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by Fannie Isela Parra Cota, Isabeli Bruno, Mónica García Montelongo, Sebastián González Villarreal, María Fernanda Villarreal, Liliana Carolina Córdova Albores, Alina Escalante Beltrán, Sergio de los Santos Villalobos
Accepted: 08/November/2024 – Published: 19/November/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-34
Abstract Background/Objective. Bacteria of the Bacillus genus have been studied since their discovery in 1872, for their ability to synthesize metabolites of interest such as proteins used to control phytopathogens. The objective of this research was to analyze the most outstanding species of the Bacillus genus, as well as the main compounds produced by these species, and the perspectives on the use of this bacterial genus for pest and disease control.
Materials and Methods. An exhaustive search was carried out in scientific articles and books to gather the most relevant information regarding the Bacillus genus, focusing on its role as a biological control agent for pests and pathogens.
Results. The Bacillus genus includes more than 427 taxa, which can be classified into different groups. Among the biological control agents (BCA) are the Bacillus cereus group, which includes B. cereus, B. anthracis, and B. thuringiensis, and the B. subtilis group, which includes B. subtilis, B. licheniformis, and B. pumilus, mainly. B. thuringiensis, through cry genes, has molecular mechanisms to synthesize a crystalline inclusion during sporulation, which contains proteins known as endotoxins or Cry proteins. B. subtilis produces substances with a high potential for biological control, such as volatile organic compounds, as well as bioactive secondary metabolites.
Conclusion. The potential of the Bacillus genus to be used as biological control agents is evident. They are widely used for the development of different biopesticides that have advantages over other products. However, it is necessary to continue conducting research from the in vitro area in the laboratory to the field, to help guarantee their biosecurity and effectiveness.
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Figure 1. Macroscopic characteristics of Bacillus cereus (A) and B. subtilis (B), belonging to the Culture Collection of Native Soil and Endophytic Microorganisms, grown at 28 °C in nutrient agar (COLMENA (www.itson.edu.mx/COLMENA) (de los Santos-Villalobos et al., 2018).
Figure 2. Cry proteins. 1-A) Primary structure, showing the organization of the domains of representative members from each Cry family, 2-A) Conserved tertiary structure, showing the positions of the three domains. B) Mechanism of action of Cry proteins in insects, initiating once the Cry proteins are proteolytically processed by proteases in the midgut of the host, separating an amino acid section in the N-terminal region and at the C-terminal end (depending on the nature of the Cry protein), thus releasing active and toxic fragments that interact with receptor proteins in the insect’s intestinal cells. Modified from Villarreal-Delgado et al., 2018.; de Maagd et al., 2001; Xu et al., 2014.
Figure 3. Characteristics of interest of Bacillus spp. for the formulation of bioinoculants.
Figure 4. Evolution of the Bacillus genus as a biopesticide in the industry.
by Célida Aurora Hernández Castillo, Patricia Rivas Valencia, Leticia Robles Yerena, Mariana Guadalupe Sánchez Alonso, Emiliano Loeza Kuk
Accepted: 26/October/2024 – Published: 05/November/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-03
Abstract Background/Objective. In all citrus-producing regions in the world, gummosis is a disease that has caused losses in citrus production. This disease is caused by several pathogens. The objectives were to identify the fungi associated with gummosis in citrus orchards of Plan Chac, Sacalum, Yucatan; and to evaluate chemical and biological alternatives for the control of fungi associated with gummosis.
Materials and Methods. From fragments of plant tissue and soil, the associated fungi were isolated. The isolates were identified morphologically in plant tissue as Lasiodiplodia pseudotheobromae and in soil as Fusarium solani and Pestalotia spp. The pathogenicity test determined that L. pseudotheobromae is an agent associated with this disease. The isolates were subjected to in vitro tests with chemical fungicides and antagonist agents.
Results. Thiabendazole showed effectiveness for F. solani with an effective concentration to inhibit 50 % of the population (EC50) of 0.0612 mg L-1, with Pestalotia spp. inhibited growth at all concentrations evaluated and for L. pseudotheobromae, it showed an EC50 of 0.0049 mg L-1. In the case of Bacillus subtilis strain QST 713, the growth of F. solani (EC50 0.0496 mg L-1), Pestalotia spp. (EC50 0.0487 mg L-1) and L. pseudotheobromae (EC50 0.0528 mg L-1) decreased. On the other hand, Trichoderma harzianum showed a greater inhibition against F. solani, Pestalotia spp. and L. pseudotheobromae of 61.08, 62.93 and 35.64 %, respectively.
