Iris Edith Peralta

Comparison of AFLPs with other markers for phylogenetic inference in wild tomatoes [Solanum L. section Lycopersicon (Mill.) Wettst.]

ac.uk Wild tomatoes (Solanum section Lycopersicon) are native to western South America. The delimitation and relationships of tomato species have differed widely depending upon whether morphological or biological species concepts are considered more important. Molecular data from mitochondrial, nuclear, and chloroplast DNA restriction fragment length polymorphisms (RFLPs), nuclear microsatellites, isozymes, and gene sequences of internal transcribed spacers of nuclear ribosomal DNA (ITS; multiple-copy), the single-copy nuclear encoded Granule-bound Starch Synthase gene (GBSSI or waxy), and morphology, have been used to examine hypotheses of species relationships. This study is a companion to the previous GBSSI gene sequence study and to the morphological study of relationships of all ten wild tomato species (including the recently described S. galapagense), with a concentration on the most widespread and variable species S. peruvianum s.l. These new AFLP data are largely concordant with the GBSSI and morphological data and in general support the species outlined in the latest treatment by C.M. Rick, but demonstrate the distinct nature of northern and southern Peruvian populations of S. peruvianum, and suggest that their taxonomy needs revision. Solanum ochranthum is supported as sister to wild tomatoes, and S. habrochaites and S. pennellii reside in a basal polytomy in the tomato clade.

New Species of Wild Tomatoes (Solanum Section Lycopersicon: Solanaceae) from Northern Peru

Abstract Solanum arcanum and S. huaylasense, two new wild tomato species segregated from Solanum peruvianum sensu lato, are described and illustrated. These two new species are placed in a key with two other segregates of S. peruvianum sensu lato: S. peruvianum sensu stricto and S. corneliomulleri, and the morphologically similar species S. chilense. We also present a list of all 13 species of wild tomatoes we recognize, and their equivalent former names in Lycopersicon.

Natural occurring epialleles determine vitamin E accumulation in tomato fruits

Vitamin E (VTE) content is a low heritability nutritional trait for which the genetic determinants are poorly understood. Here, we focus on a previously detected major tomato VTE quantitative trait loci (QTL; mQTL(9-2-6)) and identify the causal gene as one encoding a 2-methyl-6-phytylquinol methyltransferase (namely VTE3(1)) that catalyses one of the final steps in the biosynthesis of γ- and α-tocopherols, which are the main forms of VTE. By reverse genetic approaches, expression analyses, siRNA profiling and DNA methylation assays, we demonstrate that mQTL(9-2-6) is an expression QTL associated with differential methylation of a SINE retrotransposon located in the promoter region of VTE3(1). Promoter DNA methylation can be spontaneously reverted leading to different epialleles affecting VTE3(1) expression and VTE content in fruits. These findings indicate therefore that naturally occurring epialleles are responsible for regulation of a nutritionally important metabolic QTL and provide direct evidence of a role for epigenetics in the determination of agronomic traits.

Taxonomy of tomatoes in the Galápagos Islands: native and introduced species of Solanum section Lycopersicon (Solanaceae)

Abstract The Galápagos Islands are of great conservation interest due to their high proportion of endemic species. The endemic tomatoes (Solanum section Lycopersicon) of the islands have long been of interest to plant breeders. We analyse the morphology of all the Galápagos tomatoes: two endemic species, Solanum cheesmaniae and S. galapagense (the latter described here as new) and two introduced species, S. lycopersicum and S. pimpinellifolium. Morphological characters were measured on greenhouse‐grown plants raised from seeds obtained from the wild and seed‐bank accessions. Species boundaries were examined by cluster analysis and principal component analysis. Although the four taxa are distinct and therefore regarded as bona fide species they exhibit considerable intraspecific variation. A taxonomic treatment of the tomatoes in the Galápagos is provided, with keys to all solanums in the islands, descriptions, listings of representative specimens examined and full exsiccatae. Field observations of plants in the wild in the Galápagos are also included in the species descriptions. We highlight the potential for genetic contamination of the endemic tomatoes by hybridization and introgression with the two introduced species.

Solanum sect. Lycopersicon

In this review, we examine the plant group Solanum sect. Lycopersicon – a clade of 13 species, including the domesticated tomato (Solanum lycopersicum L.) and its wild relatives – along with four allied species in the immediate outgroups Solanum sects. Juglandifolia and Lycopersicoides. We summarize the geographic distribution and morphological characters of these plant groups, describing their evolutionary relationships in the context of a new taxonomic revision at the species level of all these groups. We provide an overview of the role that wild tomato species have played in the development of cytogenetic stocks, in classical and molecular genetic studies as well as in crop improvement through traditional and advanced tools. We discuss how the very narrow genetic basis of cultivated tomato germplasm has forced tomato geneticists and breeders to rely on the wealth of genetic variation present in the wild relatives to address the many breeding challenges. The numerous molecular mapping studies conducted using interspecific crosses have clearly demonstrated that the breeding value of exotic (wild) tomato germplasm goes far beyond its phenotype. These studies also show that we are still far from being able to fully exploit the breeding potential of the thousands of accessions stored in seed banks around the world, in addition to those that may still be found in natural habitats. Over the past decades, tomato breeders have been at the forefront of establishing new principles for crop breeding based on the use of wild species to improve modern cultivars. In this respect, among all model systems, the wild and domesticated species of the tomato clade have pioneered development of novel populations such as “exotic libraries.” These genetic resources, combined with the increasing knowledge deriving from the many “omics” tools, including the tomato genome sequence, are expected to further improve the efficiency with which wild tomato relatives will contribute to the improvement of this important crop.

