Analysis of phylogenetic relationships in the genus Solanum (Solanaceae) as revealed by RAPD markers

Phylogenetic relationships and genetic variation were examined in the genus Solanum based on the random amplified polymorphic DNA (RAPD) technique. Genetic distances were estimated for 42 accessions from five subgenera [Archaesolanum, Minon (Syn. Brevantherum), Leptostemonum, Potatoe, and Solanum]. This investigation provided new information and reinforced some suggestions from previous phylogenetic studies. Analysis with random markers from the total genome clearly separated Solanum sect. Dulcamara, from the other members of Solanum subg. Potatoe, and indicated that among the analysed Solanum subgenera subg. Solanum is most closely related to it. The results suggest that Solanum sect. Dulcamara should be excluded from Solanum subg. Potatoe. The subclusters formed by S. rostratum and S. citrullifolium appear to be distinct from the subcluster formed by the two accessions of S. sisymbriifolium. This topology indicates that Solanum sect. Androceras and Solanum sect. Cryptocarpum are fairly closely related, although the data suggest that the two sections should not be maintained.     

New 8-hydroxyflavonoids from Solanum section Androceras

Five new 8-hydroxyflavonoids have been identified from leaves of Solanum section Androceras: 8-methoxymyricetin 3,7,4′-trimethyl ether; 8-hydroxymyricetin 3,7,4′-trimethyl ether; 8-hydroxymyricetin 8-O-glucosylxyloside 3,7,4′-trimethyl ether; 8-hydroxychrysoeriol 7-methyl ether; 8-hydroxychrysoeriol 7-O-glucoside.     

Nitrogen-containing non-steroidal secondary metabolites of Solanum, Cyphomandra, Lycianthes and Margaranthus

Of the 49 species of Solanum studied, cuscohygrine has been detected in 25, solamine and related amines in 17 and solamine-derived amides in 16. Five species of Cyphomandra examined all contained both amines and amides. From roots of Margaranthus solanaceus cuscohygrine has been isolated which probably occurs, too, in roots of Lycianthes rantonnettii. The distribution of these compounds throughout the taxa could be of chemotaxonomic value.     

Basic steroid saponins from aerial parts of Fritillaria Thunbergii

From the aerial parts of Fritillaria thunbergii, three glycosidal Solanum alkaloids (basic steroid saponins) were isolated together with minor     

Chemophenetics of Solanum based on steroidal alkaloids

Steroidal alkaloids (SA) are nitrogen-containing specialized metabolites applied as chemophenetic markers in Solanum L. (Solanaceae). Over time, Solanum has been the focus of several molecular phylogenetic studies in an attempt to resolve its infrageneric classification and the relationship among species belonging to this genus. Here we aimed to study SA chemodiversity to identify chemical patterns and to perform a chemophenetic characterization of the Solanum genus and its major clades. Chemical literature data about Solanum steroidal alkaloids was assessed and structural variability of this biogenetic group was used in the chemometric analysis, by applying a Principal Component Analysis and Hierarchical Cluster Analysis. The results demonstrate that the SA chemodiversity in Solanum is represented by the occurrence of nine SA subtypes. The biosynthetic predominance of the spirosolane-type in Solanum clades was observed, except for the preference of the Potato clade in producing the solanidane-type. The Geminata clade displayed low SA glycosylation patterns, containing 3-oxy groups. In addition, low SA production in the Cyphomandra clade was observed. Chemical similarities between the Archaesolanum, Dulcamaroid and Morelloid clades were observed by chemometric analyses. In sum, chemophenetics was proven a reliable and additional tool to describe the array of specialized metabolites in Solanum clades, showing chemical information suitable to corroborate molecular phylogenetic studies.     

Chemical constituents from the fruits of Solanum incanum L

Phytochemical investigation of the fruits of Solanum incanum L. resulted in the isolation of nine compounds, including three steroidal glycoalkaloids (1-3), two neolignans (4–5), two simple phenolics (6–7), one monoterpene glycoside (8), and one coumarin glucoside (9). The structure elucidation of isolated compounds was determined based on NMR and mass spectral data. Compounds 4 and 9 were isolated for the first time from the genus Solanum and their chemotaxonomic significance was discussed.     

