Wild Tomato Fruit Research Articles

Phenolic compound identification in tomato fruit by UPLC-QTOF-MS

Phenolic compounds are functional food nutrients and show structural similarity, synthesized through phenylpropanoid and flavonoid biosynthetic pathway. Their structural similarity makes the separation and structure elucidation challenging. In this study, we isolated and identified phenolic compounds in tomato fruit by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Total 32 phenolic compounds were found and 13 out of them were previously unknown in tomato fruits. We elucidated nine from the 13 previously unknown components. The 3 main phenolic compounds were the same in both selected wild and cultivated tomato fruits, including chlorogenic acid, rutin and naringenin. Nevertheless, the content difference of the 3 main and 10 previously unknown phenolic compounds caused significant higher phenolic level in wild tomato fruits, compared to cultivated tomato. Based on the identified phenolic compounds, we also study their content variation in phenylpropanoid and flavonoid pathway of tomato fruit. Our results are beneficial for the improvement of phenolic nutrients in tomato fruits.

Characterizing Colonization Patterns of Clavibacter michiganensis During Infection of Tolerant Wild Solanum Species.

Clavibacter michiganensis is the Gram-positive causal agent of bacterial canker of tomato, an economically devastating disease with a worldwide distribution. C. michiganensis colonizes the xylem, leading to unilateral wilt, stem canker, and plant death. C. michiganensis can also infect developing tomato fruit through splash dispersal, forming exterior bird's eye lesions. There are no documented sources of qualitative resistance in Solanum spp.; however, quantitative trait loci conferring tolerance in Solanum arcanum and Solanum habrochaites have been identified. Mechanisms of tolerance and C. michiganensis colonization patterns in wild tomato species remain poorly understood. This study describes differences in symptom development and colonization patterns of the wild type (WT) and a hypervirulent bacterial expansin knockout (ΔCmEXLX2) in wild and cultivated tomato genotypes. Overall, WT and ΔCmEXLX2 cause less severe symptoms in wild tomato species and are impeded in spread and colonization of the vascular system. Laser scanning confocal microscopy and scanning electron microscopy were used to observe preferential colonization of protoxylem vessels and reduced intravascular spread in wild tomatoes. Differences in C. michiganensis in vitro growth and aggregation were determined in xylem sap, which may suggest that responses to pathogen colonization are occurring, leading to reduced colonization density in wild tomato species. Finally, wild tomato fruit was determined to be susceptible to C. michiganensis through in vivo inoculations and assessing lesion numbers and size. Fruit symptom severity was in some cases unrelated to severity of symptoms during vascular infection, suggesting different mechanisms for colonization of different tissues.

Yield, physicochemical quality, and antioxidant capacity of “beef” and wild tomato fruits (Solanum lycopersicum L.) as a function of the electrical conductivity of the nutrient solution

The objective of this study was to evaluate the response of three levels of electrical conductivity (2.0, 2.5 and 3.0 dS m-1) of Steiner’s nutrient solution on the yield, physicochemical quality, and antioxidant capacity of fruits from seven tomato genotypes and wild types of tomato (kidney selections). The yield, number of fruits per cluster (NFPC), average fresh fruit weight (AFWF), color, firmness, total soluble solids (TSS), total titratable acidity (TTA), vitamin C (VC), total phenols (TP), lycopene (LY) and antioxidant capacity (AC). The use of 2.5 and 3.0 dS m-1 increased the hue angle (49.05°) and TTA (0.35 and 0.36% citric acid). Among genotypes, L-51H and L-76H showed better performance (16.80 and 16.91 kg m-2, respectively), where L-28 stood out for its values of TSS, TTA, VC, TP and AC. Regarding the wild genotypes, the EC modification did not increase the yield; however, the use of 3.0 dS m-1 allowed the best results among the wild selections were SS3 (yield, AFWF and LY) and SS5 (NFPC, VC, TP and AC). The modification of the EC did not affect the yield, however, if it affected the physicochemical quality and antioxidant capacity of the analyzed materials.

