Phenotypic Identification and Genetic Analysis of a Dwarf Mutant 20F421 in Maize
Dwarf stem resources are the material basis for crop dwarf breeding,exploring dwarf stem gene resources is of great significance in breeding for dwarf crop cultivars.With the aim to clarifing the genetic characteristics and dwarf mechanism of a dwarf mutant 20F421 which was identified from radiation mutagenesis mutations using 252CF fission fast neutrons using an elite maize inbred line KWS49,the dwarf stalk mutant 20F421 was as material to construct F1 and F2 isolated populations by hybridizing with maize inbred lines PH6WC,B73,Mo17 and KWS49,respectively,and analyzed the inheritance pattern of dwarf stalk traits,and used(20F421/B73)F2 as the localization population,and transcriptome sequencing combined with bulked segregant RNA-seq(BSR-seq)methods were used for initial mapping of mutant genes.The results showed that compared with KWS49,the plant height of 20F421 was 95.2 cm which reduced by 47.89%,the ear height was 23.9 cm which reduced by 64.54%,the internodes were significantly shortened,the leaves were more erect and dense,and the self-inbreeding was good.Genetic analysis showed that the separation rate of wild type(high stem)and mutant(dwarf stem)plant traits in the F2 isolated population conformed to the 3∶1,indicating that the mutant was controlled by a single nuclear recessive gene.The BSR-seq results map the mutant gene between chromosome 177～255 Mb.By comparing with the B73 reference genome,it was found that the interval contained the dwarf stalk gene Br2,so the allele detection of 20F421 and br2 mutant hybridization were detected,and the plant height of F1 and F2 did not have trait separation,showing the phenotypes of 20F421 and br2 mutant,and it was speculated that the dwarf stalk mutant gene in 20F421 was an allele mutation of the dwarf stalk gene Br2.The results of this study would lay a foundation for further fine localization and cloning of mutant genes,and also provide important genetic resources and theoretical support for the analysis of maize dwarf mechanism and the breeding of new dwarf maize varieties.
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