AFLP data support the recognition of a new tuber-bearing Solanum species but are uninformative about its taxonomic relationships

Solanum section Petota, containing the cultivated potato and its wild relatives, is a group of around 200 species. Many of these species are morphologically very variable with unclear boundaries, and the group as a whole appears to be somewhat over-classified. Describing a new species in this group should only be undertaken with caution, and molecular data can be used to test the distinctness of any putative new taxon. AFLP markers have shown the ability to reliably distinguish species in several groups within the genus Solanum. We tested the distinctness of a new tuber-bearing Solanum species using morphological and AFLP data, and tried to establish its affiliation to the series within the section. There was clear support for the species status of the material known as Solanum hannemanii in genebank collections, but the AFLP data were inconclusive about its relationships to the other investigated species. Also, the distinction of the series Tuberosa and Megistacroloba, to which these species belong, was not supported.     

Foliar flavonoids of North American Solanum section Solanum

A total of ten flavonoids, all flavonols, were isolated from leaves of eleven species of Solanum sect. Solanum. Most species had relatively few compounds, primarily quercetin 3-O-glycosides. Little intraspecific variation in flavonoids was observed, except in S. americanum were it correlated with previously recognized races. Flavonoid data are of little help in determining ancestries of polyploid species, but do rule out S. sarrachoides as a progenitor of S. villosum and S. nigrum. Solanum sarrachoides is unique among species examined in having free flavonoid aglycones as well as extensive 3-O-methoxylation.     

Plastid trnF pseudogenes are present in Jaltomata, the sister genus of Solanum (Solanaceae): Molecular evolution of tandemly repeated structural mutations

Extensive gene duplication arranged in a tandem array is rare in the plastome of embryophytes. Interestingly, we found pseudogene copies of the trnF gene in the genus Jaltomata, the sister genus of Solanum where such gene duplication has been previously reported. In each Jaltomata sequence available we found two pseudogene copies in close 5′-proximity to the original functional gene. The size of each pseudogene copy ranged between 17 and 48 bp and the anticodon domain was identified as the most conserved element. A common ATT(G)_n motif is particularly interesting and its modifications were found to border the 3′ of the duplicated regions. Other motifs were partial residues, or entire parts of the T- and D-domains, and both domains proved to be variable in length among the pseudogenes identified. The residues of the 3′ and 5′ acceptor stem were not found among the copies. We further compared the newly discovered copies of Jaltomata with those ones previously described from Solanum and inferred phylogenetic relationships of the copies aligned. The evolution of Solanum copies, in contrast to Jaltomata, is hard to explain as resulting only in parsimonious changes since reticulate evolutionary patterns were detected among the copies. The dynamic evolutionary patterns of Solanum might be explained by possible inter- or intrachromosomal recombination.     

The discovery and phylogenetic implications of a novel 41 bp plastid DNA deletion in wild potatoes

Insertions and deletions (indels) are common in intergenic spacer regions of plastid DNA and can provide important phylogenetic characters for closely related species. For example, a 241-bp plastid DNA deletion in the trnV-UAC/ndhC intergenic spacer region has been shown to have major phylogenetic importance in determining the origin of the cultivated potato. As part of a phylogenetic study of the wild potato Solanum series Piurana group we screened 199 accessions of 38 wild potato species in nine of the 19 tuber-bearing (Solanum section Petota) series that have not been examined before for indels in the trnV-UAC/ndhC intergenic spacer region. A novel 41 bp deletion (but no 241 bp deletion) was discovered for 30 accessions of three species: S. chiquidenum (5 of 10 accessions), S. chomatophilum (19 of 28), and S. jalcae (6 of 6). Accessions with and without this deletion are found throughout much of the north-south range of all three species in northern and central Peru, but not east of the Marañón River. Multivariate morphological analyses of these 44 accessions showed no morphological associations to the deletion. The results suggest extensive interspecific gene flow among these three species, or a common evolutionary history among species that have never been suggested to be interrelated.     

