Development of backcross generations and new interspecific hybrid combinations for introgression breeding in eggplant (Solanum melongena)

Abstract

Introgression breeding can contribute to broadening the genetic background of eggplant (Solanum melongena). We used six eggplant varieties and 44 interspecific hybrids between these eggplant accessions and 10 accessions of wild relatives from the primary genepool species S. insanum and secondary genepool species S. anguivi, S. dasyphyllum, S. incanum, S. lichtensteinii, and S. tomentosum to obtain first backcross generations to S. melongena. Pollen viability in cultivated and wild parents and interspecific hybrids with S. insanum was high, while for interspecific hybrids with secondary genepool species it was variable. First backcross generations to S. melongena were obtained with interspecific hybrids of all the wild species, with the best results being obtained in crosses with hybrids between S. melongena and S. insanum. However, ample differences were observed among eggplant varieties in the success of the crosses. Additionally, the six eggplant varieties were crossed with secondary genepool species S. campylacanthum, S. lidii and S. vespertilio and with tertiary genepool species S. bonariense, S. elaeagnifolium and S. sisymbriifolium with the aim of obtaining new interspecific hybrids. Successful interspecific hybridization was achieved with the three new secondary genepool species tested and, using embryo rescue, with the tertiary genepool species S. elaeagnifolium. The new backcross generations and interspecific hybrids obtained will contribute to broadening the genetic background of the eggplant and to the genetic enhancement of this crop.

Genetics and Genomics of Cultivated Eggplants and Wild Relatives

“…Solanum linnaeanum and S. lichtensteinii produce hybrids with moderate or high fertility when crossed with eggplant , which can be also backcrossed with relative ease (Meyer et al, 2012b;Vorontsova et al, 2013;Rotino et al, 2014;Kouassi et al, 2016). However our data show that they are genetically more distant from S. melongena than S. incanum or S. insanum (Sakata and Lester, 1997;Furini and Wunder, 2004;Weese and Bohs, 2010;Vorontsova et al, 2013;Meyer et al, 2012b).…”

“…melongena (Bletsos et al, 1998;Kumchai et al, 2013;Kouassi et al, 2016;Plazas et al, 2016). No sexual hybrids have ever been reported between S. melongena and S. sisymbriifolium, while interspecific hybrids obtained through embryo rescue of the cross S. melongena x S. torvum were highly sterile and no backcrosses have been reported to date .…”

“…The difficulty in obtaining the hybrids between these two species, despite being phylogenetically close (Sakata and Lester, 1997;Vorontsova et al, 2013), might be caused by some chromosomal rearrangement or other hybridization barriers. At last, Kouassi et al (2016) reported that the backcrosses towards S. melongena of the hybrid between S. dasyphyllum (wild ancestor of S. macrocarpon) and S. melongena was successful. A clarification is provided by our data obtained from FastSTRUCTURE analysis (Fig 2) which highlights that the three cultivated species belong to clearly separate groups, suggesting that S. macrocarpon should be excluded from section Melongena (Mill.)…”

“…complex (Lester and Hasan, 1991;Lester and Kang, 1998;Kouassi et al, 2016). Solanum linnaeanum and the accession of S. lichtensteinii cluster together and close to S. melongena.…”

“…The availability of a large array of molecular markers obtained by genomic techniques allows a very efficient marker-assisted selection (MAS), by selecting the genes or quantitative trait loci (QTLs) of interest and facilitating the removal of undesirable traits of wild relatives and saving time and resources compared to the conventional breeding approach (Morrell et al, 2012;Brozynska et al, 2016). Even though the gap between eggplant and the crops with more genomic resources is still wide, a clear turnaround in this trend has occurred in the last few years (Hirakawa et al, 2014;Portis et al, 2015;Kouassi et al, 2016;Salgon et al, 2017).…”