮＡ的微卫星多态性，该位点的等位基因可多达８个。除Ｗｘ座位外，迄今已发现另外１３个基因座位也可影响ＡＡＣ。此外，遗传背景和其它非遗传因素，如开花后２０天内的气温等，对ＡＡＣ也有一定的调节作用。已对Ｗｘ基因进行测序，发现其总核苷酸长度约５．５ｋｂ，由１４个外显子和１３个内含子组成，其成熟ｍＲＮＡ的长度为２．３～２．４ｋｂ。
Apparent amylose content(ACC)is evaluated by color developing reaction of amylose and the long B chain of amylopectin with l 2 in rice.By 1987,amylose content had been contemplated to be the major determinant of cooked rice texture.Since then,more and more evidences have proved that it is the long B chain of amylopectin rather than amylose that determines the texture of cookedrice.In most cultivars,AAC is controlled by the alleles on the waxy gene locus,and 3 alleles,e.g.wx,Wx a,Wx b,were already detected based on the character of waxy protein in rice and related wild species,while microsatellite analysis revealed that there are 8 alleles on the wx locus.Moreover,mutations on other 13 loci could also lead to AAC alteration in various rice mutants.Other factors such as genetic background and environmental temperature of the first 20 days during maturing,could also affect AAC in some cases.Sequencing results showed that the wx gene consisted of 14 exons and 13 introns and the total nucleotides were about 5.5 kb long,and the mature mRNA of wx gene was about 2 3-2 4kb
出处
《浙江农业学报》
CSCD
1998年第1期47-54,共8页
Acta Agriculturae Zhejiangensis
基金
浙江省自然科学基金
关键词
表观直链淀粉
食用品质
遗传
水稻
apparent amylose content(AAC)
eating quality
genetics
Oryza sativa
