StoMYB41 positively regulates the Solanum torvum response to Verticillium dahliae in an ABA dependent manner.

MYB transcription factor despite their solid involvement in growth are potent regulator of plant stress response. Herein, we identified a MYB gene named as StoMYB41 in a wild eggplant species Solanum torvum. The expression level of StoMYB41 was higher in root than the tissues including stem, leaf, and seed. It induced significantly by Verticillium dahliae inoculation. StoMYB41 was localized in the nucleus and exhibited transcriptional activation activity. Silencing of StoMYB41 enhanced susceptibility of Solanum torvum against Verticillium dahliae, accompanied by higher disease index. The significant down-regulation of resistance marker gene StoABR1 comparing to the control plants was recorded in the silenced plants. Moreover, transient expression of StoMYB41 could trigger intense hypersensitive reaction mimic cell death, darker DAB and trypan blue staining, higher ion leakage, and induced the expression levels of StoABR1 and NbDEF1 in the leaves of Solanum torvum and Nicotiana benthamiana. Taken together, our data indicate that StoMYB41 acts as a positive regulator in Solanum torvum against Verticillium wilt.

Rapid and low-cost screening for single and combined effects of drought and heat stress on the morpho-physiological traits of African eggplant (Solanum aethiopicum) germplasm.

Drought and heat are two stresses that often occur together and may pose significant risks to crops in future climates. However, the combined effects of these two stressors have received less attention than single-stressor investigations. This study used a rapid and straightforward phenotyping method to quantify the variation in 128 African eggplant genotype responses to drought, heat, and the combined effects of heat and drought at the seedling stage. The study found that the morphophysiological traits varied significantly among the 128 eggplants, highlighting variation in response to abiotic stresses. Broad-sense heritability was high (> 0.60) for chlorophyll content, plant biomass and performance index, electrolyte leakage, and total leaf area. Positive and significant relationships existed between biomass and photosynthetic parameters, but a negative association existed between electrolyte leakage and morpho-physiological traits. The plants underwent more significant stress when drought and heat stress were imposed concurrently than under single stresses, with the impact of drought on the plants being more detrimental than heat. There were antagonistic effects on the morphophysiology of the eggplants when heat and drought stress were applied together. Resilient genotypes such as RV100503, RV100501, JAMBA, LOC3, RV100164, RV100169, LOC 3, RV100483, GH5155, RV100430, GH1087, GH1087*, RV100388, RV100387, RV100391 maintained high relative water content, low electrolyte leakage, high Fv/Fm ratio and performance index, and increased biomass production under abiotic stress conditions. The antagonistic interactions between heat and drought observed here may be retained or enhanced during several stress combinations typical of plants' environments and must be factored into efforts to develop climate change-resilient crops. This paper demonstrates improvised climate chambers for high throughput, reliable, rapid, and cost-effective screening for heat and drought and combined stress tolerance in plants.

Conventional and new genetic resources for an eggplant breeding revolution.

Eggplant (Solanum melongena) is a major vegetable crop with great potential for genetic improvement owing to its large and mostly untapped genetic diversity. It is closely related to over 500 species of Solanum subgenus Leptostemonum that belong to its primary, secondary, and tertiary genepools and exhibit a wide range of characteristics useful for eggplant breeding, including traits adaptive to climate change. Germplasm banks worldwide hold more than 19 000 accessions of eggplant and related species, most of which have yet to be evaluated. Nonetheless, eggplant breeding using the cultivated S. melongena genepool has yielded significantly improved varieties. To overcome current breeding challenges and for adaptation to climate change, a qualitative leap forward in eggplant breeding is necessary. The initial findings from introgression breeding in eggplant indicate that unleashing the diversity present in its relatives can greatly contribute to eggplant breeding. The recent creation of new genetic resources such as mutant libraries, core collections, recombinant inbred lines, and sets of introgression lines will be another crucial element and will require the support of new genomics tools and biotechnological developments. The systematic utilization of eggplant genetic resources supported by international initiatives will be critical for a much-needed eggplant breeding revolution to address the challenges posed by climate change.

