Fine Mapping And Genetic Analysis Of Cadw1 Dwarf Mutant In Pepper (Capsicum Annuum L.)

Pepper as an important vegetable crop,pepper breeding methods are changing from traditional breeding to precision breeding.The development of molecular markers for excellent traits is the focus of modern breeding methods.Shoot architecture is one of the important factors affecting the yield of pepper.Shoot architecture is mainly affected by factors such as plant height and branch number.At present,Less research on pepper dwarfing.In this paper,the dwarfed and threecenter branched Cadw1 mutant material was selected from the pepper EMS mutagenic mutant library.In this study,through the analysis of the expression profile of the mutant Cadw1 during the key developmental period,combined with BSA gene positioning and PARMS genotyping,the mechanism of capsaicin regulating dwarfing was explored,and the theoretical foundation was laid for the study of the molecular mechanism of pepper plant type development.The main research contents are as follows:1.In this study,the phenotype analysis of wild-type 8214 and Cadw1 at the seedling stage showed that there were no obvious differences in plant height,leaf shape,and branch between 8214 and Cadw1 before the six-leaf one-heart stage.In this study,the phenotype investigation of wild-type and mutants at the flowering stage showed that the Cadw1 mutant has the characteristics of multi-branched,dwarfed,lanceolate leaves,and the plant type is more compact,which indicates that the mutant Cadw1 is a pepper shoot architecture the excellent variety.2.Through microscopic observation of the stem apex at the four-leaf-one-heart stage,five-leaf-one-heart stage,and six-leaf-one-heart stage,it was found that no branch primordium differentiation occurred in the four-leaf-one-heart stage.The generation of the base.Observation of the tissue section of the shoot tip at the seedling stage showed that the cell size and layer number of the wild type and the mutant did not show significant differences in the five-leaf-one-heart stage,but the tissue structure showed obvious two-branched and three-center branched primordia.The results show that the four-leaf-one-heart stage to the five-leaf-one-heart stage is the key period for the formation of three-center branched branches,and the expression of dwarfing mutation-related genes should begin before the five-leaf one-heart stage.3.Through transcriptome sequencing analysis of the two-leaf-one-heart and fourleaf-one-heart stages of mutant and wild-type materials,it was found that the terpenoid biosynthesis pathway and brassinosteroid biosynthesis pathway in the two-leaf oneheart stage mutants The up-regulation of differential gene expression indicates that the mutant gene Cadw1 of the dwarfing mutant material may directly or indirectly participate in the brassinosteroid biosynthesis pathway,and further regulate the pepper shoot architecture,making Cadw1 exhibit a dwarfed three-center branched phenotype.4.Through exogenous hormone spray treatment,it was found that wild-type 8214 and mutant Cadw1 were not sensitive to exogenous gibberellin.It was concluded that the dwarfing phenotype of Cadw1 might not be related to gibberellin;exogenous brassinolide treated mutants The plant height is correspondingly supplemented,and it is speculated that the dwarfing phenotype of Cadw1 may be related to the synthesis of brassinolide;when the concentration of exogenous strigolactone is sprayed at a concentration of 5 μM,the mutant responds sensitively,and the mutant plant height is correspondingly Replenishing,it is concluded that the dwarfing phenotype of Cadw1 may also be related to the synthesis of strigolactone.5.In this study,genetic analysis of the phenotype of the F2 population constructed with wild-type and mutants as parents showed that the separation ratio of wild tall rod traits and mutant dwarfing traits in the F2 population accorded with 3:1,indicating that Cadw1 is short.The mutation trait is controlled by a single recessive nuclear gene.The experiment used BSA mixed pool sequencing,and analyzed and mapped the differential SNP loci.It was concluded that the differential SNP was concentrated on chromosome3 and it was speculated that the target loci should be located on chromosome 3.Combined population genotyping results showed that there was an exchange between Chr03-121862672 and Chr03-196237886.The dwarfing mutant gene should be located between Chr03-121862672 and Chr03-196237886.