Varietal Descriptors for the Distinction of Underutilized Varieties of Sechium edule (Jacq) Swartz

Abstract

Sechium edule (Jacq.) Sw. (Cucurbitaceae) is a species native to Mexico and Central America. The collection, characterization, and evaluation of accessions maintained in genebanks is essential for the conservation of this species. However, there are no specific varietal descriptors that differ from those used in a phenetic approach and are adapted to international registration guidelines to help distinguish, improve, cluster, and protect intraspecific variants of common use and those obtained by breeding. Therefore, 65 morphological descriptors (qualitative and quantitative) were evaluated in 133 accessions obtained from Mexico, Guatemala, and Costa Rica located in the National Germplasm Bank of S. edule in Mexico. These characteristics were observed to be phenetically stable for five generations under the same agroclimatic conditions. In addition, an analysis of amplified fragment length polymorphism (AFLP) was applied to 133 samples from a set of 245 accessions. According to the multivariate analysis, 26 of the 65 descriptors evaluated (qualitative and quantitative) enabled differentiation of varieties of S. edule. The AFLP analysis showed a high level of polymorphism and genetic distance between cultivated accessions and their corresponding wild ancestor. The variations in S. edule suggest that the morphological characteristics have differentiated from an essentially derived initial edible variety (ancestral original variety), but unlike other cucurbits, there is no evidence of the ancestral edible for Sechium since the seed is unorthodox and there are no relicts.

Comparison of Chayote (Sechium edule (Jacq.) Sw.) Accessions from Mexico, Japan, and Myanmar Using Reproductive Characters and Microsatellite Markers

“…However, it is necessary to increase the number of samples, expand the geographic sampling range, and utilize more informative markers (i.e., Single Nucleotide Polymorphisms, SNPs) to assess the chayote genetic diversity and morphological variation. Our study also established preliminary information to develop research to understand the response of chayote under different environments and management (i.e., commercial, cultural, and conservation) [ 52 ].…”

Genome-wide development of simple sequence repeats markers and genetic diversity analysis of chayote

“…The Germplasm National Bank of Sechium edule (BANGESe) has been established in Mexico, with most accessions originating from backyard areas. Reproductive isolation of most wild chayote materials has been influenced by consumer preferences [ 12 ]. To date, China has not carried out a systematic germplasm collection of chayote.…”

“…Due to the varying availability periods of chayote fruits across different regions and the fact that chayote is propagated through its fruits, traders are able to transfer popular local varieties from one planting area to another with ease [ 10 ]. Furthermore, 223 pairs of AFLP molecular markers were utilized to analyze 133 accessions of chayote resources from Mexico, revealing a high degree of genetic polymorphism between cultivated germplasm and their wild ancestors [ 12 ]. Moreover, the study showed that eight pairs of polymorphic SSR primers were screened from 20 chayote in Mexico by using 11 SSR markers developed, which will be helpful to characterize the population genetic structure of chayote varieties in Mexico and Latin America and decipher the dynamics of their genetic diversity [ 20 ].…”