Multivariate analysis as a key tool in chemotaxonomy of brinjal eggplant, African eggplants and wild related species

The brinjal eggplant (Solanum melongena L.) is an important vegetable species worldwide, while African eggplants (S. aethiopicum L., S. macrocarpon L.) are indigenous vegetable species of local significance. Taxonomy of eggplants and their wild relatives is complicated and still unclear. Hence, the objective of the study was to clarify taxonomic position of cultivars and landraces of brinjal, its wild relatives and African eggplant species and their wild ancestors using chemotaxonomic markers and multivariate analysis techniques for data processing, with special attention paid to the recognition of markers characteristic for each group of the plants. The total of 34 accessions belonging to 9 species from genus Solanum L. were used in the study. Chemotaxonomic analysis was based on the profiles of cuticular n-alkanes and methylalkanes, obtained using gas chromatography-mass spectrometry and gas chromatography with flame ionization detector. Standard hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used for the classification, while the latter and two-way HCA allowed to identify markers responsible for the clustering of the species. Cultivars, landraces and wild forms of S. melongena were practically identical in terms of their taxonomic position. The results confirmed high and statistically significant distinctiveness of all African eggplant species from the brinjal eggplant. The latter was characterized mostly by abundant long chain hydrocarbons in the range of 34-37 carbon atoms. The differences between both African eggplant species were, however, also statistically significant; S. aethiopicum displayed the highest contribution of 2-methylalkanes to the total cuticular hydrocarbons, while S. macrocarpon was characterized by elevated n-alkanes in the range of 25-32 carbon atoms. Wild ancestors of both African eggplant species were identical with their cultivated relatives. Concluding, high usefulness of the chemotaxonomic approach in classification of this important group of plants was confirmed.

Solar catalysed activity against methyl orange dye, cytotoxicity activity of MCF-7 cell lines and identification of marker compound by HPTLC of Lagerstroemia speciosa

The investigation was aimed to quantify the Gallic acid present in Lagerstroemia speciosa leaves (Lythraceae). The High-Performance Thin Layer Chromatography (HPTLC) quantification was performed for acetone (AE), methanolic (ME) and chloroform (CE) extract of leaves of L. speciosa. The pre-coated silica gel 60 F₂₅₄ was used for complete separation of compounds using the mobile phase pet. Ether: ethyl acetate: formic acid (5:5:1v/v).The validation of the extracts was carried out using ICH guidelines for precision, repeatability and accuracy showing the Rf 0.49 against standard Gallic acid. Linearity range for Gallic acid was done from 200 to 1000ng/spot (AE) and200 ng to 600ng/spot (ME), with Correlation, coefficient r=0.99 (AE) and 0.54 (ME) in the said concentrations. The composition in crude leaf extract was determined to be of 49.712mg (AE) and 20.125mg (ME), while it was not found in chloroform extract against standard Gallic acid. Hence the proposed method was very simple, precise, accurate and easy for the screening of the bioactive compounds present in the acetone and methanolic extracts of the leaves of L. speciosa. It was observed that the acetone extract subjected to cytotoxicity showed promising activity at higher concentrations (100 and 200μg/ml) showed 92.9% and 87.13% inhibition against MCF-7 cell lines respectively. The photocatalytic activity of the acetone and methanolic extracts of methyl orange was found to be 90.25% (190min) and 89.03% (180min) respectively. Therefore this can be used as an indicator of purity of herbal drugs and formulation containing L. speciosa.

