Gene-based microsatellite development for mapping and phylogeny studies in eggplant

<p>Abstract</p> <p>Background</p> <p>Eggplant (<it>Solanum melongena </it>L.) is a member of the <it>Solanaceae </it>family. In spite of its widespread cultivation and nutritional and economic importance, its genome has not as yet been extensively investigated. Few analyses have been carried out to determine the genetic diversity of eggplant at the DNA level, and linkage relationships have not been well characterised. As for the other <it>Solanaceae </it>crop species (potato, tomato and pepper), the level of intra-specific polymorphism appears to be rather limited, and so it is important that an effort is made to develop more informative DNA markers to make progress in understanding the genetics of eggplant and to advance its breeding. The aim of the present work was to develop a set of functional microsatellite (SSR) markers, via an <it>in silico </it>analysis of publicly available DNA sequence.</p> <p>Results</p> <p>From >3,300 genic DNA sequences, 50 SSR-containing candidates suitable for primer design were recovered. Of these, 39 were functional, and were then applied to a panel of 44 accessions, of which 38 were cultivated eggplant varieties, and six were from related <it>Solanum </it>species. The usefulness of the SSR assays for diversity analysis and taxonomic discrimination was demonstrated by constructing a phylogeny based on SSR polymorphisms, and by the demonstration that most were also functional when tested with template from tomato, pepper and potato. As a results of BLASTN analyses, several eggplant SSRs were found to have homologous counterparts in the phylogenetically related species, which carry microsatellite motifs in the same position.</p> <p>Conclusion</p> <p>The set of eggplant EST-SSR markers was informative for phylogenetic analysis and genetic mapping. Since EST-SSRs lie within expressed sequence, they have the potential to serve as perfect markers for genes determining variation in phenotype. Their high level of transferability to other <it>Solanaceae </it>species can be used to provide anchoring points for the integration of genetic maps across species.</p

Solanum aethiopicum gr. gilo and Its Interspecific Hybrid with S. melongena as Alternative Rootstocks for Eggplant: Effects on Vigor, Yield, and Fruit Physicochemical Properties of Cultivar 'Scarlatti'

Grafting is generally considered eective in ameliorating vegetable crop tolerance to bioticand abiotic stresses. The use of interspecific hybrid as rootstock for eggplant may represent a valid alternative approach to enhance eggplant performance. However, studies on the eects of different rootstocks on eggplant plant vigor, yield, and fruit quality traits often show conflicting results. Thus, an experiment was performed in two spring\u2013summer growing seasons (2014 and 2015) by grafting eggplant 'Scarlatti' F1 hybrid on two accessions of S. aethiopicum gr. gilo and on the interspecific hybrid S. melongena x S. aehtiopicum gr. gilo in comparison to the most common eggplant rootstock S. torvum. Results indicate that S. melongena x S. aethiopicum gr. gilo interspecific hybrid and S. torvum improved grafting success, plant vigor, early flowering and yield in 'Scarlatti' F1 scion. All rootstocks tested did not negatively influence fruit apparent quality traits and fruit quality composition. Moreover, fruit glycoalkaloids content remained below the recommended threshold value. These findings suggest that the use of S. melongena x S. aethiopicum gr. gilo interspecific hybrid as rootstock may be a good alternative to the most commonly used S. torvum

Reversible male sterility in eggplant

SummarySince decades, plant male sterility is considered a powerful tool for biological containment to minimize unwanted self‐pollination for hybrid seed production. Furthermore, prevention of pollen dispersal also answers to concerns regarding transgene flow via pollen from Genetically Modified (GM) crops to traditional crop fields or wild relatives. We induced male sterility by suppressing endogenous general transcription factor genes, TAFs, using anther‐specific promoters combined with artificial microRNA (amiRNA) technology (Schwab et al., 2006). The system was made reversible by the ethanol inducible expression of an amiRNA‐insensitive form of the target gene. We provide proof of concept in eggplant, a cultivated crop belonging to the Solanaceae family that includes many important food crops. The transgenic eggplants that we generated are completely male sterile and fertility can be fully restored by short treatments with ethanol, confirming the efficiency but also the reliability of the system in view of open field cultivation. By combining this system with induced parthenocarpy (Rotino et al., 1997), we provide a novel example of complete transgene containment in eggplant, which enables biological mitigation measures for the benefit of coexistence or biosafety purposes for GM crop cultivation

Genetically modified parthenocarpic eggplants: improved fruit productivity under both greenhouse and open field cultivation.