Nectar and Flower Traits of Different Onion Male Sterile Lines Related to Pollination Efficiency and Seed Yield of F1 Hybrids

ABSTRACT Honey bees are the main pollinators of onion crops for seed production, but owing to low attractiveness of flowers, pollination is often inadequate. Pollination problems result in low seed yields. This problem is accentuated when male sterile lines (MSL) are used to produce hybrid onion seeds. In this study, the effect of floral attributes and nectar composition on the preference of honey bees of four MSLs and one onion open pollinated cultivar were assessed. The chemical composition of nectar was described through the analysis of sugars, trace elements, volatile organic compounds, and phenol compounds. The samples studied showed qualitative and quantitative differences in the analyzed traits of flowers and nectar among the different lines. Furthermore, field observations showed a great difference on the number of bee visits and seed yield among the onion lines analyzed. For the first time, this study demonstrates that there are marked differences in the chemical composition of nectar and floral morphology between open pollinated and MSLs and also within MSLs. In addition, these differences were correlated with the number of visits and seed yield. Therefore, it would be possible to select indirectly the most promising productive MSL using simple determinations of chemical compounds or floral morphological characters.

Hydrophilic antioxidants from Andean tomato landraces assessed by their bioactivities in vitro and in vivo

Potential nutraceutical properties of hydrophilic antioxidants in fruits of tomato landraces collected in Andean valleys were characterised. Antioxidant metabolites were measured by HPLC-DAD-MS/MS in mature fruits and their biological activities were assessed by in vitro and in vivo methods. In vitro antioxidant capacities were established by TEAC and FRAP methods. For in vivo biological activities we used a procedure based on Caenorhabditis elegans subjected to thermal stress. In addition, Saccharomyces cerevisiae was also used as a rapid screening system to evaluate tomato antioxidant capacity. All tomato accessions displayed significant differences regarding metabolic composition, biological activity and antioxidant capacity. Metabolite composition was associated with geographical origin and fruit size. Antioxidant activities showed significant association with phenolic compounds, such as caffeoylquinic acids, ferulic acid-O-hexosides and rutin. Combination of in vitro and in vivo methods applied here allowed evaluation of the variability in nutraceutical properties of tomato landraces, which could be applied to other fruits or food products.

Determination of Volatile Organic Compounds in Andean Tomato Landraces by Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry

Fil: Cortina, Pablo Ramiro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones en Fisico-quimica de Cordoba. Universidad Nacional de Cordoba. Facultad de Ciencias Quimicas. Instituto de Investigaciones en Fisico-quimica de Cordoba; Argentina

Data on polyphenols and biological activity analyses of an Andean tomato collection and their relationships with tomato traits and geographical origin.

Data provide information about a tomato collection composed of accessions from the Andean Valley, commercial accessions and wild species. Antioxidant metabolites were measured in mature fruits of this collection, and their biological activities were assessed by both in vitro and in vivo methods. In this work, the parameters used to identify and quantify polyphenols compounds in tomato fruit by liquid chromatography coupled to diode array detector and quadrupole time of flight mass spectrometer are described. Moreover, data supporting a procedure to characterize the properties of tomato fruits to revert death by thermal stress in Caenorhabditis elegans are explained in detail. Lastly, principal component analysis and hierarchical cluster analysis of metabolites composition, antioxidant activities (in vivo and in vitro), tomato traits and geographical origin of the tomatoes collection are shown. The data presented here are related to the research article entitled “Hydrophilic antioxidants from Andean Tomato Landraces assessed by their bioactivities in vitro and in vivo” [1].

The Tomato (Solanum lycopersicum L., Solanaceae) and Its Botanical Relatives

The cultivated tomato, Solanum lycopersicum L., is a member of the small section Lycopersicon along with its 12 wild relatives. An additional four species from sections Juglandifolia and Lycopersicoides are traditionally considered as tomato wild relatives. These species are all endemic to South America, but the cultivated tomato itself has achieved worldwide distribution with the help of human populations. Tomato and its wild relatives are part of a larger monophyletic group (the Potato clade) that also contains the potatoes and their wild relatives. Here we review the taxonomic and phylogenetic history, relationships and species-level taxonomy of the cultivated tomato and its wild relatives, and highlight important studies of diversity that remain to be undertaken in the group, especially in light of global environmental and climatic change.