Difference in volatile profile between pericarp tissue and locular gel in tomato fruit

Aroma, a complex mixture of volatile compounds, plays an important role in the perception and acceptability of tomato products by consumers. Numerous studies have reported volatile profiles in tomatoes based on measurement of the whole fruit or pericarp tissue, however, little is understood regarding the volatile compositions in the inner tissues. The objective of this study was to investigate the differences in volatile profile between pericarp tissue and Iocular gel in tomato fruit. Based on HS-SPME-GC-MS analysis, totally 42 volatile compounds were detected in FL 47 and Tasti-Lee tomato fruits. Regardless of cultivars, a substantial higher concentration of total volatile compounds was observed in pericarp than that in/ocular gel, associated with higher levels of aldehydes, hydrocarbons, and nitrogen compounds. Pericarp tissue possessed higher levels of cis-3-hexenal, hexanal, heptanal, octanal, nonanal, cymene, terpinolene, undecane, dodecane, 2-phenylethanol, 6-methyl-5-hepten-2-one, 2-methylbutyl acetate, 1-nitro-pentane, and 1-nitro-2-phenylethane, while the abundances of 2-methylpropanal, butanal, 2-methylbutanal, 2-methyl-2-butenal, 2-methylpropanol, 3-methylbutanol, 2-methylbutanol, and 2-butanone were higher in Iocular gel. Principal component analysis （PCA） and cluster analysis using GC-MS and electronic nose （E-nose） data discriminated the two tissues.

Regulations of m^(6)A methylation on tomato fruit chilling injury

Tomato fruit are sensitive to chilling injury(CI)during cold storage.Several factors have been discovered to be involved in chilling injury of tomato fruit.Plant hormones play an important regulatory role,however,the relationship between chilling injury and N6-methyladenosine(m^(6)A)methylation of transcripts in plant hormone pathways has not been reported yet.In order to clarify the complex regulatory mechanism of m^(6)A methylation on chilling injury in tomato fruit,Nanopore direct RNA sequencing was employed.A large number of enzymes and transcription factors were found to be involved in the regulation process of fruit chilling injury,which were associated with plant hormone,such as 1-aminocyclopropane 1-carboxylate synthase(ACS),aspartate aminotransferase(AST),auxin response factor(ARF2),ethylene response factor 2(ERF2),gibberellin 20-oxidase-3(GA20ox)and jasmonic acid(JA).By conjoint analysis of the differential expression transcripts related to chilling injury andm^(6)Amethylation differential expression transcripts 41 differential expression transcripts were identified involved in chilling injury including 1-aminocyclopropane-1-carboxylate oxidase(ACO)and pectinesterase(PE)were down-regulated and heat shock cognate 70 kD protein 2(cpHSC70),HSP70-binding protein(HspBP)and salicylic acid-binding protein 2(SABP2)were up-regulated.Our results will provide a deeper understanding for chilling injury regulatory mechanism and post-harvest cold storage of tomato fruit.

Relationship Between Ca ^(2+)-CaM and Ethylene-Induced PG Activity in Tomato Fruit

Polygalacturonase (PG) was studied during ripening and senescence of postharvest tomato fruit at pink stage at low and normal temperature. The results showed that the PG activity increased, then decreased during ripening and senescence of tomato. Low temperature inhibited but ethylene enhanced PG activity. Ethylene also enhanced calmodulin content, which was dependent on Ca 2+concentration in cell. When EGTA(Ca 2+chelator), verapamil(Vp) and LaCl 3(Ca 2+channel blockers), trifluoperazine and chloropromaize (two CaM antagonisms) were used to treat tomato fruit at green mature stage with ethylene, they could reverse ethylene-induced increase in PG activity, but Vp, chloropromaize (CPZ), trifluoperazine (TFP) could not directly influence PG activity, which indirectly indicated that influx of Ca 2+ from the extracellular space including the cell wall via the Ca 2+ channel localized in plasma membrane and CaM were required for ethylene-induced PG activity increase and that ethylene signal transduction may be related to Ca 2+CaM messenger system.

