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Summary: Tomato (Solanum lycopersicum), which is used for both processing and fresh markets, is a major crop species that is the top ranked vegetable produced over the world. Tomato is also a model species for research in genetics, fruit development and disease resistance. Genetic resources available in public repositories comprise the 12 wild related species and thousands of landraces, modern cultivars and mutants. In addition, high quality genome sequences are available for cultivated tomato and for several wild relatives, hundreds of accessions have been sequenced, and databases gathering sequence data together with genetic and phenotypic data are accessible to the tomato community. Major breeding goals are productivity, resistance to biotic and abiotic stresses, and fruit sensorial and nutritional quality. New traits, including resistance to various biotic and abiotic stresses and root architecture, are increasingly being studied. Several major mutations and quantitative trait loci (QTLs) underlying traits of interest in tomato have been uncovered to date and, thanks to new populations and advances in sequencing technologies, the pace of trait discovery has considerably accelerated. In recent years, clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing (GE) already proved its remarkable efficiency in tomato for engineering favorable alleles and for creating new genetic diversity by gene disruption, gene replacement, and precise base editing. Here, we provide insight into the major tomato traits and underlying causal genetic variations discovered so far and review the existing genetic resources and most recent strategies for trait discovery in tomato. Furthermore, we explore the opportunities offered by CRISPR/Cas9 and their exploitation for trait editing in tomato. Significance Statement: The pace of trait discovery in tomato has considerably accelerated in recent years thanks to advances in deep sequencing and other 'omics technologies. Here we review the genetic resources and current powerful forward genetic strategies, allowing discovery of QTLs, genes and mutations underlying remarkable traits in tomato. We also show how CRISPR/Cas9 GE now provides unprecedented opportunities for candidate gene validation, creation of new genetic diversity and breeding of improved tomato varieties. [ABSTRACT FROM AUTHOR]

Summary: RNA sequencing (RNAseq) reads from cape gooseberry plants (Physalis peruviana) infected with Fusarium oxysporumf. sp. physali (Foph) were mapped against the lineage‐specific transcriptome of Fusarium oxysporumf. sp. lycopersici (Fol) to look for putative effector genes. Homologues of Fol SIX1(designated SIX1a and SIX1b), SIX7, SIX10, SIX12, SIX15 and Ave1were identified. The near identity of the Foph and Fol SIX7, SIX10 and SIX12genes and their intergenic regions suggest that this gene cluster may have undergone recent lateral transfer. Foph SIX1a and SIX1bwere tested for their ability to complement a SIX1 knockout mutant of Fol. This mutant shows reduced pathogenicity on susceptible tomato plants, but is able to infect otherwise resistant tomato plants carrying the I‐3 gene for Fusarium wilt resistance (SIX1 corresponds to Avr3). Neither SIX1a nor SIX1b could restore full pathogenicity on susceptible tomato plants, suggesting that any role they may play in pathogenicity is likely to be specific to cape gooseberry. SIX1b, but not SIX1a, was able to restore avirulence on tomato plants carrying I‐3.These findings separate the recognition of SIX1 from its role as an effector and suggest direct recognition by I‐3. A hypervariable region of SIX1undergoing diversifying selection within the F. oxysporum species complex is likely to play an important role in SIX1 recognition. These findings also indicate that I‐3could potentially be deployed as a transgene in cape gooseberry to protect this emerging crop from Foph.Alternatively, cape gooseberry germplasm could be explored for I‐3homologues capable of providing resistance to Foph. [ABSTRACT FROM AUTHOR]

Abstract: An understanding of biocontrol activities is important when developing microorganism‐based alternatives to conventional fungicides. From our bacterial collection, we selected two strains (BBC023 and BBC047) for their outstanding antagonistic capacity against fungal phytopathogens and growth‐promoting abilities towards Arabidopsis thaliana. According to physiological and molecular characterizations, both strains were classified as Bacillus amyloliquefaciens and were tested against Botrytis cinerea in vitro and in a tomato. Both strains secrete lipopeptide‐like compounds that contribute to their in vitro antagonism. SEM‐images showed altered B. cinerea mycelial structures that were consistent with previous reports of the direct action of lipopeptides against fungal hyphae. The strains were applied to the roots (R), leaves (foliar ‐ F) or root/leaves (R/F) on tomato plants. All treatments significantly reduced the severity of B. cinerea infection (measured as a control index). However, only root applications (R and R/F) led to growth promotion in the tomato plants. We detected the production of indole acetic acid (IAA) and 2,3‐butanediol as growth promotion traits in the two strains. For both strains, the R/F treatment showed the highest control index, suggesting a synergic effect of direct antagonism against B. cinerea and resistance induction in the plant. In addition, in vitro antagonism of BBC023 and BBC047 against B. cinerea was similar; whereas in the F application, strain BBC047 significantly improved plant resistance and maintained a higher population density over time on tomato leaves, compared to BBC023. BBC047 was also able to produce a complex and robust biofilm in Msgg medium compared with that of BBC023. We linked the reduced biocontrol of BBC023 on leaves with its limited ability to generate robust biofilms and colonize the phylloplane. At last, we highlight the potential of the native Bacillus strains as promising alternatives for the development of bioproducts for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Summary: In the present study, we investigated the role of Trichoderma virens (TriV_JSB100) spores or cell‐free culture filtrate in the regulation of growth and activation of the defence responses of tomato (Solanum lycopersicum) plants against Fusarium oxysporum f. sp. lycopersici by the development of a biocontrol–plant–pathogen interaction system. Two‐week‐old tomato seedlings primed with TriV_JSB100 spores cultured on barley grains (BGS) or with cell‐free culture filtrate (CF) were inoculated with Fusarium pathogen under glasshouse conditions; this resulted in significantly lower disease incidence in tomato Oogata‐Fukuju plants treated with BGS than in those treated with CF. To dissect the pathways associated with this response, jasmonic acid (JA) and salicylic acid (SA) signalling in BGS‐ and CF‐induced resistance was evaluated using JA‐ and SA‐impaired tomato lines. We observed that JA‐deficient mutant def1 plants were susceptible to Fusarium pathogen when they were treated with BGS. However, wild‐type (WT) BGS‐treated tomato plants showed a higher JA level and significantly lower disease incidence. SA‐deficient mutant NahG plants treated with CF were also found to be susceptible to Fusarium pathogen and displayed low SA levels, whereas WT CF‐treated tomato plants exhibited moderately lower disease levels and substantially higher SA levels. Expression of the JA‐responsive defensin gene PDF1 was induced in WT tomato plants treated with BGS, whereas the SA‐inducible pathogenesis‐related protein 1 acidic (PR1a) gene was up‐regulated in WT tomato plants treated with CF. These results suggest that TriV_JSB100 BGS and CF differentially induce JA and SA signalling cascades for the elicitation of Fusarium oxysporum resistance in tomato. [ABSTRACT FROM AUTHOR]

Summary: Verticillium wilts caused by soilborne fungal species of the Verticillium genus are economically important plant diseases that affect a wide range of host plants and are notoriously difficult to combat. Perception of pathogen(‐induced) ligands by plant immune receptors is a key component of plant innate immunity. In tomato, race‐specific resistance to Verticillium wilt is governed by the cell surface‐localized immune receptor Ve1 through recognition of the effector protein Ave1 that is secreted by race 1 strains of Verticillium spp. It was previously demonstrated that transgenic expression of tomato Ve1 in the model plant Arabidopsis thaliana leads to Verticillium wilt resistance. Here, we investigated whether tomato Ve1 can confer Verticillium resistance when expressed in the crop species tobacco (Nicotiana tabcum) and cotton (Gossypium hirsutum). We show that transgenic tobacco and cotton plants constitutively expressing tomato Ve1 exhibit enhanced resistance against Verticillium wilt in an Ave1‐dependent manner. Thus, we demonstrate that the functionality of tomato Ve1 in Verticillium wilt resistance through recognition of the Verticillium effector Ave1 is retained after transfer to tobacco and cotton, implying that the Ve1‐mediated immune signalling pathway is evolutionary conserved across these plant species. Moreover, our results suggest that transfer of tomato Ve1 across sexually incompatible plant species can be exploited in breeding programmes to engineer Verticillium wilt resistance. [ABSTRACT FROM AUTHOR]

