Morphological Diversity, Genetic Characterization, and Phytochemical Assessment of the Cypriot Tomato Germplasm

Plant Biostimulants Enhance Tomato Resilience to Salinity Stress: Insights from Two Greek Landraces

Salinity, one of the major abiotic stresses in plants, significantly hampers germination, photosynthesis, biomass production, nutrient balance, and yield of staple crops. To mitigate the impact of such stress without compromising yield and quality, sustainable agronomic practices are required. Among these practices, seaweed extracts (SWEs) and microbial biostimulants (PGRBs) have emerged as important categories of plant biostimulants (PBs). This research aimed at elucidating the effects on growth, yield, quality, and nutrient status of two Greek tomato landraces ('Tomataki' and 'Thessaloniki') following treatments with the Ascophyllum nodosum seaweed extract 'Algastar' and the PGPB 'Nitrostim' formulation. Plants were subjected to bi-weekly applications of biostimulants and supplied with two nutrient solutions: 0.5 mM (control) and 30 mM NaCl. The results revealed that the different mode(s) of action of the two PBs impacted the tolerance of the different landraces, since 'Tomataki' was benefited only from the SWE application while 'Thessaloniki' showed significant increase in fruit numbers and average fruit weight with the application of both PBs at 0.5 and 30 mM NaCl in the root zone. In conclusion, the stress induced by salinity can be mitigated by increasing tomato tolerance through the application of PBs, a sustainable tool for productivity enhancement, which aligns well with the strategy of the European Green Deal.

A Novel Sorbitol-Based Flow Cytometry Buffer Is Effective for Genome Size Estimation across a Cypriot Grapevine Collection

Flow cytometry (FCM) is a widely used technique to study genome size (C-value), but recalcitrant metabolites in grapevines often hinder its efficiency in grapevine research. The aim of the present study was (i) to develop a novel buffer tailormade for the nuclei isolation of grapevines and (ii) to characterize a Cypriot germplasm collection based on C-values. A local cultivar "Xinisteri" was used as a pilot test to evaluate a Sorbitol-based buffer, while sprouting, young, and fully matured leaves were examined to evaluate the developmental parameter. The novel Sorbitol buffer was shown to have a coefficient of variation (CV) of 4.06%, indicating improved properties compared to other commonly used FCM buffers [WPB (7.69%), LB01 (6.69%), and LB (7.13%), respectively]. In addition, a significant variation in genome size between genotypes was found in a comprehensive application with 24 grape varieties. Nucleic content (2C) ranged from 0.577/1C pg for the "Assyrtiko" cultivar up to 0.597/1C pg for the "Spourtiko" cultivar, revealing a 17.6/1C Mbp difference. The lowest coefficient of variation (CV) across all entries was found in the variety "Ofthalmo" (2.29%), while the highest was observed in "Pinot Noir" (3.44%). Anova analysis revealed several distinct clusters, showing that in several cases, C-values can be used as a simple method to distinguish grapevine cultivars.

Genome Size Variation across a Cypriot Fabeae Tribe Germplasm Collection

DNA content is an important trait linked to the evolutionary routes of taxa and often connected to speciation. In the present study, we studied C-values variation across the Cypriot Fabeae gene pool. Several hundred plants (Vicia spp., Lens spp., Pisum spp.) were sampled across Cyprus. Accurate estimates were established by flow cytometry and propidium iodine staining for 155 discrete populations/accessions. A ten-fold variation was detected across lineages with 1C DNA content varying from 1.584 pg for V. cretica (ARI02420) to 13.983 pg for V. faba (ARI00187). In general, flow cytometry was precise for the characterization of species, even though there were instances of genome overlapping across taxa. Most analyses in the current work refer to species that have not been characterized before by flow cytometry (or any other DNA content estimation method). Still, a correlation to C-values previously reported in Kew Plant DNA C-values database was attempted. A high degree of correlation except for V. dalmatica was established. The evaluation of genome size trait in relation with the Fabeae phylogeny, revealed that Pisum and Lens genera were rather homogenous, but an astonishing fluctuation was shown for Vicia spp. Moreover, it was established that genome up- or down-scaling was not directly linked to speciation drivers. The genomic size measurements presented here could deliver extra quality control for the identification and characterization of taxa in germplasm collections, particularly in cases where species share morphological characters.

