Imoh Odirichi Nnennaya, Shigita Gentaro, Sugiyama Mitsuhiro, Dung Tran Phuong, Tanaka Katsunori, Takahashi Mami, Nishimura Kazusa, Monden Yuki, Nishida Hidetaka, Goda Mashaer, Pitrat Michel, Kato Kenji
Graduate School of Environmental and Life Science, Okayama University, Okayama, 700-8530, Japan.
Department of Life Science Systems, Technical University of Munich, Freising 85354, Germany.
Ann Bot. 2025 Aug 16;135(7):1329-1344. doi: 10.1093/aob/mcaf028.
Africa is rich in wild species of Cucumis and is considered one of the places of origin of melon. However, our knowledge of African melon is limited, and genetic studies using melon germplasms with wide geographical coverage are required. Here, we analysed the genetic structure of African melons, with emphasis on Sudan.
Ninety-seven accessions of African melon were examined along with 77 reference accessions representing Asian melon and major horticultural groups. Molecular polymorphisms in the nuclear and chloroplast genomes were investigated using 12 RAPD, 7 SSR and 3 SNP markers. Horticultural traits, including seed size, were measured for 46 accessions, mainly from Sudan.
African melons were divided into large and small seed-types based on seed length: large seed-type from Northern Africa and small seed-type from Western and Southern Africa. Both seed types are common in Sudan. Molecular genetic diversity in these geographical populations was as high as in India, the Asian centre of melon domestication. Large seed-types from Northern Africa were assigned to Pop4 by structure analysis and had Ib cytoplasm in common with Cantalupensis, Inodorus and Flexuosus. Small seed-types were highly diversified and geographically differentiated; specifically, Pop1 with Ia cytoplasm in Southern Africa and South Asia, Pop2 with Ia in East Asia, including Conomon and Makuwa, and Pop3 with Ia or Ic in Africa. Sudanese small seed-types were grouped in Pop3, while their cytoplasm type was a mixture of Ia and Ic. Sudanese Tibish had Ic cytoplasm, which was unique in Africa, common in Western Africa and Sudan, and also found in wild or feral types.
Melon of Ic lineage, including Tibish, originated from wild melon in the 'western Sudan region', and independently of melon with Ia or Ib cytoplasm, which originated in Asia. This clearly indicates the polyphyletic origin of melon.
非洲拥有丰富的黄瓜属野生种，被认为是甜瓜的起源地之一。然而，我们对非洲甜瓜的了解有限，需要利用广泛地理覆盖的甜瓜种质进行遗传研究。在此，我们分析了非洲甜瓜的遗传结构，重点是苏丹地区。
研究了97份非洲甜瓜种质，同时分析了77份代表亚洲甜瓜和主要园艺群体的参考种质。利用12个RAPD、7个SSR和3个SNP标记研究了核基因组和叶绿体基因组中的分子多态性。对46份主要来自苏丹的种质测量了包括种子大小在内的园艺性状。
根据种子长度，非洲甜瓜分为大种子型和小种子型：大种子型来自北非，小种子型来自西非和南非。两种种子类型在苏丹都很常见。这些地理群体中的分子遗传多样性与甜瓜驯化的亚洲中心印度一样高。结构分析将来自北非的大种子型归为群体4，它们与罗马甜瓜、冬甜瓜和弯曲甜瓜一样具有Ib细胞质。小种子型高度多样化且具有地理分化；具体而言，南非和南亚具有Ia细胞质的群体1，东亚包括越瓜和马泡瓜具有Ia细胞质的群体2，非洲具有Ia或Ic细胞质的群体3。苏丹的小种子型归为群体3，而它们的细胞质类型是Ia和Ic的混合。苏丹的蒂比什具有Ic细胞质，这在非洲是独特的，在西非和苏丹很常见，在野生或野生类型中也有发现。
包括蒂比什在内的Ic谱系甜瓜起源于“苏丹西部地区”的野生甜瓜，独立于起源于亚洲的具有Ia或Ib细胞质的甜瓜。这清楚地表明了甜瓜的多系起源。