Comparative Proteomic Analysis of Roots from a Wild Eggplant Species Solanum sisymbriifolium in Defense Response to Verticillium dahliae Inoculation.

Eggplant verticillium wilt, caused by Verticillium spp., is a severe eggplant vascular disease. Solanum sisymbriifolium, a wild species of eggplant that is resistant to verticillium wilt, will be beneficial for genetically modifying eggplants. To better reveal the response of wild eggplant to verticillium wilt, proteomic analysis by iTRAQ technique was performed on roots of S. sisymbriifolium after exposure to Verticillium dahliae, and some selected proteins were also validated using parallel reaction monitoring (PRM). After inoculation with V. dahliae, the phenylalanine ammonia lyase (PAL) and superoxide dismutase (SOD) enzymes and the malondialdehyde (MDA) and soluble protein (SP) of S. sisymbriifolium roots all exhibited an increase in activity or content compared with that of the mock-inoculated plants, especially at 12 and 24 h post-inoculation (hpi). A total of 4890 proteins (47.04% of the proteins were from S. tuberosum and 25.56% were from S. lycopersicum according to the species annotation) were identified through iTRAQ and LC-MS/MS analysis. A total of 369 differentially expressed proteins (DEPs) (195 downregulated and 174 upregulated) were obtained by comparison of the control and treatment groups at 12 hpi, and 550 DEPs (466 downregulated and 84 upregulated) were obtained by comparison of the groups at 24 hpi. The most significant Gene Ontology (GO) enrichment terms at 12 hpi were regulation of translational initiation, oxidation-reduction, and single-organism metabolic process in the biological process group; cytoplasm and eukaryotic preinitiation complex in the cellular component group; and catalytic activity, oxidoreductase activity, and protein binding in the molecular function group. Small molecule metabolic, organophosphate metabolic, and coenzyme metabolic processes in the biological process group; the cytoplasm in the cellular component group; and catalytic activity and GTPase binding in the molecular function group were significant at 24 hpi. Then, KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis was performed, and 82 and 99 pathways (15 and 17, p-value < 0.05) were found to be enriched at 12 and 24 hpi, respectively. Selenocompound metabolism, ubiquinone, and other terpenoid-quinone biosyntheses, fatty acid biosynthesis, lysine biosynthesis, and the citrate cycle were the top five significant pathways at 12 hpi. Glycolysis/gluconeogenesis, biosynthesis of secondary metabolites, linoleic acid metabolism, pyruvate metabolism, and cyanoamino acid metabolism were the top five at 24 hpi. Some V. dahliae-resistance-related proteins, including phenylpropanoid-pathway-related proteins, stress and defense response proteins, plant-pathogen interaction pathway and pathogenesis-related proteins, cell wall organization and reinforcement-related proteins, phytohormones-signal-pathways-related proteins, and other defense-related proteins were identified. In conclusion, this is the first proteomic analysis of S. sisymbriifolium under V. dahliae stress.

The Past Is Present: Coevolution of Viruses and Host Resistance Within Geographic Centers of Plant Diversity.

Understanding the coevolutionary history of plants, pathogens, and disease resistance is vital for plant pathology. Here, I review Francis O. Holmes's work with tobacco mosaic virus (TMV) framed by the foundational work of Nikolai Vavilov on the geographic centers of origin of plants and crop wild relatives (CWRs) and T. Harper Goodspeed's taxonomy of the genus Nicotiana. Holmes developed a hypothesis that the origin of host resistance to viruses was due to coevolution of both at a geographic center. In the 1950s, Holmes proved that genetic resistance to TMV, especially dominant R-genes, was centered in South America for Nicotiana and other solanaceous plants, including Capsicum, potato, and tomato. One seeming exception was eggplant (Solanum melongena). Not until the acceptance of plate tectonics in the 1960s and recent advances in evolutionary taxonomy did it become evident that northeast Africa was the home of eggplant CWRs, far from Holmes's geographic center for TMV-R-gene coevolution. Unbeknownst to most plant pathologists, Holmes's ideas predated those of H.H. Flor, including experimental proof of the gene-for-gene interaction, identification of R-genes, and deployment of dominant host genes to protect crop plants from virus-associated yield losses.

