Tomato Fruit Size Research Articles

Genetic diversity and population structure of a modified three-way tomato hybrids for determining fruit size traits

The assessment of genetic diversity and genetic structure of crops has a vital impact on the plant breeding program, including the characterization, use and conservation of genetic material. The genetic diversity and genetic structure of a set of 94 F3 tomato hybrids were assessed with 25 polymorphic SNP markers of quantitative trait loci (QTLs) underlying fruit size in tomatoes using Sequenom Mass ARRAY system. A total of 50 alleles were amplified and the average polymorphic information content (PIC) was 0.2220. Nei's genetic distance ranged from 0 to 0.62. Therefore, single nucleotide sequence (SNP) markers detected a significantly high degree of polymorphism in tomato hybrids. Cluster analysis using the unweighted pair group method with arithmetic mean methods (UPMA) indicated that the tomato hybrids studied are grouped into four main groups, which is to some extent consistent with the size, shape and number of locules of the tomatoes studied. Analysis of population structure with SNP markers revealed three subpopulations. Association mapping using 25 SNP markers detected 9 markers with a significant association with mean fruit weight, fruit length, fruit diameter, number of locules, and fruit shape index. The nine markers detected in this study are recommended for the tomato fruit size improvement breeding program.

The CELL NUMBER REGULATOR FW2.2 protein regulates cell-to-cell communication in tomato by modulating callose deposition at plasmodesmata.

FW2.2 (standing for FRUIT WEIGHT 2.2), the founding member of the CELL NUMBER REGULATOR (CNR) gene family, was the first cloned gene underlying a quantitative trait locus (QTL) governing fruit size and weight in tomato (Solanum lycopersicum). However, despite this discovery over 20 yr ago, the molecular mechanisms by which FW2.2 negatively regulates cell division during fruit growth remain undeciphered. In the present study, we confirmed that FW2.2 is a membrane-anchored protein whose N- and C-terminal ends face the apoplast. We unexpectedly found that FW2.2 is located at plasmodesmata (PD). FW2.2 participates in the spatiotemporal regulation of callose deposition at PD and belongs to a protein complex which encompasses callose synthases. These results suggest that FW2.2 has a regulatory role in cell-to-cell communication by modulating PD transport capacity and trafficking of signaling molecules during fruit development.

On-Plant Size and Weight Estimation of Tomato Fruits Using Deep Neural Networks and RGB-D Imaging

Highlights Deep learning-based instance segmentation models were applied and evaluated for tomato fruit detection. Mask R-CNN with vision transformer backbone showed the highest accuracy for tomato instance detection. Size and weight estimation indexes were calculated using tomato region depth data from instance segmentation models. Area-based index has higher accuracy for weight estimation than indexes based on weight and height information. Abstract. The size and weight of fruits are crucial factors in yield prediction and determining harvesting time. Machine vision, including fruit detection, is a key technology in the automated monitoring and harvesting of fruits. In particular, deep learning-based fruit-detection methods have been actively applied. Estimation of fruit size after fruit detection requires depth information, which can be acquired using depth imaging. RGB-D cameras include color and depth information required for fruit detection and size estimation. In this study, the RGB-D imaging technique was used to estimate the size and weight of tomatoes. Furthermore, deep learning-based instance segmentation models, including Mask R-CNN, YOLACT, and RTMDet for tomato fruit detection, were trained and evaluated. The proposed method estimated the fruit width with a root mean square error (RMSE) of 4 mm, a mean absolute percentage error (MAPE) of 4.28%, and a fruit height with an RMSE of 5.12 mm and a MAPE of 6.42%. Furthermore, the weight-prediction model based on the area index estimated the tomato fruit weight with an RMSE of 19.69 g and MAPE of 9.44%. Thus, the method can be used for accurate size and weight estimation and can be applied in growth monitoring and automated tomatoes harvesting. Keywords: Deep learning, Fruit sizing, Instance segmentation, RGB-D, Tomato.

Regulation of Cell Wall Remodeling is an Important Factor in the Reduction of Tomato Fruit Size Immediately after Fruit Set Induced by Salinity Conditions

Regulation of Cell Wall Remodeling is an Important Factor in the Reduction of Tomato Fruit Size Immediately after Fruit Set Induced by Salinity Conditions

Idiosyncratic and dose-dependent epistasis drives variation in tomato fruit size.

