Abstract: This work aims to explore the relationship between the encoding of the third sub-unit of cytochrome oxidase in the 4th complex subunit of mitochondrial respiratory chain（COX3）and the cytoplasmic male sterility（CMS）of pepper,for providing a reference in studying the relationship between pepper CMS and energy metabolism. Pepper cytoplasmic sterile line 9704A and maintainer line 9704B were used as material,CaCOX3 gene was amplified using specific primers based on the sequence of capsicum mitochondrial genome in GenBank. Its bioinformation and spatiotemporal expression were analyzed and the difference between 2 lines was compared. The cloned target CaCOX3 gene from the 9704A and the 9704B were consistent,the whole length was 798 bp,and encoded 265 amino acid residues. The expressions of CaCOX3 gene in different tissues of the 9704B were different：the highest in pericarp and the lowest in leaves. CaCOX3 gene expressed differently during the different developing periods of the bud of both lines. CaCOX3 gene expressions in the proliferative stage of sporogenetic cells and the meiotic stage of pollen mother cells of 9704A line were significantly lower than those of 9704B. The expressions in both lines were the same at the stage of microspore monocytes. The expressions in the CMS line was significantly higher than that in the maintainer line at the microspore maturation. In sum,the spatiotemporal expressions of CaCOX3 gene were different in the CMS line 9704A and the maintainer line 9704B,resulting in the abnormal energy metabolism and then infertility.

Key words: pepper（Capsicum annuum L.）, cytoplasmic male sterility, CaCOX3, fluorescent quantitative PCR