African eggplant-associated virus: Characterization of a novel tobamovirus identified from Solanum macrocarpon and assessment of its potential impact on tomato and pepper crops.

A novel tobamovirus was identified in a fruit of Solanum macrocarpon imported into the Netherlands in 2018. This virus was further characterized in terms of host range, pathotype and genomic properties, because many tobamoviruses have the potential to cause severe damage in important crops. In the original fruit, two different genotypes of the novel virus were present. The virus was able to infect multiple plant species from the Solanaceae family after mechanical inoculation, as well as a member of the Apiaceae family. These species included economically important crops such as tomato and pepper, as well as eggplant and petunia. Both tomato and pepper germplasm were shown to harbor resistance against the novel virus. Since most commercial tomato and pepper varieties grown in European greenhouses harbor these relevant resistances, the risk of infection and subsequent impact on these crops is likely to be low in Europe. Assessment of the potential threat to eggplant, petunia, and other susceptible species needs further work. In conclusion, this study provides a first assessment of the potential phytosanitary risks of a newly discovered tobamovirus, which was tentatively named African eggplant-associated virus.

Novel R2R3 MYB transcription factors regulate anthocyanin synthesis in Aubergine tomato plants.

BACKGROUND: A high content in anthocyanins, for their health beneficial properties, represents an added value for fruits and vegetables. Tomato (Solanum lycopersicum) is one of the most consumed vegetables worldwide and is rich in vitamins and carotenoids. In recent years, purple-skinned tomatoes, enriched of anthocyanins, were produced recovering allelic variants from wild Solanum species. The molecular basis of the Anthocyanin fruit (Aft) locus, exploited by breeders to activate the anthocyanin synthesis in tomato epicarp, has been recently identified in the correct splicing of the R2R3 MYB gene AN2like. Aubergine (Abg) is a tomato accession which introgressed from Solanum lycopersicoides a locus activating the synthesis of anthocyanins in the fruit. The Abg locus was mapped in the region of chromosome 10 containing Aft and the possibility that Abg and Aft represented alleles of the same gene was hypothesized. RESULTS: We dissected the R2R3 MYB gene cluster located in the Abg genomic introgression and demonstrated that AN2like is correctly spliced in Abg plants and is expressed in the fruit epicarp. Moreover, its silencing specifically inhibits the anthocyanin synthesis. The Abg allele of AN2like undergoes alternative splicing and produces two proteins with different activities. Furthermore, in Abg the master regulator of the anthocyanin synthesis in tomato vegetative tissues, AN2, is very poorly expressed. Finally, a novel R2R3 MYB gene was identified: it encodes another positive regulator of the pathway, whose activity was lost in tomato and in its closest relatives. CONCLUSION: In this study, we propose that AN2like is responsible of the anthocyanin production in Abg fruits. Unlike wild type tomato, the Abg allele of AN2like is active and able to regulate its targets. Furthermore, in Abg alternative splicing leads to two forms of AN2like with different activities, likely representing a novel type of regulation of anthocyanin synthesis in tomato.

Exploring the genetic diversity and population structure of scarlet eggplant germplasm from Rwanda through iPBS-retrotransposon markers.