BACKGROUND: Parthenocarpy, or fruit development in the absence of fertilization, has been genetically engineered in eggplant and in other horticultural species by using the DefH9-iaaM gene. The iaaM gene codes for tryptophan monoxygenase and confers auxin synthesis, while the DefH9 controlling regions drive expression of the gene specifically in the ovules and placenta. A previous greenhouse trial for winter production of genetically engineered (GM) parthenocarpic eggplants demonstrated a significant increase (an average of 33% increase) in fruit production concomitant with a reduction in cultivation costs. RESULTS: GM parthenocarpic eggplants have been evaluated in three field trials. Two greenhouse spring trials have shown that these plants outyielded the corresponding untransformed genotypes, while a summer trial has shown that improved fruit productivity in GM eggplants can also be achieved in open field cultivation. Since the fruits were always seedless, the quality of GM eggplant fruits was improved as well. RT-PCR analysis demonstrated that the DefH9-iaaM gene is expressed during late stages of fruit development. CONCLUSIONS: The DefH9-iaaM parthenocarpic gene is a biotechnological tool that enhances the agronomic value of all eggplant genotypes tested. The main advantages of DefH9-iaaM eggplants are: i) improved fruit productivity (at least 30–35%) under both greenhouse and open field cultivation; ii) production of good quality (marketable) fruits during different types of cultivation; iii) seedless fruit with improved quality. Such advantages have been achieved without the use of either male or female sterility genes

A polyphenol rich extract from Solanum melongena L. DR2 peel exhibits antioxidant properties and anti-herpes simplex virus type 1 activity in vitro

DR2B and DR2C extracts, obtained by ethanolic maceration of peel from commercially and physiologically ripe aubergine berries, were studied for the antioxidative cytoprotective properties and anti-HSV-1 activity, in line with the evidence that several antioxidants can impair viral replication by maintaining reducing conditions in host cells. The antioxidative cytoprotective effects against tBOOH-induced damage were assessed in Caco2 cells, while antiviral activity was studied in Vero cells; polyphenolic fingerprints were characterized by integrated phytochemical methods. Results highlighted different compositions of the extracts, with chlorogenic acid and delphinidin-3-rutinoside as the major constituents; other peculiar phytochemicals were also identified. Both samples reduced reactive oxygen species (ROS) production and exhibited scavenging and chelating properties. DR2C partly counteracted the tBOOH-induced cytotoxicity, with a remarkable lowering of lactate metabolism under both normoxia and hypoxia; interestingly, it increased intracellular GSH levels. Furthermore, DR2C inhibited the HSV-1 replication when added for 24 h after viral adsorption, as also confirmed by the reduction of many viral proteins’ expression. Since DR2C was able to reduce NOX4 expression during HSV-1 infection, its antiviral activity may be correlated to its antioxidant properties. Although further studies are needed to better characterize DR2C activity, the results suggest this extract as a promising new anti-HSV-1 agent

Open field trial of genetically modified parthenocarpic tomato: seedlessness and fruit quality

BACKGROUND: Parthenocarpic tomato lines transgenic for the DefH9-RI-iaaM gene have been cultivated under open field conditions to address some aspects of the equivalence of genetically modified (GM) fruit in comparison to controls (non-GM). RESULTS: Under open field cultivation conditions, two tomato lines (UC 82) transgenic for the DefH9-RI-iaaM gene produced parthenocarpic fruits. DefH9-RI-iaaM fruits were either seedless or contained very few seeds. GM fruit quality, with the exception of a higher β-carotene level, did not show any difference, neither technological (colour, firmness, dry matter, °Brix, pH) nor chemical (titratable acidity, organic acids, lycopene, tomatine, total polyphenols and antioxidant capacity – TEAC), when compared to that of fruits from control line. Highly significant differences in quality traits exist between the tomato F1 commercial hybrid Allflesh and the three UC 82 genotypes tested, regardless of whether or not they are GM. Total yield per plant did not differ between GM and parental line UC 82. Fruit number was increased in GM lines, and GM fruit weight was decreased. CONCLUSION: The use in the diet of fruits from a new line or variety introduces much greater changes than the consumption of GM fruits in comparison to its genetic background. Parthenocarpic fruits, produced under open field conditions, contained 10-fold less seeds than control fruits. Thus parthenocarpy caused by DefH9-RI-iaaM gene represents also a tool for mitigating GM seeds dispersal in the environment

Antioxidant activity and antiherpetic effects of a Solanum melongena L. genotype.

