The Comparative Genomics Study Of Cytoplasmic Male Sterility Line9704A Of Capsicum Annuum

In this study, the cytoplasmic male sterility (CMS) line9704A and its correspondence homonuclear maintainer line9704B are used as materials, which breeded by Hunan Academy of Agricultural Sciences--Institute of Vegetables. We performed Solexa sequencing of mitochondrial DNA (mtDNA) of the CMS line and we obtained136kb chloroplast genome of the CMS line as well. Besides, we performed transcriptome sequencing of the pepper flower buds of the CMS line9704A and its correspondence homonuclear maintainer line9704B. We identified different expression genes, then cloned Chalcone Synthase CHS gene which displayed significant expression difference. What’s more, we tested the expression of the gene by realtime fluorescence quantitative RT-PCR. The main results are:1. The sequenced mtDNA genome was analyzed. We blast DNA sequences and analyzd the rpl5-rpsl4region is a "hot spot" for mtDNA rearrangements. Although high-frequency rearrangement in the region, no directly evidence proved that the region is related to CMS.2. The partial9704A chloroplast genome was analyzed. By reference with the complete chloroplast genomes of male sterility pepper FS4401that some13different contigs were found by comparative analysis. Gene ontology analysis results show that9704A has one more molecule in transport. But no evidence support that differences in these gene regions are crorrelated to the male sterility.3. The transcriptome of the pepper flower buds of9704A and9704B was analyzed. A total of1203genes displayed significant expression difference. It was found that521genes showed higher expression levels in the CMS line whereas682genes had higher expression in the maintainer line. Those differentially expressed genes suggested that the pepper CMS may exsit more complex molecular mechanisms.4. We cloned a CHS gene which encodes Chalcone Synthase that is16times different expression higer in9704B flower than it is in9704A. The Chalcone Synthase is a key enzyme in the flavonoid biosynthetic pathway. The biosynthesis and metabolism of flavonols play an improtant role in the development of anthers and pollen. We speculated CHS gene of9704A may crorrelated to its male sterility. 5. The realtime fluorescence quantitative RT-PCR of CHS gene in different tissues of9704A and9704B. The result showed that the expression level of the gene in the CMS line was abnormal that the gene’s expression in vegetative roots and leaves in some high leval compare to9704B but lower in its flower. So we conjectured CHS is a key gene which crorrelated to the male sterility. But the specific molecular mechanism remains to be revealed!...