Development and Genetic Characterization of Advanced Backcross Materials and An Introgression Line Population of Solanum incanum in a S. melongena Background

Abstract

Advanced backcrosses (ABs) and introgression lines (ILs) of eggplant (Solanum melongena) can speed up genetics and genomics studies and breeding in this crop. We have developed the first full set of ABs and ILs in eggplant using Solanum incanum, a wild eggplant that has a relatively high tolerance to drought, as a donor parent. The development of these ABs and IL eggplant populations had a low efficiency in the early stages, because of the lack of molecular markers and genomic tools. However, this dramatically improved after performing genotyping-by-sequencing in the first round of selfing, followed by high-resolution-melting single nucleotide polymorphism genotyping in subsequent selection steps. A set of 73 selected ABs covered 99% of the S. incanum genome, while 25 fixed immortal ILs, each carrying a single introgressed fragment in homozygosis, altogether spanned 61.7% of the S. incanum genome. The introgressed size fragment in the ILs contained between 0.1 and 10.9% of the S. incanum genome, with a mean value of 4.3%. Sixty-eight candidate genes involved in drought tolerance were identified in the set of ILs. This first set of ABs and ILs of eggplant will be extremely useful for the genetic dissection of traits of interest for eggplant, and represents an elite material for introduction into the breeding pipelines for developing new eggplant cultivars adapted to the challenges posed by the climate-change scenario.

Performance of a Set of Eggplant (Solanum melongena) Lines With Introgressions From Its Wild Relative S. incanum Under Open Field and Screenhouse Conditions and Detection of QTLs

“…From the IL population of Solanum incanum (MM577) developed in the S. melongena (AN-S-26) background [16], a set of 16 ILs were selected based on a maximization of representation of the genome of S. incanum and on seed availability (Figure 1). The recipient parent, AN-S-26, is a non-prickly Spanish local variety of eggplant from the region of Andalusia that has anthocyanin pigmentation in several vegetative parts of the plant, such as stems and leaf veins, and has large obovoid purple fruits.…”

“…The average size of the introgressions in the chromosomes was 55.94 Mb, with a range of 2 to 125 Mb, being chromosome 10 the less covered (1.8%) and chromosome 8 the most covered (97.2%) ( Table 1). For further details about the marker-assisted selection of the introgressions, refer to Gramazio et al [16].…”

“…In the present paper, we describe the first eggplant study on phenotyping and QTL analysis using an IL population with introgressions from an eggplant wild relative [16]. The results will provide relevant information on the phenotypic characteristics of the ILs with introgressions from a wild relative and may allow identifying stable QTLs for important traits.…”

“…However, in the last years, significant efforts have been done to develop new materials that will help in dissecting complex and quantitative traits, many of them using eggplant wild relatives as a source of variation [11][12][13][14][15]. Only recently, the first introgression line (IL) population, using S. incanum L. as a donor parent, has been developed in eggplant [16]. Solanum incanum is a wild species naturally distributed in desertic and dryland areas from northern Africa to Pakistan that belongs to the secondary genepool of common eggplant [17,18].…”

Development and validation of microsatellite markers fromde novotranscriptome assembly of eggplant (Solanum melongenaL.) and its putative progenitorS. incanumL. cultivars

“…Number of QTLs and mapping studies are reported for morphological traits in eggplant like fruit shape, size, colour, and prickliness [16, 17, 20], yield-related traits [21, 22], biochemical traits like location of CGA and polyphenol oxidase genes [9, 23], resistance to Ralstonia solanaceaerum [24], resistance to fungal wilts [25], resistance against Fusarium wilt [26], tolerance to bacterial wilt [27], and so on. Detailed biochemical and genetic information has been accumulated in eggplant for assessment of genetic diversity, QTL detection, and mapping based studies using range of molecular markers such as RAPD, AFLP, ISSR, SSR, SRAP, ESTs, and SNP [9, 16, 17, 26, 28–37]. These reports provide useful grounds for deciphering mechanisms underlying genetic control of the complex traits which are fundamental to the eggplant research program.…”