The tomato leaf miner ( Tuta absoluta) is a serious pest of tomato ( Solanum lycopersicum) in the tropics and subtropics. Previous World Vegetable Center studies identified selected accessions of S. galapagense, S. cheesmaniae and S. pimpinellifolium that were resistant to whitefly ( Bemisia tabaci Genn.) and spider mite ( Tetranychus urticae Koch). Here, we evaluated these accessions for resistance to T. absoluta based on the number of eggs from choice bioassays, and larval mortality and adults emerged percentages in no-choice feeding bioassays at WorldVeg Eastern and Southern Africa (WorldVeg) and the International Centre for Insect Physiology and Ecology ( icipe). At WorldVeg, S. galapagense exhibited high resistance in both choice and no-choice bioassays. There was strong negative correlation between larval mortality and adults emerged percentages in the no-choice feeding bioassays. Results from the icipe experiments were consistent with those of the WorldVeg screening, except for S. pimpinellifolium accession , which was susceptible at icipe. Tuta absoluta is rapidly spreading and the resistance sources reported here will be valuable in breeding tomato varieties resistant to this insect and others. [ABSTRACT FROM AUTHOR]

Insect-plant interactions involving species of the genus Solanum have been intensively studied, resulting in several articles on insect-plant interactions. However, the interactions between herbivores and the fruits of Solanum lycopersicum (tomato) are not well known. Neoleucinodes elegantalis is a borer that causes great yield losses in S. lycopersicum crops because of the direct damage that it causes to the fruits and the difficulty of controlling it. In the field, the outside of a tomato fruit infested with the larvae of N. elegantalis is visually similar to uninfested fruits. Even a minor injury by herbivores can elicit a defensive response. Due to the lack of studies on interactions between fruit borers and S. lycopersicum, our aim in this study was to determine the locations of S. lycopersicum fruit in which the N. elegantalis larvae prefer to feed. An evaluation of nutritional sources was done through histochemical and biochemical tests and the defensive response of the S. lycopersicum fruit to attack by N. elegantalis larvae was evaluated through the detection of protease inhibitors ( PIs) and lipoxygenase ( LOX) activity. Our results show that the columella region is preferred by the N. elegantalis larvae and that this region has a nutritional source. Furthermore, attack by N. elegantalis larvae in the columella does not induce a significant increase in lipoxygenase activity and PIs. Thus, our results provide a better understanding of the interaction between the larvae of N. elegantalis and S. lycopersicum fruits and a better understanding of the evolution of plant-herbivore interactions, with an emphasis on the choice of feeding location as a strategy to avoid plant defences. [ABSTRACT FROM AUTHOR]

Over the last two decades, begomovirus diseases have increased in importance in Brazilian tomato crops. The major management strategy in Brazil is the application of insecticides to control the whitefly vector, but this is often unsuccessful. The objective of this work was to study the spatial and temporal progression of the disease in two processing tomato production areas in Central Brazil. A total of 24 plots (225 plants each) in six fields were evaluated weekly by visual inspection for plants with begomovirus symptoms. The predominant begomovirus in tomato plants with symptoms was Tomato severe rugose virus, and it was also detected in weeds and other crop plants. No correlation between incidence of begomovirus disease and whitefly population was found. The disease progression was rapid, with a slightly aggregated distribution of plants with symptoms. No relevant differences were observed in the temporal and spatial analyses, although an important difference was detected between plots located at the centre (PC) and the edge (PE) of the fields. In the temporal analysis, the begomovirus incidence and area under disease progress curve values were lower in PC than in PE. In the spatial analysis, plants with begomovirus symptoms were more aggregated in PC than in PE. These results suggest that the distribution of plants with symptoms in PC and PE could be a result of three dissemination mechanisms: one random (primary) and two aggregated, a real secondary spread, and a false secondary spread. The implications of these differences on disease management are discussed. [ABSTRACT FROM AUTHOR]

Kidney bean ( Phaseolus vulgaris) plants exhibiting foliar yellow mosaic symptoms and some leaf crumpling were identified in the Al Batinah region of Oman. Rolling circle amplification and polymerase chain reaction identified a bipartite begomovirus (family Geminiviridae) and a betasatellite in association with the symptomatic plants. Analysis of full-length sequences showed the virus to be Mungbean yellow mosaic Indian virus ( MYMIV) and the betasatellite Tomato leaf curl betasatellite (To LCB). This is the first identification of a legume-adapted begomovirus in Oman and the first identification of MYMIV in association with the betasatellite To LCB. The isolate of MYMIV from Oman shows the greatest levels of sequence identity to isolates occurring in South Asia and South-East Asia, suggesting that the virus has only recently been introduced. The significance of these findings is discussed. [ABSTRACT FROM AUTHOR]

The tomato leaf miner Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a devastating pest of tomato plants originating from South America. In this study, the effect of three tomato cultivars on the life table parameters of T. absoluta was investigated. Data were analysed based on age-stage, two-sex life table theory. The net reproduction rate ( R0) of T. absoluta on Falkato, Isabella and Grandella cultivars was determined as 15.73 ± 3.35, 17.66 ± 3.33 and 10.03 ± 4.10 eggs, respectively. The intrinsic rate of increase ( r) value on those cultivars was 0.09 ± 0.007, 0.095 ± 0.006 and 0.074 ± 0.017 day−1, respectively. Finite population rates of increase ( λ) were 1.095 ± 0.008, 1.099 ± 0.007 and 1.076 ± 0.018 day−1, and mean generation times ( T) on the three cultivars were 30.09 ± 0.29, 30.22 ± 0.27 and 31.12 ± 0.65 days, respectively. The egg incubation period, pre-adult duration and fecundity on these tomato cultivars was also calculated. The results showed no significant differences between r, R0, and T on the three tested tomato cultivars. These findings can be useful for developing an integrated pest management strategy against this noxious pest. [ABSTRACT FROM AUTHOR]

Ralstonia solanacearum causes bacterial wilt disease in Solanaceae spp. Expression of the Phytophthora inhibitor protease 1 ( PIP1) gene, which encodes a papain-like extracellular cysteine protease, is induced in R. solanacearum-inoculated stem tissues of quantitatively resistant tomato cultivar LS-89, but not in susceptible cultivar Ponderosa. Phytophthora inhibitor protease 1 is closely related to Rcr3, which is required for the Cf-2-mediated hypersensitive response ( HR) to the leaf mould fungus Cladosporium fulvum and manifestation of HR cell death. However, up-regulation of PIP1 in R. solanacearum-inoculated LS-89 stems was not accompanied by visible HR cell death. Nevertheless, upon electron microscopic examination of inoculated stem tissues of resistant cultivar LS-89, several aggregated materials associated with HR cell death were observed in xylem parenchyma and pith cells surrounding xylem vessels. In addition, the accumulation of electron-dense substances was observed within the xylem vessel lumen of inoculated stems. Moreover, when the leaves of LS-89 or Ponderosa were infiltrated with 106 cells mL−1 R. solanacearum, cell death appeared in LS-89 at 18 and 24 h after infiltration. The proliferation of bacteria in the infiltrated leaf tissues of LS-89 was suppressed to approximately 10-30% of that in Ponderosa, and expression of the defence-related gene PR-2 and HR marker gene hsr203J was induced in the infiltrated tissues. These results indicated that the response of LS-89 is a true HR, and induction of vascular HR in xylem parenchyma and pith cells surrounding xylem vessels seems to be associated with quantitative resistance of LS-89 to R. solanacearum. [ABSTRACT FROM AUTHOR]

Begomoviruses are one of the major pathogens in tomato crops worldwide. In Venezuela, six begomovirus species have been described infecting tomato: Potato yellow mosaic virus ( PYMV), Euphorbia mosaic Venezuela virus (Eu MVV), Merremia mosaic virus (Me MV), Tomato chlorotic leaf distortion virus (To CLDV), Tomato yellow margin leaf curl virus ( TYMLCV) and Tomato yellow leaf curl virus ( TYLCV). In this study, the occurrence of these viruses was analysed by PCR in 338 tomato plants exhibiting virus-like symptoms. Sixty-three per cent of the plants were positive at least to one of the begomoviruses tested. PYMV and TYLCV were the most frequent viruses showing 39.6 and 23.7% occurrence, respectively. Phylogenetic analyses revealed two groups of PYMV isolates from several Caribbean Basin countries. The first group clustered isolates from several countries, including Venezuela, and the second group clustered only Colombian isolates. Due to the high prevalence of PYMV and TYLCV in Venezuela, it is suggested that the surveillance and control strategies currently applied in the country should be focused on these two begomoviruses. [ABSTRACT FROM AUTHOR]

