Studies on the fungi associated with tomato fruit rots and effects of environment on storage

Seven fungi associated with fruit rot of tomato were isolated includingFusarium equiseti, F. chlamydosporum, Alternaria solani, Geotrichum candidum, Acremonium recifei, Aspergillus flavus andA. niger. They were all pathogenic on tomato fruits, most pathogenic beingGeotrichum candidum followed byA. niger. Least rot was caused byAlternaria solani. The optimum temperature for maximum rotting caused byG. candidum, A. niger andA. flavus was 30°C. The relative humidity for maximum rot ranged from 70–90%. Tomato fruits stored well at 0–10°C and rather poorly at 20–30°C. Fruits stored at 35°C showed blemishes. The best RH for storage ranged between 60 and 90%.     

Application of homobrassinolide enhances growth,yield and quality of tomato

Brassinosteroids (BRs) have emerged as pleiotropic phytohormone owing to their wide function in crop growth and metabolism. Homobrassinolide (HBR) being an analogue of BRs is known to improve the growth, yield and quality parameters in many crop plants. Thus, an evaluation study was conducted for two years (2018 and 2019) to elucidate the performance of tomato plants (Solanum lycopersicum L.) to a novel group of phytohormone,HBR. The field experiment comprised of seven treatments with homobrassinolide 0.04% (Emulsifiable Concentrate) EC at four different concentrations (0.06, 0.08, 0.10 and 0.12 g active ingredient (a.i.) ha^?1) and two well-known growth promoters viz., Gibberellic acid (GA), Naphthalene Acetic Acid (NAA) along with the untreated control. Plant height and chlorophyll concentration were found significantly different in both years of experiment as well as among the different treatments. HBR at 0.12 g a.i. ha^?1 was found better with maximum number of fruits (77.36 plant^?1), fruit length (6.72 cm), fruit breadth (6.45 cm) and fruit weight (80.52 g) over other concentrations and treatments. Fruit yield was more pronounced in the plots treated with plant growth regulators compared to untreated control. However, significantly higher fruit yield of 91.07 t ha^?1 (62.58 t ha^?1 with untreated control) along with improved quality traits viz., fruit firmness (4.11 kg cm^?2), ascorbic acid content (24.09 mg 100 g^?1), total soluble solids (4.43°Brix) and keeping quality (12.50 days) was recorded in 0.12 g a.i. ha^?1 HBR treated plots. Thus, it can be inferred that HBRapplication would be a better option to enhance growth, yield as well as quality traits in tomato.     

Extremely elongated tomato fruit controlled by four quantitative trait loci with epistatic interactions

Cultivated tomato (Lycopersicon esculentum) encompass a wide range of fruit shape and size variants. This variation can be used to genetically dissect the molecular basis of ovary and fruit morphology. The cultivar Long John displays an extremely elongated fruit phenotype, while the wild relative Lycopersicon pimpinellifolium LA1589 produces fruit that are nearly perfect spheres, typical of wild tomatoes. Quantitative trait mapping of an F2 population between Long John and LA1589 revealed four fruit shape QTLs, located on chromosomes 2, 3, 7 and 11. The primary role of the fruit shape QTL located on chromosome 7, ljfs7, is to control pericarp elongation. The primary role of the fruit shape QTLs on chromosome 2, 3 and 11 (ljfs2, ljfs3 and ljfs11, respectively) is to control pear shape, measured as the eccentricity index. QTL map position and the effect of the loci on fruit shape suggested that ljfs2 and ljfs7 are allelic to the well-studied fruit shape loci ovate and sun, respectively. ljfs3 and ljfs11 map near the previously identified, but less characterized, fruit shape loci fs3.2 and fs11.1, respectively. This result suggests that most of the variation in tomato fruit shape is controlled by a few major QTLs. Although eccentricity and pericarp elongation were largely controlled by independent growth processes, significant interactions were detected between all four fruit shape loci in the control of eccentricity. This indicates that the three eccentricity loci, ljfs2, ljfs3 and ljfs11, epistatically control the same developmental process, while ljfs7 had a pleiotropic effect on eccentricity. Received: 27 March 2001 / Accepted: 7 May 2001     

