AUTHOR=Wang Ling , Li Junfeng , Yang Fen , Dai Dongyang , Li Xiang , Sheng Yunyan 

TITLE=A preliminary mapping of QTL qsg5.1 controlling seed germination in melon (Cucumis melo L.)

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.925081

DOI=10.3389/fpls.2022.925081

ISSN=1664-462X

ABSTRACT=Melon (Cucumis melo L.) seed germination significantly affects its economic value. Cultivation of melon varieties with high germination ability and seedling vigor is efficient in large-scale melon propagation In this study, two melon genotypes differing in their germination ability, P5 with low P10 with high germination ability, were used to identify the optimal seed germination conditions by evaluating different water immersion times and germination temperatures. The germination rate of the P5 and P10 parental genotypes and their segregating population, consisting of 358 F2:3 families, were evaluated for two years to identify their genetic basis. QTL analysis was performed on a high-density genetic map constructed using SLAF (Specific-Locus Amplified Fragment Sequencing). The germination rate of F1 and F2 populations treated with water immersion for 8 hours (h) at 28℃ and measured at 48h showed a normal distribution Genetic mapping carried out using the high-density genetic revealed 8 QTLs in chromosomes 2, 4, 5, 6 and 8 controlling melon seed germination, of which 2020/2021-qsg5.1 was consistently significant in both years of experimentation. qsg5.1 explained 15.13% of the phenotypic variance with an LOD of 4.1. To fine map the candidate region of qsg5.1, 8 CAPS (Cleaved Amplified Polymorphism Sequences) markers were used to construct a genetic map with another 421 F2 individual fruits. The major QTL qsg5.1 was located between SNP53 and SNP54 within a 55.96 Kb interval containing 4 genes. qRT-PCR gene expression analysis of the candidate genes showed that MELO3C031219.2 (Phosphorus transporter PHO-5) exhibited a significant gene expression difference between the parental lines at 24, 32 and 48h after germination, potentially being the underlying gene controlling melon seed germination. These results provide a theoretical basis for the molecular mechanisms controlling melon seed germination and can practically contribute to further improving germination to increase commercial melon propagation efficiency.