An integrated genomic and biochemical approach to investigate the potentiality of heirloom tomatoes: Breeding resources for food quality and sustainable agriculture

A revival of interest in traditional varieties reflects the change in consumer preferences and the greater awareness of the quality of locally grown products. As ancient cultivars, heirlooms have been selected for decades in specific habitats and represent nowadays potential germplasm sources to consider for breeding high-quality products and cultivation in sustainable agriculture. In this study, 60 heirloom tomato (Solanum lycopersicum L.) accessions, including diverse varietal types (beefsteak, globe, oxheart, plum, and cherry), were profiled over two seasons for the main chemical and biochemical fruit traits. A medium-high level of heritability was found for all traits ranging from 0.52 for soluble solids to 0.99 for fruit weight. The average content of ascorbic acid was ~31 mg 100 g^-1 of fw in both seasons, while the greatest variability was found for carotenoids with peaks of 245.65 μg g^-1 of fw for total lycopene and 32.29 μg g^-1 of fw for β-carotene. Dissection of genotypic (G) and seasonal (Y) factors highlighted genotype as the main source of variation for all traits. No significant effect of Y and G × Y was found for ascorbic acid and fruit weight, respectively, whereas a high influence of Y was found on the variation of lycopene. Molecular fingerprinting was performed using the 10K SolCAP array, yielding a total of 7,591 SNPs. Population structure, phylogenetic relationships, and principal components analysis highlighted a differentiation of plum and cherry genotypes with respect to the beefsteak and globe types. These results were confirmed by multivariate analysis of phenotypic traits, shedding light on how breeding and selection focused on fruit characteristics have influenced the genetic and phenotypic makeup of heirlooms. Marker-trait association showed 11 significantly associated loci for β-carotene and fruit weight. For β-carotene, a single variant on chromosome 8 was found at 12 kb to CCD8, a cleavage dioxygenase playing a key role in the biosynthesis of apocarotenoids. For fruit weight, a single association was located at less than 3 Mbp from SLSUN31 and fw11.3, two candidates involved in the increasing of fruit mass. These results highlight the potentiality of heirlooms for genetic improvement and candidate gene identification.

Simple Sequence Repeat Markers Reveal Genetic Diversity and Population Structure of Bolivian Wild and Cultivated Tomatoes (Solanum lycopersicum L.)

The western part of South America is a centre of diversity for tomatoes, but genetic diversity studies are lacking for parts of that region, including Bolivia. We used 11 simple sequence repeat (SSR) markers (including seven novel markers) to evaluate genetic diversity and population structure of 28 accessions (four modern cultivars, four advanced lines, nine landraces, 11 wild populations), and to compare their genetic variation against phenotypic traits, geographical origin and altitude. In total, 33 alleles were detected across all loci, with 2–5 alleles per locus. The top three informative SSRs were SLM6-11, LE20592 and TomSatX11-1, with polymorphism information content (PIC) of 0.65, 0.55 and 0.49, respectively. The genetic diversity of Bolivian tomatoes was low, as shown by mean expected heterozygosity (He) of 0.07. Analysis of molecular variance (AMOVA) revealed that 77.3% of the total variation was due to variation between accessions. Significant genetic differentiation was found for geographical origin, cultivation status, fruit shape, fruit size and growth type, each explaining 16–23% of the total variation. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) tree and principal coordinate analysis (PCoA) scatter plot both revealed differentiation between accessions with determinate flowers and accessions with indeterminate flowers, regardless of cultivation status. The genetic profiles of the accessions suggest that the Bolivian tomato gene pool comprises both strictly self-pollinating and open-pollinating genotypes.