Mining Heat Stress Associated Genes in Tomato Fruit (Solanum lycopersicum L.) Through RNA-seq

Tomato(Solanum lycopersicum L.)is a thermophilic vegetable crop,but sensitive to high temperature stress,especially under the greenhouse conditions.Due to global climate changes,heat stress has now become a great threat to tomato production and fruit quality.Many studies have been conducted to determine the functions of genes in tomato responsive to abiotic and biotic stresses,but transcriptomic information on heat stress responses of tomato fruit is still limited.To investigate heat stress associated genes in tomato fruit,a cDNA library was constructed using fruit harvested from tomato cv.P19-9 plants grown under 42℃for 0,1,2 and4 h and the expression profiles of heat stress responsive genes in tomato fruit were analyzed through RNA-seq.A total of 632224558 clean high quality paired-end reads were obtained and then mapped to reference genome for RNA-seq analysis.After quality control analysis,alignment analysis and transcript assembly,a total of 55457 RNA transcripts were obtained with functional annotations.Overall,6869 differentially expressed genes(DEGs)were identified with a significant response to one or more of the three heat stress treatment times.Based on GO enrichment analysis,22 genes potentially involved in tomato thermo-tolerance were selected and validated for their expressions through qPCR.The expression profile of tomato fruit genes obtained in this study could shed light on the mechanism and gene editing breeding projects for tomato thermo-tolerance.These findings could also benefit improvement of harvest and storage of tomato in greenhouse.

Over-expression of GhDWF4 gene improved tomato fruit quality and accelerated fruit ripening

Brassinosteroids（BRs）, a class of steroidal phytohormones are essential for many biological processes in plant. However, little is known about their roles in fruit development. Tomato is a highly valuable vegetable and has been adopted as the model species for studying fruit growth, development, and ripening. To understand the role of endogenous BRs in the development of tomato fruit, the expression patterns of three homologues of DWF4 gene were investigated and the transgenic tomato plants were generated in which the Gh DWF4 gene from upland cotton（Gossypium hirsutum L.） was ectopically expressed. The contents of main quality components were analyzed in fruits of transgenic tomato line and non-transgenic line（control plant, CP） when the fruit was mature. Sl CYP90B3 that possesses high homology with Gh DWF4 preferentially expressed in mature fruit. Significantly higher contents of soluble sugar, soluble proteins, and vitamin C were obtained in fruit of transgenic tomato lines compared with those in the CP. Furthermore, overexpressing Gh DWF4 promoted fruit growth and ripening. The weight per fruit was increased by about 23% in transgenic lines. In addition, overexpressing Gh DWF4 promoted the germination of transgenic tomato seeds and hypocotyl elongation of seedlings. These results indicated that overexpressing Gh DWF4 gene in tomato could increase the contents of many nutrients in fruit and accelerate fruit ripening. It is suggested that increased endogenous BRs in fruit affect the growth and development of tomato fruit and therefore improved the nutrient quality of tomato.

Reducing the carbon emissions from Qianxi tomato fruits preservation by cold atmospheric plasma

China has pledged to reach its dual-carbon goals(i.e.,carbon peak and carbon neutrality)at the end of 2060.To reduce carbon emission in food preservation industry,the preservation effects of cold atmospheric plasma intermittent treatment(1 min/6 h each day,PL4)combined with 15℃ and 4℃ only on Qianxi tomato fruits during 7 d storage were investigated.Results indicated that the firmness,L*,sensory taste,glutathione(GSH)content,mineral(Fe,P,K)content,polyphenol oxidase activity of PL4 tomatoes were significantly increased than that in Control during earlier period storage,with worse weight loss,titratable acid,a*,b*,lycopene content,·OH radical scavenging capacity and same moisture content,total soluble solids,polysaccharide content,total phenolics content,total flavonoid content,ascorbic acid content,1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity,pectin methylesterase activity.Moreover,the power and R134a consumption of PL4 were highly decreased by around 56.4 kW·h and 0.3 g respectively during whole storage as compared to Control,and reduced more than 99.8%carbon emission based on equipment using stage.All in all,this study illustrated that PL4 treatment can be applied as an ecofriendly,low carbon and sustainable preservation strategy for short-term storage of fruits under 4℃ or higher temperature.

