Characterization of interspecific hybrids and first backcross generations from crosses between two cultivated eggplants (Solanum melongena and S. aethiopicum Kumba group) and implications for eggplant breeding

Abstract

Common (Solanum melongena L.) and scarlet (S. aethiopicum L.) eggplants are cultivated for their fruits and form part of the same genepool. We have studied plant and fruit characteristics, pollen viability and seed set, phenolics content, and fruit flesh browning in accessions of S. melongena and S. aethiopicum Kumba group, as well as interspecific hybrids between these species and first backcross generations to each parental species. Respective genotypes were also characterized with seven polymorphic SSR markers. The results demonstrate that many differences exist for plant and fruit morphology among S. melongena, S. aethiopicum and the interspecific hybrids. The latter are very vigorous and generally intermediate between the two parents, except for fruit size which is smaller (and parthenocarpic due to a high pollen sterility) than those of any of the parents. Backcross progenies also exhibited morphological variation with moderate heritability values for the attributes evaluated. Variation for fruit size was present in the backcross generations but fruits were small resulting in little variation for fruit shape. Backcross plants with moderate fertility produced seeded fruits. Primary hybrids had fruit phenolics content similar to that of S. aethiopicum, the parent with lowest phenolics concentration, and were heterotic for fruit flesh browning. Backcross progenies were quite variable for both traits. SSR markers did not reveal segregation distortion in the backcross generations for these interspecific hybrids. The results demonstrate that generations derived from sexual interspecific hybridization can be a powerful tool for S. melongena and S. aethiopicum Kumba group breeding.

Diversity in composition of scarlet (S. aethiopicum) and gboma (S. macrocarpon) eggplants and of interspecific hybrids between S. aethiopicum and common eggplant (S. melongena)

“…In the first part of our study, scarlet eggplant proved of interest as a source of variation for breeding programmes directed to improve several quality traits of common eggplant. As occurs for morphological characters (Prohens et al, 2012), interspecific hybrids between scarlet and common eggplants are generally, with the exception of moisture content and pH, intermediate between both parents for chemical and nutritional composition traits, but with values generally more similar to scarlet eggplant parents.…”

“…Also, given that both species can be crossed with S. melongena (Daunay et al, 1991;Oyelana and Ugborogho, 2008;Prohens et al, 2012;Khan et al, 2013;Rotino et al, 2014), they may represent a valuable genetic resource for common eggplant breeding. In this respect, the results of this study indicate that scarlet eggplants are a source of variation of great interest for the improvement of eggplant cultivars, for higher content of proteins, total soluble sugars and fibre, while gboma eggplants are a good source of variation for total carbohydrates, vitamin C, and total phenolics.…”

“…Obtaining interspecific hybrids between scarlet and/or gboma eggplants and common eggplant is a key step on the way of reciprocal improvement of these three crops, as backcrosses of the hybrids to both species have been obtained (Toppino et al, 2008;Prohens et al, 2012;Khan et al, 2014;Rotino et al, 2014). In the case of gboma eggplant, interspecific hybrids with common eggplant are highly sterile (Bletsos et al, 2004;Khan et al, 2013) and no backcross generations to any of the parents have been reported, which limits the use of interspecific hybridization between both eggplants for breeding new gboma or common eggplant varieties.…”

“…Therefore, the study of the diversity for chemical and nutritional composition in different types of cultivars will be useful for the selection and breeding of improved varieties of scarlet and gboma eggplant. Also, given the feasibility of reciprocal introgression between scarlet and common eggplant (Toppino et al, 2008;Prohens et al, 2012;Khan et al, 2014;Rotino et al, 2014), the evaluation of interspecific hybrids of these two cultivated eggplants can also provide information of interest for breeding.…”

Angolan vegetable crops have unique genotypes of potential value for future breeding programmes

“…14,15 Both scarlet and gboma eggplants are also important genetic resources for common eggplant (S. melongena L.) breeding, as the three species can be intercrossed, thus producing hybrids with intermediate fertility. 16 Two accessions of the very variable Solanum lichtensteinii were also collected in Huíla province. This species grows as a weed in disturbed and overgrazed areas, along roadsides and is used as a traditional medicine.…”