Tomato yellow leaf curl virus ( TYLCV) is one of the most widespread begomoviruses transmitted by the whitefly Bemisia tabaci that cause tomato yellow leaf curl virus diseases ( TYLCDs). TYLCD losses can be especially severe in open-field tomato ( Solanum lycopersicum L.) crops. TYLCV is particularly well known and widespread in the Mediterranean (Med) countries where TYLCD control is mostly based on insecticidal control of B. tabaci populations. Unfortunately, Tunisian B. tabaci populations include Middle East-Asia Minor I and the Med species that have developed resistance to many classes of insecticides. Therefore, TYLCD-resistant cultivars are essential for sustainable disease management. Six TYLCD resistance genes ( Ty) have been introgressed from wild species into cultivated tomato and are available for breeding. Information on the Ty genes or gene combinations is useful for breeding resistant cultivars. To this end, 14 tomato lines carrying different Ty gene combinations and two susceptible tomato entries were evaluated for TYLCD incidence and severity in two field trials during late season in Tunisia. Entries with Ty-1/ Ty-3 + Ty-2 offered the highest levels of resistance in Tunisia. [ABSTRACT FROM AUTHOR]

We recently identified a defense-related tomato ( Solanum lycopersicum) NAC ( NAM, ATAF1,2, CUC2) transcription factor, NAC1, that is subjected to ubiquitin-proteasome system-dependent degradation in plant cells. In this study, we identified a tomato ubiquitin ligase (termed SEVEN IN ABSENTIA3; SINA3) that ubiquitinates NAC1, promoting its degradation., We conducted coimmunoprecipitation and bimolecular fluorescence complementation to determine that SINA3 specifically interacts with the NAC1 transcription factor in the nucleus. Moreover, we found that SINA3 ubiquitinates NAC1 in vitro and promotes NAC1 degradation via polyubiquitination in vivo, indicating that SINA3 is a ubiquitin ligase that ubiquitinates NAC1, promoting its degradation. Our real-time PCR analysis indicated that, in contrast to our previous finding that NAC1 mRNA abundance increases upon Pseudomonas infection, the SINA3 mRNA abundance decreases in response to Pseudomonas infection., Moreover, using Agrobacterium-mediated transient expression, we found that overexpression of SINA3 interferes with the hypersensitive response cell death triggered by multiple plant resistance proteins., These results suggest that SINA3 ubiquitinates a defense-related NAC transcription factor for degradation and plays a negative role in defense signaling. [ABSTRACT FROM AUTHOR]

Late blight (LB), caused by Phytophthora infestans, is one of the most devastating diseases of tomato ( Solanum lycopersicum) worldwide. Due to the emergence of new and aggressive P. infestans isolates, identifying new genetic resistance to LB is a priority in tomato breeding. Recently, we reported the identification of several Solanum pimpinellifolium accessions with strong LB resistance. In this study, we investigated the utility of resistant accession PI 163245 for tomato breeding by examining heritability ( h2) of resistance and the response to selection for resistance. Estimates of h2 based on F2 : F3 and F3 : F4 parent : offspring correlation analyses averaged 0.79 and 0.94, respectively, suggesting the heritable nature of LB resistance in PI 163245. Analysis of response to selection for resistance from F2 to F4 generations indicated a realized h2 of 0.63, confirming the utility of this resistance in tomato breeding. Two methods of estimating the minimum number of loci involved indicated the presence of one major resistance locus. Currently, genetic mapping and breeding efforts are underway to further confirm the viability of this accession for improving tomato LB resistance. [ABSTRACT FROM AUTHOR]

Bacterial wilt is a serious problem affecting many important food crops. Recent studies have indicated that treatment with biotic or abiotic stress factors may increase the resistance of plants to bacterial infection. This study investigated the effects of magnesium oxide nanoparticles (MgO NP) on disease resistance in tomato plants against Ralstonia solanacearum, as well as its antibacterial activity. The roots of tomato seedlings were inoculated with R. solanacearum and then immediately treated with MgO NP; the treated plants showed very little inhibition of bacterial wilt. In contrast, when roots were drenched with a MgO NP suspension prior to inoculation with the pathogen, the incidence of disease was significantly reduced. Rapid generation of reactive oxygen species such as O2−˙ radicals was observed in tomato roots treated with MgO NP. Further O2−˙ was rapidly generated when tomato plant extracts or polyphenols were added to the MgO NP suspension, suggesting that the generation of O2−˙ in tomato roots might be due to a reaction between MgO NP and polyphenols present in the roots. Salicylic acid-inducible PR1, jasmonic acid-inducible LoxA, ethylene-inducible Osm, and systemic resistance-related GluA were up-regulated in both the roots and hypocotyls of tomato plants after treatment of the plant roots with MgO NP. Histochemical analyses showed that β-1,3-glucanase and tyloses accumulated in the xylem and apoplast of pith tissues of the hypocotyls after MgO NP treatment. These results indicate that MgO NP induces systemic resistance in tomato plants against R. solanacearum. [ABSTRACT FROM AUTHOR]

Bacterial speck, caused by Pseudomonas syringae pv. tomato ( Pst), is an economically important disease of tomato, resulting in yield loss of marketable fruit. Management of bacterial speck is a challenge in commercial production fields due to the limited efficacy of current disease management strategies, as the pathogen acquires resistance to antibiotics and fixed copper bactericides and host resistance has not proven durable. Therefore, it is essential to develop alternative disease management strategies, like biological control. In this study, the efficacy of the commercially available biocontrol agent Bacillus subtilis QST 713 along with copper hydroxide was tested against Pst under greenhouse conditions. QST 713 reduced significantly disease severity and incidence compared to control and the copper hydroxide treatment; subsequently, the Pst population was lower in the QST 713-treated plants compared to control. In parallel, QST 713 and copper hydroxide increased plant height compared to control and mock plants. Furthermore, the quantitative PCR analysis of PR1a, PR1b and Pin2 expression suggests a positive role for Pin2 in the plant protective activity of QST 713, as Pin2 expression was significantly higher in the QST 713-treated plants challenged with Pst compared to the control Pst-inoculated plants. [ABSTRACT FROM AUTHOR]

Tomato chlorosis virus (To CV) is the causal agent of an emerging virus disease of tomatoes which causes significant economic losses worldwide. The rapid spread of To CV is associated with the increasing whitefly population in many countries. In this study, a highly efficient and practical one-step reverse transcription loop-mediated isothermal amplification ( RT- LAMP) was developed for the rapid detection of To CV in infected plant or whitefly. This RT- LAMP assay can detect To CV either in total RNA or crude RNA extracted from infected plants using a water bath within 1 h. The presence of To CV in RT- LAMP products could be evaluated as ladder-like bands in an agarose gel or visualized in-tube with inclusion of a SYBR Green I dye under UV or daylight. RT- LAMP was 100-1000 times more sensitive compared to conventional RT- PCR for the detection of To CV. RT- LAMP amplification was specific to To CV, and no false reactions were detected when other viruses were tested. The developed RT- LAMP assay was also able to detect To CV from purified RNA extracted from its vector whitefly. This is the first report of the application of the RT- LAMP to detect To CV. The RT- LAMP assay developed in this study provides a rapid, sensitive and practical approach to facilitate the surveillance and management of To CV. [ABSTRACT FROM AUTHOR]

The bacteriophage CMP1 endolysin gene ( lys), encoding, a peptidase that was shown to effectively reduce Clavibacter michiganensis by specifically hydrolysing its murein, was transferred into tomato plants by Agrobacterium-mediated transformation. The presence of the gene was verified by PCR and the gene product was confirmed in immunoblots and stably expressed over three generations. Transgenic tomato plants did not show disease symptoms after infection with C. michiganensis subsp. michiganensis, despite the fact that small amounts of bacteria could still be identified in xylem sap and leaf extracts, although in significantly reduced amounts. [ABSTRACT FROM AUTHOR]