Epistasis between genes is traditionally studied with mutations that eliminate protein activity, but most natural genetic variation is in cis-regulatory DNA and influences gene expression and function quantitatively. In this study, we used natural and engineered cis-regulatory alleles in a plant stem-cell circuit to systematically evaluate epistatic relationships controlling tomato fruit size. Combining a promoter allelic series with two other loci, we collected over 30,000 phenotypic data points from 46 genotypes to quantify how allele strength transforms epistasis. We revealed a saturating dose-dependent relationship but also allele-specific idiosyncratic interactions, including between alleles driving a step change in fruit size during domestication. Our approach and findings expose an underexplored dimension of epistasis, in which cis-regulatory allelic diversity within gene regulatory networks elicits nonlinear, unpredictable interactions that shape phenotypes.

Improvement by application of three nanomaterials on flavor quality and physiological and antioxidant properties of tomato and their comparison

In recent years, it has been found that the flavor quality of tomato is continuously reduced compared with the original tomato varieties. Studies have found that nanomaterials can improve crop quality, but the differences and related mechanisms among different nanomaterials were not reported. In this study, nano-Se, nano-TiO2 and nano-CeO2 were spraying on tomato, and the effects of the three nanomaterials on the flavor quality and physiological and antioxidant properties of fruits were analyzed and compared. The results showed compared with nano-TiO2 and nano-CeO2, nano-Se showed more obvious positive effects. Nano-Se increased the size and weight of tomato fruits and the levels of soluble sugar, promoted the accumulation of photosynthetic pigment, decreased the content of titratable acid, and also changed the expression of related genes, finally making the fruit sweeter; it also promoted the accumulation of antioxidant substances and nutrients such as lycopene, ascorbic acid, salicylic acid, GSH, SOD and CAT and decreased the content of MDA, H2O2 and OFR thus improving the antioxidant performance of fruits; the contents of volatiles were also increased and the olfactory experience of tomato was improved. Nano-TiO2 and nano-CeO2 also improved the flavor quality and antioxidant properties of tomato, but the degree was lower than nano-Se. This experiment provided references for selecting more appropriate nanomaterials to improve tomato quality, and revealed the effects and mechanisms of different nanomaterials on tomato quality.

NAC transcription factor NOR-like1 regulates tomato fruit size.

NOR-like1 regulates tomato fruit size by targeting SlARF9, SlGRAS2, SlFW3.2, and SlFW11.3 genes involved in cell division and cell expansion. Fruit size is an important agricultural character that determines the yield of crops. Here, we found that NAC transcription factor NOR-like1 regulated fruit size by regulating cell layer number and cell area in tomato. Over-expressing NOR-like1 gene in tomato reduced fruit weight and size, whereas the knock-out of NOR-like1 increased fruit weight and size. At the molecular level, NOR-like1 binds to the promoter of SlGRAS2, SlFW3.2, and SlFW11.3 to repress their transcription, while it also binds to the promoter of ARF9 to activate its transcription. Overall, these results expand the biological function of NOR-like1 and deepen our understanding of the transcriptional network that regulates tomato fruit size.

ASYMMETRIC LEAVES 2 and ASYMMETRIC LEAVES 2-LIKE are partially redundant genes and essential for fruit development in tomato.

Fruit size and shape are controlled by genes expressed during the early developmental stages of fruit. Although the function of ASYMMETRIC LEAVES 2 (AS2) in promoting leaf adaxial cell fates has been well characterized in Arabidopsis thaliana, the molecular mechanisms conferring freshy fruit development as a spatial-temporal expression gene in tomato pericarp remain unclear. In the present study, we verified the transcription of SlAS2 and SlAS2L, two homologs of AS2, in the pericarp during early fruit development. Disruption of SlAS2 or SlAS2L caused a significant decrease in pericarp thickness as a result of a reduction in the number of pericarp cell layers and cell area, leading to smaller tomato fruit size, which revealed their critical roles in tomato fruit development. In addition, leaves and stamens exhibited severe morphological defects in slas2 and slas2l single mutants, as well as in the double mutants. These results demonstrated the redundant and pleiotropic functions of SlAS2 and SlAS2L in tomato fruit development. Yeast two-hybrid and split-luciferase complementation assays showed that both SlAS2 and SlAS2L physically interact with SlAS1. Molecular analyses further indicated that SlAS2 and SlAS2L regulate various downstream genes in leaf and fruit development, and that some genes participating in the regulation of cell division and cell differentiation in the tomato pericarp are affected by these genes. Our findings demonstrate that SlAS2 and SlAS2L are vital transcription factors required for tomato fruit development.

