Phenotypic Analysis And Genetic Localization Of A Maize Small Kernel Mutant Ks

Maize（Zea mays L.）is the most important resources of human food and animal feed,and it is also significant industrial materials Improve maize yield is one of the most important topics in scientific research work,the corn maize grain size is one of the main factors that affect production,study the molecular mechanism of regulating the grain size and to determine the grain size control of genes,not only has important theoretical value,but also can be applied to the practice,to improve the corn production plays an important role..The mutant used in this study was a natural maize grain mutant ks（kernel small）discovered from the intermediate material of breeding.The grain size of the mutant was smaller than that of the wild-type control,and all other developmental stages were normal.Genetic analysis showed that the mutant character was controlled by a pair of recessive single genes.In this study,phenotypic analysis and activity determination of starch synthase were carried out using existing stable mutant materials with smaller corn seeds.In addition,two genetic isolates,the F₂ generation populations of ks/B73 and ks/chang 7-2,were used to fine locate the target genes regulating grain size through linkage genetic analysis and using SSR molecular markers,providing new ideas for genetic improvement of maize yield and genetic elements for molecular breeding.The research results are as follows:Phenotype and physiological and biochemical analysis of the mutantThe protein content in the mutant grain was higher than that in the wild type,and the starch content was slightly lower than that in the wild type.The results of scanning electron microscopy showed that compared with the wild type,the starch grains in the mutant grains were smaller in size and more compact in structure.The germination rate and germination potential of mutant maize and wild maize were not significantly different.In the process of corn grain development,the activity of starch synthesis related enzymes was determined.The results showed that the activity of UGPase and AGPase in mutant was significantly lower than that of wild type corn,while the activity of GBSS was significantly higher than that of wild type corn 15 days after pollination.This suggests that the mutant gene may affect the activity of these two key enzymes in the starch synthesis pathway,and thus affect the starch synthesis,resulting in the corresponding changes in grain composition and structure.Localization of mutant genesA total of 56 pairs of effective SSR molecular markers were used in the localization process.Preliminary mapping analysis showed that the genes related to grain size were located near the centromere of the fifth chromosome of maize,between the SSR molecular markers GY86 and GY87,and closely linked with the marker GY87,with the genetic distance of 4.2 cM.The genetic distance between GY86 and GY86 was 7.4 cM.Sixteen pairs of SSR primers between the two markers were selected for further fine localization of the mutant gene,and the gene was located in the region of 10 Mb.