Herpes Simplex Virus type 1 (HSV-1) is a recurrent human virus, which develops quickly resistance to drugs commercially available, so increasing the need to study new sources of bioactive antiviral agents. To this end, extracts from medicinal plants, essential oils or fruits with antiviral properties are widely investigated in order to found the bioactive compounds. Among them, flavonoids and anthocyanins have been shown to inhibit the HSV-1, due to a probable virucidal action, likely antioxidant mechanisms (Khan et al., 2005). Besides, it is generally accepted that oxidative stress plays an important role in the pathogenesis of viral diseases (Peterhans, 1997). Also Solanaceae glycoalkaloids were found to be active against HSV-1 (Ikeda et al., 2000). On the basis of these evidences, in the present study, the antioxidant and antiherpetic properties of a DR2 eggplant (Solanum melongena L.) genotype (Mennella et al., 2012) were studied. Eggplant fruit is one of the most common vegetable consumed all around the world and an important source of both polyphenols and glycoalkaloids, including delphinidin, nasunin, chlorogenic acid and solamargine (Mennella et al., 2010). To perform the experiments, a 70% ethanol extract (pH 3) from the peel of the DR2 eggplant fruit, at both the commercial (B) and physiological (C) stage of ripeness, was prepared. The polyphenolic content was evaluated by high-performance thin-layer chromatography (HPTLC) and determined colorimetrically. Different antioxidant mechanisms, among which the radical scavenging power and the ability to block the ROS generation (by reducing and/or chelating mechanisms) were studied (Di Sotto et al., 2013). The antiherpetic activity of the extracts (DR2-B and DR2-C) was evaluated by the plaque assay in monkey kidney epithelial (Vero) cells, after infection with HSV-1 (Civitelli et al., 2014). In agreement with the colorimetric determinations, the HPTLC analysis showed the presence of different polyphenols in both the extracts, particularly the anthocyanin, delphinidin 3-O-β-rutinoside. The samples possessed antioxidant properties, being able to scavenge different radical species and to block the ROS generation by chelating mechanisms. As regard the antiherpetic activity, in spite of a null effect of DR2-B, the extract DR2-C inhibited the HSV-1 replication in a dose-dependent manner, reaching a 93% inhibition at concentration of 500 g/ml. When administered during different phases of the virus life-cycle, DR2-C inhibited the viral replication of about 50% during the adsorption period: these data were confirmed by the immunoblotting analysis, in which several herpetic proteins resulted inhibited. Present data highlight that DR2-C extract possess antiherpetic properties, likely due to an impairment of specific steps of the virus life-cycle. Taking into account that the HSV-1 replication requires an impairment of the intracellular redox status, the antioxidant properties of DR2-C extract, likely due to the presence of different polyphenolic compounds, could be involved in the antiviral effects found. In conclusion, the beneficial antioxidant and antiherpetic properties of DR-2C suggest a possible application of S. melongena as dietary supplement, or included in topical formulations, to treat the herpetic skin symptomatic lesions

New Insights on Eggplant/Tomato/Pepper Synteny and Identification of Eggplant and Pepper Orthologous QTL

Eggplant, pepper and tomato are the most exploited berry-producing vegetables within the Solanaceae family. Their genomes differ in size, but each has 12 chromosomes which have undergone rearrangements causing a redistribution of loci. The genome sequences of all three species are available but differ in coverage, assembly quality and percentage of anchorage.Determining their syntenic relationship and QTL orthology will contribute to exploit genomic resources and genetic data for key agronomic traits.The syntenic analysis between tomato and pepper based on the alignment of 34,727 tomato CDS to the pepper genome sequence, identified 19,734 unique hits. The resulting synteny map confirmed the 14 inversions and 10 translocations previously documented, but also highlighted 3 new translocations and 4 major new inversions. Furthermore, each of the 12 chromosomes exhibited a number of rearrangements involving small regions of 0.5-0.7 Mbp.Due to high fragmentation of the publicly available eggplant genome sequence, physical localization of most eggplant QTL was not possible, thus, we compared the organization of the eggplant genetic map with the genome sequence of both tomato and pepper. The eggplant/tomato syntenic map confirmed all the 10 translocations but only 9 of the 14 known inversions; on the other hand, a newly detected inversion was recognized while another one was not confirmed. The eggplant/pepper syntenic map confirmed 10 translocations and 8 inversions already detected and suggested a putative new translocation.In order to perform the assessment of eggplant and pepper QTL orthology, the eggplant and pepper sequence-based markers located in their respective genetic map were aligned onto the pepper genome. GBrowse in pepper was used as reference platform for QTL positioning. A set of 151 pepper QTL were located as well as 212 eggplant QTL, including 76 major QTL (PVE ≥ 10%) affecting key agronomic traits. Most were confirmed to cluster in orthologous chromosomal regions.Our results highlight that the availability of genome sequences for an increasing number of crop species and the development of ultra-dense physical maps provide new and key tools for detailed syntenic and orthology studies between related plant species