Characterization Of ZmGRAS17 Regulatory Genes Related To Starch Synthesis In Maize(Zea May L.)

Maize is one of the important food crops in the world,is also a high yield of grain crops in recent years,not only can be used as food for human and animal,and can also provide important raw material for industrial production,have more and more important position in the production of human life.The starch occupies most of the proportion in maize grain,and improve the starch content is very important to increase production of crop.According to the structure,the starch can be divided into different amylose and amylopectin,and their proportion in the starch directly affect the processing,the physical and chemical properties of starch,to affect the use of the starch.At the same time,amylose and amylopectin also have different properties and purposes due to the difference of itself structure.Therefore,studying how to enhance and improve corn starch content in grain and the proportion of amylose and amylopectin,which contributes to the further study of starch metabolic pathway,it has important theoretical significance and practical significance to improve the starch content and quality in the further study of metabolic pathways of the starch.This experiment screened a gene related to starch synthesis by the transcriptome sequencing data combined with bioinformatics analysis,and has carried on the preliminary exploration for ZmGRAS17 about function and mechanism in the starch metabolic pathways through the overexpression technology technology of corn genes expressed.Received the following main results:1.According to different tissue expression pattern analysis and ioinformatics,we screen a gene named ZmGRAS17 related to starch synthesis,and clone the gene from maize inbred lines B73.The gene encoding area is 1527 bp,encoding 508 amino acids.Its the relative molecular is 56.08 kDa,and isoelectric point at 5.91.The analysis of amino acid showed that ZmGRAS17 belongs to DELLA branch of GRAS family protein.2.The analysis of tissue expression pattern shows that ZmGRAS17 in the eight groups such as root,stem and leaf,tassel,filaments,grain,embryo and endosperm were,expression quantity in endosperm is higher obviously than other groups;especially express the highest amount in the endosperm of 20 days after pollination.3.The results of experimental about transcription activity shows that yeast cells carring the conversion of pGBKT7-ZmGRAS17 can not growth normally in SD/Trp-His-Ade/X-α-GAL on three short plates,only growth in SD/Trp-short board.It showed ZmGRAS17 don’t have alpha galactose glucoside enzyme activity,these results suggest that ZmGRAS17 without own capacity in yeast.4.The experimental about subcellular localization shows according to the expression of the fusion protein carring ZmGRAS17 and GFP is localated in the cell membrane.The ZmGRAS17 does not have the characteristics of transcription factors,and do not belong to the transcription factors.5.Compared with wild type and empty carrier,there were no significant differences on other growth phenotype in the transgenic plants of ZmGRAS17 excessive express,except the long and thick of grain have shrinked.The analysis of the grain starch content found that the total starch content of enetically engineered seed grain was lower than that of wild type and the carrier,was reduced by 3.16% than wild type,and amylose content was down 16.86% than wild type.The SEM experiments found that the central and back of the starch granules in ZmGRAS17 genetically modified seeds has not changed was empty carrier and wild type,but the abdomen of starch granule has changed obviously.The abdominal amyloid shows a dense uniform distribution in seeds of wild type and empty carrier,and doesn’t have free starch granules,while abdominal amyloid of enetically modified seeds are loosely arranged,and have a lot of spherical single grain starch grains.The analysis of soluble sugar content in grain found that compared with wild type and empty carrier,soluble sugar content of transgenic plants increased slightly.The statistical studies of on grain agronomic traits have found that the transgenic plants relative to the wild type and empty vehicle plant,grain length has changed little,and significantly lower grain width and thickness,was reduced by 3.74% and 6.19% respectively than wild type,grain weight was also significantly lower than the wild type,was reduced by 10.63%.These experimental results indicate that the expression of ZmGRAS17 gene influencing initially the starch granule structure and size.