UV-B辐射增强和CO2浓度倍增的复合作用对番茄生长和果实品质的影响

以番茄（Lycopersicon esculeutum）为研究对象,在人工模拟8.40 kJ·m^-2的UV-B辐射和700 μmol·mol^-1的CO₂浓度复合处理下,研究了番茄的生长和果实品质变化.结果表明,UV-B辐射使番茄的株高、鲜重、干重、总叶绿素、叶绿素a、叶绿素b、光合速率、水分利用效率、可溶性蛋白、维生素c及番茄红素等降低,导致果实品质恶化;而CO₂浓度倍增作用相反.在UV-B辐射增强和CO₂浓度倍增复合作用下,番茄的上述指标与对照相比差异不明显.分析认为,CO₂倍增与UV-B辐射增强复合处理下,CO₂的正效应作用可以减轻甚至抵消UV-B辐射的负效应.     

Drought susceptibility of two tomato (Lycopersicum esculentum) varieties

The effects of three levels of moisture under greenhouse conditions and also identical moisture levels under field conditions, on the growth yield and water relations of two tomato cultivars, Fireball and Ife I, were investigated. The objective was to ascertain the drought susceptibility of these two tomato cultivars. The cultivar, Ife I, was more drought susceptible than Fireball and the drought susceptibility increased with the level of soil water stress. The drought tolerance, of Fireball is attributed to a lower leaf area, better root system development in terms of average root length and rooting depth, and a higher leaf water potential. The higher leaf stomatal resistances of Fireball variety suggest an inbuilt mechanism to regulate water vapour flow in times of stress.     

Comparison of the organization of the mitochondrial genome in tomato somatic hybrids and cybrids

Summary The organization of the mitochondrial genome in somatic hybrids and cybrids regenerated following fusion of protoplasts from cultivated tomato, Lycopersicon esculentum, and the wild species, L. Pennellii, was compared to assess the role of the nuclear genotype on the inheritance of organellar genomes. No organellar-encoded traits were required for the recorvery of either somatic hybrids or cybrids. The organization of the mitochondrial genome was characterized using Southern hybridization of restriction digestions of total DNA isolated from ten cybrids and ten somatic hybrids. A bank of cosmid clones carrying tomato mitochondrial DNA was used as probes, as well as a putative repeated sequence from L. pennellii mitchondrial DNA. The seven cosmids used to characterize the mitochondrial genomes are predicted to encompass at least 60% of the genome. The frequency of nonparental organizations of the mitochondrial genome was highest with a probe derived from a putative repeat element from the L. pennellii mitochondrial DNA. There was no difference in the average frequency of rearranged mitochondrial sequences in somatic hybrids (12%) versus cybrids (10%), although there were individual cybrids with a very high frequency of novel fragments (30%). The frequency of tomato-specific mtDNA sequences was higher in cybrids (25%) versus somatic hybrids (12%), suggesting a nuclear-cytoplasmic interaction on the inheritance of tomato mitochondrial sequences.     

Genetic mapping of ripening and ethylene-related loci in tomato

 The regulation of tomato fruit development and ripening is influenced by a large number of loci as demonstrated by the number of existing non-allelic fruit development mutations and a multitude of genes showing ripening-related expression patterns. Furthermore, analysis of transgenic and naturally occurring tomato mutants confirms the pivotal role of the gaseous hormone ethylene in the regulation of climacteric ripening. Here we report RFLP mapping of 32 independent tomato loci corresponding to genes known or hypothesized to influence fruit ripening and/or ethylene response. Mapped ethylene-response sequences fall into the categories of genes involved in either hormone biosynthesis or perception, while additional ripening-related genes include those involved in cell-wall metabolism and pigment biosynthesis. The placement of ripening and ethylene-response loci on the tomato RFLP map will facilitate both the identification and exclusion of candidate gene sequences corresponding to identified single gene and quantitative trait loci contributing to fruit development and ethylene response. Received: 26 October 1998 / Accepted: 13 November 1998     

