Distribution of Three Cytoplasm Types in Onion (Allium cepa L.) Cultivars Bred in Korea and Japan

다국어 초록 (Multilingual Abstract)

Previously, we reported a molecular marker designed on the basis of variation of mitochondrial genome organization for distinction of three onion (Allium cepa L.) cytoplasm types (Normal, CMS-T, and CMS-S). The CMS-T and CMS-S cytoplasms are involved in induction of cytoplasmic male-sterility, both of which are utilized in development of F1 hybrid cultivars. Reliable application of this molecular marker was tested for 116 onion cultivars developed in Korea and Japan. The molecular marker was successfully utilized to identify specific cytoplasm types of all tested cultivars, showing reliable application of the molecular marker and absence of another unidentified cytoplasm type in tested cultivars. The frequency of CMS-T cytoplasm was high in cultivars developed in Korea compared with those developed in Japan. CMS-T cytoplasm is responsible for CMS-T male-sterility of which inheritance pattern of fertility restoration is complex due to involvement of at least three restorer-of-fertility genes. On the other hand, a few cultivars containing CMS-S cytoplasm were identified in Korean cultivars. CMS-S male-sterility is more stable in diverse environmental conditions, and its fertility restoration is controlled by only a single gene, rendering CMS-S suitable for establishment of molecular breeding systems. This distribution pattern was the most evident in late-maturing cultivars. The frequency of normal cytoplasm was relatively high in early-maturing cultivars, implying most early-maturing cultivars are still open-pollinated varieties.