Analysis of genetic variability of commercial melon cultivars using SSR molecular markers

Heterosis and Combining Ability for Fruit Yield, Sweetness, β-Carotene, Ascorbic Acid, Firmness and Fusarium Wilt Resistance in Muskmelon (Cucumis melo L.) Involving Genetic Male Sterile Lines

Ten genetically diverse inbred lines, including two genic male sterile lines, of muskmelon (Cucumis melo L.) were crossed in a half-diallel to generate 45 F1 hybrids. These hybrids, along with the parental lines and commercial check, were evaluated for their fruit yield, level of phytochemicals and Fusarium wilt resistance. Both additive and non-additive genetic variances were important in governing the expression of all of the traits; however, the additive gene action for the fruit weight (g), flesh thickness (cm), rind thickness (mm), firmness (lb inch−2), β-carotene content (mg/100 g), non-additive variance for fruit yield (t ha−1), fruit number, total soluble solids (TSS, °Brix), ascorbic acid (mg/100 g) and reaction to Fusarium wilt were comparatively more important. The parental line MM-625 was the best general combiner for fruit yield, rind thickness and β-carotene content (mg/100 g). The exotic line Riogold was the best combiner for flesh thickness and firmness. The netted inbred line MM-610 was the best general combiner for fruit weight, ascorbic acid and reaction to Fusarium wilt. The inbred lines KP4HM-15 and MM-916 were the best general combiners for the number of fruits per vine and TSS. The best cross-combinations for fruit yield ha−1 and TSS were MS-1×M-610 and Kajri×MM-904, respectively. The hybrids KP4HM-15×MM Sel-103 and KP4HM-15×MM-1831 recorded the highest standard heterosis for fruit yield and TSS. The landrace-derived inbred lines Kajri, MM Sel-103 and KP4HM-15 produced moderate-to-highly FW-resistant hybrids. Out of the 121 SSR markers applied, 70 exhibited parental polymorphism. The markers DM0561, CMAAAGN14, TJ147, CMMS35_3, CMAGN45 and DE1337 identified specific/unique alleles in certain parental genotypes. Thus, the findings of this study revealed that the novel inbred lines can effectively be combined to generate heterotic F1 hybrids for yield and other traits, such as rind and flesh thickness, TSS, β-carotene content and firmness. Furthermore, SSR markers can potentially be utilized to confirm the genetic diversity among the parental lines, and for the DNA fingerprinting of F1 hybrids.

Deciphering the Patterns of Genetic Admixture and Diversity in the Ecuadorian Creole Chicken

Simple Summary

In Ecuador, the production of Ecuadorian Creole chicken is of crucial importance in the economy and for the nutrition of families. These chickens represent a focal point in scientific research for three main reasons: (1) they are an unknown genetic resource derived from 500 years of environmental and human selection and represent an important reservoir of genetic variability and adaptability; (2) Ecuadorian Creole chicken production is normally familiar, in a marginal dimension, and it is an important source of economic input for medium–low income communities; and (3) being a local genetic resource, it is available to local communities without intermediary international enterprises and represents the starting point for food sovereignty. We aimed to measure the level of genetic diversity and its phylogenetic position compared with other outgroup breeds using information from microsatellite and mitochondrial markers. Our results showed that these chicken populations represent a great reservoir of genetic variability; however, the genetic fragmentation owing to the high geographical diversity of the country could compromise the conservation status and, therefore, the establishment of an official breeding program is needed for the conservation and valuation of these avian populations, with this genetic characterization being a first step.

Abstract

Latin American Creole chickens are generally not characterized; this is the case in Ecuador, where the lack of scientific information is contributing to their extinction. Here, we developed a characterization of the genetic resources of Ecuadorian chickens located in three continental agroecosystems (Pacific coastal, Andean, and Amazonian). Blood samples of 234 unrelated animals were collected in six provinces across Ecuador: Bolívar, Chimborazo, Cotopaxi, Guayas, Morona Santiago, and Tungurahua, in order to perform a genetic characterization and population structure assessment using the AVIANDIV project microsatellites panel (30 loci) and D-loop sequences of mitochondrial DNA and comparing with reference data from other breeds or genetic lines. The results indicate that Ecuadorian Creole chickens are the result of the admixture of different genetic groups that occurred during the last five centuries. While the influence of South Spanish breeds is demonstrated in the colonial age, genetic relationships with other breeds (Leghorn, Spanish fighter cock) cannot be discarded. The geographical configuration of the country and extreme climate variability have influenced the genetic isolation of groups constituting a homogeneous genetic status into the whole population. This is not only a source of genetic variation, but also a critical point because genetic drift produces a loss of genetic variants.