Identification And Analysis Of PHT And PAP Gene Family And Thier Application In The Screening Of Low Phosphorus Tolerant Germplasm In Brassica Rapa

The leafy vegetables represented by cabbage(Brassica rapa)have a short growth cycle,a high replanting index,and a high fertilizer requirement during cultivation,and excessive fertilizer application is a common problem in their cultivation.Excessive application of fertilizers can cause a number of problems,so how to reduce fertilizer application while ensuring yield is one of the problems to be solved in the cultivation of vegetable crops.Phosphorus transporter(PHT)and purple acid phosphatase(PAP)play important roles in various aspects of plant phosphorus acquisition,phosphorus transport and reuse.Therefore,identification and analysis of PAP and PHT gene family members responsive to low phosphorus in cabbage crops,mining for molecular markers associated with low phosphorus responsive members are important for subsequent screening or germplasm innovation of low phosphorus tolerant responsive varieties using techniques such as molecular assisted selection or gene editing.Based on the above knowledge,this study screened and identified information on the gene members encoding PHT and PAP in cabbage that respond to low phosphorus,and mined for SSR loci associated with the low phosphorus response members.Further,the polymorphisms of the identified SSR loci were analyzed using 87 common cabbage vegetable varieties in the market,and the potential of using SSR loci in the screening of low phosphorus tolerant germplasm was analyzed based on the results of the comprehensive evaluation of the phenotypes of the 87 varieties with low phosphorus treatment.Meanwhile,this thesis also edited Br PAP36,a low phosphorus response member,using CRISPR/Cas9 technology,which laid the material basis for subsequent research on the function of Br PAP36 or germplasm innovation based on this gene.The specific results are as follows.1,A total of 53 genes of PHTs were identified in B.rapa,which can be divided into five subfamilies.Among them,15 Br PHTs responded to low phosphorus stress,all of them were members of the Br PHT1 subfamily,and one SSR locus with polymorphism SSRBr PHT1:30 was mined among the responding members.2,39 genes of PAPs were isolated in B.rapa,which could be classified into three subclades and six subclades.Among them,15 Br PAPs responded to low phosphorus stress,and five SSR loci with polymorphism,SSRBr PAP12,SSRBr PAP13,SSRBr PAP33 and SSRBr PAP38,were mined in the responding members.3,The comprehensive evaluation of the low phosphorus tolerance ability of 87 varieties was completed and classified into two categories.Combining the results of the comprehensive evaluation of low phosphorus tolerance and the genotype analysis of the associated SSR loci for members of low phosphorus response Br PHTs and Br PAPs,it was found that two loci,SSRBr PAP33 and SSRBr PAP22,were in high agreement with the phenotype.4,Using CRISPR/Cas9,we completed the editing of the low phosphorus response member Br PAP36 and created a new allele type,which laid the material basis for the subsequent functional study of this gene.The above findings provide a gene source and material basis for and utilize the low phosphorus responsive members of Br PHTs and Br PAPs for germplasm resource screening and innovation.