BACKGROUND A binary co-occluded mixture ( HearSP1B: LB6) of Helicoverpa armigera single nucleopolyhedrovirus ( HearNPV) variants was previously found to be highly pathogenic under laboratory conditions. The insecticidal efficacy and persistence of this mixture were determined in greenhouse and field-grown tomato crops in Spain and Portugal. RESULTS Concentrations of 109-1011 occlusion bodies ( OBs) L−1 of HearSP1B: LB6 resulted in 89-100% mortality of larvae on treated tomato plants in growth chambers. In protected tomato crops, application of 1010 OBs L−1 of HearSP1B: LB6 was as effective as Bacillus thuringiensis ( Bt) and spinosad in reducing the percentage of damaged fruits, and resulted in higher larval mortality than the Bt treatment. In open-field tomato crops, virus treatments were as effective in reducing the percentage of damaged fruit as spinosad, Bt and chlorpyrifos treatments. The persistence of the insecticides on tomato plants was negatively correlated with solar radiation in both field and greenhouse settings. Residual insecticidal activity of OBs on protected tomato crops at 6 days post-application was 55 and 35% higher than that of Bt and spinosad respectively. On field-grown tomato, OB persistence was significantly lower than with spinosad or chlorpyrifos. CONCLUSION The efficacy and persistence of HearSP1B: LB6 OBs were comparable with those of commercial insecticides in both field and greenhouse tomato crops. Future studies should focus on reducing application rates to determine insecticidal efficacy at lower OB concentrations. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Knowing that actin microfilaments play a key role in the mobilization of the defence-associated cellular responses, the aim of this study was to compare changes affecting the actin cytoskeleton in tomato cells after inoculation with germinated microconidia of a biocontrol (Fo47, Fom24) or a pathogenic (Fol8) strain of Fusarium oxysporum. Actin microfilaments were observed by labelling with TRITC-phalloidin combined with fluorescence microscopy. Results showed that only tenuous changes in the actin cytoskeleton architecture occurred after inoculation with the biocontrol strains whereas the actin cytoskeleton was significantly altered after inoculation with the pathogenic one. In the two types of interaction, cell death occurs and can be considered as one key component of cell defence responses. A pharmacological approach using cytochalasins was chosen to determine whether the inhibition of actin polymerization differently affects the kinetics of tomato cell death. Data showed that cytochalasins reduced cell death induced by the biocontrol strain Fo47, and in contrast, increased cell death induced by the pathogenic strain Fol8, suggesting that the pathway leading to cell death differs in the protective and compatible interactions. [ABSTRACT FROM AUTHOR]

Controlled glasshouse experiments were conducted to investigate the temporal progress of powdery mildew and its effects on host dynamics of tomato, without and with one fungicide application. Healthy tomato transplants (5- to 6-week old) were artificially inoculated with powdery mildew, and disease progress as well as host growth were monitored in both fungicide sprayed and unsprayed treatments and compared with non-inoculated plants. Actual disease severity on a plant basis increased in unsprayed plants reaching maximum severity in the proportionate range of 0.53-0.83. One fungicide spray significantly reduced the maximum disease severity by two- to fourfolds. Despite adjustments for defoliation, declines in the proportion of disease severity between successive assessments were evident. Whereas the estimated growth rates of diseased plants were significantly lower than that of healthy plants, no significant differences were observed in the maximum leaf area formed of inoculated and non-inoculated plants. A considerable effect of the powdery mildew epidemics was manifested through hastened shrivelling and defoliation of diseased leaves within the tomato canopy. An average of 18-29% and 40-52% of leaves had abscised from the plant canopy at the last date of assessment in sprayed and non-sprayed plants, respectively. Accordingly, defoliation accounted for 14-33.3% and 58.3-63.1% losses in leaf area of sprayed and non-sprayed plants, respectively. Duration of healthy leaf area and yield of inoculated plants were also significantly reduced by powdery mildew epidemics. [ABSTRACT FROM AUTHOR]

Alleles conferring quantitative resistance to late blight disease [Phytophthora infestans (Mont.) de Bary] were introgressed into cultivated tomato [Solanum lycopersicum (L.)] from resistant wild tomato (Solanum habrochaites Knapp and Spooner). Two sets of sub-near-isogenic lines (sub-NILs) were marker-selected so that each contained resistance QTL alleles from S. habrochaites chromosome 5 or 11. We conducted a combining ability study with the sub-NILs to evaluate the potential utility of the resistance QTL alleles for breeding F1 hybrid cultivars and identify sub-NILs with the highest combining ability for late blight disease resistance. The sub-NILs were mated with inbred testers in factorial mating designs (Design II). F1 hybrid progeny from these two sets of sub-NILs, in which each hybrid was heterozygous for one or more QTL resistance alleles on chromosome 5 or 11, were evaluated for P. infestans resistance in replicated field and growth chamber experiments. Differences in combining ability were found in growth chamber but not field experiments, suggesting that sub- NILs contributed similar levels of resistance to their F1 hybrid progeny in the field, but different levels in the growth chamber. Significant QTL x environment interactions were detected across field and growth chamber experiments. We identified sub-NILs that expressed P. infestans resistance in F1 hybrid combinations, suggesting that these sub-NILs could be useful for breeding F1 hybrid varieties with enhanced resistance. The expression of quantitative resistance to P. infestans in F1 hybrids derived from each sub- NIL parent was provided by multiple QTL alleles from S. habrochaites. [ABSTRACT FROM AUTHOR]

The avirulence determinant triggering the resistance conferred by the tomato gene Sw-5 against Tomato spotted wilt virus ( TSWV) is still unresolved. Sequence comparison showed two substitutions ( C118Y and T120N) in the movement protein NSm present only in TSWV resistance-breaking ( RB) isolates. In this work, transient expression of NSm of three TSWV isolates [ RB1 ( T120N), RB2 ( C118Y) and non-resistance-breaking ( NRB)] in Nicotiana benthamiana expressing Sw-5 showed a hypersensitive response ( HR) only with NRB. Exchange of the movement protein of Alfalfa mosaic virus ( AMV) with NSm supported cell-to-cell and systemic transport of the chimeric AMV RNAs into N. tabacum with or without Sw-5, except for the constructs with NBR when Sw-5 was expressed, although RB2 showed reduced cell-to-cell transport. Mutational analysis revealed that N120 was sufficient to avoid the HR, but the substitution V130I was required for systemic transport. Finally, co-inoculation of RB and NRB AMV chimeric constructs showed different prevalence of RB or NBR depending on the presence or absence of Sw-5. These results indicate that NSm is the avirulence determinant for Sw-5 resistance, and mutations C118Y and T120N are responsible for resistance breakdown and have a fitness penalty in the context of the heterologous AMV system. [ABSTRACT FROM AUTHOR]

An in-depth understanding of plant-mediated interactions between herbivores and their natural enemies is essential in community ecology and co-evolution, and for developing sustainable pest management strategies. The influence of Myzus persicae ( Sulzer) ( Hemiptera: Aphididae)-induced tomato plant [ Solanum lycopersicum L. ( Solanaceae)] volatile compounds on the olfactory responses of Bemisia tabaci ( Gennadius) ( Hemiptera: Aleyrodidae), three predator species [ Coccinella septempunctata L., Propylea japonica ( Mulstant) (both Coleoptera: Coccinellidae), and Orius sauteri ( Poppius) ( Hemiptera: Anthocoridae)], two whitefly parasitoid species [ Encarsia formosa ( Gahan) and Encarsia sophia ( Girault & Dodd) ( Hymenoptera: Aphelinidae)], and one aphid parasitoid species [ Aphidius gifuensis Ashmead ( Hymenoptera: Aphidiidae)] were examined in two-choice tests using a four-arm olfactometer. Tomato plants were experimentally manipulated for aphid density, duration of aphid feeding, and interval between aphid removal and the behavioral test. We also compared the systemic effects of aphid feeding on the olfactory behavior of whiteflies and natural enemies according to three relative leaf positions: the aphid-infested leaf itself and two adjacent leaves (above and below). Bemisia tabaci were deterred by the odors of the leaves infested with aphids in all treatments. All six natural enemies were attracted to the leaves infested with aphids. Bemisia tabaci deterrence by volatiles was greater for leaves at the highest aphid density, and with increasing duration of exposure to aphid feeding. In contrast, the attraction to leaves was greater for the three parasitoids than for the three predators both with increasing aphid density and increasing duration of plant exposure to aphids. There was no significant influence of leaf position on preference of B. tabaci, the two species of lady beetles, and the aphid parasitoid. The two Encarsia species were attracted to the leaf above the aphid-infested leaves, indicating that systemic volatiles were released by adjacent leaves. On the other hand, O. sauteri was only attracted by the aphid-infested leaf itself. Our results showed that M. persicae-infested host plants emitted volatiles that could inhibit the colonization by B. tabaci and also attract natural enemies of both aphids and whiteflies. The results of this study may need to be considered further for optimizing pest management methods. [ABSTRACT FROM AUTHOR]