BACKGROUND: Scarlet eggplant (Solanum aethiopicum gr. gilo) is a part of African indigenous vegetables and acknowledged as a source of variations in the breeding of Brinjal. Since its genetic diversity is still largely unexplored, therefore genetic diversity and population structure of this plant were investigated in this study. METHODS AND RESULTS: Scarlet eggplant germplasm made of fifty-two accessions originated from two districts of Rwanda was assessed by employing the iPBS-retrotransposon markers system. Twelve most polymorphic primers were employed for molecular characterization and they yielded 329 total bands whereupon 85.03% were polymorphic. The recorded mean polymorphism information content was 0.363 and other diversity indices such as; mean the effective number of alleles, mean Shannon's information index and gene diversity with the following values; 1.298, 0.300 and 0.187 respectively. A superior level of diversity was noticed among accessions from Musanze district. The model-based structure, neighbor-joining, and principal coordinate analysis (PCoA) gathered scarlet germplasm in a divergence manner to their collection district. Analysis of molecular variance (AMOVA) displayed that the utmost variations (81%) in scarlet eggplant germplasm are resulting in differences within populations. CONCLUSIONS: The extensive diversity of scarlet eggplant in Rwanda might be used to form the base and genetic resource of an exhaustive breeding program of this economically important African indigenous vegetable. For instance, accessions MZE53 and GKE11 might be proposed as parent candidates due to their high relative genetic distance (0.6781).

Anther and Isolated Microspore Culture in Eggplant (Solanum melongena L.).

Eggplant is one of the five important, worldwide-distributed solanaceous crops. The use of anther culture technology to produce pure, 100% homozygous doubled haploid lines for hybrid seed production is possible since 1982, where the first protocol of wide application to different eggplant materials was published. From then on, different improvements and adaptations to different materials have been made. In parallel, protocols to implement isolated microspore culture technology in eggplant have been developed principally in the last decade, which opens the door for a more efficient DH production in this species. In this chapter, two protocols, one for anther and other for isolated microspore culture in eggplant, are described. Some steps and materials are common to both approaches. A detailed description of each step from is provided.

The biosynthetic pathway of potato solanidanes diverged from that of spirosolanes due to evolution of a dioxygenase.

Potato (Solanum tuberosum), a worldwide major food crop, produces the toxic, bitter tasting solanidane glycoalkaloids α-solanine and α-chaconine. Controlling levels of glycoalkaloids is an important focus on potato breeding. Tomato (Solanum lycopersicum) contains a bitter spirosolane glycoalkaloid, α-tomatine. These glycoalkaloids are biosynthesized from cholesterol via a partly common pathway, although the mechanisms giving rise to the structural differences between solanidane and spirosolane remained elusive. Here we identify a 2-oxoglutarate dependent dioxygenase, designated as DPS (Dioxygenase for Potato Solanidane synthesis), that is a key enzyme for solanidane glycoalkaloid biosynthesis in potato. DPS catalyzes the ring-rearrangement from spirosolane to solanidane via C-16 hydroxylation. Evolutionary divergence of spirosolane-metabolizing dioxygenases contributes to the emergence of toxic solanidane glycoalkaloids in potato and the chemical diversity in Solanaceae.

SmFLS negatively regulates peel coloring of eggplant (Solanum melongena) under high temperature.

The SmFLS gene was cloned from eggplant and has an ORF of 1014 bp encoding 337 amino acids. The deduced protein sequence of SmFLS was 88.07% and 84.94% identical to homologs encoded by StFLS in Solanum tuberosum and SlFLS in S. lycopersicum, respectively. SmFLS contains typical DIOX_N and 2OG-Fe (II)_Oxy functional domains, as well as five strictly conserved amino acid residues (H223, D225, H279, R289, and S291) related to FLS enzyme activity. Phylogenetic tree analysis showed that SmFLS had the closest genetic relationship with the FLS genes in potato and tomato. At a high temperature of 35 °C, the expression level of SmFLS was higher than that of the control in the same period, and it reached extremely significant levels on 15DAF and 20DAF, at which the eggplant peel color became lighter accordingly. Upon overexpression of SmFLS in eggplant, the flavonol content of transformed plants was significantly higher than that of untransformed plants, and the peel color was lighter than that of the control. The results indicate that SmFLS negatively regulates eggplant peel coloration under high temperature.

Combining genome composition and differential gene expression analyses reveals that SmPGH1 contributes to bacterial wilt resistance in somatic hybrids.