Genome-Wide Identification and Expression Analysis of the fw2.2-like Gene Family in Pear

Fruit size is a major factor determining yield, quality, and consumer acceptability. fw2.2 (fruit weight-2.2) is a primary quantitative trait locus that was the first to be cloned, accounting for 30% of the variation in tomato fruit size. The various homologs of fw2.2 (fw2.2-like) have been identified in many plants and belong to a large family. To date, there has been no report that has carried out a comprehensive identification of fw2.2-like members in pear. In this study, a total of 14 fw2.2-like genes were identified in the pear (Pyrus bretschneideri Rehd) genome and designated as PbFWL1-14. All of the PbFWL genes were unevenly distributed on nine chromosomes, and each chromosome contained between one and four genes. All PbFWL proteins contained more than two conserved motifs, and PbFWL genes contained more than one intron, and the genes of the same subfamily seemed to have a similar intron gene structure. According to the neighbor-joining phylogenetic tree, a total of 78 fw2.2/CNR (cell number regulator) from five plant species, including pear, maize, tomato, peach, rice, and physalis, could be divided into seven subgroups, and PbFWL proteins were mainly distributed in subgroups 1, 3, 4, 5, and 6. The Ka/Ks analysis also revealed that the fw2.2-like gene family of pear may have been subjected to strong purifying selection pressure during its evolution. A cis-element analysis found that many cis-elements responsive to hormones and stress were discovered in promotion regions for all PbFWLs. When combining real-time quantitative PCR analysis detection results, PbFWL1/2/5 were found to be the most likely candidate genes for regulating pear fruit size.

Application of Compost, as a Peat Substitute, and Foliar Spray of Chitosan and/or Roots Inoculation With Beneficial Fungus Increases Tomato Plants Productivity and Fruit Size

Application of Compost, as a Peat Substitute, and Foliar Spray of Chitosan and/or Roots Inoculation With Beneficial Fungus Increases Tomato Plants Productivity and Fruit Size

SlCK2α as a novel substrate for CRL4 E3 ligase regulates fruit size through maintenance of cell division homeostasis in tomato.

This study unravels a novel regulatory module (CRL4-CK2α-CDK2) involving fruit size control by mediating cell division homeostasis (SlCK2α and SlCDK2) in tomato. Fruit size is one of the crucial agronomical traits for crop production. UV-damaged DNA binding protein 1 (DDB1), a core component of Cullin4-RING E3 ubiquitin ligase complex (CRL4), has been identified as a negative regulator of fruit size in tomato (Solanum lycopersicum). However, the underlying molecular mechanism remains largely unclear. Here, we report the identification and characterization of a SlDDB1-interacting protein putatively involving fruit size control through regulating cell proliferation in tomato. It is a tomato homolog SlCK2α, the catalytic subunit of the casein kinase 2 (CK2), identified by yeast two-hybrid (Y2H) assays. The interaction between SlDDB1 and SlCK2α was demonstrated by bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP). RNA interference (RNAi) and CRISPR/Cas9-based mutant analyses showed that lack of SlCK2α resulted in reduction of fruit size with reduced cell number, suggesting it is a positive regulator on fruit size by promoting cell proliferation. We also showed SlDDB1 is required to ubiquitinate SlCK2α and negatively regulate its stability through 26S proteasome-mediated degradation. Furthermore, we found that a tomato homolog of cell division protein kinase 2 (SlCDK2) could interact with and specifically be phosphorylated by SlCK2α, resulting in an increase of SlCDK2 protein stability. CRISPR/Cas9-based genetic evidence showed that SlCDK2 is also a positive regulator of fruit size by influencing cell division in tomato. Taken together, our findings, thus, unravel a novel regulatory module CRL4-CK2α-CDK2 in finely modulating cell division homeostasis and the consequences on fruit size.

