Metabolism of radioactively labeled quinic acid and shikimic acid in healthy and Fusarium-infected tomato plants

Radioactivity from quinic acid-U-¹⁴C was readily incorporated into chlorogenic acid and shikimic acid in healthy andFusarium-infected tomato plants of two varieties, Bonner Beste (susceptible) and Moneymaker (resistant); radioactively labeled shikimic acid, on the other hand, was converted neither to quinic acid nor to chlorogenic acid.Infection led to increased incorporation of¹⁴C inton-butanol extractives, and alcohol-soluble and insoluble esters, except in the resistant variety after feeding of shikimic acid-U-¹⁴C. After infection incorporation into the non-hydrolyzable fraction—which a.o. contains lignin—decreased in the susceptible variety, but it increased in the resistant variety, particularly after administration of shikimic acid-U-¹⁴C.Samenvatting Radioactief kinazuur werd in gezonde en metFusarium geïnfecteerde tomateplanten behorende tot twee variëteiten, Bonner Beste (vatbaar) en Moneymaker (resistent), in chlorogeenzuur en shikimizuur omgezet; laatstgenoemde verbinding werd echter noch in kinazuur, noch in chlorogeenzuur omgezet.Infectie leidde tot een toegenomen incorporatie van¹⁴C in metn-butanol extraheerbare verbindingen, en in alcohol-oplosbare en onoplosbare esters, behalve na toediening van radioactief shikimizuur in de resistente variëteit. Incorporatie in de zg. niethydrolyseerbare fractie, die o.a. lignine bevat, bleek in de vatbare variëteit na infectie geringer te zijn, maar in de resistente variëteit na infectie toe te nemen, vooral na toediening van shikimizuur.     

The occurrence of acid hydrolyzable phenolics in relation toFusarium wilt disease in tomato plants

Infection of a susceptible tomato variety led to an accumulation of acid hydrolyzable phenolic acids. This accumulation doesn't support the view in which the phenolic acids are hold to be responsible for the resistance against the wilting disease.Samenvatting Infectie van een voorFusarium vatbare tomatevariëteit leidde tot een vermeerdering van in zuur hydrolyseerbare fenolzuren. Deze vermeerdering ondersteunt de mening niet, dat juist de fenolzuren verantwoordelijk zijn voor de resistentie tegen de verwelkingsziekte.     

The effect of rufianic acid on tomato wilt in relation to calcium supply

Tissue browning and wilting ofFusarium-infected tomato plants were suppressed by rufianic acid. However, calcium proved to be necessary for the action of rufianic acid as a therapeutant. An interrelationship between the effects of Ca supply and of rufianic acid on wilt disease in tomato plants and on growth was demonstrated.The amino acid contents of the exudates of decapitated plants and the Ca supply were found to be inversely related. Rufianic acid caused a decrease in the concentration of amino acids in exudates of infected as well as of healthy plants.In several respects rufianic acid kept infected plants in a near normal condition.     

Mobility of oxathiapiprolin in and between tomato plants

BACKGROUND

Oxathiapiprolin (OXPT; FRAC code 49) is a new piperidinyl-thiazole isooxazoline anti-oomycete fungicide that targets oxysterol-binding proteins. The fungicide is known to translocate acropetally from root to shoot to protect plants against fungal attack.

RESULTS

OXPT is ambimobile. It can also translocate basipetally from shoot to root. OXPT exhibits an unprecedented capacity for trans-plant protection. When two tomato plants are grown in one pot, and one is treated with OXPT (on the stem, leaves or apex), while the other plant and soil surface are adequately covered, both plants become protected against late blight caused by Phytophthora infestans.

CONCLUSION

Trans-plant systemic protection induced by OXPT involves translocation of the fungicide from the shoot of the treated plant to its root, exudation into the soil and uptake by the root of the neighboring untreated plant to protect it against the disease. Liquid chromatography–tandem mass spectrometry analyses confirmed the occurrence of OXPT in root exudates of OXPT-treated tomato plants in quantities sufficient to protect detached tomato leaves and intact plants against P. infestans. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Persistence and translocation of a benzothiadiazole derivative in tomato plants in relation to systemic acquired resistance against Pseudomonas syringae pv tomato