The Yield and Diseases-Pest Performance of Breeding Materials for Tomatoes (Lycopersicon esculentum) Sourced from Different Exotic Sources

A study was conducted with 36 tomato germplasm [PGRC (19), The Netherlands (7), Japan (2), and Bangladesh (9)] with 3 check varieties in the research field of the Olericulture Division of Horticulture Research Centre (HRC), Bangladesh Agricultural Research Institute (BARI), Gazipur during the winter season of 2022-23 to identify promising tomato breeding germplasm. All the germplasm showed differences in most of the parameters studied. Considerable variation was observed for fruit yield per hectare varied from 39 to 144 tons, while the highest fruit yield per hectare was harvested from the germplasm viz., BD 7759B, BD 7757, BD 7751, BD 7301, QM, BD 7759A, BD 7762, QF, BD 7753, BD 8886, BD 10351, NL-1A, SLA-19. The number of locules, total soluble solids (TSS) and plant height at last harvest varied from 2 to 6.6, 2.6 to 5.9%, and 66 to 154cm, respectively. The TYLCV infection (%) and leaf-sucking pest infestation (%) were observed with a 1 to 20% range in the field condition in both cases. So, we can select that germplasm has zero per cent infestation. Considering the plant growth habit, earliness, different yield contributing horticultural traits, virus and pest infestation thirteen germplasm viz., BD 7759B, BD 7757, BD 7751, BD 7301, QM, BD 7759A, BD 7762, QF, BD 7753, BD 8886, BD 10351, NL-1A, SLA-19 were selected as breeding materials for further tomato improvement program.

警惕新发病毒番茄褐色皱果病毒Tomato brown rugose fruit virus对我国番茄产业的危害

番茄褐色皱果病毒Tomato brown rugose fruit virus(ToBRFV)于2014年首次在以色列发现,随后传播到欧洲、美洲以及亚洲等地。ToBRFV在番茄叶片上引起花叶,更重要的是在番茄果实上引起褐色皱缩斑,导致番茄完全失去商品价值,是番茄安全生产的重大威胁。为遏制ToBRFV的传播,多个国家已经将该病毒列入检疫对象。2019年,我们在山东番茄上检测到该病毒。本文综述了ToBRFV发生与危害、寄主范围和症状、传播方式、基因组结构、检测方法,并提出了防治建议,希望有助于防范该病毒在我国的扩散。

Role of the tomato fruit ripening regulator MADS-RIIM in resistance to Botrytis cinerea infection

Tomato MADS-RIN(RIN)transcription factor has been shown to be a master activator regulating fruit ripening.Recent studies have revealed that in addition to activating many other cell wall genes,it also represses expression of XTH5,XTH8,and MAN4a,which are positively related to excess flesh softening and cell wall degradation,which might indicate it has a potential role in pathogen resistance of ripening fruit.In this study,both wild-type(WT)and RIN-knockout(RIN-KO)mutant tomato fruit were infected with Botrytis cinerea to investigate the function of RIN in defense against pathogen infection during ripening.The results showed that RIN-KO fruit were much more sensitive to B.cinerea infection with larger lesion sizes.Transcriptome data and qRT-PCR assay indicate genes of phenylalanine ammonialyase (PAL)and chitinase(CHI)in RIN-KO fruit were reduced and their corresponding enzyme activities were decreased.Transcripts of genes encoding pathogenesis-related proteins(PRs),including PR1a,PRSTH2,and APETALA2/Ethylene Response Factor(AP2/ERF)including ERF.A1,Pti5,Pti6,ERF.A4,were reduced in RIN-KO fruit compared toWT fruit.Moreover,in the absence of RIN the expression of genes encoding cell wallmodifying enzymes XTH5,XTH8,MAN4a has been reported to be elevated,which is potentially correlated with cell wall properties.When present,RIN represses transcription of XTH5 by activating ERF.F4,a class II(repressor class)EffFgene family member,and ERF.F5.These results support the conclusion that RIN enhances ripening-related resistance to gray mold infection by upregulating pathogen-resistance genes and defense enzyme activities as well as reducing accumulation of transcripts encoding some cell wall enzymes.

Enrichment of health-promoting lutein and zeaxanthin in tomato fruit through metabolic engineering

Carotenoids constitute a large group of natural pigments widely distributed in nature.These compounds not only provide fruits and flowers with distinctive colors,but also have significant health benefits for humans.Lutein and zeaxanthin,both oxygen-containing carotenoids,are considered to play vital roles in promoting ocular development and maintaining eye health.However,humans and mammals cannot synthesize these carotenoid derivatives,which can only be taken from certain fruits or vegetables.Here,by introducing four endogenous synthetic genes,SlLCYE,SlLCYB,SlHYDB,and SlHYDE under fruit-specific promoters,we report the metabolic engineering of lutein/zeaxanthin biosynthesis in tomato fruit.Transgenic lines overexpression of one(SlLCYE),two(SlLCYE and SlLCYB;SlLCYB and SlHYDB),and all these four synthetic genes re-established the lutein/zeaxanthin biosynthetic pathways in the ripe tomato fruit and thus resulted in various types of carotenoid riched lines.Metabolic analyses of these engineered tomato fruits showed the strategy involved expression of SlLCYE tends to produceα-carotene and lutein,as well as a higher content of β-carotene and zeaxanthin was detected in lines overexpressing SlLCYB.In addition,the different combinations of engineered tomatoes with riched carotenoids showed higher antioxidant capacity and were associated with a significantly extended shelf life during postharvest storage.This work provides a successful example of accurate metabolic engineering in tomato fruit,suggesting the potential utility for synthetic biology to improve agronomic traits in crops.These biofortified tomato fruits could be also exploited as new research subjects for studying the health benefits of carotenoid derivatives.