The Impact of Various LED Light Spectra on Tomato Preservation

Major losses of fresh tomatoes happen during post-harvest storage due to prompt senescence and diseases. The aim of the research was to evaluate the effects of different spectra of LED lights on the post-harvest preservation of ascorbic acid, lycopene, and total soluble solids, the weight and size of tomato fruits, as well as to determine the optimal exposure time and distance of irradiation and extension of shelf-life. Therefore, experiments were carried out in a climate chamber with shelves equipped with three different light spectra: red light-emitting diodes, red–blue–white light-emitting diodes, and ultraviolet-light-emitting diodes. Light treatment had a certain positive effect on the firmness, size, and mass of samples. Thus, tomato fruits (Panekra) exposed to the spectra of LED lights demonstrated a better quality of firmness and mass compared to the control samples (non-preserved) of tomatoes. The treatments with RL significantly improved the concentration of lycopene than FL and UV-LED lights, although the highest concentration of lycopene was observed in the control samples for the first 7 days of the storage. After 21 days, the ascorbic acid content in the red spectrum was found to be much higher than in the other two spectra and control samples, coming in at about 1.8 mg/100 mL compared to 1.0 mg/100 mL for the control samples. Total soluble solids also increased significantly after preservation, rising from 3.9 °Brix in the control samples to roughly 7.3 °Brix in samples preserved using the full spectrum after 21 days. Overall, the results of the study demonstrated that tomato preservation using the investigated techniques induced lycopene concentration, ascorbic acid, and total soluble solids concentrations. The results derived from this study provide highly useful information in the field of post-harvest preservation.

Effect of the application of organic amendment and microorganisms that promote plant growth on tomato production (Solanum lycopersicum L.)

It is important to conserve and improve water use efficiency and crop productivity in arid and semi-arid zones. For which, the use of beneficial microorganisms and water retainers can help in the tolerance of plants to drought conditions. Therefore, the objective of this work was to determine the effect of inoculation with MPCV- plant growth promoting microorganisms (Azospirillum brasilense and mycorrhizal fungi) and the application of organic amendment of potassium acrylate on the production of tomato plants (Solanum lycopersicum L.). A greenhouse trial was carried out with a completely randomized experimental design with 4 treatments (T1: Control without application of amendment or MPCV; T2: application of K acrylate amendment; T3: with MPCV inoculation; T4: with joint application of K acrylate amendment and MPCV), with 15 replicates. The highest production and size of tomato fruits was achieved with the inoculation of MPCV (T3) and with the application of K acrylate (T2) individually. The inoculation with Azospirillum brasilense and mycorrhizal fungi, and the application of the organic amendment of potassium acrylate at the time of transplanting tomato (Solanum lycopersicum L.) improves growth and increases its production.

The impact of elevated CO2 concentration on fruit size, quality, and mineral nutrient composition in tomato varies with temperature regimen during growing season

The impact of elevated CO2 concentration on fruit size, quality, and mineral nutrient composition in tomato varies with temperature regimen during growing season

Action of high concentration of carbon dioxide on size and ripening of tomato fruit

Elevated carbon dioxide concentration (eCO2) has the potential to modify tomato fruit size. However, the role of eCO2 on the rate of fruit growth and the time of fruit ripening remains elusive. Here, we report that the decrease in number of cell per area in the pericarp of mature fruits was associated with a significant enhancement in cell area, which in turn increased fruit yield and concentration of minerals. Moreover, the maximal fruit expansion rate was increased by eCO2 conditions, which was associated with enhanced of transcripts encoding expansin proteins in pericarp tissues of immature fruits. However, the duration of fruit expansion was not affected by eCO2, suggesting that fruit expansion rate is more flexible than expansion duration upon eCO2 treatment. High CO2 increased concentrations of ethylene and carotenoids during fruit ripening, which resulted in a slight acceleration of maturation. Thus, our study highlights the potential role of eCO2 in determining tomato fruit size and ripening.

The Mechanism of MADS-box Gene SlMBP3 Modulating Tomato Fruit Size

The Mechanism of MADS-box Gene SlMBP3 Modulating Tomato Fruit Size

Cytokinins is involved in regulation of tomato pericarp thickness and fruit size.

Although cytokinins (CKs) regulate fruit development, no direct genetic evidence supports the role of endogenous CKs in pericarp growth or development or fruit size. Here, we report that the reduction in levels of endogenous active CKs via overexpression of the CK-inactivating enzyme gene AtCKX2 specifically in fruit tissues resulted in reduced pericarp thickness and smaller fruit size compared with wild-type control fruits. Pericarp thickness and single fruit weight in transgenic plants were significantly reduced. Analysis of paraffin sections showed that the reduced pericarp thickness was due largely to a decreased number of cells, and thus decreased cell division. Transcriptome profiling showed that the expression of cell division- and expansion-related genes was reduced in AtCKX2-overexpressing fruits. In addition, the expression of auxin-signaling and gibberellin-biosynthetic genes was repressed, whereas that of gibberellin-inactivating genes was enhanced, in AtCKX2-overexpressing fruits. These results demonstrate that endogenous CKs regulate pericarp cell division and subsequently fruit size. They also suggest that CKs interact with auxin and gibberellins in regulating tomato pericarp thickness and fruit size.