Studies on fungi associated with tomato fruits and effectiveness of some commercial fungicides against three pathogens

Among 39 fungal species and one variety belonging to 16 genera isolated from 116 healthy tomato fruits collected from markets in Assiut, Egypt, during 1994,Aspergillus niger was found to be the most prevalent, being isolated from 84.6% of the samples. Of 11 species recovered from 156 diseased tomatoes,Alternaria alternata, Rhizopus stolonifer andA. niger were the most common and isolated from 52.7%, 35.9% and 25.0% of the samples, respectively. Experiments for comparison of the effects of medium containing tomato juice with synthetic medium on the mycelial growth of nine fungal species indicated that, the tomato juice medium was more suitable for growth of all fungal species. The effect of five commercial fungicides and sodium hypochlorite when applied as post-harvest dips after inoculation was studied in laboratory againstA. alternata, A. niger andR. stolonifer. At 10 and 100 µg ml^–1, neither of the fungicide caused a noticeable inhibition ofAlternaria rot. At 1000 µg ml^–1 benlate, rovral and sumisclex completely preventedAlternaria andAspergillus rot, whereas cuprosan and ridomil were ineffective against rotting caused byA. niger. Rhizopus rot development was inhibited by over 50% with one treatment only (rovral at 1000 µg ml^–1). Sodium hypochlorite has good curative properties against fruit rots especially those caused byA. alternata andA. niger.     

Identifying the loci responsible for natural variation in fruit size and shape in tomato

Fruit size and shape are two major factors determining yield, quality and consumer acceptability for many crops. Like most traits important to agriculture, both are quantitatively inherited. Despite their economic importance none of the genes controlling either of these traits have been cloned, and little is known about the control of the size and shape of domesticated fruit. Tomato represents a model fruit-bearing domesticated species characterized by a wide morphological diversity of fruits. The many genetic and genomic tools available for this crop can be used to unraveal the molecular bases of the developmental stages which presumably influence fruit architecture, size and shape. The goal of this review is to summarize data from the tomato QTL studies conducted over the past 15 years, which together allow the identification of the major QTLs responsible for fruit domestication in tomato. These results provide the starting point for the isolation of the genes involved in fruit-size/shape determination in tomato and potentially other fruit-bearing plants. Received: 21 January 1999 / Accepted: 12 March 1999     

Identification of novel small RNAs in tomato (<Emphasis Type="Italic">Solanum lycopersicum</Emphasis>)

To date, the majority of plant small RNAs (sRNA) have been identified in rice, poplar and Arabidopsis. To identify novel tomato sRNAs potentially involved in tomato specific processes such as fruit development and/or ripening, we cloned 4,018 sRNAs from tomato fruit tissue at the mature green stage. From this pool of sRNAs, we detected tomato homologues of nine known miRNAs, including miR482; a poplar miRNA not conserved in Arabidopsis or rice. We identified three novel putative miRNAs with flanking sequence that could be folded into a stem-loop precursor structure and which accumulated as 19-24nt RNA. One of these putative miRNAs (Put-miRNA3) exhibited significantly higher expression in fruit compared with leaf tissues, indicating a specific role in fruit development processes. We also identified nine sRNAs that accumulated as 19–24nt RNA species in tomato but genome sequence was not available for these loci. None of the nine sRNAs or three putative miRNAs possessed a homologue in Arabidopsis that had a precursor with a predicted stem-loop structure or that accumulated as a sRNA species, suggesting that the 12 sRNAs we have identified in tomato may have a species specific role in this model fruit species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Water deficit, root demography, and the causes of internal blackening in field-grown tomatoes:(Lycopersicon esculentum Mill.)