KEY MESSAGE: Clarification of the genome composition of the potato + eggplant somatic hybrids cooperated with transcriptome analysis efficiently identified the eggplant gene SmPGH1 that contributes to bacterial wilt resistance. The cultivated potato is susceptible and lacks resistance to bacterial wilt (BW), a soil-borne disease caused by Ralstonia solanacearum. It also has interspecies incompatibility within Solanaceae plants. Previously, we have successfully conducted the protoplast fusion of potato and eggplant and regenerated somatic hybrids that showing resistance to eggplant BW. For efficient use of these novel germplasm and improve BW resistance of cultivated potato, it is essential to dissect the genetic basis of the resistance to BW obtained from eggplant. The strategy of combining genome composition and transcriptome analysis was established to explore the gene that confers BW resistance to the hybrids. Genome composition of the 90 somatic hybrids was studied using genomic in situ hybridization coupled with 44 selected eggplant-specific SSRs (smSSRs). The analysis revealed a diverse set of genome combinations among the hybrids and showed a possibility of integration of alien genes along with the detection of 7 smSSRs linked to BW resistance (BW-linked SSRs) in the hybrids. Transcriptome comparison between the resistant and susceptible gene pools identified a BW resistance associated gene, smPGH1, which was significantly induced by R. solanacearum in the resistant pool. Remarkably, smPGH1 was co-localized with the BW-linked SSR emh01E15 on eggplant chromosome 9, which was further confirmed that smPGH1 was activated by R. solanacearum only in the resistant hybrids. Taken together, the identified gene smPGH1 and BW-linked SSRs have provided novel genetic resources that will aid in potato breeding for BW resistance.

Anther Culture in Eggplant (Solanum melongena L.).

For a long time, conventional breeding methods have been used to obtain pure, 100% homozygous lines for hybrid seed production in crops of agronomic interest. However, by doubled haploid technology, it is possible to produce 100% homozygous plants derived from precursors of male gametophytes (androgenesis), to accelerate the production of pure lines, which implies important time and cost savings. In this chapter, a protocol for anther culture in eggplant is described, from donor plant growth conditions to regeneration and acclimation of doubled haploid plants, as well as a description of how to analyze ploidy levels of regenerated plants.

A novel hydroxycinnamoyl transferase for synthesis of hydroxycinnamoyl spermine conjugates in plants.

BACKGROUND: Hydroxycinnamoyl-spermine conjugates (HCSpm) are a class of hydroxycinnamic acid amides (HCAAs), which not only are instrumental in plant development and stress response, but also benefit human health. However, HCSpm are not commonly produced in plants, and the mechanism of their biosynthesis remains unclear. In previous investigations of phenolics in Solanum fruits related to eggplant (Solanum melongena L.), we discovered that Solanum richardii, an African wild relative of eggplant, was rich in HCSpms in fruits. RESULTS: The putative spermine hydroxycinnamoyl transferase (HT) SpmHT was isolated from S. richardii and eggplant. SrSpmHT expression was high in flowers and fruit, and was associated with HCSpm accumulation in S. richardii; however, SpmHT was hardly detected in eggplant cultivars and other wild relatives. Recombinant SpmHT exclusively selected spermine as the acyl acceptor substrate, while showing donor substrate preference in the following order: caffeoyl-CoA, feruloyl-CoA, and p-coumaroyl-CoA. Molecular docking revealed that substrate binding pockets of SpmHT could properly accommodate spermine but not the shorter, more common spermidine. CONCLUSION: SrSpmHT is a novel spermine hydroxycinnamoyl transferase that uses Spm exclusively as the acyl acceptor substrate to produce HCSpms. Our findings shed light on the HCSpm biosynthetic pathway that may allow an increase of health beneficial metabolites in Solanum crops via methods such as introgression or engineering HCAA metabolism.

Effect of eugenol fumigation treatment on chilling injury and CBF gene expression in eggplant fruit during cold storage.