Steroidal glycoalkaloid profiling and structures of glycoalkaloids in wild tomato fruit

Steroidal glycoalkaloids (SGAs) constitute one of the main groups of secondary metabolites in tomato fruit. However, the detailed composition of SGAs other than α-tomatine, dehydrotomatine and esculeoside A, remains unclear. Comparative SGA profiling was performed in eight tomato accessions, including wild tomato species by HPLC-Fourier transform ion cyclotron resonance mass spectrometry (HPLC-FTICR/MS). On the basis of molecular formulae obtained from accurate m/z and fragmentation patterns by multistage MS/ MS (MS(n)), 123 glycoalkaloids in total were screened. Detailed MS(n) analysis showed that the observed structural diversity was derived from various chemical modifications, such as glycosylation, acetylation, hydroxylation and isomerization. Total SGA content in each tomato accession was in the range of 121-1986 nmol/gfr.wt. Furthermore, the compositional variety of SGA structures was distinctive in some tomato accessions. While most tomato accessions were basically categorized as α-tomatine-rich or esculeoside A-rich group, other specific SGAs also accumulated at high levels in wild tomato. Here, five such SGAs were isolated and their structures were determined by NMR spectroscopic analysis, indicating three of them were presumably synthesized during α-tomatine metabolism.

Sucrose Synthase in Wild Tomato, Lycopersicon chmielewskii, and Tomato Fruit Sink Strength

Here it is reported that sucrose synthase can be readily measured in growing wild tomato fruits (Lycopersicon chmielewskii) when suitable methods are adopted during fruit extraction. The enzyme also was present in fruit pericarp tissues, in seeds, and in flowers. To check for novel characteristics, the wild tomato fruit sucrose synthase was purified, by (NH(4))(2)SO(4) fraction and chromatography with DE-32, Sephadex G-200, and PBA-60, to one major band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The following characteristics were obtained: native protein relative molecular weight 380,000; subunit relative molecular weight 89,000; K(m) values with: sucrose 53 millimolar, UDP 18.9 micromolar, UDP-glucose 88 micromolar, fructose 8.4 millimolar; pH optima between 6.2 to 7.3 for sucrose breakdown and 7 to 9 for synthesis; and temperature optima near 50 degrees C. The enzyme exhibited a high affinity and a preference for uridylates. The enzyme showed more sensitivity to divalent cations in the synthesis of sucrose than in its breakdown. Sink strength in tomato fruits also was investigated in regard to sucrose breakdown enzyme activities versus fruit weight gain. Sucrose synthase activity was consistently related to increases in fruit weight (sink strength) in both wild and commercial tomatoes. Acid and neutral invertases were not, because the published invertase activity values were too variable for quantitative analyses regarding the roles of invertases in tomato fruit development. In rapidly growing fruits of both wild and commercially developed tomato plants, the activity of sucrose synthase per growing fruit, i.e. sucrose synthase peak activity X fruit size, was linearly related to final fruit size; and the activity exceeded fruit growth and carbon import rates by at least 10-fold. In mature, nongrowing fruits, sucrose synthase activities approached nil values. Therefore, sucrose synthase can serve as an indicator of sink strength in growing tomato fruits.

Isolation and Characterization of a Novel, Developmentally Regulated Proteinase Inhibitor I Protein and cDNA from the Fruit of a Wild pecies of Tomato

A novel member of the proteinase Inhibitor I family having a trypsin inhibitor specificity was isolated from the fruit of the wild tomato species Lycopersicon peruvianum (L.) Mill. (LA 107) and characterized. The protein is among the isoinhibitors of Inhibitor I that comprise 50% of the soluble proteins in the fruit of this wild species of tomato. A cDNA corresponding to the inhibitor protein and mRNA was isolated and characterized. The Inhibitor I mRNA represented 0.06% of the poly(A) RNA and gene copy number reconstruction experiments gave an estimate of two to four genes/haploid genome. The open reading frame of the cDNA codes for a protein of 111 amino acids having a 42-amino acid prepropolypeptide. The NH2-terminal sequence of the first 21 amino acids of the purified Inhibitor I protein confirmed that the cDNA was identical to the protein. The amino acid sequence of the L. peruvianum fruit Inhibitor I exhibits 74% identity with the wound-inducible Inhibitor I from tomato leaves. Whereas all previously identified members of the Inhibitor I family have either Met, Leu, or Asp at the P1 site and can inhibit enzymes such as chymotrypsin, subtilisin, and elastase, the fruit Inhibitor I possesses Lys at the P1 position. Thus, this is the first member of the extensive Inhibitor I family from plants and animals that exhibits trypsin inhibitory specificity. The presence of this inhibitor in wild tomato fruit may reflect a functional role to protect the tissues against herbivory.