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.

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.

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.

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.

Two Lycopene β-Cyclases Genes from Sweet Orange (Citrus sinensis L. Osbeck) Encode Enzymes With Different Functional Efficiency During the Conversion of Lycopene-to-Provitamin A

Citrus fruits are rich in carotenoids.In the carotenoid biosynthetic pathway,lycopene β-cyclase（LCYb,EC：1.14.-.-） is a key regulatory enzyme in the catalysis of lycopene to β-carotene,an important dietary precursor of vitamin A for human nutrition.Two closely related lycopene β-cyclase cDNAs,designated CsLCYb1 and CsLCYb2,were isolated from the pulp of orange fruits（Citrus sinensis）.The expression level of CsLCYb genes is lower in the flavedo and juice sacs of a lycopeneaccumulating genotype Cara Cara than that in common genotype Washington,and this might be correlated with lycopene accumulation in Cara Cara fruit.The CsLCYb1 efficiently converted lycopene into the bicyclic β-carotene in an Escherichia coli expression system,but the CsLCYb2 exhibited a lower enzyme activity and converted lycopene into the β-carotene and the monocyclic γ-carotene.In tomato transformation studies,expression of CsLCYb1 under the control of the cauliflower mosaic virus（CaMV） 35S constitutive promoter resulted in a virtually complete conversion of lycopene into β-carotene,and the ripe fruits displayed a bright orange colour.However,the CsLCYb2 transgenic tomato plants did not show an altered fruit colour during development and maturation.In fruits of the CsLCYb1 transgenic plants,most of the lycopene was converted into β-carotene with provitamin A levels reaching about 700 μg g-1DW.Unexpectedly,most transgenic tomatoes showed a reduction in total carotenoid accumulation,and this is consistent with the decrease in expression of endogenous carotenogenic genes in transgenic fruits.Collectively,these results suggested that the cloned CsLCYb1 and CsLCYb2 genes encoded two functional lycopene β-cyclases with different catalytic efficiency,and they may have potential for metabolite engineering toward altering pigmentation and enhancing nutritional value of food crops.

Effects of Ca^(2+)/CaM Messenger System Inhibitors on Ethylene-Induced Increase in Lycopene Content

The changes of lycopene content during ripening and senescence of tomato fruit and the relationship between ethylene glycol-bis (EGTA, Ca 2+ chelator), verapamil (Vp, Ca 2+ channel blockers), trifluoperazine (TFP), chloropromaize (CPZ) (CaM antagonism) and ethylene-induced increase in lycopene content in tomato fruit were investigated. Lycopene content accumulated obviously during ripening and senescence of tomato fruit after harvest at pink stage. Low temperature inhibited but ethylene enhanced the lycopene content. Meanwhile, ethylene also promoted calmodulin (CaM) content in tomato fruit, which was related to the concentration of ethylene. When EGTA, Vp, TFP and CPZ with ethylene were used to treat tomato fruit, ethylene-induced increase in lycopene content could be reversed, indicating that blocking Ca 2+ channel in plasma membrane or chelating extracellular Ca 2+ or inhibiting the activity of CaM could decrease the action of ethylene, and suggesting that Ca 2+-CaM messenger system may be involved in lycopene increase induced by ethylene.

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.