Phenotypic and Genotypic Diversity of the Tomato Germplasm From the Lazio Region in Central Italy, With a Focus on Landrace Distinctiveness

Italy is a recognized secondary center of diversification for cultivated tomato (Solanum lycopersicum L.). The study of phenotypic and genetic diversity in landrace collections is important for germplasm conservation and valorization. Here, we set up to study the tomato germplasm collected in the region of Lazio in Central Italy, with a focus on the distinctiveness among landraces and the attribution of membership to unnamed accessions. Our regional collection included 32 accessions belonging to eight different locally recognized landraces and 19 unnamed accessions. All accessions were gathered from local farmers and are preserved in the collection held at the Regional Agency for the Development and the Innovation of Lazio Agriculture (ARSIAL) and at the University of Tuscia. We included 13 control genotypes comprising nine landraces from neighbor regions and four reference cultivars. The collection showed wide phenotypic variability for several qualitative and quantitative traits, such as leaf border and shape, inflorescence type, fruit shape, green shoulder, fruit weight (range 14-277 g), locule number (2-12), shape index (0.54-2.65), yield (0.24-3.08 kg/plant), and soluble solids (3.4-7.5°B). A few landraces showed uncommon phenotypes, such as potato leaf, colorless fruit epidermis, or delayed ripening. Multivariate analysis of 25 cardinal phenotypic variables separated the accessions into two distinct groups; accessions showing a flattened-ribbed fruit were distinguished from those with round to elongate fruits with smooth structure. Genotyping analysis of 7,720 SNPs was performed using the tomato array platform SolCAP, to point out the genetic relationship among the studied accessions. A neighbor-joining tree analysis allowed to confirm or deny phenotypic data and to assign some of the unnamed accessions to recognized groups. Allelic status at marker loci linked to resistance genes commonly used in breeding identified accessions putatively derived from modern material or commercial hybrids, thus not classifiable as landraces. Overall, this study provided the information useful to preserve, valorize, and juridically protect tomato local landraces from the Lazio region and will in addition be helpful to their improvement by breeding.

Morphological and molecular characterization of some Tomato (Solanum lycopersicum L.) genotypes collected from Erzincan Province of Turkey

BACKGROUND

Turkey is a country with different geographical features and therefore it is extremely diverse in plant diversity. Tomato is one of the most important vegetables produced both in the world and in Turkey. In this study, it was aimed to determine the genetic diversity of 24 tomato genotypes collected from local farmers from "Center villages" and "Üzümlü" district in Erzincan province.

METHODS AND RESULTS

Morphological (qualitative and quantitative) and ISSR(Inter Simple Sequence Repeat)were used to determine genetic diversity among genotypes. Contribution rates of morphological properties to the first three main components differed. Genotype 24 was found to be higher than other genotypes with important quantitative morphological features such as fruit length, fruit width, fruit weight and soluble solid content (SSC). Considering the overall morphological traits, a wide variation was detected between genotypes. Genotypes were divided into 2 main groups according to the evaluation with molecular markers. According to the molecular findings obtained. The polymorphism rate ranged from 0 to 100% and the average polymorphism rate was calculated as 80%.

CONCLUSIONS

Present findings revealed the diversity in tomato genotypes collected from Erzincan province and may constitute the bases for further breeding studies in tomato and will bring an integrity in tomato identification studies.