Cuticular hydrocarbons and sucrose esters as chemotaxonomic markers of wild and cultivated tomato species (Solanum section Lycopersicon)

The tomato (Solanum lycopersicum L.) is one of the most important vegetables worldwide. Due to the limited genetic variability, wild related species are considered as potential gene pool for breeding cultivated plants with enriched genetic basis. Taxonomic relations between tomato species at the level of single groups and taxa still remain, however, not fully resolved. Hence, in addition to already reported classification based on the morphology of the plants and molecular markers, we proposed chemotaxonomic approach to unveil some aspects of tomato taxonomy. Cuticular hydrocarbons and surface sucrose esters (SEs) were used as chemotaxonomic markers. Classification based on the cuticular hydrocarbon profile was in good agreement with other taxonomic studies as long as between-species differences were taken into account. Clear separation of the common tomato and closely related species from the majority of S. pennellii accessions was obtained. In the same time, however, S. pennellii revealed broad variation: based on the results, three highly distinct types of these plants were proposed, among them one type was very similar to cultivated tomato and its relatives. Addition of SEs profiles to the dataset did not impair the classification, but clarified the position of S. pennellii. The results suggest possible hybrid origin of some of S. pennellii and wild S. lycopersicum accessions, and the approach proposed has a potential to identify such hybrid plant lines.

Short-Term Water Deficit Changes Cuticular Sterol Profile in the Eggplant (Solanum melongena)

Crop irrigation uses a majority of a total world water supply, at the same time displaying low efficiency. As the expected, future water requirements are higher than the current ones; there is a risk of a growing deficit of water for the agricultural use. Hence, there is an arising need for better understanding the effects of water deprivation on the crop plants. Eggplant (Solanum melongena L.) is a vegetable crop cultivated in arid and semi-arid parts of the world. Because of its high water demands, the eggplant is a convenient model organism for studies concerning the effects of water deficit on the plant growth. The objective of the study was to determine the impact of short-term water deficit on eggplant leaf cuticular waxes and total sterols. Water deprivation did not affect the amount and composition of aliphatic components of cuticular waxes. Significant decrease in the total cuticular sterols and the increase in cuticular cholesterol were observed as an effect of water deficit. In contrast, some of the free internal sterols were more abundant in water-deprived plants. The possible importance of these observations, including increased biosynthesis of defensive compounds and the need to maintain the cell membrane stability, was discussed.

HPTLC Fingerprint Profile (Phenolics) of Selected Cyathea Species from Western Ghats, South India

HPTLC analysis was performed to study the phenolics, flavonoids, and tannins profile of Cyathea nilgirensis Holttum, Cyathea gigantea (Wall. ex. Hook.) Holttum, and Cyathea crinita (Hook.) Copel. The maximum number of bands was observed in the ethanolic extracts of C. crinita. The phenolic bands with Rf values 0.05, 0.32, 0.43, 0.75 (quercetin), and 0.83 demonstrated their occurrence in all the three studied species of Cyathea. Flavonoids with Rf values 0.05, 0.23, 0.30, 0.43, and 0.73 showed their presence in the three studied species of Cyathea. Tannins with the Rf values 0.05, 0.09, and 0.82 determined their existence in all the three studied Cyathea species. Gallic acid was present only in C. crinita with the Rf value 0.49. The developed HPTLC profiles can be used for identification and quantitative determination of phenolics, flavonoids, and tannins. This method is also suitable for rapid screening of Cyathea species for chemotypic assessment and also for quality control purposes.

Analysis of triterpenoids and phytosterols in vegetables by thin-layer chromatography coupled to tandem mass spectrometry

Three TLC methods were used for an initial screening of some common plant triterpenoids and phytosterols in cuticular wax extracts of different vegetables (zucchini, eggplant, tomato, red pepper, mangold, spinach, lettuce, white-colored radicchio di Castelfranco, raddichio Leonardo, white cabbage, red cabbage and savoy cabbage). The preliminary experiments showed that the studied vegetables are potential sources of triterpenoids and phytosterols. To identify the compounds present in the extracts with high certainty, the first TLC-MS(2) method was developed for the analysis of eight triterpenoids (lupeol, α-amyrin, β-amyrin, cycloartenol, cycloartenol acetate, lupeol acetate, lupenone and friedelin) and two phytosterols (β-sitosterol and stigmasterol). This method takes the advantages of: (1) a satisfactory separation of the target compounds; (2) their differentiation according to the band colors; and (3) the potential of their discrimination by the acquired first-order mass (MS) and product ion (MS(2)) spectra. Since the closely eluting compounds have complex and similar MS(2) spectra, distinguishing between them was possible by the proposed characteristic ions. Using a custom-built mass spectral library, the head to tail MS(2) spectra comparison of sample test solution zones and standard aided the compound identification. In addition to the molecular mass information, the developed atmospheric pressure chemical ionization method (APCI) in positive ion mode provided structural information, regarding the presence of functional group in the molecule. This approach resulted in many positively assigned compounds in the investigated vegetable waxes, from which more than a half are reported for the first time.