The effect of eugenol (EUG) on chilling injury (CI) to eggplant fruit (Solanum melongena L.) was investigated. Eggplant fruit were pre-treated with 25 µL/L EUG, and then stored at 4 °C for 12 days. Results showed that EUG fumigation treatment effectively retarded the CI development, reduced pulp browning, weight loss, and malondialdehyde (MDA) content, and sustained soluble solids content (SSC) and proline content. Moreover, the activities of polyphenol oxidase (PPO) and peroxidase (POD) were inhibited by EUG. C-repeat/dehydration-responsive element binding factors (CBF) genes are transcription factors playing a critical role in cold acclimation. To illuminate the molecular regulation of EUG on chilling tolerance in eggplant fruit, a 1151 bp SmCBF gene was identified and the effect of EUG on SmCBF expression was determined by RT-qPCR. EUG resulted in a higher SmCBF expression. These findings suggested that EUG treatment had potential effect on alleviating CI in eggplant fruit.

Embryogenic competence of microspores is associated with their ability to form a callosic, osmoprotective subintinal layer.

Microspore embryogenesis is an experimental morphogenic pathway with important applications in basic research and applied plant breeding, but its genetic, cellular, and molecular bases are poorly understood. We applied a multidisciplinary approach using confocal and electron microscopy, detection of Ca2+, callose, and cellulose, treatments with caffeine, digitonin, and endosidin7, morphometry, qPCR, osmometry, and viability assays in order to study the dynamics of cell wall formation during embryogenesis induction in a high-response rapeseed (Brassica napus) line and two recalcitrant rapeseed and eggplant (Solanum melongena) lines. Formation of a callose-rich subintinal layer (SL) was common to microspore embryogenesis in the different genotypes. However, this process was directly related to embryogenic response, being greater in high-response genotypes. A link could be established between Ca2+ influx, abnormal callose/cellulose deposition, and the genotype-specific embryogenic competence. Callose deposition in inner walls and SLs are independent processes, regulated by different callose synthases. Viability and control of internal osmolality are also related to SL formation. In summary, we identified one of the causes of recalcitrance to embryogenesis induction: a reduced or absent protective SL. In responding genotypes, SLs are markers for changes in cell fate and serve as osmoprotective barriers to increase viability in imbalanced in vitro environments. Genotype-specific differences relate to different responses against abiotic (heat/osmotic) stresses.

Shedding new light on the origin and spread of the brinjal eggplant (Solanum melongena L.) and its wild relatives.

PREMISE OF THE STUDY: While brinjal eggplant (Solanum melongena L.) is the second most important solanaceous fruit crop, we lack firm knowledge of its evolutionary relationships. This in turn limits efficient use of crop wild relatives in eggplant improvement. Here, we examine the hypothesis of linear step-wise expansion of the eggplant group from Africa to Asia. METHODS: We use museum collections to generate nuclear and full-plastome data for all species of the Eggplant clade. We combine a phylogenomic approach with distribution data to infer a biogeographic scenario for the clade. KEY RESULTS: The Eggplant clade has Pleistocene origins in northern Africa. Dispersals to tropical Asia gave rise to Solanum insanum, the wild progenitor of the eggplant, and to African distinct lineages of widespread and southern African species. Results suggest that spread of the species to southern Africa has been recent and likely facilitated by large mammalian herbivores, such as the African elephant and impala feeding on Solanum fruit. CONCLUSIONS: Rather than a linear 'Out Of Africa' sequence, our results are more consistent with an initial dispersal event into Asia, and subsequent wide dispersal and differentiation across Africa driven by large mammalian herbivores. Our evolutionary results will affect future work on eggplant domestication and affect the use of wild relatives in breeding of this increasingly important solanaceous crop.

Engineered gray mold resistance, antioxidant capacity, and pigmentation in betalain-producing crops and ornamentals.