Influence of Ripening Stage on Quality Parameters of Five Traditional Tomato Varieties Grown under Organic Conditions

Consumers demand traditional, tasty tomatoes in contrast to new hybrid cultivars that have poor sensory characteristics. Some physicochemical parameters (total soluble solids, pH, titratable acidity, color and firmness), functional properties (vitamin C, lycopene, β-carotene and total antioxidant activity) and sensory characteristics of five traditional tomato varieties (T1-T5) in three ripening stages, grown under organic conditions, were evaluated. These were compared to the commercial hybrid ‘Baghera’, grown in the same conditions. Firmness of all varieties declined and the color parameters L* and H* decreased, whereas a* and a*/b* increased progressively with ripening. Lycopene also increased with ripening in all varieties, with the highest content being 132.64 mg kg−1 fw for T4. All traditional tomato varieties were richer in lycopene than commercial ones in the two last ripening stages. Vitamin C content ranged widely between 27.33 and 267.27 mg kg−1 fw. Among the traditional varieties, T2 (BGV003524) stood out due to its highest total soluble solids and vitamin C contents, total antioxidant activity, and H* and a*/b*; this variety was also the most appreciated by panelists. These traditional varieties could be an alternative to commercial cultivars, as they have good quality characteristics and can satisfy consumer demand for organic produce.

A Simple and Effective Bioassay Method Suitable to Comparative In Vitro Study of Tomato Salt Tolerance at Early Development Stages

In vitro evaluation of tomato seeds and seedlings for salt tolerance has undoubted advantages (high productivity, as well as stability and reproducibility of the obtained experimental data due to the maintenance of constant controlled conditions) in comparison with open-field system and pot experiments. However, even high-quality seeds greatly differ in the uniformity of germination capacity and germination energy. Heterogeneous germination in the habit and developmental stage of plant material significantly distorts the obtaining of relevant experimental data suitable for correct interpretation. In our study, we propose a simple and effective bioassay method suitable to comparative in vitro study of tomato salt tolerance using shoot apex of seedlings at the early first-true-leaf stage. Shoot apexes cultured the on the root induction medium (RIM) supplemented with 0.2 mg/L indole-3-butyric acid (IBA) and NaCl at different concentrations (0–250 mM NaCl) revealed significant differences between two tomato genotypes (line YaLF and cv. Rekordsmen) at the organismal (measurements of CO₂ gas exchange), organ (rhizogenesis frequency; number and length of de novo regenerated roots; root fresh (RFW) and dry (RDW) weights; shoot fresh (SFW) and dry (SDW) weights), tissue (the average cross-sectional area of epidermal and mesophylls cotyledonary cells) and cellular (ultrastructure of chloroplast and nuclear compartments) development levels. In addition, a quantitative comparison of proline and photosynthetic pigments contents under 75 and 150 mm NaCl treatments showed a different response between two tomato genotypes. The proposed methodological approach can be used for other plants with a high response to auxin-induced rhizogenesis in vitro, as well as for the comparative in vitro assessment of other abiotic stresses.

Artificial neural networks and genetic dissimilarity among saladette type dwarf tomato plant populations

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New dwarf tomato genotypes were obtained for future breeding programs.

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Germplasm has agronomic potential, nutritional quality, and pest resistance.

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ANNs are efficient for the study of genetic dissimilarity in dwarf tomato germplasm.

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The BC₁F₃ UFU 13-1 population showed greater genetic dissimilarity.

Studies have shown that dwarf plants have the potential for use in obtaining hybrids. The aim of this study was to evaluate the agronomic potential and genetic dissimilarity of saladette type dwarf tomato plant populations through the use of artificial neural networks (ANNs). The following traits were analyzed: mean fruit weight, transverse and longitudinal fruit diameter, fruit shape, pulp thickness, locule number, internode length, soluble solids content, and β-carotene, lycopene, and leaf zingiberene contents. A dendrogram obtained by the unweighted pair-group method with arithmetic mean (UPGMA) and Kohonen self-organizing maps (SOM) agreed in the distinction of the BC₁F₃ populations from the dwarf donor parent. SOM was more consistent in identifying the genetic similarities among the BC₁F₃ dwarf tomato plant populations and allowed for the determination of weights of each variable in the cluster formation. The UFU SDi 13-1 BC₁F₃ population was revealed to be a promising option for obtaining saladette type dwarf tomato plant lines.