Research On The Relationship Of Inbreeding Depression And Genomic Methylation Of Chinese Cabbage

Chinese cabbage(Brassica rapa L.s sp. Pekinensis) is cruciferae Brassica vegetable, typical hermaphroditic outcrossing crops;Chinese cabbage is indispensable vegetables of Chinese people’s daily life, and it has a relatively prominent status in agricultural economy, especially in the North arctic-alpine region. Cabbage is primary vegetable in winter and spring whose cultivated area and consumption are among the top of all kinds of vegetables.With the evolution of biological population the ubiquity viability depression phenomenon of inbred cabbage. The major characteristic of inbreeding depression showed weak disease resistance,heading decreased, weakened plant growth and plant viability decline.People have done a lot of researches about the inbreeding depression of species from the genetic perspective, while substantive progress haven’t obtained yet. So it’s a significance to study the molecular mechanism of inbreeding recession of Chinese cabbage.This experiment investigated heading condition during inbreeding depression of Chinese cabbage. Mean while using euzyme-linked immunosorbent assay to detect endogenous hormone of Chinese cabbage. And by using Illumina high-throughput sequencing and Bisulfite sequencing technology of plant material A209 inbred depression before and after the transcriptome sequencing and genome-wide methylation sequencing; Through the conjoint analysis of heading investigation, hormone content and gene expression and whole genome methylation sequencing to explore the relationship of cabbage inbreeding depression and genome DNA methylation. Main conclusions are as follows:(1) Through the high inbred A209(12067) and derivative progeny A209(13358) of cabbage survey found that high generation selfing lead to degeneration of cabbage.(2) To plant seedling, rosette stage and heading stage before and after depression endogenous hormones measured and found that after the depression plant auxin content is lower.(3) Genomic DNA methylation level changes before and after the depression, the methylation level depression material reduce;But differentially expressed genes, elevated depression material methylation level than decrease.(4) Before and after the depression detected 31,066 total changes in gene expression, which up regulate the expression of 14735, 16331 down regulated,significantly differentially expressed genes total of 7274, a significant rate of 23.48%.(5) Br DRM2, Br DDM1 of methylation related gene,performed relatively q PCR expression analysis,gene expression levels increased depression material,relative expression analysis and genome sequencing transcriptome same expression.(6) To key gene of auxin synthetic Bra IAA30 and Br PIN5, Br ARF19 of polar auxin transport related genes performed relative expression q PCR analysis,discover Br IAA30 and Br PIN5,Br ARF19 relative expression decreased of after the depression, initially identified Br IAA30, Br PIN5, Br ARF19 associated with inbreeding depression.