A reproducible and accurate procedure, based on HPLC analysis, has been developed to determine simultaneously acibenzolar‐S‐methyl (CGA 245 704) and its acid derivative (CGA 210 007) in tomato leaves. The limit of detection and quantification of the method are 0.015 and 0.15 mg litre^?1 for CGA 245 704 and 0.030 and 0.30 mg litre^?1 for CGA 210 007. In tomato plants treated with 250 µM CGA 245 704, it was found that the inducer rapidly translocates from treated leaves (cotyledons, 1st and 2nd) to untreated leaves (3rd to 5th), with the maximum translocation (40% of the total quantity found) occurring 8 h after the treatment. CGA 245 704 residues decreased as time elapsed in both treated and untreated tomato leaves, reaching negligible values 72 h after treatment. The acid derivative, CGA 210 007, was formed in tomato plants as early as 2 h after CGA 245 704 treatment, albeit only in the treated leaves. CGA 210 007 residues decreased in treated tomato leaves with a trend similar to that observed for CGA 245 704. Treatment of tomato plants with CGA 245 704 or CGA 210 007 at 250 µM systemically protected the plants against Pseudomonas syringae pv tomato attacks, the causal agent of bacterial speak disease. Evidence of this were reductions in the degree of infection, the bacterial lesion diameter and the bacterial growth in planta. Since neither CGA 245 704 nor CGA 210 007 inhibited bacterial growth in vitro and the protection against bacterial speak of tomato was observed when the two compounds were completely degraded, the protection must be due to the activation of the plant's defence mechanisms. © 2001 Society of Chemical Industry     

Determination of 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid in tomato plants and other commercial crops by microcoulometric gas chromatography

A residue method based on microcoulometric gas chromatography is described for 2,4-D and 2,4,5-T in tomato plants and other commercial crops. Intensive cleanup includes extractions with two different buffers and, after conversion of the free acids to the methyl esters, final cleanup is achieved with a Kontes Sweep Co-distillation Apparatus. With a sample weight of 100 g of tomato plant, 0.5 μg can be determined with a recovery of 72 to 96% for 2,4-D and 94 to 100% for 2,4,5-T.     

Effect of jasmonic acid on the induction of polyphenoloxidase and peroxidase activities in relation to date palm resistance against Fusarium oxysporum f. sp. albedinis

Bayoud, caused by Fusarium oxysporum f. sp. albedinis (Foa), is the most damaging disease of date palm in Morocco. In the present study we have investigated the effect of jasmonic acid (JA) on two defence-related enzymes, namely peroxidases (POX) and polyphenoloxidases (PPO) in date palm seedlings root. Our data show that exogenous application of JA at a concentration of 50 μM increased the activity of both enzymes. The increase of POX activity in the presence of JA was much more important than that observed following infection with the pathogen. As compared to untreated plants, PPO activity was 2.2 and 1.3 times higher in BSTN and JHL cultivars respectively. In addition, PAGE analysis revealed increased band intensity of the major constitutive isoforms of POX and PPO in both JA-treated and Foa-treated seedlings. Close examination of symptomatic and asymptomatic plants showed that root tissues of symptomatic plants were massively colonized by Foa. Also, disease development in these plants appeared to involve a marked degradation of the host cell walls early during the process of pathogen invasion. In contrast, the presence of Foa in asymptomatic plants induced limited necrotic lesions (hypersensitive-reaction like lesions) that were probably involved in reducing the progression of the pathogen. Together, our findings indicate that JA is capable of enhancing date palm root resistance to infection by Foa via the activation of defence-related enzymes such as PPO and POX.     

Preventive and post‐infection control of Botrytis cinerea in tomato plants by hexanoic acid

The antifungal activity of hexanoic acid on the phytopathogen Botrytis cinerea was studied. This chemical inhibited both spore germination and mycelial growth in vitro in a concentration‐ and pH‐dependent manner, and stopped spore germination at a very early stage, preventing germ‐tube development. The minimum fungicidal concentration (MFC) for in vitro spore germination was 16 mm . Hexanoic acid also inhibited in vitro mycelial growth of germinated spores at an MFC of 12 mm . Studies performed to characterize the mechanisms underlying the antimicrobial effect of hexanoic acid showed that it alters fungal membrane permeability. In addition, hexanoic acid treatment increased the levels of spermine, spermidine, putrescine and cadaverine in B. cinerea mycelia. Spray application of hexanoic acid at fungicidal concentrations on 4‐week‐old tomato plants prior to fungal inoculation reduced necrosis diameter by approximately 60%. Application of the same hexanoic acid concentrations on previously infected plants reduced further necrosis expansion by around 30%. The results suggest that this chemical acts as a preventive and curative fungicide. Interestingly, treatments with hexanoic acid at concentrations below the MFC in hydroponic solution prior to fungal inoculation significantly reduced necrosis area. These results suggest an inducer effect of plant responses for hexanoic acid treatments at these concentrations. Hexanoic acid is a good candidate for safe antifungal treatments for the control of B. cinerea, which is responsible for many economic losses on fruits, vegetables and flowers.     

