Development of New Molecular Markers for the Identification of Male Sterile Cytoplasm in Peppers (Capsicum annuum L.)

Cytoplasmic male sterility (CMS) induced by mutant mitochondria genome, has been used for commercial seed production of 171 hybrid cultivars in diverse crops. In pepper (Capsicum annuum L.); two sterile cytoplasm specific gene organization, atp6-2 and cavil were identified. An open reading frame, 01:1456 nearby cavil gene has been speculated to induce male sterility (MS) by mutagenic analysis. Moreover, molecular markers for atp6-2 and caxII of mitochondrial genotype (mitotype) were developed. However, the Cytoplasmic MS specific markers, atp6SCAR and coxIISCAR markers appeared in both N and S cytoplasms when polymerase chain reaction (PCR) cycles prolonged more than 40 cycles. Since the reported molecular markers were dominant markers, the presence of the faint sterile-specific band in normal cytoplasm may lead to the mis-classification of pepper breeding lines. To solve this problem, one common forward primer and two different reverse primers specific to normal coxII and sterile orf456 genes were designed after analyzing their gene organizations. By using these three primers. N and S cavil specific bands were co-amplified in male-sterile lines, but only normal coxII specific band was amplified in maintainer lines. Since the reverse primer for sterile cavil was specifically designed 275 bp downstream of orf456, relatively stable PCR amplification patterns were observed regardless of the number of PCR cycles. These primer sets easily identified different mitotypes among the divergent breeding lines, commercial cultivars and diverse germplasms.