Maturity assessment of tomato fruit based on electrical impedance spectroscopy

Ripening is important to tomato quality,taste and nutrition.In this study,the maturity of plant-fruit was on-line investigated based on electrical impedance spectroscopy(EIS).The electrodes with sensing unit for contact force between samples and electrodes were designed.After fruits turn into green-white,impedance measurements were conducted on the fruit samples at various ripening stages in the range of 1 Hz to 1 MHz.The optimal frequencies(100 Hz,1 kHz and 1 MHz)for maturity assessment were selected and five electrical impedance parameters at three sensitive frequencies were determined.The equivalent circuit model with CPE was developed and the model performance was evaluated.The soluble solid content and pH of fruit were determined and analyzed to explain the variations in EIS parameters sufficiently.Results showed that the impedance,phase angle,resistance,reactance and capacitance increased with the progression of maturity.The selected impedance parameters could be used to classify tomato samples into immature class or mature class with the accuracy of 88.3%.Impedance analysis for different samples from the same branch demonstrated that the ripening stage of all other samples could be predicted and assessed by the impedance spectroscopy from one sample.

Biological and molecular characterization of tomato brown rugose fruit virus and development of quadruplex RT-PCR detection

Tomato brown rugose fruit virus(ToBRFV) is a novel tobamovirus firstly reported in 2015 and poses a severe threat to the tomato industry. So far, it has spread to 10 countries in America, Asia, and Europe. In 2019, ToBRFV was identified in Shandong Province(ToBRFV-SD), China. In this study, it was shown that ToBRFV-SD induced mild to severe mosaic and blistering on leaves, necrosis on sepals and pedicles, and deformation, yellow spots, and brown rugose necrotic lesions on fruits. ToBRFV-SD induced distinct symptoms on plants of tomato, Capsicum annumm, and Nicotiana benthamiana, and caused latent infection on plants of Solanum tuberosum, Solanum melongena, and N. tabacum cv. Zhongyan 102. All the 50 tomato cultivars tested were highly sensitive to ToBRFV-SD. The complete genomic sequence of ToBRFV-SD shared the highest nucleotide and amino acid identities with isolate IL from Israel. In the phylogenetic tree constructed with the complete genomic sequence, all the ToBRFV isolates were clustered together and formed a sister branch with tobacco mosaic virus(TMV). Furthermore, a quadruplex RT-PCR system was developed that could differentiate ToBRFV from other economically important viruses affecting tomatoes, such as TMV, tomato mosaic virus, and tomato spotted wilt virus. The findings of this study enhance our understanding of the biological and molecular characteristics of ToBRFV and provide an efficient and effective detection method for multiple infections, which is helpful in the management of ToBRFV.

Expression of ipt gene driven by tomato fruit specific promoter and its effects on fruit development of tomato

Fruit specific promoter (2A12) from Lycopersi-com esculentum and cDNA of isopentenyl-transferase (ipt) from Ti plasmid of Agrobacterium tumerfaciens C58 were cloned by PCR procedure respectively. Two plant expression vectors with 2A12/gus or 2A12/ipt were respectively constructed. These two chimeric genes were transferred into tomato by Agrobacterium mediated procedure. The results of Southern hybridization showed that the fusion genes had been integrated into tomatoes. The result of gus histochemi-cal staining showed that 2A12 had high fruit specific expressive capability in transgenic tomato. The ipt expression resulted in accumulation of high level of cytokinins (CTKs) in fruit lead to developmental changes in fruits and seeds. The fruit of ipt transformed tomato had the hyperplastic placenta with very few seeds or even seedless. The shelf life of transgenic fruits elongated for 1-2 weeks. The ratio of fruit set, the dry weight of fruit and the crude protein content in fruit were increased, while

