Phenotyping of Eggplant Wild Relatives and Interspecific Hybrids with Conventional and Phenomics Descriptors Provides Insight for Their Potential Utilization in Breeding.

Prashant Kaushik,Jaime Prohens,Mariola Plazas,Santiago Vilanova,Pietro Gramazio

doi:10.3389/fpls.2016.00677

Prashant Kaushik, Jaime Prohens + Show 3 more

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https://doi.org/10.3389/fpls.2016.00677

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Abstract

Eggplant (Solanum melongena) is related to a large number of wild species that are a source of variation for breeding programmes, in particular for traits related to adaptation to climate change. However, wild species remain largely unexploited for eggplant breeding. Detailed phenotypic characterization of wild species and their hybrids with eggplant may allow identifying promising wild species and information on the genetic control and heterosis of relevant traits. We characterizated six eggplant accessions, 21 accessions of 12 wild species (the only primary genepool species S. insanum and 11 secondary genepool species) and 45 interspecific hybrids of eggplant with wild species (18 with S. insanum and 27 with secondary genepool species) using 27 conventional morphological descriptors and 20 fruit morphometric descriptors obtained with the phenomics tool Tomato Analyzer. Significant differences were observed among cultivated, wild and interspecific hybrid groups for 18 conventional and 18 Tomato Analyzer descriptors, with hybrids generally having intermediate values. Wild species were generally more variable than cultivated accessions and interspecific hybrids displayed intermediate ranges of variation and coefficient of variation (CV) values, except for fruit shape traits in which the latter were the most variable. The multivariate principal components analysis (PCA) reveals a clear separation of wild species and cultivated accessions. Interspecific hybrids with S. insanum plotted closer to cultivated eggplant, while hybrids with secondary genepool species generally clustered together with wild species. Many differences were observed among wild species for traits of agronomic interest, which allowed identifying species of greatest potential interest for eggplant breeding. Heterosis values were positive for most vigor-related traits, while for fruit size values were close to zero for hybrids with S. incanum and highly negative for hybrids with secondary genepool species. Our results allowed the identification of potentially interesting wild species and interspecific hybrids for introgression breeding in eggplant. This is an important step for broadening the genetic base of eggplant and for breeding for adaptation to climate change in this crop.

Highlights

Eggplant (Solanum melongena L.) is an important vegetable in tropical and subtropical regions across the world, where it is a source of dietary fiber, micronutrients and bioactive compounds (Mennella et al, 2010; Niño-Medina et al, 2014; San José et al, 2014)
Significant differences (P < 0.05) were found among average values for the groups constituted by cultivated eggplant, wild relatives and interspecific hybrids for 18 out of the 27 conventional descriptors (Table 3)
For the eight Tomato Analyzer descriptors related to fruit size the cultivated eggplant presented significantly higher values than wild species, while for Ovoid it had lower values; interspecific hybrids presented intermediate values, in most cases being significantly different from both cultivated eggplant and wild species (Table 4)

Summary

Introduction

Eggplant (Solanum melongena L.) is an important vegetable in tropical and subtropical regions across the world, where it is a source of dietary fiber, micronutrients and bioactive compounds (Mennella et al, 2010; Niño-Medina et al, 2014; San José et al, 2014). The narrow genetic base of eggplant, probably a consequence of a genetic bottleneck during its domestication in Southeast Asia (Meyer et al, 2012), is a limitation to obtain major breeding advances This limited genetic diversity contrasts with the large morphological and genetic variation present in the eggplant wild relatives (Meyer et al, 2012; Vorontsova et al, 2013; Vorontsova and Knapp, in press). Eggplant is a member of the so-called “spiny solanums” group (Solanum subgenus Leptostemonum), which contains many wild species from the Old World, most of them from Africa (Vorontsova et al, 2013; Vorontsova and Knapp, in press) These wild species could represent a source of variation for developing a new generation of eggplant cultivars with dramatically improved yield and quality, as well as for addressing the challenges posed by adaptation to the climate change. With a few exceptions (Rotino et al, 2014; Liu et al, 2015), eggplant breeders have largely neglected the potential of wild species for eggplant breeding, and contrarily to other crops like tomato (Díez and Nuez, 2008), wild relatives have not made a relevant contribution to the development of new eggplant cultivars

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