Advances in tomato breeding for pest resistance have been achieved via gene introgression from wild Solanum (section Lycopersicon) species ( Solanaceae). Ninety-nine F3 families derived from an interspecific cross using as parental lines Solanum lycopersicum L. ' LAM-148' (susceptible standard) and Solanum pimpinellifolium L. ' TO-937-15' (multiple pest resistance accession with type IV glandular trichomes and acylsugar accumulation) were evaluated for their resistance against the whitefly Bemisia tabaci ( Gennadius) ( Hemiptera: Aleyrodidae) biotype B in free-choice and no-choice tests for oviposition and adult colonization. The parental lines and eight F3 families with contrasting levels of resistance against the whitefly were selected and investigated in additional assays, which included the estimation of trichome densities and foliar acylsugar levels. The F3 families BTR-302 and BTR-331 exhibited low amounts of eggs of whitefly and transgressive segregation for type IV glandular trichome density with values greater than that of TO-937-15 plants. However, the tested families did not surpass the total foliar acylsugar content found in TO-937-15. BTR-331 exhibited low colonization in the free-choice test and it was the least preferred F3 family in the no-choice test. The higher resistance levels of BTR-331 were associated with a positive combination of higher type IV trichome density and higher acylsugar levels. Some F3 families displayed reduced fruit set due to the presence of flowers with style exertion of the antheridial-cone. Fruit weight at harvest stage of the selected families (from 4.9 to 14.5 g) was lower than that of LAM-148 (139.5 g) but higher than that of TO-937-15 plants (1.3 g). Therefore, although difficult to reach due to the simultaneous segregation of many polygenic traits, the combination of high B. tabaci resistance levels with superior horticultural traits is feasible. These results confirm TO-937-15 as a source of biotype B resistance. From the breeding standpoint, the genetic similarity between S. lycopersicum and S. pimpinellifolium would allow a more efficient resistance introgression by facilitating recombination and minimizing the potentially undesirable linkage drag associated with this trait. [ABSTRACT FROM AUTHOR]

The expression pattern of pathogenesis-related genes PR-1, PR-2 and PR-5, considered as markers for salicylic acid ( SA)-dependent systemic acquired resistance ( SAR), was examined in the roots and shoots of tomato plants pre-treated with SA and subsequently infected with root-knot nematodes ( RKNs) ( Meloidogyne incognita). PR-1 was up-regulated in both roots and shoots of SA-treated plants, whereas the expression of PR-5 was enhanced only in roots. The over-expression of PR-1 in the whole plant occurred as soon as 1 day after SA treatment. Up-regulation of the PR-1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles ( J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA-treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR-1, PR-2 and PR-5 was also examined in the roots and shoots of susceptible and Mi-1-carrying resistant tomato plants infected by RKNs. Nematode infection produced a down-regulation of PR genes in both roots and shoots of SA-treated and untreated plants, and in roots of Mi-carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR-1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR-like response to RKNs in tomato. [ABSTRACT FROM AUTHOR]

BACKGROUND Tomato yellow leaf curl virus disease ( TYLCVD) causes severe to economic losses in tomato crops in China. The control of TYLCVD is based primarily on the use of synthetic insecticide to control its vector whitefly ( Bemisia tabaci). To look for an alternative method for disease control, we investigated the effect of eugenol on controlling TYLCVD. The potential of eugenol to trigger systemic acquired resistance ( SAR) in tomato (Jiangsu 14) plants against TYLCV was also investigated. RESULTS In greenhouse experiments, eugenol significantly reduced disease severity when applied as a foliar spray, thus demonstrating a systemic effect. The disease spread rapidly in control plants and by the end of the experiment almost all control plants showed severe symptoms. Eugenol also induced H2O2 accumulation in tomato plants. Activities of peroxidase ( POD), polyphenol oxidase ( PPO) and phenylalanine ammonia lyase ( PAL) were significantly induced compared with those of control plants. As further consequences, increase of salicylic acid ( SA) levels and expression of PR-1 proteins, a molecular marker of SAR in tomato, could also be observed. CONCLUSION This is the first report of eugenol as an elicitor and its ability to suppress plant virus diseases under greenhouse conditions. It is suggested that eugenol has the potential to be an effective biocontrol agent against TYLCV in tomato plants. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Eight trials were carried out in 2011 and 2012 in Northern Italy to evaluate the efficacy of grafting, compost and biofumigation with Brassica carinata against Colletotrichum coccodes on tomato. Four trials were carried out in commercial farms, and four trials were carried out in plastic tunnels at an experimental centre. The rootstocks ' Armstrong', ' Arnold', ' Beaufort', ' Big Power', ' Brigeor', ' Emperador', ' King Kong', ' Spirit' and ' Superpro V295' were tested. Host plants included several tomato F1 hybrids: ' Amantino', ' Arawak', ' CLX 37438', ' Cauralina', ' CU 8301', ' CU 8506', ' DRK 7021', 'E 34431', 'E 50070', ' EXP', ' Gotico', ' Ingrid', ' ISI 61401', ' ISI 61402', ' Profitto', ' Punente', ' Rugantino' and ' Tomahawk'. Tomato roots from the control plots were 34 to 87% diseased in both naturally and artificially infested soil. Among the nineteen commercial tomato hybrids tested, in the presence of a very high disease pressure in a naturally infested soil, ' Rugantino' was the least affected by C. coccodes, showing 32% infected roots. 'Tomahawk' grafted onto ' Arnold', ' Armstrong' and ' Superpro V295' was significantly less affected by C. coccodes, while ' Arawak' grafted onto ' Armstrong', ' Arnold', ' Emperador' and ' Beaufort' provided very good control of root rot in the different trials. Compost addition and biofumigation with Brassica pellets were also tested with and without grafting. Soil amendment with compost, in the case of the ' Arawak' and ' Tomahawk', resulted in a slightly improved disease control only on non-grafted plants. When grafting and biofumigation were combined in a soil naturally infested with C. coccodes and Meloidogyne arenaria, biofumigation did not improve C. coccodes control in comparison with grafting alone. In a naturally infested soil, compost alone and combined with biofumigation improved disease control only on non-grafted ' Tomahawk' plants. In general, grafting by itself provided very good results in terms of disease control, which were not significantly improved by combination with compost and/or biofumigation. [ABSTRACT FROM AUTHOR]

In high-tech, heated tomato glasshouses, stem infections caused by Botrytis cinerea usually end up girdling the stem, resulting in plant death and consequently high economic losses. Such infections originate primarily from wounds created during leaf pruning, a common cultural practice in which it is intended to remove leaves completely, resulting in smooth stem wounds. However, hasty leaf pruning often results in numerous petiole stubs accidentally left behind. In this study analysis of disease incidences clearly proved that pruning leaves flush to the stem resulted in absolute resistance of the stem wounds, whereas petiole stubs displayed a high level of susceptibility to B. cinerea. Postponing inoculation of wounds after pruning indicated that development of nearly complete resistance occurs within 48 h after deleafing. Monitoring of the wound wetness period showed that drying of the wound surface is not the cause of the decreased susceptibility, contrary to what was commonly believed. Tomato mutants deficient in disease signalling showed altered phenotypes for susceptibility to B. cinerea, indicating that defences against this pathogen in petiole stubs depend on ethylene signalling. Additionally, the decreased susceptibility of mutants deficient in the biosynthesis of jasmonates and abscisic acid suggest an antagonistic effect of these signal molecules. On the other hand, resistance of smooth stem wounds could not be altered by disruption of salicylic acid, ethylene, jasmonate or abscisic acid signalling. This indicates that this remarkable absolute resistance to B. cinerea does not depend on the major disease signalling pathways. [ABSTRACT FROM AUTHOR]