Lack of synergistic effects in tomato plants co-infected with tomato severe rugose virus and tomato chlorosis virus

The begomovirus Tomato severe rugose virus (ToSRV) and the crinivirus Tomato chlorosis virus (ToCV), in single and co-infections, are very common in tomato crops in Brazil. Both viruses are transmitted by the whitefly Bemisia tabaciMEAM1 (biotype B). The objective of this study was to analyse the interaction between ToSRV and ToCV in tomato plants of cultivars Santa Clara and Kada. Plants at 15, 30 and 45 days after emergence were inoculated with 30 viruliferous B. tabaci per plant. The following treatments were compared: plants inoculated with ToSRV, ToCV, ToSRV + ToCV, and healthy (control). The interaction between these viruses was analysed by measuring the virus titre by qPCR and the fresh and dry weights of the aerial parts of the tomato plants. Based on two independent assays, no significant effects for co-infection of ToSRV and ToCV on virus titres and plant development were observed compared to single infections. The dry weight of tomato plants of both cultivars infected with ToSRV, ToCV, or co-infected did not differ significantly. However, the dry weight of Santa Clara tomato plants infected with ToSRV, ToCV and ToSRV + ToCV showed mean reductions of 21.5%, 25.5% and 32%, respectively, compared to healthy plants, and mean reductions for Kada were 31.7%, 37.5% and 38%, respectively.     

Antioxidative effects of the acetone fraction and vanillic acid from Chenopodium murale on tomato plants

From the active acetone fraction of Chenopodium murale , vanillic acid was isolated and identified, based on ¹H and ¹³C nuclear magnetic resonance spectral analyses. Free phenolic compounds inside the active acetone were qualified and quantified by using high performance liquid chromatography analysis, which revealed the presence of seven compounds with an abundance of vanillic and p -hydroxybenzoic acids. The allelopathic potential of the acetone fraction and vanillic acid was evaluated through laboratory bioassays against tomato plants. Our results showed that the allelopathic potential induced by low concentrations of the acetone fraction and vanillic acid stimulated the germination and growth of tomato and had stimulating effects on the activity of some antioxidant enzymes. We observed an enhancement in the activity of catalase, peroxidase, superoxide dismutase, and polyphenol oxidase, as well as the content of soluble protein and phenolic glycoside. Meanwhile, the levels of free phenolic compounds, H₂O₂, and lipid peroxidation decreased. The highest stimulations were recorded at 50 p.p.m. of acetone fraction and 0.5 p.p.m. of vanillic acid. In contrast, the highest concentrations exerted negative effects on all the measured parameters to record the maximum value of inhibition at 400 p.p.m. of acetone fraction and 4 p.p.m. of vanillic acid. These results proved the antioxidative effects of active acetone and vanillic acid at low concentrations and their potent use as a stimulator for tomato germination and growth.     

The role of salicylic acid in defense response of tomato to root-knot nematodes

Salicylic acid (SA) is involved in hypersensitive reactions of plants to incompatible pathogens and in systemic acquired resistance (SAR) after the attack of necrosis-inducing pests. The possible involvement of SA in defense responses of tomato to root-knot nematodes (Meloidogyne spp., RKNs) was investigated. SA was found not to be responsible for the inhibition of catalase (CAT) detected in the early stages of Meloidogyne-tomato incompatible interactions. CAT extracted from leaves was inhibited only after treatment of the seedlings with SA concentrations as high as 4 mM. Most of the amount of free SA found in plants after SA treatment was detected in the leaves. SA (0.2 mM) was found to cause a competitive inhibition of CAT only at high substrate (H₂O₂) concentrations. Under different conditions it did not affect, or even enhanced, the enzyme activity. Therefore, it is suggested that SA-mediated CAT inhibition does not operate early in resistance against RKN in tomato, although it might have a role in the consequent lesion formation. Plant uptake of SA was detected by immersion of roots of 1-month-old seedlings in aqueous solutions of SA and SA plus a soil humic acid. Considering the low level of free SA retained by roots, the capacity of exogenously provided SA to act as an elicitor of resistance to root pests is considered unlikely.     

The viscosity of mineral oils in relation to their ability to inhibit the transmission of stylet-borne viruses

Thirteen fractions were obtained by distillation of the mineral oil Bayol 50 (ESSO 2214) and these were tested for their ability to inhibit the transmission of potato virus Y to red pepper. The less viscous fractions <8 cSt at 37°C (52 SUS) were shown to be less active, the more viscous fractions were more active than Bayol 50 with a viscosity of 8 cSt at 37°C. Sunoco 7E, a mineral oil with a viscosity of 14.2 cSt at 37°C (74 SUS) was shown to be significantly more active than Bayol 50. The difference in emulgator had no influence on these results. We, therefore, recommed to choose mineral oils with a viscosity of at least 12 cSt at 37°C (=66 SUS) for future work on the inhibition of the transmission of stylet-borne viruses.Samenvatting Door destillatie van de minerale olie Bayol 50 (ESSO 2214) werden 13 fracties verkregen die getoetst werden op hun vermogen de overdracht van aardappelvirus Y naar paprika te verhinderen. De minder viskeuze fracties, <8 cSt bij 37°C (52 SUS), bleken minder, de hoger viskeuze fracties meer activiteit te bezitten dan Bayol 50 zelf. Sunoco 7E, een minerale olie met een viscositeit van 14,2 cSt bij 37°C (74 SUS) bleek significant actiever dan Bayol 50 met een viscositeit van 8 cSt bij 37°C (52 SUS). Een verschil in emulgator had geen invloed op deze resultaten. Op grond van deze gegevens is het aan te bevelen geen minerale olie te gebruiken met een viscositeit lager dan 12 cSt bij 37°C (66 SUS) indien men de overdracht van een nonpersistent virus zo effectief mogelijk wenst te verhinderen.     