Deficiency in a very-long-chain fatty acid β-ketoacyl-coenzyme a synthase of tomato impairs microgametogenesis and causes floral organ fusion

Previously, it was shown that β-ketoacyl-coenzyme A synthase ECERIFERUM6 (CER6) is necessary for the biosynthesis of very-long-chain fatty acids with chain lengths beyond C₂₈ in tomato (Solanum lycopersicum) fruits and C₂₆ in Arabidopsis (Arabidopsis thaliana) leaves and the pollen coat. CER6 loss of function in Arabidopsis resulted in conditional male sterility, since pollen coat lipids are responsible for contact-mediated pollen hydration. In tomato, on the contrary, pollen hydration does not rely on pollen coat lipids. Nevertheless, mutation in SlCER6 impairs fertility and floral morphology. Here, the contribution of SlCER6 to the sexual reproduction and flower development of tomato was addressed. Cytological analysis and cross-pollination experiments revealed that the slcer6 mutant has male sterility caused by (1) hampered pollen dispersal and (2) abnormal tapetum development. SlCER6 loss of function provokes a decrease of n- and iso-alkanes with chain lengths of C₂₇ or greater and of anteiso-alkanes with chain lengths of C₂₈ or greater in flower cuticular waxes, but it has no impact on flower cuticle ultrastructure and cutin content. Expression analysis confirmed high transcription levels of SlCER6 in the anther and the petal, preferentially in sites subject to epidermal fusion. Hence, wax deficiency was proposed to be the primary reason for the flower fusion phenomenon in tomato. The SlCER6 substrate specificity was revisited. It might be involved in elongation of not only linear but also branched very-long-chain fatty acids, leading to production of the corresponding alkanes. SlCER6 implements a function in the sexual reproduction of tomato that is different from the one in Arabidopsis: SlCER6 is essential for the regulation of timely tapetum degradation and, consequently, microgametogenesis.

Leaf cuticular n-alkanes as markers in the chemotaxonomy of the eggplant (Solanum melongena L.) and related species

The complex of species formed by eggplant (Solanum melongena L.) and its wild and weedy relatives (mainly S. incanum L. and S. insanum L.) is characterised by an extreme morphological divergence that is not always associated with genetic variation. The taxonomy of so-called 'spiny Solanum' species (subgenus Leptostemonum) is therefore extremely unclear. Cultivated eggplant lacks resistance to pests that frequently occur among the wild forms and species. As these wild plants are a potential gene pool for improvement of eggplant cultivars, knowledge of the characteristics of taxonomic relations between plants of different origin is crucial. We suggest using the leaf cuticular n-alkane chain length distribution pattern as an alternative taxonomic marker for eggplant and related species. The results are in good agreement with current knowledge of the systematics of these plants; at the same time, the method developed here is useful for verifying plant identification based on morphological traits. Analysis of 13 eggplant cultivars, five accessions of S. incanum and two lines of S. macrocarpon enabled the intraspecific variation within eggplant to be assessed as low. There was wide variability among S. incanum accessions, probably because plants described as S. incanum are members of a number of different species. Some Asian accessions (sometimes described as S. insanum) were found to be almost identical to S. melongena, while a truly wild African S. incanum plant showed extensive similarity. The usefulness of the chemotaxonomic approach in dealing with the S. melongena-S. incanum complex is discussed.