An internal blackening disorder may cause substantial losses in the value of tomatoes grown for processing. The disorder resembles an internal form of blossom-end rot and appears to be more common in dry seasons. In an experiment to test whether the internal blackening is caused by water deficit and whether it is indeed blossom-end rot, plots of cv. Cannery Row were irrigated to keep the soil moisture deficit <50 mm and others were sheltered from rain and not irrigated from early flowering onwards. Shoot growth (total and fruit dry mass) was measured destructively at intervals, and root growth and death nondestructively using minirhizotrons. There was a greater incidence of internal blackening and blossom-end rot, and lower Ca concentrations, in the fruit of non-irrigated plants. Root growth and root death were accelerated in these plants around the time that internally-blackened fruit were set. Although the internal blackening syndrome shared some features with blossom-end rot some differences were apparent in this experiment. It is suggested that internal blackening could have resulted from increased root competition for photosynthate, leading to abnormal seed development. Root turnover was appreciable (30–40% of the roots survived 28 days). This suggests there may be substantial errors in contemporary models of dry matter partitioning in tomato crops.     

A comparison of shoot regeneration from protoplasts and leaf discs of different genotypes of the cultivated tomato

Summary Shoot regeneration from leaf discs and leaf mesophyll protoplasts of 11 genotypes of Lycopersicon esculentum (the cultivated tomato), were compared. In both regeneration procedures genotypic differences were observed between inbred lines, and also between F1 hybrids and their parental lines. In the tested hybrid genotypes no heterosis effect with respect to shoot regeneration capacity was observed. A correlation between shoot regeneration from leaf discs and from leaf mesophyll protoplasts was apparent in the tested genotypes. This suggests that using the described procedure, shoot regeneration from leaf discs can be usef for rapid pre-screening for regeneration capacity from protoplasts of tomato genotypes.     

Expression of Arabidopsis APETALA1 in tomato reduces its vegetative cycle without affecting plant production

Important agronomic traits such as fruit quality, harvesting efficiency or production largely depend on flowering time. We have analysed the effect of the overexpression of the Arabidopsis APETALA1 MADS-box gene on vegetative and reproductive growth of tomato. Constitutive expression of APETALA1 in tomato plants has major effects on the length of their growth cycle as well as on their growth habit. Transgenic tomato plants initiated flowering after the production of 6 vegetative nodes as compared to 11 nodes for the wild type plants. Most of tomato 35S:AP1 plants also showed determinate growth habit, similar to the phenotype of self pruning tomato mutants, as well as an initial reduction of their axillary growth. Moreover, development and fertility of flowers were not affected in plants expressing AP1. Consequently, fruit formation in transgenic plants grown under greenhouse conditions occurred normally, which permitted a similar fruit yield compared to control plants. Since traits conferred by AP1 expression are dominant, its expression in tomato breeding lines could provide advantages for the development of new hybrid varieties with shorter generation time, determinate growth, and reduced pruning requirements.     

Meristem maintenance and compound-leaf patterning utilize common genetic mechanisms in tomato

Balancing shoot apical meristem (SAM) maintenance and organ formation from its flanks is essential for proper plant growth and development and for the flexibility of organ production in response to internal and external cues. Leaves are formed at the SAM flanks and display a wide variability in size and form. Tomato (Solanum lycopersicum) leaves are compound with lobed margins. We exploited 18 recessive tomato mutants, representing four distinct phenotypic classes and six complementation groups, to track the genetic mechanisms involved in meristem function and compound-leaf patterning in tomato. In goblet (gob) mutants, the SAM terminates following cotyledon production, but occasionally partially recovers and produces simple leaves. expelled shoot (exp) meristems terminate after the production of several leaves, and these leaves show a reduced level of compoundness. short pedicel (spd) mutants are bushy, with impaired meristem structure, compact inflorescences, short pedicels and less compound leaves. In multi drop (mud) mutants, the leaves are more compound and the SAM tends to divide into two active meristems after the production of a few leaves. The range of leaf-compoundness phenotypes observed in these mutants suggests that compound-leaf patterning involves an array of genetic factors, which act successively to elaborate leaf shape. Furthermore, the results indicate that similar mechanisms underlie SAM activity and compound-leaf patterning in tomato.     

