Study Of Critical Starch Synthesis Genes (sbeâ… and Waxy) In Corn Grain

Maize (zea mays L.) is a widely planted crop in the world. According to its structure，starch can be divided into amylose and amylopectin．The starch with high amylopectin，ismainly used in food industry, and the starch with high amylose has a broader market outlookin medicine， textile， environmental protection and other fields that demand a hugequantity．Amylose extender (ae) is the major gene that controls amylose content. Meanwhilethere are modifier genes affecting amylose content, while waxy is the major gene that controlsamylopectin content. The results are as follows:(1) sbeⅠ is a critical modifier gene of ae, sbeⅠ explained49%of total amylose variance;(2) Promoters of three waxy maize inbred lines have different mutations, however, theycarried an identical mutation in the promoter regulatory factor binding site;(3) The waxy gene cDNA of waxy-A had4SNPs, but only the464(A-G) substitution (inthe4thexon) led to Asp155to Gly155, and result in the looser binding of GBSS I with starch.(4) The waxy gene of waxy-B had4bp deletion in7thexon and26bp deletion in7thintron leading to the waxy gene cDNA inserted36bp fragments originally belonged to7thintron, GBSS I was not detected in extract amyloplast and purified starch granule-boundprotein;(5) The retrotransposon that inserted in waxy gene of waxy-C also existed in chr2andchr4, GBSS I was not detected in extract amyloplast and purified starch granule-boundprotein.