Phenotypic Analysis and Preliminary Mapping of Wheat Dwarf Small-Kernel Mutant smk56

ZHANG Fuyan; SUN Congwei; CHEN Xiaojie; WANG Jiahuan; CHENG Zhongjie; ZHAO Wan; MA Xuhui; ZHANG Jianwei; FAN Jialin

doi:10.15933/j.cnki.1004-3268.2025.02.003

Abstract：A dwarf and small grain mutant smk56(small kernel 56)with stable phenotypic inheritance was obtained from the seeds of wheat variety Zhoumai 22,which was mutagenized by China's first microgravity science experiment satellite,Shijian-10.The phenotype and endosperm starch morphology of smk56 were analyzed and observed.The mutant was hybridized with the wild type Zhoumai 22(WT)to construct an F2 segregating population.The plant height,thousand-grain weight and other agronomic traits of F2:3 families were investigated,and the genetic analysis of the mutant gene was carried out.Then,the bulked segregant analysis sequencing(BSA-Seq),exon capture sequencing and linkage analysis were used for preliminary location of the mutant gene.The results showed that compared with WT,smk56 had no significant difference in seedling habits,leaf color,panicle type,heading stage and mature stage;Plant height of smk56 significantly decreased by 14.51%,and thousand-grain weight significantly decreased by 21.83%;Additionally,spike length,effective spikelet number,internode length below the spike,grain number per spike,grain length and grain width were all significantly or extremely significantly decreased;The starch granules of smk56 had poor filling degree and a more loosely arrangement structure,with underdeveloped starch bodies in endosperm cells,but there was no significant difference in the arrangement and shape regularity of starch granules between smk56 and WT.Genetic analysis indicated that the smk56 trait was controlled by a single recessive gene,which was preliminarily mapped to a region on the wheat chromosome 6D,spanning from 23.18 cM to 35.54 cM on the genetic map,and closely linked to the marker gwm469,with the flanking molecular markers of cfd1 and cfd132.In summary,the dwarf and small grains of wheat mutant smk56 may be caused by the shortening of stem internodes and the poor development of amyloplasts in grain endosperm cells;The target gene is preliminarily mapped to the wheat chromosome 6D genetic map of 23.18-35.54 cM,with a genetic distance of 12.36 cM,and it is speculated that this region may habor a novel important gene related to the formation of plant height and thousand-grain weight in wheat.