Salt tolerance of soybean cultivars

Soybean (Glycine max) cv. Clark tolerated NaCl salinity up to osmotic potential in soil -1800 kPa, cv. Forest to -1500 kPa and cv. Kint to -1200 kPa. The tolerance of cvs. Clark and Forest was found to be related to the accumulation of soluble proteins, amino acids, proline, K and Ca. The sensitivity of cv. Kint was found to be associated with decrease in water, saccharide, protein, K and Ca contents. The leaf osmotic potential decreased in cvs. Clark and Forest while remained unchanged in cv. Kint. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study on simulation models of tomato fruit quality related to cultivation environmental factors

Plant growth simulation models are valuable tools for optimizing the environmental factors and managing crop cultivation in cultural facilities. Researches presently on tomato simulation models have mainly focused on the plant growth and development, growth stages, dry matter production and distribution, however, no report on modeling of tomato fruit quality has been published yet. In this study, the method of accumulated Thermal Effectiveness and PAR (TEP) was employed to model the dynamic relationship between the major quality indicators and the environmental factors. Data of both indicators of tomato fruit quality and environmental factors, temperature and solar radiation of the cultivation environment, were collected under multiple protected structures like solar greenhouse and plastic tunnel for tomato production. The variety of simulation models were established based on the effects of temperature and solar radiation on tomato quality formation, and independently tested with the modeling data. The results show that the dynamic changes of the indicators of fruit quality after fruit set are accorded with the amount of accumulated TEP and individual indicators of fruit quality are suitable to its specific models. The fruit hardness is well accorded with a formula of generalized least squares FHi = k₁ + k₂ × TEPi + k₃ × TEPi² ; Fruit soluble sugar content is in a formula of Logistic model  . Fruit organic acid content is in a formula of generalized least squares OACi = n₁ + n₂ × TEPi + n₃ × TEPi². Fruit tannin content is in a formula of Johnson Schumacher model  . According to the established fruit hardness model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.9396, 0.9181, 0.8910 and 0.9523, respectively and values of root mean square error (RMSE) are 0.833 kg/cm², 0.942 kg/cm², 0.628 kg/cm² and 0.738 kg/cm², respectively. Based on the established fruit soluble sugar content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.8596, 0.9420, 0.9027 and 0.9473, respectively and the values of RMSE are 1.011%, 0.710%, 0.771% and 0.608%, respectively. On the basis of the established fruit organic acid content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.8856, 0.9025, 0.9183 and 0.8768, respectively and the values of RMSE are 0.029%, 0.030%, 0.024% and 0.023%, respectively. According to the established fruit tannin content model, the determination coefficient R² values based on the 1:1 beeline between the simulated values and the measured values of the first, second, third and the fourth truss of fruit are 0.9481, 0.9219, 0.9521 and 0.8911, respectively and the values of RMSE are 13.41 mg/kg, 14.04 mg/kg, 13.92 mg/ kg and 16.78 mg/kg, respectively. All of the coefficients of determination R² are higher than 0.85, and the values of RMSE are generally smaller, which means the modeling is accurate and well accordance. This study will form a theoretic basis and provide technical support for the management of tomato production and environment control under plastic tunnel and solar greenhouse cultivation.     

Identification and characterization of a novel locus controlling early fruit development in tomato

Cultivated tomatoes (Lycopersicon esculen- tum) encompass a wide range of fruit size and shape variants. This variation provides the basis for dissecting the genetic and molecular pathways of ovary and fruit development. One fruit shape variant is displayed by the cultivar Sun 1642 (TA491). TA491 has an elongated fruit phenotype, while the wild relative L. pimpinellifolium LA1589 produces fruit that are nearly perfect spheres, a shape typical of wild tomatoes. Developmental studies indicated that the differences in fruit shape between TA491 and LA1589 are determined by events occurring immediately after pollination and extending to 14 days post-pollination. Quantitative trait mapping revealed a single major locus on chromosome 7 (named sun) to be responsible for the differential development of TA491 and LA1589 fruit. Other fruit shape loci characterized in tomato (e.g. fs8.1 and ovate) exert their effects before anthesis and early in ovary development. sun is the first major locus identified in tomato controlling fruit shape through post-pollination events. Received: 17 November 2000 / Accepted: 24 November 2000     

