Identification of proteins associated with cytoplasmic male sterility in pepper (Capsicum annuum L.)

• This is the first study on pepper CMS using a proteomic approach.
• 13 protein spots were detected differently between CMS line and its maintainer line.
• Low-expression of triosephosphate isomerase results in a reduction in ATP production.
• Over-expression of aspartic protease played important roles in the occurrence of CMS.

Pepper (Capsicum annuum L.) is a globally important and often cross-pollinated vegetable that exhibits significant heterosis. Though cytoplasmic male sterility (CMS) has an important value for pepper hybrid production, its molecular mechanism remains unclear. To explore the molecular mechanism of CMS in pepper at the proteome level, we examined the anther proteomes of a cytoplasmic male sterile line FS1030A and its maintainer line FS1030B by transmission electronic microscopy (TEM) during abortion at the microspore mother cell stage. Two dimension difference gel electrophoresis (2D-DIGE) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) analyses were used to determine differentially expressed proteins. About 1070 anther protein spots were detected on each gel, and 13 protein spots were expressed differently between FS1030A and FS1030B (p < 0.05). Twelve of the thirteen protein spots (92.3%) were successfully identified by NCBInr as nine proteins, namely down-regulated triosephosphate isomerase, actin, glutathione S-transferase (GST), Cu/Zn superoxide dismutase (Cu/Zn-SOD), and up-regulated branched-chain α-keto acid dehydrogenase E3 subunit, ketol-acid reductoisomerase (KARI), aspartic protease, and nascent polypeptides. The low-expression of triosephosphate isomerase involved in glycolysis impacts oxidative phosphorylation significantly and ultimately results in a reduction in ATP production, and over-expression of aspartic protease blocking normal programmed cell death (PCD) played important roles in the occurrence of CMS-FS1030A. This is the first study on pepper CMS using a proteomic approach. These findings provide a good basis for further studies of CMS in pepper.