Polymorphism and structural variation of rps16 group-II intron in the Solanum species

Nucleotide sequences of the self-splicing group-II intron of rps16 have first been determined in nine species of the Solanum genus. It was found that the observed variations in the intron length (855–864 bp) was associated with indels of 1 to 9 bp. Altogether, five indels and 50 nucleotide substitutions were detected, which were used to identify six Solanum haplotypes. Although the intron sequence was in general fairly well conserved, the distribution of the described mutations among its structural elements corresponding to six pre-RNA domains was qualitatively and quantitatively nonuniform. The highest polymorphism levels were observed in domains I, II, and IV. The sequence of domain V was absolutely invariable, which is in agreement with its functional significance. The chloroplast rpS16 intron sequences have been characterized in nine Solanum species. The intron length ranged from 855 bp to 864 bp, which is associated with 1–9-nucleotide indels. In total five indels and 50 nucleotide substitutions have been detected and six Solanum haplotypes have been revealed. Solanum rpS16 introns has been characterized by mutation rate heterogeneity between structure regions of all six domains its pre-RNA. Intron domains I, II, IV are shown to be more variable. Sequences of the domain V are invariant, that agrees with its functional significance.     

Nitrogen-containing compounds from Solanum lyratum Thunb

The medicinal plant Solanum lyratum Thunb（Solanaceae）is distributed widely in China. The present phytochemical investigation on S. lyratum led to the isolation of ten known Nitrogen-containing compounds. Compounds 1, 2, 3, 6, 9 were isolated for the first time from this plant and compounds 8,10 were obtained for the first time from Solanum. Compound 10 was isolated from Solanaceae family and obtained outside from Loganiaceae family for the first time. This has important chemotaxonomic significance on solanaceae.     

Fruit anatomy of species of Solanum sect. Acanthophora (Solanaceae)

The fruits of 10 species of Solanum sect. Acanthophora were studied. Cross and/or longitudinal and/or tangential microtome sections, stained mostly with astra blue/basic fuchsin, were made for microscopic examination. Three different kinds of cells were found in the epidermis, immediately below which a hypodermis, consisting in any of four types of structures, was always found. The mesocarp exhibits two histologically differentiated zones, an external one (formed by normal or spongy parenchyma, according to the species), and an internal one, commonly juicy, and with proliferations among the seeds. The diagnostic value of all these structures is assessed. Morpho-anatomical information is used to define fruit types beyond the berry, traditionally described for Solanum, and the probable dispersal syndrome related to them is discussed. Fruit similarities are slightly noticeable in several cases, while differences may be the result of their sexual system – which affects specially the size – and their histology, which is related to the dispersal syndrome. The comparison of our data with previous molecular phylogeny of the section suggests that a significant morphological variation is not associated with significant DNA sequence changes.     

Species-Specific Identification from Incomplete Sampling: Applying DNA Barcodes to Monitoring Invasive Solanum Plants

Comprehensive sampling is crucial to DNA barcoding, but it is rarely performed because materials are usually unavailable. In practice, only a few rather than all species of a genus are required to be identified. Thus identification of a given species using a limited sample is of great importance in current application of DNA barcodes. Here, we selected 70 individuals representing 48 species from each major lineage of Solanum, one of the most species-rich genera of seed plants, to explore whether DNA barcodes can provide reliable specific-species discrimination in the context of incomplete sampling. Chloroplast genes ndhF and trnS-trnG and the nuclear gene waxy, the commonly used markers in Solanum phylogeny, were selected as the supplementary barcodes. The tree-building and modified barcode gap methods were employed to assess species resolution. The results showed that four Solanum species of quarantine concern could be successfully identified through the two-step barcoding sampling strategy. In addition, discrepancies between nuclear and cpDNA barcodes in some samples demonstrated the ability to discriminate hybrid species, and highlights the necessity of using barcode regions with different modes of inheritance. We conclude that efficient phylogenetic markers are good candidates as the supplementary barcodes in a given taxonomic group. Critically, we hypothesized that a specific-species could be identified from a phylogenetic framework using incomplete sampling–through this, DNA barcoding will greatly benefit the current fields of its application.     