The N-terminal domain (amino acids 1-130) of the replication-associated protein ( Rep130) of Tomato yellow leaf curl Sardinia virus ( TYLCSV) retains the ability of full-length Rep to localize to the nucleus and to down-regulate C1 transcription when ectopically expressed in plants, both functions being required to inhibit homologous viral replication. In this study, we analysed the effect of Rep130 expression on virus resistance and the plant transcriptome in the natural and agronomically important host species of TYLCSV, Solanum lycopersicum. Tomato plants accumulating high levels of Rep130 were generated and proved to be resistant to TYLCSV. Using an in vitro assay, we showed that plant-expressed Rep130 also retains the catalytic activity of Rep, thus supporting the notion that this protein domain is fully functional. Interestingly, Rep130-expressing tomatoes were characterized by an altered transcriptional profile resembling stress-related responses. Notably, the serine-type protease inhibitor ( Ser- PI) category was over-represented among the 20 up-regulated genes. The involvement of Rep130 in the alteration of host mRNA steady-state levels was confirmed using a distinct set of virus-resistant transgenic tomato plants expressing the same TYLCSV Rep130, but from a different, synthetic, gene. Eight genes were found to be up-regulated in both types of transgenic tomato and two encoded Ser- PIs. Four of these eight genes were also up-regulated in TYLCSV-infected wild-type tomato plants. Implications with regard to the ability of this Rep domain to interfere with viral infections and to alter the host transcriptome are discussed. [ABSTRACT FROM AUTHOR]

BACKGROUND Tomatoes and potatoes are the top produce affected in terms of value lost in the USA. Postharvest losses can occur anywhere from the time of harvest to the consumers' decision to eat or discard the food. These data support the importance of finding sustainable strategies to minimise food waste and preserve resources. This study evaluated the potential application of chlorine dioxide gas ( ClO2) technology to control the postharvest spoilage of Roma tomatoes by Alternaria alternata and Stemphylium vesicarium. RESULTS Data analysis showed that exposure time was a significant factor for fungal disease control ( P < 0.05). After 3 min of treatment, mycelial growth was completely inhibited for A. alternata and S. vesicarium. Similar results were observed for conidial germination. The efficacy of ClO2 treatments was also studied under in vivo conditions. While untreated Roma tomatoes developed white moulds and black spots after 5 days of storage, produce decay was significantly ( P < 0.05) delayed after 5 and 7 min treatments for S. vesicarium and A. alternata respectively. CONCLUSION The use of ClO2 in the food industry is regulated by both the FDA and the EPA. Currently, only acidified sodium chlorite solutions are approved for the control of micro-organisms in water used to wash fruits and vegetables. No direct applications of ClO2 gas on fresh fruits and vegetables can be found in the regulations. More data are required by the two agencies to demonstrate that residues of ClO2 on produce surfaces are acceptable for human consumption. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Tomato line 30.4 was obtained engineering the nucleocapsid ( N) gene of tomato spotted wilt virus into plant genome, and immunity to tomato spotted wilt virus infection of its self-pollinated homozygous progeny was observed. Despite the presence of a high amount of transgenic transcripts, transgenic proteins have not been detected, suggesting a mechanism of resistance mediated by RNA. In the present study, we identify post-transcriptional gene silencing as the main mechanism of resistance, which is able to spread systemically through grafting, and show that the line 30.4 resistant plants produce both 24 and 21-22 nt N-gene specific siRNA classes. The transgenic locus in chromosome 4 shows complex multiple insertions of four T-DNA copies in various orientations, all with 3′ end deletions in the terminator and part of the N gene. However, for three of them, polyadenylated transcripts are produced, due to flanking tomato genome sequences acting as alternative terminators. Interestingly, starting at the fifth generation after the transformation event, some individual plants show a tomato spotted wilt virus-susceptible phenotype. The change is associated with the disappearance of transgene-specific transcripts and siRNAs, and with hyper-methylation of the transgene, which proceeds gradually through the generations. Once it reaches a critical threshold, the shift from post-transcriptional gene silencing to transcriptional silencing of the transgene eliminates the previously well established virus resistance. [ABSTRACT FROM AUTHOR]

Deficiency of abscisic acid (ABA) in the sitiens mutant of tomato ( Solanum lycopersicum) culminates in increased resistance to Botrytis cinerea through a rapid epidermal hypersensitive response ( HR) and associated phenylpropanoid pathway-derived cell wall fortifications. This study focused on understanding the role of primary carbon : nitrogen ( C : N) metabolism in the resistance response of sitiens to B. cinerea. How alterations in C : N metabolism are linked with the HR-mediated epidermal arrest of the pathogen has been also investigated., Temporal alterations in the γ-aminobutyric acid ( GABA) shunt, glutamine synthetase/glutamate synthase ( GS/ GOGAT) cycle and phenylpropanoid pathway were transcriptionally, enzymatically and metabolically monitored in both wild-type and sitiens plants. Virus-induced gene silencing, microscopic analyses and pharmacological assays were used to further confirm the data., Our results on the sitiens- B. cinerea interaction favor a model in which cell viability in the cells surrounding the invaded tissue is maintained by a constant replenishment of the tricarboxylic acid ( TCA) cycle through overactivation of the GS/ GOGAT cycle and the GABA shunt, resulting in resistance through both tightly controlling the defense-associated HR and slowing down the pathogen-induced senescence., Collectively, this study shows that maintaining cell viability via alterations in host C : N metabolism plays a vital role in the resistance response against necrotrophic pathogens. [ABSTRACT FROM AUTHOR]

Infection of tomato by potato purple top ( PPT) phytoplasma causes disruption of gibberellin ( GA) homeostasis in the plant host. Such pathologically-induced GA deficiency can be partially reversed by exogenous application of GA. This study was designed to explore the role of GA in tomato defence response against phytoplasmal disease, and to determine whether pretreatment with GA would protect healthy tomato seedlings from subsequent phytoplasmal infection and disease development. Our results revealed that, following exogenous GA application and subsequent PPT phytoplasma graft inoculation, there was an apparently coordinated down-regulation of the gene encoding a key GA signalling component and growth repressor known as DELLA protein ( GAI) and up-regulation of genes involved in salicylic acid ( SA) synthesis ( ICS1), signalling ( NIM1) and downstream defence responses ( PRP-1). Our results also indicated that differential regulation of the above genes was correlated with an increase in activities of defence-related enzymes β-1,3-glucanase and chitinase. The data presented in this communication provide evidence to suggest that GA may act via DELLA and SA signalling pathways to modulate host defence in response to PPT phytoplasma infection. Although the GA pretreatment-induced defence was not sufficient to prevent a systemic infection, it reduced phytoplasma titre and significantly attenuated disease symptoms. While the actual molecular mechanism underlying the GA-induced plant defence remains elusive, findings from the current study open new opportunities for in-depth studies of the functional role of the GA signalling network during defence response against phytoplasmal infection. [ABSTRACT FROM AUTHOR]

In order to better understand resistance to Phytophthora infestans in tomato, we compared the global gene expression of the susceptible tomato, M82, with its more resistant near-isogenic line, 6-2 ( IL6-2), under field conditions using a microarray with more than 12 800 tomato expressed sequence tags ( ESTs). Because variance in the field was a major concern, we investigated the likelihood of false positives or false negatives and demonstrated that either probability was very low. The two isolines had indistinguishable constitutive gene expressions prior to inoculation. However, a few genes were particularly prone to variation in both isolines in the absence of P. infestans. Included among these genes were catalase, genes coding for pathogenesis-related proteins, endochitinase and cytochrome P450. In response to inoculation with P. infestans, a time course of gene expression identified 1248 transcripts that were similarly induced or repressed in each line, and 991 that were differentially expressed between the two lines. These differences provide hypotheses to explain the difference in resistance between the two isolines. For example, one hypothesis is that genes up-regulated in IL6-2 in response to inoculation with P. infestans, but not up-regulated in M82, contribute to the resistance in IL6-2. Using virus-induced gene silencing ( VIGS), we were able to partially silence two such genes-one encoded a protein with homology to an R gene with the Toll/interleukin-1 receptor-nucleotide-binding site-leucine-rich repeat ( TIR-NBS- LRR) motif ( 37O19) and the other encoded a peroxisomal membrane protein ( 35P7). Partial silencing of 37O19 reduced the resistance in IL6-2 ( P = 0.001), but had no effect on the response of M82. Partial silencing of 35P7 reduced the resistance in IL6-2 moderately significantly ( P = 0.067), but had no effect in M82. We expect that hypotheses developed from this gene expression study performed under field conditions will provide an important avenue to an accurate understanding of the genes involved in resistance. [ABSTRACT FROM AUTHOR]