Complex cellular and molecular events determining fruit size.

The understanding of plant organ-size determination represents an important challenge, especially because of the significant role of plants as food and renewable energy sources and the increasing need for plant-derived products. Most of the knowledge on the regulation of organ growth and the molecular network controlling cell division and cell expansion, the main drivers of growth, is derived from arabidopsis. The increasing use of crops such as tomato for research is now bringing essential information on the mechanisms underlying size control in agronomically important organs. This review describes our current knowledge, still very scarce, of the cellular and molecular mechanisms governing tomato fruit size and proposes future research to better understand the regulation of growth in this important crop.

Machine learning approach for automatic recognition of tomato-pollinating bees based on their buzzing-sounds.

Bee-mediated pollination greatly increases the size and weight of tomato fruits. Therefore, distinguishing between the local set of bees-those that are efficient pollinators-is essential to improve the economic returns for farmers. To achieve this, it is important to know the identity of the visiting bees. Nevertheless, the traditional taxonomic identification of bees is not an easy task, requiring the participation of experts and the use of specialized equipment. Due to these limitations, the development and implementation of new technologies for the automatic recognition of bees become relevant. Hence, we aim to verify the capacity of Machine Learning (ML) algorithms in recognizing the taxonomic identity of visiting bees to tomato flowers based on the characteristics of their buzzing sounds. We compared the performance of the ML algorithms combined with the Mel Frequency Cepstral Coefficients (MFCC) and with classifications based solely on the fundamental frequency, leading to a direct comparison between the two approaches. In fact, some classifiers powered by the MFCC-especially the SVM-achieved better performance compared to the randomized and sound frequency-based trials. Moreover, the buzzing sounds produced during sonication were more relevant for the taxonomic recognition of bee species than analysis based on flight sounds alone. On the other hand, the ML classifiers performed better in recognizing bees genera based on flight sounds. Despite that, the maximum accuracy obtained here (73.39% by SVM) is still low compared to ML standards. Further studies analyzing larger recording samples, and applying unsupervised learning systems may yield better classification performance. Therefore, ML techniques could be used to automate the taxonomic recognition of flower-visiting bees of the cultivated tomato and other buzz-pollinated crops. This would be an interesting option for farmers and other professionals who have no experience in bee taxonomy but are interested in improving crop yields by increasing pollination.

Evaluating Performance of Cherry and Slicer Tomato Cultivars in Greenhouse and Open Field Conditions: Yield and Fruit Quality

Tomato (Solanum lycopersicum L.) is one of the most extensively cultivated horticultural crops in the world. Factors such as yield, size, taste, and lycopene content are important criteria that may impact the selection of tomato cultivars for different production systems. The aim of the current study was to evaluate different slicer and cherry tomato cultivars for production under greenhouse and open field conditions. Three cultivars of slicer (BHN 964, Trust, and Geronimo) and cherry (BHN 268, Favorita, and Sakura) tomatoes were tested using randomized complete block design in 2019 and 2020. Results showed that the performance of tested cultivars differed under greenhouse verses open field conditions. Among cherry tomato cultivars in 2020, BHN 268 and Sakura produced significantly greater yield under open field conditions, while under greenhouse conditions yield of BHN 268 was the lowest. Similarly, cherry tomato fruit size from ‘BHN 268’ and ‘Sakura’ was also significantly greater than ‘Favorita’ under field conditions, whereas under greenhouse conditions, the fruit size of ‘Sakura’ was significantly greater than both ‘BHN 268’ and ‘Favorita’. Among slicer tomato cultivars, BHN 964 produced significantly greater yield and had a greater average fruit size than the other two cultivars under greenhouse conditions in 2020 while, Geronimo produced significantly similar or larger yield and had a similar average fruit size compared with BHN 964 under open field conditions. Tomatoes produced under open field conditions were rated significantly greater for taste compared with those produced under greenhouse conditions. Lycopene content in both slicer and cherry tomato cultivars was influenced by the interaction of production type, cultivars, and harvest time. Therefore, it can be concluded that BHN 964 and Geronimo were the highest in lycopene among slicer tomato cultivars for greenhouse and open field production, respectively. Among cherry tomato cultivars, BHN 268 was the highest in lycopene for open field production and Sakura for greenhouse production. Additionally, open field–produced tomatoes taste better than greenhouse-produced tomatoes, but lycopene content may be constrained for mid- and late-season fruits due to high temperature conditions under open field conditions.