Gene Expression Analysis Of Brassica Napus-orychophragmus Violaceus Additions

Orychophragmus violaceus(L.) O.E.Schulz(2n=24,OO)belongs to the Cruciferae family and has strong cold resistance, shade tolerance and extensive adaptability. Its flowers are purple. With high oil content in its seeds and high ratio of linoleic acid, the plant is a good germplasm for breeding. In this study, four addition lines derived from the somatic hybrids(2n=62,AACCOO) between Brassica napus L.(2n=38,AACC) and O. violaceus were used, expressing the serrated leaves from O. violaceus(Line 1), the female sterility(Line S), carrying the chromosome with dominant r RNA genes over those from B. napus and slightly purple petals(Line 4), harboring the alien chromosome with partially dominant r RNA genes(Line 6). Transcriptome sequencing(RNA-seq) were used to analyze the gene expressions of these four additions,(1) to reveal the influence of the additional O. violaceus chromosomes on the gene expression in B. napus;(2) to study the impact of alien r RNA genes with different degrees of dominance on the gene expression of the recipient B. napus;(3) to clarify the similarities and differences of gene expressions between the four additional line plants. The main results are as follows:1. One pair of alien O. violaceus chromosomes was included in Lines 1, 4 and S, but only single one in Line 6. RNA-seq and bioinformatics analyses were performed in comparison with two parental species and the result showed that the obvious changes in gene expressions occurred in four lines, but the least alterations in Line 6. The number of DEGs in Line 4 was 2.5 times of that in Line 6, 1.5 times of that in Lines 1 and S.2. The number of DEGs from C genome totally was more than that from A genome. But from the percent of DEGs vs total genes in corresponding genome, A genome tended to be more affected by the alien chromosomes. Among three subgenomes(LF—the least fractionated blocks, MF1—the medium fractionated blocks,MF2—the most fractionated blocks) within both A and C genomes, MF1 was most influenced, but MF2 was least affected.3. As to the influence of alien chromosomes on the gene expressions of individual chromosomes in B. napus, some specific chromosomes were preferentially affected by in different lines, which was displayed through making large number of genes within certain segment differentially expressed in the same direction. Furthermore, some chromosomal segments in A5 and C5 chromosomes seemed to be specifically influenced by nucleolar dominance in Lines 4 and 6.4. The DEGs of four additions were mainly enriched in these GO terms: cell part, intracellular part, intracellular organelle and membrane-bounded organelle. It meant that addition line plants could be different from Brassica napus in these aspects.In conclusion, the gene expression of B, napus was disturbed by the alien chromosomes with different degrees for A、C genomes, their subgnomes, different chromosomes. The different expressions of alien r RNA genes contributed differently to the gene expression of the corresponding addition lines. The differently expressed genes were largely related with cell parts and their functions.