Identification of novel sex determination loci in Japanese weedy melon

• Published in: Theoretical and applied genetics 2023-06, Vol.136 (6), p.136-136, Article 136
• Main Authors: Nashiki, Akito, Matsuo, Hiroki, Takano, Kota, Fitriyah, Fauziatul, Isobe, Sachiko, Shirasawa, Kenta, Yoshioka, Yosuke
• Format: Article
• Language: English
• Subjects: Agriculture; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cucurbitaceae; Cucurbitaceae - genetics; Cultivars; Flowers; Flowers & plants; Flowers - genetics; Gene regulation; Genes; Genetic aspects; Genetic research; Genetics; Hermaphrodites; Life Sciences; Melons; Molecular modelling; Mosses; Original Article; Plant Biochemistry; Plant Breeding; Plant Breeding/Biotechnology; Plant Genetics and Genomics; Population genetics; Primordia; Quantitative trait loci; Sex determination; Sex determination, Genetic; Single-nucleotide polymorphism
• ISSN: 0040-5752; 1432-2242
• DOI: 10.1007/s00122-023-04381-3

Key message Japanese weedy melon exhibits unique sex expression with interactions between previously reported sex determination genes and two novel loci. Sex expression contributes to fruit quality and yield in the Cucurbitaceae. In melon, orchestrated regulation by sex determination genes explains the mechanism of sex expression, resulting in a great variety of sexual morphologies. In this study, we examined the Japanese weedy melon UT1, which does not follow the reported model of sex expression. We conducted QTL analysis using F 2 plants for flower sex on the main stem and the lateral branch and mapped “occurrence of pistil-bearing flower on the main stem” locus on Chr. 3 ( Opbf3.1 ) and “type of pistil-bearing flower” (female or bisexual) loci on Chr. 2 ( tpbf2.1 ) and Chr. 8 ( tpbf8.1 ). The Opbf3.1 included the known sex determination gene CmACS11 . Sequence comparison of CmACS11 between parental lines revealed three nonsynonymous SNPs. A CAPS marker developed from one of the SNPs was closely linked to the occurrence of pistil-bearing flowers on the main stem in two F 2 populations with different genetic backgrounds. The UT1 allele on Opbf3.1 was dominant in F 1 lines from crosses between UT1 and diverse cultivars and breeding lines. This study suggests that Opbf3.1 and tpbf8.1 may promote the development of pistil and stamen primordia by inhibiting CmWIP1 and CmACS-7 functions, respectively, making the UT1 plants hermaphrodite. The results of this study provide new insights into the molecular mechanisms of sex determination in melons and considerations for the application of femaleness in melon breeding.