The Marker Development And Sequence Repeat Characteristics Analysis Of Brassica Mitochondrial Genome

Brassica is an important genus of cruciferous, which contains a number of crops,such as Brsssica rapa, Brassica oleracea, Brassica juncea, Brassica napus and so on.With the rapid development of molecular biology, genome-based research is widely usedin field of the analysis of genetic diversity, the construction of genetic map, genelocalization, marker-assisted selection etc. At present, the development of SSR markersin Brassica species can not meet the current needs, and the development of SSR markersof the mitochondrial genome in Brassica is quite less.This study, based on mitochondrial genome, analyzed the SSR features and genomicdistribution information of Brassica mitochondrial genome, and developed thecorresponding SSR markers. This paper has analyzed the sequence repeat of Brassicamitochondrial genome, developed SSR marker and performed genetic diversity tovalidate SSR markers. The results are as follows:(1) The comparison of the single nucleotide, the composite nucleotide andthree-nucleotide compound repeats of the mitochondrial genome of each specie showedthat: the content of the single nucleotide is the highest proportion, accountting for88.89%, in Brassica rapa, which is higher than that of other four species. The proportionof compound simple sequence repeats in Brassica juncea is10.53%, which is higher thanthat of other four species. Brassica rapa and Brassica carinata only have the singlenucleotide simple sequence repeat.(2) The analysis of various types of transposons shows the percentage percentages oftransposons of the genomes of Brassica oleracea and Brassica rapa were2.635%and2.713%, respectively; next, the corresponding percentages of Brassica napus (pol) andBrassica napus (nap) proportion were2.669%and1.742%, respectively; finally, theproportion of Brassica juncea and Brassica carinata was2.713%and1.742%,,respectively.(3) The copy number of tandem repeat sequences in mitochondrial genome of Brassicarapa and Brassica juncea. Theses showed that the characteristics of tandem repeats oftwo species are similar. And the percentages of insertion deletion of Brassica oleracea(CC), Brassica napus (AACC) and Brassica carinata (BBCC) were respectively1.3%,1.3%and1.8%.(4) The analysis of inverted repeat sequence of Brassica species shows that the numberof left and right indels of inverted repeats of Brassica rapa were301.7and302,resptectively, while that of the other Brassica species are less than200.0.(5) Mitochondrial genome often controls of cytoplasmic sterility. According to theBrassica mitochondrial genome information and the analysis of patterns of variation ofthese genes for cytoplasmic sterility is better helpful to understand the reasons for thenew CMS generated. Among these primers,17pairs of specific SSR sequences werefound, and BM036primers can be used to distinguish Brassica oleracea and otherspecies clearly. In addition,12pairs of primers can distinguish Brassica carinata fromother species; Infertility gene orf222-3and orf224-3can distinguish Brassica napus andother species. This research analyzed the SSR features of mitochondrial genome of Brassica fivespecies and developed17pairs of specific primers of the mitochondrial genome ofBrassica. These results can be applied to better distinguish the parts of Brassica speciesand are beneficial for the identification of Brassica species.