Analysis of eggplant (<Emphasis Type="Italic">Solanum melongena</Emphasis>)-related germplasm: morphological and AFLP data contribute to phylogenetic interpretations and germplasm utilization

A total of 94 Solanum accessions, including eggplants and related species, were morphologically characterized based on greenhouse observations, and molecularly analysed by the AFLP technique. Morphological parameters were helpful in assessing similarities or differences among accessions, and molecular data were used to support morphological conclusions. A dendrogram was computed based on the Dice genetic distances using the neighbour-joining method. The analysis was efficient in the assignment of a species name for eight out of nine accessions that were not previously classified, and revealed that 14 further accessions were misnamed in the collection originally received. The results indicate that the taxonomy of Solanum sections and subgenera including several species should be reconsidered. The AFLP technique was revealed as an efficient tool in determining genetic relationships among species. In general, morphological observations were consistent with molecular data, indicating that both approaches complemented to define the phylogenetic status of a large genus like Solanum. In terms of eggplant breeding, the molecular analysis of the Melongena complex, and of the other sections of the subgenus Leptostemonum, establishes useful germplasm relationships in the gene pool available for the genetic improvement of the cultivated species. The results we have provided highlight an urgent necessity to include molecular parameters in handling and characterizing the genebank-deposited germplasm related to cultivated crops.Communicated by F. Salamini     

Epidermal hair morphology in Solanum L. section Solanum

Scanning electron microscopy was used to examine stem, leaf, staminal and stylar hairs on species belonging to Solanum L. section Solanum. The surface morphology of these hairs is illustrated. Simple, uniseriate hairs characterize the section Solanum, and these may have eglandular or glandular heads; they are usually multicellular, but in some species the stylar hairs appear to be unicellular. In addition, stalked glands, described here as spherical, four-celled glands, are universally present in species belonging to the section Solanum.     

Homologs of APETALA1/FRUITFULL in Solanum plants

The MADS-box APETALA1 genes control plant transition to flowering and the floral morphogenesis proper. The experimental evidence of APETALA1 overexpression presumes that this class of genes can also directly affect time to flowering. We therefore cloned and compared homologs of APETALA1 class genes from potato (Solanum tuberosum cultivars adapted to long day conditions) and its wild relative Solanum demissum, a short-day subtropical species. The homologs isolated from these plants belong to the subclass FRUITFULL. The inconsiderable variations in the primary structure of these homologs cannot explain the diverse photoperiodic reactions of particular Solanum genotypes.     

Ethnobotany,phytochemistry and pharmacology of Podocarpus sensu latissimo (s.l.)

The genus Podocarpus sensu latissimo (s.l.) was initially subdivided into eight sections. However, based on new information from different morphological and anatomical studies, these sections were recognised as new genera. This change in nomenclature sometimes is problematic when consulting ethnobotanical data especially when selecting plants for pharmacological screening, thus there is a need to clear any ambiguity with the nomenclature. Species of Podocarpus s.l. are important timber trees in their native areas. They have been used by many communities in traditional medicine and as a source of income. Podocarpus s.l. is used in the treatment of fevers, asthma, coughs, cholera, distemper, chest complaints and venereal diseases. Other uses include timber, food, wax, tannin and as ornamental trees. Although extensive research has been carried out on species of Podocarpus s.l over the last decade, relatively little is known about the African species compared to those of New Zealand, Australia, China and Japan. Phytochemical studies have led to the isolation and elucidation of various terpenoids and nor- and bis-norditerpenoid dilactones. Biflavonoids of the amentoflavone and hinokiflavone types have also been isolated. Nor- and bis-norditerpenes are said to be taxonomic markers for this genus. Recent in vitro and in vivo studies have shown antitumor, antimicrobial, anti-inflammatory, antioxidant, larvicidal, plant and insect growth regulation activities. Various studies have yielded important natural bioactive products and two of them are worth mentioning. Taxol, a significant anticancer agent has been isolated from Podocarpus gracilior and totarol, a diterpenoid isolated from various species and now commercially produced as a potent antibacterial and antioxidant agent. Findings from this review supports the use of an ethnobotanical and chemotaxonomical approach in selecting plants for pharmacological screening since most of the species in the different morphological groups have similar uses. Also the isolated compounds have chemotaxonomic value amongst the groups. Some of the biological activities identified from extracts and compounds isolated from Podocarpus s.l. support the rationale behind the medicinal uses of these species.     

Studies on Indian Solanum I. Alkaloid content and detection of solasodine

Fruits and/or leaves of 31 species ofSolanum that grow in India have been assayed for total alkaloid content and the presnce of solasodine in them has been determined by TLC. This survey revealed that 12 species contained solasodine and thatS. khasianum, S. elaeagnifolium, S. auriculatum andS. giganteum contained sufficient quantity of total alkaloid to warrant further studies on these plants in order to determine whether they could be developed as sources of raw materials for the steroid industry.