Identification And Analysis Of Leaf Curvature Related Genes In Brassica Rapa

The Brassicaceae family contains many species. B. rapa is the main vegetable andoilseed source, which cultivated in worldwide. B. rapa includes morphologically andgenetically diverse plant groups. Leaf curvature plays a critical role and directly relevantsto the quality and quantity of yield in B. rapa. In this study, leaf morphology of naturalvariation was analyzed in95core collections of B.rapa. The genes releated to leafcurvature have been identified by comparative genomic analyses between A. thaliana andB. rapa. Candidate genes were acquried by association analysis between leaf morphologytrait and the expression profile. Mutation sites of candidate gene were excavated andgenetic polymorphism were explored in638accessions belonging to13cultivar groups.Finally, the temporal and spatial expression pattern of candidate gene was described byqRT-PCR. The conclusions of this dissertation are as follows:1、 There was rich and popular variation in19quantity characters. All traits were dividedinto three principal components, leaf size composition factor, leaf shape compositionfactor and leaflike wing composition factor. There were significantly difference in leafphenotype between heading group and non-heading group.2、 There were90putative genes in B. rapa as the orthologs of50genes in A. thaliana.All but two genes were successfully mapped on10chromosomes of B. rapa. Most ofthese genes existed more than one copy in B. rapa. By association analysis betweenleaf morphology trait and the expression profile of these genes, it showed thatBrARF3.1correlated significantly with leaf curvature along transverse axis.3、 The G2263C site of BrARF3.1would lead to change of amino acid Gln to His. Thesite had the bias distribution trend between heading and non-heading group. In addition,BrARF3.1gene structure and phylogenetic relationship were analyzed.4、 A CAPS marker for identifying the key mutation site G2263C of BrARF3.1wasdesigned. The functional mutation site had strong differentiation between headinggroup and non-heading group and may be artificial selection loci. We found that theaccessions with G genotype possed with leaf phenotype in heading group and the otheraccessions with C genotype tend toward the leaf phenotype in non-heading group.5、 BrARF3.1was stable expression in all stages of heading accession (Chiffu), while itwas the advantage of expression in rosette stage of non-heading accession (SZQ). Inthe heading stage of Chiffu, the expression difference of BrARF3.1was not obviousfrom the outside to the inside of the blades. But this gene had the highest expression inthe inside of the petiole. All results suggested that candidate gene BrARF3.1maybeinvolved in the regulation of leaf curvature development.These can be used in improvement of leaf traits which have great impact on quantityand quality of B. rapa through marker-assisted breeding. The genetic analysis of leafcurvature will be helpful for providing basis for the mechanism of leafy head formationprocess.