Betalains are tyrosine-derived red-violet and yellow plant pigments known for their antioxidant activity, health-promoting properties, and wide use as food colorants and dietary supplements. By coexpressing three genes of the recently elucidated betalain biosynthetic pathway, we demonstrate the heterologous production of these pigments in a variety of plants, including three major food crops: tomato, potato, and eggplant, and the economically important ornamental petunia. Combinatorial expression of betalain-related genes also allowed the engineering of tobacco plants and cell cultures to produce a palette of unique colors. Furthermore, betalain-producing tobacco plants exhibited significantly increased resistance toward gray mold (Botrytis cinerea), a pathogen responsible for major losses in agricultural produce. Heterologous production of betalains is thus anticipated to enable biofortification of essential foods, development of new ornamental varieties, and innovative sources for commercial betalain production, as well as utilization of these pigments in crop protection.

Comparative proteomic analysis of eggplant (Solanum melongena L.) heterostylous pistil development.

Heterostyly is a common floral polymorphism, but the proteomic basis of this trait is still largely unexplored. In this study, self- and cross-pollination of L-morph and S-morph flowers and comparison of embryo sac development in eggplant (Solanum melongena L.) suggested that lower fruit set from S-morph flowers results from stigma-pollen incompatibility. To explore the molecular mechanism underlying heterostyly development, we conducted isobaric tags for relative and absolute quantification (iTRAQ) proteomic analysis of eggplant pistils for L- and S-morph flowers. A total of 5,259 distinct proteins were identified during heterostyly development. Compared S-morph flowers with L-morph, we discovered 57 and 184 differentially expressed proteins (DEPs) during flower development and maturity, respectively. Quantitative real time polymerase chain reactions were used for nine genes to verify DEPs from the iTRAQ approach. During flower development, DEPs were mainly involved in morphogenesis, biosynthetic processes, and metabolic pathways. At flower maturity, DEPs primarily participated in biosynthetic processes, metabolic pathways, and the formation of ribosomes and proteasomes. Additionally, some proteins associated with senescence and programmed cell death were found to be upregulated in S-morph pistils, which may lead to the lower fruit set in S-morph flowers. Although the exact roles of these related proteins are not yet known, this was the first attempt to use an iTRAQ approach to analyze proteomes of heterostylous eggplant flowers, and these results will provide insights into biochemical events taking place during the development of heterostyly.

Transcriptome analysis and molecular marker discovery in Solanum incanum and S. aethiopicum, two close relatives of the common eggplant (Solanum melongena) with interest for breeding.

BACKGROUND: Solanum incanum is a close wild relative of S. melongena with high contents of bioactive phenolics and drought tolerance. S. aethiopicum is a cultivated African eggplant cross-compatible with S. melongena. Despite their great interest in S. melongena breeding programs, the genomic resources for these species are scarce. RESULTS: RNA-Seq was performed with NGS from pooled RNA of young leaf, floral bud and young fruit tissues, generating more than one hundred millions raw reads per species. The transcriptomes were assembled in 83,905 unigenes for S. incanum and in 87,084 unigenes for S. aethiopicum with an average length of 696 and 722 bp, respectively. The unigenes were structurally and functionally annotated based on comparison with public databases by using bioinformatic tools. The single nucleotide variant calling analysis (SNPs and INDELs) was performed by mapping our S. incanum and S. aethiopicum reads, as well as reads from S. melongena and S. torvum available on NCBI database (National Center for Biotechnology Information), against the eggplant genome. Both intraspecific and interspecific polymorphisms were identified and subsets of molecular markers were created for all species combinations. 36 SNVs were selected for validation in the S. incanum and S. aethiopicum accessions and 96 % were correctly amplified confirming the polymorphisms. In addition, 976 and 1,278 SSRs were identified in S. incanum and S. aethiopicum transcriptomes respectively, and a set of them were validated. CONCLUSIONS: This work provides a broad insight into gene sequences and allelic variation in S. incanum and S. aethiopicum. This work is a first step toward better understanding of target genes involved in metabolic pathways relevant for eggplant breeding. The molecular markers detected in this study could be used across all the eggplant genepool, which is of interest for breeding programs as well as to perform marker-trait association and QTL analysis studies.