Blossom-end rot (BER) in tomato fruit ( Solanum lycopersicum) is believed to be a calcium (Ca2+) deficiency disorder, but the mechanisms involved in its development are poorly understood. Our hypothesis is that high expression of pectin methylesterases (PMEs) increases Ca2+ bound to the cell wall, subsequently decreasing Ca2+ available for other cellular functions and thereby increasing fruit susceptibility to BER. The objectives of this study were to evaluate the effect of PME expression, and amount of esterified pectins and Ca2+ bound to the cell wall on BER development in tomato fruit. Wild-type and PME-silenced tomato plants were grown in a greenhouse. At full bloom, flowers were pollinated and Ca2+ was no longer provided to the plants to induce BER. Our results show that suppressing expression of PMEs in tomato fruit reduced the amount of Ca2+ bound to the cell wall, and also reduced fruit susceptibility to BER. Both the wild-type and PME-silenced fruit had similar total tissue, cytosolic and vacuolar Ca2+ concentrations, but wild-type fruit had lower water-soluble apoplastic Ca2+ content and higher membrane leakage, one of the first symptoms of BER. Our results suggest that apoplastic water-soluble Ca2+ concentration influences fruit susceptibility to Ca2+ deficiency disorders. [ABSTRACT FROM AUTHOR]

Experiments on larvicide and ovicide activity of 13 insecticides in semi-natural conditions showed a medium to low efficacy of bio-insecticides on all instars of Tuta absoluta ( Meyrick) except for B acillus thuringiensis Berliner var. kurstaki which was distinguished by an average mortality of 72.5%. Spinosad and Spinetoram based insecticides showed high efficiency in controlling all instars of larvae with respectively an average mortality of 66.5% and 85.6%. However, this study revealed a unique ovicide effect of azadirachtin-neem oil based insecticide with 43.8% egg mortality. [ABSTRACT FROM AUTHOR]

The tomato borer Tuta absoluta ( Lepidoptera: Gelechiidae) has been a recognized pest in South America since the 1960s, quickly spreading to the major tomato-producing countries in the region. A series of studies regarding this pest's biology, ecology and management were conducted to contain tomato losses within acceptable levels. Although cultural control methods were attempted against T. absoluta, as were the development of resistant tomato varieties and the use of pheromones and natural enemies, insecticides are still the main control method used. The sex pheromone of T. absoluta was identified, confirmed and synthesized in the late 1990s and it is currently used for detection and monitoring of this species, but improved sampling plans are still necessary for its use in decision-making regarding insecticide use. Insecticide use has shifted from earlier reliance on organophosphates, pyrethroids, cartap and abamectin to insect growth regulators and, more recently, to novel insecticides. Unfortunately, the overreliance on insecticide use led to problems with insecticide resistance in the region, which is a current matter of concern not only in South America, but also elsewhere since introduced strains may carry insecticide-resistance genes at high frequency even without local selection in the site of introduction. [ABSTRACT FROM AUTHOR]

SUMMARY Extensive research in the area of plant innate immunity has increased considerably our understanding of the molecular mechanisms associated with resistance controlled by a dominant resistance gene. In contrast, little is known about the molecular basis underlying the resistance conferred by quantitative trait loci (QTLs). In this study, using the interaction of tomato ( Solanum lycopersicum) with Oidium neolycopersici, we compared the cytological, biochemical and molecular mechanisms involved in both monogenic and polygenic resistances conferred by a dominant gene ( Ol-1) and three QTLs ( Ol-qtls), respectively. Our results showed that the three Ol-qtls jointly confer a very high level of broad-spectrum resistance and that the resistance is associated with both the hypersensitive response and papillae formation, with the hypersensitive response being prevalent. Both H2O2 and callose accumulation, which are coupled with Ol-1-mediated resistance, are also associated with the resistance conferred by Ol-qtls. Further, we analysed the pathogen-induced transcript profiles of near-isogenic lines carrying the three Ol-qtls and the Ol-1 gene. Transcript profiles obtained by cDNA-amplified fragment length polymorphism analysis showed that, on fungal challenge, about 70% of the transcript-derived fragments are up-regulated in both susceptible and resistant genotypes. Most of the sequenced transcript-derived fragments showed homology to genes with functions in defence responses, suggesting that defence-responsive genes responsible for basal defence are involved in both monogenic and polygenic resistances conferred by Ol-1 and Ol-qtls, respectively. Although about 18% of the identified transcript-derived fragments are specific for either monogenic or polygenic resistance, their expression patterns need to be further verified by quantitative reverse transcriptase-polymerase chain reaction. [ABSTRACT FROM AUTHOR]

Summary The plant receptor-like kinase somatic embryogenesis receptor kinase 3 (SERK3)/brassinosteroid insensitive 1-associated kinase 1 (BAK1) is required for pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI). Here we show that a distinct member of the SERK family, SERK1, is required for the full functioning of Mi-1, a nucleotide binding leucine-rich repeat (NB-LRR) resistance protein. Mi-1 confers resistance to Meloidogyne spp. (root-knot nematodes, RKNs) and three phloem-feeding insects, including Macrosiphum euphorbiae (potato aphid). SERK1 was identified in a tobacco rattle virus (TRV)-based virus-induced gene silencing (VIGS) screen in Nicotiana benthamiana. The screen was based on the suppression of a pest-independent hypersensitive response triggered by a constitutively active form of Mi-1, Mi-DS4. To assess the role of SERK1 in Mi-1-mediated resistance, Solanum lycopersicum (tomato) SlSERK genes were cloned. Three SlSERK members were identified with homologies to Arabidopsis AtSERK1 or AtSERK3/BAK1, and were named SlSERK1, SlSERK3A and SlSERK3B. SlSERK1 is ubiquitously expressed in tomato. Reducing SlSERK1 transcript levels in resistant plants, using gene-specific TRV- SERK1 VIGS, revealed a role for SlSERK1 in Mi-1-mediated resistance to potato aphids, but not to RKNs. In addition, Mi-1-dependent SlWRKY72 gene regulation was compromised in SlSERK1-silenced plants, placing SlSERK1 in the Mi-1 signaling pathway. Silencing SlSERK1 in a susceptible tomato background did not reduce the susceptibility to aphids, indicating that SlSERK1 is unlikely to be an essential virulence target. SlSERK1 is an active kinase, mainly localized at the plasma membrane. This work identifies a critical early component of Mi-1 signaling, and demonstrates a role for SlSERK1 in NB-LRR-mediated immunity. [ABSTRACT FROM AUTHOR]

BACKGROUND: The tomato red spider mite, Tetranychus evansi (Baker and Pritchard), is a serious pest of solanaceous crops in many African countries. In this study an investigation has been conducted to establish whether mutation of the para-type sodium channel underlies pyrethroid resistance in T. evansi strains collected in Southern Malawi. RESULTS: Two T. evansi strains fromMalawi showed tolerance to the organophosphate chlorpyrifos and resistance (20-40-fold) to the pyrethroid bifenthrin, butwere susceptible to two contemporary acaricides (abamectin and fenpyroximate) in insecticide bioassays. Cloning of a 3.1 kb fragment (domains IIS5 to IVS5) of the T. evansi para gene from pyrethroid-resistant and pyrethroid-susceptible strains revealed a single non-synonymousmutation in the resistant strains that results in an amino acid substitution (M918T) within the domain II region of the channel. Although novel to mites, this mutation confers high levels of resistance to pyrethroids in several insect species where it has always been associated with another mutation (L1014F). This is the first report of the M918T mutation in the absence of L1014F in any arthropod species. Diagnostic toolswere developed that allow sensitive detection of thismutation in individualmites. CONCLUSION: This is the first study of pyrethroid resistance in T. evansi and provides contemporary information for resistance management of this pest in SouthernMalawi. [ABSTRACT FROM AUTHOR]

