| Maize is one of the main crops of food,feed,and industrial raw materials,and it occupies an important position in agricultural production.Maize kernel mutants are good materials for studying kernel traits.Constructing a mutant library of maize kernel traits,identifying and digging out more functional genes related to kernel traits,can enrich maize genetic resources and lay a foundation for maize molecular design and breeding.In this study,EMS was used to mutate the backbone of corn inbred line Zheng58 to construct a mutant library of corn kernel traits,and gene mapping of a kernel size mutant was carried out.The main findings are as follows:(1)A maize kernel mutant library was constructed.The maize inbred line Zheng 58 was mutated with an EMS mutagen at a concentration of 0.067%.A total of 648 mutants with kernel traits were identified among the 3585 inbred ears of the M2 generation.Ears,the separation ratio of normal grains and mutant grains on 415 ears accorded with the characteristics of single gene recessive 3:1.The mutant traits of these kernel mutants mainly include 8 types of empty peel,black kernel,small kernel,white kernel,shrunken kernel,sweet corn,ear sprouting,and high oil kernel.The corresponding mutant ear numbers are518,respectively.50,35,14,13,7,7,and 4 mutation rates were 14.45%,1.39%,0.98%,0.39%,0.36%,0.20%,0.20%,0.11%.The number of mutant ears(648)accounted for18.08% of the total harvested ears(3585).Thirty-seven of the 415 mutant ears that meet the3:1 separation ratio were selected for further mutation character identification and genetic analysis.There are 26 ears whose offspring have the same mutant characters as the previous generation,and both the upper and lower generations meet the 3:1 ratio.Separation ratio.(2)Gene mapping was performed on a grain size mutant mn7.The corn small grain mutant mn7 showed smaller grains and whiter color.The hundred-grain weight of the mutant grain is 13.13 g,which is 39.8% of the wild type.From 10 days after pollination to harvest,the fresh weight and dry weight of the mutant grains were significantly lower than those of the wild type;the paraffin sections of the grains at 8d,10 d and 12 d after pollination showed that the endosperm development of the mutant grains was relatively slow.The ratio of the number of normal grains to the number of mutant grains in the M2 generation of the mutant conforms to the segregation ratio of 3:1(χ2=2.43),and the backcross progeny conforms to the segregation ratio of 1:1(χ2=2.38;χ2=2.73).Crossing mn7 with multiple maize inbred lines,the ratio of the number of normal grains to the number of mutant grains in the F2 generation all meets the segregation ratio of 3:1,indicating that the mn7 mutant traits are single-gene recessive and in different genetic backgrounds on stable expression.The F2 population containing 348 individuals obtained by self-crossing the self-selected maize inbred line 19HL3012 with the homozygous mutant mn7 was used to locate the gene in the bin7.02 region on the 7th maize chromosome between the SSR molecular markers umc2327 and SYM232 5.8 Within the range of c M,the distance from umc2327 is 4.4c M,and the distance from SYM232 is 1.4c M.The linked molecular markers also include SYM176,AY105589,SYM217,umc1339,and SYM192.The linkage sequence of the target gene and its nearby molecular markers is SYM176-AY105589-umc2327-mn7-SYM232-SYM217-umc1339-SYM192.Preliminary bioinformatics analysis indicated that mn7 may be a new gene or new allele regulating grain development. |
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