Changes of Activities in NAD Kinase and NADP PhosphataseDuring Ripening and Senescence of Tomatoand Strawberry Fruits

Activities of NAD kinase(NADK)and NADP phosphatase and relationship between the two enzymes and temperature, respiration, ethylene production and trifluoperazine(TFP) were studied during ripening and senescence of strawberry and tomato fruits after harvest at 4℃ and 20℃. The activity of NAD kinase in strawberry decreased slowly during first four days, then increased gradually. The NADP phosphatase activity increased at the second day, decreased the next day,then increased again. In tomato fruit, the activities of NAD kinase and NADP phosphatase increased at the second day, decreased with the ripening and senescence of the fruit. The change trend of NAD kinase and respiration in the two fruits were similar, the same were NADP phosphatase and ethylene production. TFP enhanced the activity of NAD kinase and had little effect on NADP phosphatase. Low temperature(4℃) activated the NAD kinase and reduced the activity of NADP phosphatase. These results indicated that the NAD kinase and NADP phosphatase were related to the ripening and senescence of strawberry and tomato fruits. The activation of NAD kinase probably postponed the ripening and senescence of the fruits.

Functional Characterization and RNAi-Mediated Suppression Reveals Roles for Hexose Transporters in Sugar Accumulation by Tomato Fruit

Hexoses accumulate to high concentrations （-200 mM） in storage parenchyma cells of tomato fruit. Hexoses are sourced from the fruit apoplasm as hydrolysis products of phloem-imported sucrose. Three hexose transporters （LeHT1, LeHT2, LeHT3）, expressed in fruit storage parenchyma ceils, may contribute to hexose uptake by these cells. An analysis of their full-length sequences demonstrated that all three transporters belong to the STP subfamily of monosaccharide transporters that localize to plasma membranes. Heterologous expression of LeHT1 （and previously LeHT2, Gear et al., 2000）, but not LeHT3, rescued a hexose transportimpaired yeast mutant when raised on glucose or fructose as the sole carbon source. Biochemically, LeHT1, similarly to LeHT2, exhibited transport properties consistent with a high- affinity glucose/H^＋ symporter. Significantly, LeHT1 and LeHT2 also functioned as low-affinity fructose/H^＋ symporters with apparent Km values commensurate with those of fruit tissues. A substantial reduction （80-90%） in fruit expression levels of all LeHT genes by RNAi-mediated knockdown caused a 55% decrease in fruit hexose accumulation. In contrast, photoassimilate production by source leaves and phloem transport capacity to fruit were unaffected by transporter knockdown. Collectively, these findings demonstrate that LeHTs play key roles in driving accumulation of hexoses into storage parenchyma cells during tomato fruit development.

Cell Wall Microstructure Analysis Implicates Hemicellulose Polysaccharides in Cell Adhesion in Tomato Fruit Pericarp Parenchyma

Methods developed to isolate intact cells from both unripe and ripe tomato fruit pericarp parenchyma have allowed the cell biological analysis of polysaccharide epitopes at the surface of separated cells. The LM7 pectic homogalacturonan epitope is a marker of the junctions of adhesion planes and intercellular spaces in parenchyma systems. The LM7 epitope persistently marked the former edge of adhesion planes at the surface of cells separated from unripe and ripened tomato fruit and also from fruits with the Cnr mutation. The LM 11 xylan epitope was associated, in sections, with cell walls lining intercellular space but the epitope was not detected at the surface of isolated cells, being lost during cell isolation. The LM15 xyloglucan epitope was present at the surface of cells isolated from unripe fruit in a pattern reflecting the former edge of cell adhesion planes/intercellular space but with gaps and apparent breaks. An equivalent pattern of LM15 epitope occurrence was revealed at the surface of cells isolated by pectate lyase action but was not present in cells isolated from ripe fruit or from Cnr fruit. In contrast to wild-type cells, the LM5 galactan and LM21 mannan epitopes occurred predominantly in positions reflecting intercellular space in Cnr, suggesting a concerted alteration in cell wall microstructure in response to this mutation. Galactanase and mannanase, along with pectic homogalacturonan-degrading enzymes, were capable of releasing cells from unripe fruit parenchyma. These observations indicate that hemicellulose polymers are present in architectural contexts reflecting cell adhesion and that several cell wall polysaccharide classes are likely to contribute to cell adhesion/cell separation in tomato fruit pericarp parenchyma.

