Genetic diversity and population structure of Indian melon (Cucumis melo L.) landraces with special reference to disease and insect resistance loci

Abstract

This study was aimed to examine the genetic diversity and population structure of Indian melon landraces with special reference to disease and insect resistance loci. Thirty-six simple sequence repeat (SSR) markers along with seven markers at disease and insect resistance loci were used for this purpose on a panel of 91 accessions available at Indian Institute of Horticultural Research, Bengaluru, India. Model-based structure analysis revealed the presence of four groups that were consistent with the results of principal coordinate analysis (PCoA). The delineation of populations was mostly based on geography with improved varieties as a separate group. Ten accessions have been identified to possess beneficial alleles at all the selected disease resistance loci and shall be useful for incorporating multiple disease resistance after phenotypic validation. The results obtained in the current study demonstrate the importance of the Indian melon group as a valuable genetic reservoir and the need to plan strategies for its conservation and utilization in breeding programmes.

Assessment of genetic diversity and population structure in melon (Cucumis melo L.) germplasm using microsatellite markers: Implications towards its varietal improvement

“…Similarly, Hu et al (2019) identified four clusters using cluster analysis, while their STRUCTURE analysis indicated three subpopulations, roughly corresponding to the varietal melon germplasm used in their study. Previous studies employing SSR markers in Indian melon accessions revealed two structural groups (K = 2) (Reddy et al 2016;Saha et al 2022), corroborated by PCoA clustering into two distinct groups. The study discovered 28 genotypes with admixed lines containing genetic material from another population (Falush et al 2003).…”

“…This extensive gene flow likely accounts for the prevalence of numerous admixed lines within the germplasm collection. The notable factors contributing to this high gene flow could be ongoing anthropogenic seed dispersal over time and space, crosspollination behavior, genetic drift, as well as natural and artificial hybridization between improved cultivars and local landraces, which may have facilitated the domestication of diverse and intermediate forms of melon (Reddy et al 2016). F ST serves as a genetic measure of population variation, with values exceeding 0.15 signifying significant differentiation (Frankham et al 2002).…”

“…In the latest classification, Pitrat (2017) reported 19 intraspecific melon groups, with a recommendation of merging the groups, cantalupensis and reticulatus. All these infraspecific groups of melon are cross-compatible with one another, resulting in intermediate forms that are widely domesticated (Reddy et al 2016).…”

“…Previous research has utilized microsatellite markers to examine the genetic diversity and population structures of melon (Tzitzikas et al 2009;Raghami et al 2014;Hu et al 2019;Chikh-Rouhou et al 2021). However, despite India's probable status as the center of origin and domestication, there have been limited investigations conducted on the genetic relationships between native and exotic melons and their wild relatives (Reddy et al 2016;Saha et al 2022) with a larger set of germplasm and molecular markers. Therefore, the present study aimed at classifying the genetic diversity and population structure of 96 melon germplasms, comprising native and exotic genotypes from six varietal (cantalupensis, reticulatus, inodorus, momordica, conomon and callosus) classes from four horticultural groups, using microsatellite markers.…”

Crop Landraces and Indigenous Varieties: A Valuable Source of Genes for Plant Breeding

“…have been utilized in melon landraces, for the study of genetic diversity, molecular fingerprinting of genetic material, and association with variable traits such as resistance to biotic and abiotic stresses. Forty-nine Indian landraces and varieties were studied using SSR markers, revealing beneficial alleles at loci conferring resistance to Fusarium wilt, downy mildew, powdery mildew, aphids, and viruses [ 142 ]. Using GBS sequencing, Pavan et al [ 143 ] detected 25,422 SNPs by examining 72 accessions of Apulia in Southern Italy, including landraces of a winter melon, namely chate melon, which is also known by the folk name of ‘Carosello’ and ‘Barattiere’ that was never characterized before.…”