Mitochondrial Proteomic Analysis Of Cytoplasmic Male Sterile Line In Beet (Beta Vulgaris L.)

Cytoplasmic male sterility(CMS)is a maternally inherited condition in which higher plants fail to produce functional pollen.CMS is a useful trait for commercial hybrid breeding,because inactive pollen eliminates the need for the expensive process of stamen removal.It is reported that CMS is often associated with mitochondrial dysfunction.In plants,mitochondrial proteins co-segregated with the CMS and have been shown to play an important role in the formation of CMS.Sugar beet(Beta vulgaris L.)is one of the important raw materials for the sugar industry,its output is second only to sugar cane.Understanding the molecular mechanism of CMS in beets at the protein level,is of great significance for improving the quality of hybrid seeds and commercial production of hybrid seeds in beets.In this study,mitochondrial proteomics analysis was performed on the beet CMS line using the isobaric tag for relative and absolute quantitation(i TRAQ)technology,quantitative real-time PCR(q RT-PCR)and transmission electron microscope(TEM).The following results were obtained:Transmission electron microscopy(TEM)was used to observe the morphological changes in different stages of the anther tissues of the male sterile line,its maintainer line,and the restorer line.Four factors related to the occurrence of CMS,including tapetum development,tetrad development,microspore development,and anther wall development.The mitochondrial proteomics of the male sterile line,its maintainer line and the restorer line were studied using i TRAQ.A total of 538 differentially expressed proteins(DEPs)were identified,including 191 DEPs between DY5-CMS and DY5-O,190 DEPs between DY5-CMS and CL6,and 157 DEPs between CL6 and DY5-O.538 DEPs were analyzed by bioinformatics including GO analysis,Pathway analysis,and Network analysis.The results of GO analysis have shown that DEPs are mainly involved in metabolic processes,cellular processes and single organism processes,and have binding and catalytic activity,and are highly enriched in cells and organelles.Pathway results have shown that most DEPs are involved in carbohydrate and energy metabolism and protein metabolism.The STRING analysis has revealed 5DEPs that occupied the key regulatory sites of a protein association network.The roots,leaves,and anthers of the sugar beet male sterile line,its maintainer lineand the restorer line as materials,q RT-PCR analysis was performed to investigate gene expression change and thirteen genes were selected to be analyzed.In the roots and leaves,the consistency of gene expression between transcriptional and protein levels was poor,which may be due to the fact that some proteins are regulated at the two levels of transcription and post-translational modification,or that metabolic pathways undergo abnormal changes during abortion.Besides,only one gene in the leaves was consistent with the roots pattern,which may associated with the selective expression of the gene.In anthers,10 genes in the male sterile line were significantly higher than in the maintainer line during the first period of anther development.These genes mainly involved in carbohydrate and energy metabolism,protein metabolism,and binding.In conclusion,the main causes of CMS in sugar beet were discussed,including abnormal tapetum degradation,abnormal tetrads separation,microspore developmental defects,abnormal development of anther wall,abnormal protein metabolism,defects in carbohydrates and energy metabolism and binding reactions were blocked.