Identification of Regulatory DNA Elements Using Genome-wide Mapping of DNase I Hypersensitive Sites during Tomato Fruit Development

Development and ripening of tomato fruit are precisely controlled by transcriptional regulation, which de- pends on the orchestrated accessibility of regulatory proteins to promoters and other c/s-regulatory DNA elements. This accessibility and its effect on gene expression play a major role in defining the develop- mental process. To understand the regulatory mechanism and functional elements modulating morpholog- ical and anatomical changes during fruit development, we generated genome-wide high-resolution maps of DNase I hypersensitive sites （DHSs） from the fruit tissues of the tomato cultivar ＂Moneymaker＂ at 20 days post anthesis as well as break stage. By exploring variation of DHSs across fruit development stages, we pinpointed the most likely hypersensitive sites related to development-specific genes. By detecting binding motifs on DHSs of these development-specific genes or genes in the ascorbic acid biosynthetic pathway, we revealed the common regulatory elements contributing to coordinating gene transcription of plant ripening and specialized metabolic pathways. Our results contribute to a better understanding of the regulatory dynamics of genes involved in tomato fruit development and ripening.

Tomato Fruit Development and Ripening Are Altered by the Silencing of LeEIN2 Gene

Loss-of-function ethylene insensitive 2 （EIN2） mutations showed ethylene insensitivity in Arabidopsis, which indicated an essential role of EIN2 in ethylene signaling. However, the function of EIN2 in fruit ripening has not been investigated. To gain a better understanding of EIN2, the temporal regulation of LeEIN2 expres- sion during tomato fruit development was analyzed. The expression of LeEIN2 was constant at different stages of fruit development, and was not regulated by ethylene. Moreover, LeEIN2-silenced tomato fruits were developed using a virus-induced gene silencing fruit system to study the role of LeEIN2 in tomato fruit ripening. Silenced fruits had a delay in fruit development and ripening, related to greatly descended expression of ethylene-related and ripening-related genes in comparison with those of control fruits. These results suggested LeEIN2 positively mediated ethylene signals during tomato development. In addition, there were fewer seeds and Iocules in the silenced fruit than those in the control fruit, like the phenotype of parthenocarpic tomato fruit. The content of auxin and the expression of auxin-regulated gene were declined in silenced fruit, which indicated that EIN2 might be important for crosstalk between ethylene and auxin hormones.

Proteomics study of the effects of high pigment-1 on plastid differentiation during the ripening of tomato fruits

The chloroplast-to-chromoplast difference is a highly regulated process.Tomato(Solanum lycopersicum)high-pigment mutant hp-1 shows an enhanced accumulation of carotenoids coupled with an increase in the volume and number of plastids.However,how chromoplasts of hp-1 acquire their specific metabolic characteristics is still unclear.A comparison of proteome profiles from plastids at the mature green,breaker,and red stages of tomato fruits showed 45 differentially expressed proteins.These identified proteins fell into six different functional categories.Our results showed that most of the proteins related to the Calvin cycle increased transitorily only at the early breaker stage,and remained unchanged at the early red stage.We found 18 proteins that were differentially expressed between the wild type and hp-1.The abundance of GCPE in chromoplasts of hp-1 was higher than that in the wild type.Meanwhile,we found that heat shock proteins were only present specifically in the mature green stage chromoplasts of hp-1 but not in the wild type.This suggested that GCPE and heat shock proteins might play important roles in the accumulation of high carotenoids in hp-1.Overall,our results could be helpful for understandingchloroplast-to-chromoplast differentiation and the function of hp-1.

Effects on Sucrose Metabolism,Dry Matter Distribution and Fruit Quality of Tomato Under Water Deficit

Four irrigation treatments were designed with 2,4,6 and 8 d intervals to irrigate, respectively. Watering was stopped when the reading of the moisture tension sensor reached zero. The results indicated that glucose and fructose content of tomato's fruit were increased but sucrose content was decreased with fruit growth and development. In different stages, carbohydrate content of tomato fruit in the treatment 3 was the highest, in the treatment 2 was higher, and in the other treatments was the lowest. SS(sucrose synthase)activity was decreased but SPS(sucrose phosphate synthase)activity was increased with development of tomato. SS and SPS activity were increased but acid invertase and neutral invertase activity of ripe stage were decreased under deficit irrigation. Glucose and fructose content were increased in leaves of tomato under water deficit. Soluble sugars, organic acid and the ratio of sugar/acid in tomato fruits were increased and dry matter accumulation of plant was enhanced under water deficit. But the growth of fruits upside the plant and its dry matter accumulation were badly affected under water stress.