Spanish Melon Landraces: Revealing Useful Diversity by Genomic, Morphological, and Metabolomic Analysis

Abstract

Spain is a secondary centre of the diversification of the melon (Cucumis melo L.), with high diversity represented in highly appreciated landraces belonging to the Flexuosus and Ibericus groups. A collection of 47 accessions of Flexuosus, Chate, Piel de Sapo, Tendral, Amarillo, Blanco, and Rochet was analysed using a genotyping-by-sequencing (GBS) approach. A total of 66,971 quality SNPs were identified. Genetic analysis differentiated Ibericus accessions and exotic materials (Ameri, Momordica, Kachri, and Agrestis), while Flexuous accessions shared ancestry between them. Within the Ibericus group, no clear genomic distinction could be identified for the different landraces evaluated, with accessions of different landraces showing high genetic similarity. The morphological characterization confirmed that the external colour and fruit shape had been used as recognition patterns for Spanish melon landraces, but variability within a landrace exists. Differences were found in the sugars and acid and volatile profiles of the materials. Flexuosus and Chate melons at the immature commercial stage accumulated malic acid and low levels of hexoses, while Ibericus melons accumulated high contents of sucrose and citric acid. Specific trends could be identified in the Ibericus landraces. Tendral accumulated low levels of sugars and citric acid and high of malic acid, maintaining higher firmness, Rochet reached higher levels of sugars, and Amarillo tended to lower malic acid contents. Interestingly, high variability was found within landraces for the acidic profile, offering possibilities to alter taste tinges. The main volatile organic compounds (VOCs) in Flexuosus and Chate were aldehydes and alcohols, with clear differences between both groups. In the Ibericus landraces, general trends for VOC accumulation could be identified, but, again, a high level of variation exists. This situation highlights the necessity to develop depuration programs to promote on-farm in situ conservation and, at the same time, offers opportunities to establish new breeding program targets and to take advantage of these sources of variation.

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

“…Their results gave preliminary information for the evolution and dissemination of melon in various geographic locations and provided a plethora of SNPs in known QTL regions underlying fruit quality and other horticultural traits, namely sex expression, ovary pubescence, leaf and fruit morphology, and flesh soluble solid content [ 145 ]. Moreover, GBS was applied on 47 accessions belonging to Spanish melon landraces to perform an in-depth study and characterization of this melon germplasm collection [ 146 ]. To examine the genetic diversity of prevailing varieties in China, Target-seq technology was utilized by Zhang et al [ 147 ] to screen out genome-wide SSRs and SNPs from 149 re-sequenced accessions and established the DNA fingerprint of 259 accessions of which 84 were landraces.…”

Comparative analysis of Cucurbita pepo genomes shed light in agronomic traits variation

“…To investigate the population structure, the analyses were conducted following the procedure described in Flores-León et al [102]. Admixture analysis was performed on the eight accessions using admixture-linux-1.3.0 [103] with default parameters in an unsupervised mode of K = 1 to 10.…”

Breeding Melons for Resistance to Viral and Fungal Diseases. Exploiting the Multi-Resistant Accession TGR-1551

“…This allows the identification of a high number of SNPs distributed throughout the genome. GBS has been used to study the genomic variability of melon as well as to fine map interesting traits (Flores-León et al, 2022;Gonzalo et al, 2019;Pavan et al, 2017;Pereira et al, 2018;. A cheaper alternative to GBS, also based on the use of restriction enzymes and sequencing is DarTseq.…”