基于县域单元的中国人粮关系及其变化研究

以基于县域尺度的1980年、1990年、2000年的统计资料为基础,采用人口粮食匹配曲线、基尼系数等指标,分析计算中国县域尺度的人口粮食关系,揭示中国县域人-粮关系及其演变规律,旨在为统筹解决国家粮食安全问题提供科学依据。研究结果表明：1）1980-2000年我国人口粮食匹配不均衡程度越来越高,一方面说明我国粮食生产集...     

Induced resistance in tomato plants to the toxin-dependent necrotrophic pathogen Alternaria alternata

A necrotrophic pathogen, the tomato pathotype of Alternaria alternata (Aa) causes Alternaria stem canker on tomato. Its pathogenicity depends on the production of host-specific AAL-toxin. Pre-inoculation with nonpathogenic Aa or pretreatment an elicitor prepared from Aa reduced disease symptoms by the pathogen. Salicylic acid (SA)- and jasmonic acid (JA)-dependent defense responses in tomato are not involved in the resistance to the pathogen induced by nonpathogenic Aa. The results suggest that an alternative and unknown signaling pathway independent of SA- and JA-signaling might modulate the induced resistance by activating the expression of the multiple defense genes.     

The colonization processes of Myrtus communis by strains of Pseudomonas savastanoi with a differential ability to produce phytohormones

The ability to produce indole-3-acetic acid (IAA) through the indole-3-acetamide (IAM) pathway as well as cytokinins is a common trait of Pseudomonas savastanoi populations causing disease on oleander and olive. These phytohormones are required for the induction and development of an outgrowth of plant cell tissue termed a knot. However, in myrtle orchards of Sardinia (Italy), strains of P. savastanoi unable to produce cytokinins were found coexisting with cytokinin-producing strains. Data presented here show that the ability to produce IAA through the IAM pathway is also a variable trait within this population, raising questions on the exact role of these plant growth substances in the disease process on myrtle. Three P. savastanoi strains were selected based on their differential ability to produce phytohormones in vitro, and their interaction with the host was investigated over a period of 8 months using histological methods. All strains successfully invaded the infected twigs, moving systemically (unhalted by host defences) upward and downward from the inoculation point, both by completely degrading the cell walls and by taking advantage of the xylem vessels and intercellular spaces. Moreover, all strains induced the development of cankers, which slowly evolved into typical knots only on the twigs inoculated with the phytohormone-producing strains. This study further demonstrates that cytokinins and IAA are essential for knot development; moreover, it ascertains that bacterial production of cytokinins is not necessary for host colonization and for the expression of pathogenicity (i.e. the ability to cause disease) of P. savastanoi on myrtle.     

Salicylic acid mitigates physiological and proteomic changes induced by the SPCP1 strain of Potato virus X in tomato plants

Induction of resistance by salicylic acid (SA) exogenous treatment is a complementary approach to control plant diseases. SA effect on Potato virus X (SPCP1 strain) – infected tomato plants was examined by analyzing their physiological parameters and proteomic profiling at initial infection. PVX-SPCP1 altered photosynthesis and carbohydrate synthesis proteins and elicited stress proteins. SA partially offset reduction in photosynthetic rate during infection by increasing mesophyll conductance. SA counteracted these changes through stabilization of photosystem II, increased proteins related with thermotolerance and stress, and decreased proteins related with stomatal opening. The strongest effects of SA occurred at the beginning of the pathogenesis cycle.     

Chlorophyll content of tomato yellow leaf curl virus-infected tomatoes in relation to virus resistance

A good association was found between chlorophyll content of TYLCV-infected tomato lines and individual F₂ plants, and their TYLCV resistance which was evaluated visually. Moreover, by examining the resistance of the F₃ progeny it was demonstrated that determination of chlorophyll content provided an earlier and more precise quantitative evaluation of resistance than visual evaluation. The chlorophyll test is simple and useful for studying virus-vector-plant interactions and estimating TYLCV resistance in extensive breeding programs.