Location Of Leaf Margin Notch Gene In Leaf Mustard And Development And Utilization Of Molecular Marker

Lobed leaf is a strong adaptation of plants to adversity,which was related to plant photosynthesis.Leaf mustard（Brassica juncea）with more lobed leaf the ratio of petiole is higher,which is more advantageous in processing.However,the production of leaf mustard is often troubled by early bolting.Therefore,breeding leaf mustard germplasm resources with lobed leaf and bolting resistance traits in production and processing is important.Thus,two leaf mustard doubled haploid（DH）lines with round leaf‘MN001’and lobed leaf‘MU056’were used as parents to constructed F_2,BC₁and F₄populations.Photosynthesis and yield of leaf mustard were measured to research the advantage of lobed leaf traits.And we constructed three mixed pool with lobed leaf pool,round leaf pool and middle pool to sequence,and combined with the Graded Pool-seq（GPS）association analysis to locate the lobed leaf trait in F₂generation.Gene annotations,bioinformatics and q RT-PCR analysis were used to analyze candidate genes.Molecular marker assisted breeding of leaf mustard varieties with lobed leaf and bolting resistance traits by development of the SSR molecular markers.The results were as follows:1.Observation on genetic characteristics of lobed leaf and light energy utilization analysisThe result showed that 714 plants with lobed leaf and 286 round leaf in F₂segregating population,which is in accordance with segregation law of Mendel’s genetic law of 3:1 by the chi-square test（χ²=3.303,p=0.069）.Photosynthesis analysis showed that light compensation point of lobed leaf mustard was about 2 times that of round leaf,and the Pn value of F₁was between the parents.And significant difference of yield were evident among lobed leaf and round leaf after 65 days of planting.2.GPS analysis to locate the candidate interval,gene annotation to select candidate genes and gene expression analysis by q RT-PCRRelated to lobed leaf traits were located within a region of physical distance of0.6 Mb（18.4 Mb-19.0 Mb）on chromosome 10 of the A genome,by GPS association analysis in F₂segregating generation.And one candidate gene Bju A040054 related to leaf morphogenesis was selected by GO analysis in the target interval.Expression levels of Bju A040054 was higher in the leaf margin than leaf inside by reverse transcription quantitative PCR（q RT-PCR）analysis,and Bju A040054 showed a clear difference between round leaf and lobed leaf.3.Development and application of SSR molecular markers46 SSR marker sequences were developed in the candidate interval,and one SSR marker primer No.A10-32 had selected with distinguished polymorphism by parents and F₁,and F₁possessed the complementary bands of parents.The marker is linked to Bju A040054 by BC₁population validation,and the physical distance was 29.6 kb.Apply the SSR marker identification the seed purity of mixed‘Qianqing No.5’is90.9%,and 20 leaf mustard plants with lobed leaf and bolting resistance traits were selected at the seedling stage by the development SSR markers with lobed leaf and bolting resistance.The marker can be used for varieties assisted selection breeding and seed purity identification of leaf mustard at the seedling stage.