The Mi-1.2 gene in tomato, Solanum lycopersicum L. (Solanaceae), confers resistance against several herbivores, including the potato aphid, Macrosiphum euphorbiae (Thomas) (Hemiptera: Sternorrhyncha: Aphididae) and the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Sternorrhyncha: Aleyrodidae). Previous studies on the tissue localization of resistance have given varying results; whitefly resistance was attributed to factors localized in the mesophyll or epidermis, whereas aphid resistance was attributed to factors localized in the phloem. Our study utilizes the direct current electrical penetration graph (DC-EPG) technique to compare aphid feeding behavior on resistant ( Mi-1.2+) and susceptible ( Mi-1.2−) tomato plants. This study also compares the impact of resistance on the feeding behavior of two aphid clones that vary in their virulence, or their ability to survive and reproduce on resistant plants. Previous work had shown that the avirulent WU11 clone is almost completely inhibited by resistance, whereas the semi-virulent WU12 clone can colonize resistant hosts. Here, DC-EPG analysis shows that both aphid clones take longer to initiate cell sampling and to establish a confirmed sieve element phase on resistant plants than on susceptible hosts, and have shorter ingestion periods on resistant plants. However, the magnitude of these deterrent effects is far less for the semi-virulent clone than for the avirulent aphids. In particular, the WU12 clone is less sensitive to factors that limit sieve element ingestion, showing shorter non-probe duration and rapidly establishing sustained phloem ingestion on resistant plants when compared to the WU11 clone. We conclude that, in addition to previously described factors in the phloem that inhibit ingestion, Mi-mediated aphid resistance also involves factors (possibly in the mesophyll and/or epidermis) that delay initiation of phloem salivation, and that act in the intercellular spaces to deter the first cell sampling. Furthermore, the relative effectiveness of these components of resistance differs among insect populations. [ABSTRACT FROM AUTHOR]

The article presents a study on the development of virulence and genetic polymorphism of the nematode Meloidogyne incognita from the prolonged exposure of nematicides and the growth of resistant tomato cultivars. It mentions that nematicidal treatments have contributed to the development of virulence in nematodes from the continuous exposure to nematicides and the growing resistant of the varieties have resulted a 6.6 increase of the nematode's invasion potential.

The article presents a study which examines the persistence, metabolism and safety evaluation of thiamethoxam in tomato crop. It states that thiamethoxam is a neoicotinoid insecticide that has been accepted to use in various crop worldwide. In conclusion, the thiamethoxam was recommended has doubled the recommended use rate effectivity controlled aphids, whiteflies, and Helicovera.

Late blight, caused by Phytophthora infestans, is one of the most destructive diseases of tomato in Taiwan. A total of 655 isolates of P. infestans, including 29 isolates from potato, was collected from major tomato and potato production areas of Taiwan during 1991 to 2006. Isolates were characterized for their pathogenicity, mating type, in vitro metalaxyl sensitivity and molecular genotype (including allozyme pattern, mitochondrial genomic haplotype and DNA fingerprint) to monitor population changes in P. infestans. The population of P. infestans in Taiwan underwent a dramatic genetic shift in the 1997–1998 cool growing season. Isolates collected from tomato before 1997 were aggressive to tomato but not potato; most isolates obtained after 1998, were aggressive to both hosts. Metalaxyl sensitivity of isolates changed from sensitive/intermediate before 1997 to resistant since 1998. Similarly, the isolates obtained before 1997 were all US-1 clonal lineage (including variants US-1.1, US-1.2, US-1.3 and US-1.4). During the 1997–1998 cool growing season, the US-11 clonal lineage and the TW-1 genotype appeared, possibly introduced on imported table potatoes. The US-11 lineage spread rapidly and since 1999 has almost completely displaced the old population in Taiwan. Mating type determined by pairing with A1 and A2 reference isolages of P. parasitica, showed all isolates were of the A1 mating type, suggesting that the A2 mating type had not become established in Taiwan. The increasing percentage (up to 42.3% in 2006) of the US-11 variants (including US-11.l, US-11.2, US-11.3 and US-11.4) implied that genomic diversity of the pathogen is changing quickly. Therefore, it is important to continuously monitor the population changes of P. infestans and develop an integrated management strategy for this disease. [ABSTRACT FROM AUTHOR]

We examined the effects of the Pto resistance locus on the population dynamics of Pseudomonas syringae pv. tomato (Pst) strains in field experiments with the nearly isogenic tomato lines Rio Grande (RG, susceptible to Pst races 0 and 1) and Rio Grande-Pto (RG-Pto, resistant to Pst race 0, susceptible to Pst race 1). Pst strain SM78-1Smr (race 0) grew well under field conditions and caused ample bacterial speck disease on susceptible RG plants. In contrast, strain DC3000 failed to establish large populations when inoculated onto field grown RG plants. Mean population sizes of SM78-1Smr were 4–5 orders of magnitude larger on RG than RG-Pto plants indicating that RG-Pto plants were highly effective in attenuating pathogen population development. Most of the sampled leaflets from RG-Pto field plots harboured small numbers of SM78-1Smr. However, population sizes SM78-1Smr as large as 105–106 CFU were found on a few leaflets. Bacteria isolated from these leaflets had phenotypes characteristic of Pst race 1 strains. In growth chamber plant assays, the bacterial strains grew well and caused typical speck lesions on RG-Pto plants. The strains appeared to be race-shift mutants of SM SM78-1Smr. Interestingly, results from DNA hybridization experiments demonstrated that the race-shift mutants were deleted for the avirulence gene, avrPto but not for avrPtoB. [ABSTRACT FROM AUTHOR]

Tomato ( Solanum lycopersicum) production in tropical and subtropical regions of the world is limited by the endemic presence of Tomato yellow leaf curl virus (TYLCV). Breeding programmes aimed at producing TYLCV-resistant tomato cultivars have utilized resistance sources derived from wild tomato species. So far, all reported breeding programmes have introgressed TYLCV resistance from a single wild tomato source. Here, we tested the hypothesis that pyramiding resistances from different wild tomato species might improve the degree of resistance of the domesticated tomato to TYLCV. We have crossed TYLCV-resistant lines that originated from different wild tomato progenitors, Solanum chilense, Solanum peruvianum, Solanum pimpinellifolium, and Solanum habrochaites. The various parental resistant lines and the F1 hybrids were inoculated in the greenhouse using viruliferous whiteflies. Control, non-inoculated plants of the same lines and hybrids were exposed to non-viruliferous whiteflies. Following inoculation, the plants were scored for disease symptom severity, and transplanted to the field. Resistance was assayed by comparing yield of inoculated plants to those of the control non-inoculated plants of the same variety. Results showed that the F1 hybrids between the resistant lines and the susceptible line suffered major yield reduction because of infection, but all hybrids were more resistant than the susceptible parent. All F1 hybrids resulting from a cross between two resistant parents, showed a relatively high level of resistance, which in most cases was similar to that displayed by the more resistant parent. In some cases, the hybrids displayed better levels of resistance than both parents, but the differences were not statistically significant. The F1 hybrid between a line with resistance from S. habrochaites and a line with resistance from S. peruvianum (HAB and 72-PER), exhibited the lowest yield loss and the mildest level of symptoms. Although the resistance level of this F1 hybrid was not statistically different from the level of resistance displayed by the 72-PER parent itself, it was statistically better than the level of resistance displayed by the F1 hybrids between 72-PER and any other resistant or susceptible line. [ABSTRACT FROM AUTHOR]

Viable cells of Clavibacter michiganensis subsp. michiganensis (CMM), the causal agent of bacterial canker of tomato, were discriminated from the dead cells by quantitative real-time polymerase chain reaction (PCR), after the bacterial solution was treated with the DNA binding dye ethidium monoazide (EMA). The primers and TaqMan probe, based on the 16S-23S rDNA spacer sequences, were highly specific for CMM at the subspecies level. The detection limit of the direct real-time PCR was 103 colony forming units per mL (cfu mL−1) in samples and with an apparent sensitivity of 2 cfu of target cells in PCR reaction solution. Application of this method allows for selective quantification of viable cells of CMM and facilitates monitoring the pathogen in tomato seeds. [ABSTRACT FROM AUTHOR]

Novel types of anti-oomycetic compounds have been designed and prepared. The synthetic approach to these mandelamides is outlined. Biological data demonstrate their high efficacy against important plant diseases such as tomato and potato late blight (Phytophthora infestans De Bary) and grape downy mildew (Plasmopara viticola Berliner & de Toni). Structure-activity relationship studies are discussed. The new development product mandipropamid is presented. [ABSTRACT FROM AUTHOR]