The Comparative Analysis Of Cms-associated Gene In Sugar-beet Mitochondria And The RNA Editing Of Atp6Gene

Sugar-beet (Beta vulgaris) is one of the important sugar crops in the world. Inorder to take best advantage of sugar-beet cytoplasmic male sterile lines in heterosisutility, it has a very important sense to explore the mechanism of cytoplasmic malesterility (CMS) theoretically. Cytoplasmic male sterility (CMS) is a maternallyinherited condition in which a plant is unable to produce functional pollen. It occursin many plant species and is often associated with chimerical mitochondrial openreading frames. RNA editing exists extensively in mitochondrial genome of the higherplant, and is a critical step for producing functional proteins. A large number ofstudies show that there may be some relationship between RNA editing andCytoplasmic Male Sterility (CMS). Thus study on CMS-associated genes inmitochondrial genome and RNA editing could help us understand the molecularmechanism of CMS more in-depth. In this paper，using sugar beet of same cytoplasmbut different nuclei (DY5and TA33) as the experimental materials，CMS-associatedgenes and RNA editing of mitochondrial atp6gene was analyzed．Using PCR as the most important technical, CMS-associated genes coxⅠ、coxⅡ、orf129and orf324was contrast and detected. Agarose gel electrophoresis resultsshowed that cytochrome oxidase subunit gene the coxI and coxⅡ in education tomaintain the differential bands between the fertile lines and the male sterile lines,indicating that they may not the candidate genes in the CMS; Open reading frameorf129in the four kinds of experimental materials were not striped, it is not directlyrelated to the formation of the CMS. However, the open reading frame orf324appearing only in the male sterile line could be speculated that it may be a candidategene resulting in CMS.Combination of direct sequencing, cloning sequencing and RT-PCR technology,RNA editing of mitochondrial atp6gene was studied. The results showed that the4experimental materials share the same8editing sites found in conservative area ofatp6gene transcripts. All of the editing sites were C-U conversion and they alloccurred at the1st or the2nd position of codons, which might change the amino acidresidues type, such as the transformation of Ser (Hydrophobic parameter0.8) to Leu(Hydrophobic parameter3.8) in the second editing site. Moreover, the RNA editing ofmitochondrial atp6gene of sugar-beet can alter protein’s hydrophobicity and increasethe conservation among species. In addition, the editing frequency analysis results showed that all of editing sitesin the atp6gene transcription were partially edited, and in general terms the editingfrequency of the male sterile line were lower than the fertile maintainer line. To sumup, there were some connection between the RNA editing of atp6gene andCytoplasmic Male Sterility in sugar-beet mitochondrial genome but still not sure thatit was the dominant factor resulting in CMS, and the change of editing frequency maybe a result along with CMS.