Salt tolerance in Lycopersicon species. IV. Efficiency of marker-assisted selection for salt tolerance improvement

The usefulness of marker-assisted selection (MAS) to develop salt-tolerant breeding lines from a F₂ derived from L. esculentum x L. pimpinellifolium has been studied. Interval mapping methodology of quantitative trait locus (QTL) analysis was used to locate more precisely previously detected salt tolerance QTLs. A new QTL for total fruit weight under salinity (TW) near TG24 was detected. Most of the detected QTLs [3 for TW, 5 for fruit number, (FN) and 4 for fruit weight (FW)] had low R ² values, except the FW QTL in the TG180-TG48 interval, which explains 36.6% of the total variance. Dominant and overdominant effects were detected at the QTLs for TW, whereas gene effects at the QTLs for FJV and FW ranged from additive to partial dominance. Phenotypic selection of F₂ familes and marker-assisted selection of F₃ families were carried out. Yield under salinity decreased in the F₂ generation. F₃ means were similar to those of the F₁ as a consequence of phentoypic selection. The most important selection response for every trait was obtained from the F₃ to F₄ where MAS was applied. While F₃ variation was mainly due to the within-family component, in the F₄ the FN and FW between-family component was larger than the within-family one, indicating an efficient compartmentalization and fixation of QTLs into the F₄ families. Comparison of the yield of these families under control versus saline conditions showed that fruit weight is a key trait to success in tomato salt-tolerance improvement using wild Lycopersicon germplasm. The QTLs we have detected under salinity seem to be also working under control conditions, although the interaction family x treatment was significant for TW, thereby explaining the fact that the selected families responded differently to salinity.     

Highly efficient Agrobacterium-mediated transformation and plant regeneration system for genome engineering in tomato

Tomato (Solanum lycopersicum L.) is an important vegetable and nutritious crop plant worldwide. They are rich sources of several indispensable compounds such as lycopene, minerals, vitamins, carotenoids, essential amino acids, and bioactive polyphenols. Plant regeneration and Agrobacterium-mediated genetic transformation system from different explants in various genotypes of tomato are necessary for genetic improvement. Among diverse plant growth regulator (PGR) combinations and concentrations tested, Zeatin (ZEA) at 2.0 mg l^?1 in combination with 0.1 mg l^?1 indole-3-acetic acid (IAA) generated the most shoots/explant from the cotyledon of Arka Vikas (36.48 shoots/explant) and PED (24.68 shoots/explant), respectively. The hypocotyl explant produced 28.76 shoots/explant in Arka Vikas and 19.44 shoots/explant in PED. In contrast, leaf explant induced 23.54 shoots/explant in Arka Vikas and 17.64 shoots/explant in PED. The obtained multiple shoot buds from three explant types were elongated on a medium fortified with Gibberellic acid (GA₃) (1.0 mg l^?1), IAA (0.5 mg l^?1), and ZEA (0.5 mg l^?1) in both the cultivars. The rooting was observed on a medium amended with 0.5 mg l^?1 indole 3-butyric acid (IBA). The transformation efficiency was significantly improved by optimizing the pre-culture of explants, co-cultivation duration, bacterial density and infection time, and acetosyringone concentration. The presence of transgenes in the plant genome was validated using different methods like histochemical GUS assay, Polymerase Chain Reaction (PCR), and Southern blotting. The transformation efficiency was 42.8% in PED and 64.6% in Arka Vikas. A highly repeatable plant regeneration protocol was established by manipulating various plant growth regulators (PGRs) in two tomato cultivars (Arka Vikas and PED). The Agrobacterium-mediated transformation method was optimized using different explants like cotyledon, hypocotyl, and leaf of two tomato genotypes. The present study could be favourable to transferring desirable traits and precise genome editing techniques to develop superior tomato genotypes.