Conclusion. In the management of gummosis in citrus fruits, the use of biological agents such as Trichoderma and B. subtilis can be efficiently included, offering alternatives with less impact on the environment
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Figure 1. Front and back of isolates in PDA culture medium of fungi related to the gummosis of citrus fruits. A) Six-day old Lasiodiplodia pseudotheobromae culture, obtained from tissue from the cortex. B) Six-day old Fusarium solani culture. C) Six-day old Pestalotia spp. culture, both obtained from the soil.
Figure 2. Microscopic morphology of fruiting Lasiodiplodia pseudotheobromae bodies. A, B and C) Globose pycnidial conidiomata, D) mature septate conidia with longitudinal striations, E conidiogenous cells and paraphyses and F) immature aseptate conidia.
Figure 3. Microscopic morphology of Fusarium solani associated to the gummosis in citrus fruits. A) Phialides and conidia grouped into flower heads, B) Mature septated conidia, C) Mature microconidia.
Figure 4. Symptoms and signs caused by Lasiodiplodia pseudotheobromae on citrus fruits, A) stem necrosis, B) presence of pycnidia on stems, and C) production of exudate or gum.
Figure 5. In vitro effect of fungicides against fungi associated to the gummosis of citrus fruits in five days. Growth of Fusarium solani: A) Medium with Thiabendazole at 0.5 mg L-1. B) Medium with Carbendazim at 0.8 mg L-1. C) Medium with Benomyl at 50 mg L-1. D) Control. Growth of Lasiodiplodia pseudotheobromae: E) Medium with Thiabendazole at 0.01 mg L-1. F) Medium with Benomyl at 0.1 mg L-1. G) Medium with Mancozeb at 50 mg L-1. H) Control. Growth of Pestalotia spp.: I) Medium with Thiabendazole at 0.01 mg L-1. J) Medium with Benomyl al 1 mg L-1. K) Medium with Mancozeb at 100 mg L-1. L) Control.
Figure 6. Effect of Trichoderma spp. In the development of fungi associated to the gummosis of citrus fruits. A) Fusarium solani vs T. harzianum. B) F. solani vs T. viride. C) Pestalotia spp vs T. harzianum. D) Pestalotia vs T. viride. E) Lasiodiplodia pseudotheobromae vs T. harzianum. F) L. pseudotheobromae vs T. viride.
Table 1. Treatments evaluated for the control of phytopathogenic fungi associated to the gummosis of citrus fruits in Plan Chac, Sacalum, Yucatan.
Table 2. Mean effective concentration (EC50) (mg L-1) of each fungicide tested in vitro for the inhibition of the mycelial growth of Fusarium solani obtained from citrus orchards in Plan Chac, Sacalum, Mexico.
Table 3. Mean effective concentration (EC50) (mg L-1) of each fungicide tested in vitro for the inhibition of the mycelial growth of Pestalotia spp. obtained from citrus orchards in Plan Chac, Sacalum, Yucatan.
Table 4. Mean effective concentration (EC50) (mg L-1) of each fungicide tested in vitro for the inhibition of the mycelial growth of Lasiodiplodia pseudotheobromae obtained from citrus orchards in Plan Chac, Sacalum, Yucatan.
Table 5. Percentage of mycelial growth inhibition by the effect of Trichoderma against F. solani, Pestalotia spp. and L. pseudotheobromae.
by Leonardo Miguel Nava Eugenio, Dolores Vargas Álvarez, Eleuterio Campos Hernández, Flaviano Godínez Jaimes, Roxana Reyes Ríos, Mairel Valle de la Paz, Daniel Perales Rosas
Accepted: 15/October/2024 – Published: 05/November/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-04
Abstract Antecedents/Objectives. Guerrero is an important producer of roselle (Hibiscus sabdariffa); therefore, the objective was to evaluate the inhibitory effect of resins in vitro using four factors: technique (disc in agar or Kirby Bauer and well in agar), resins (B. linanoe, J. curcas, mixture of both and Thiabendazole), volume (10, 20 and 30 μL) and phytopathogenic fungi (C. cassiicola, F. oxysporum and F. solani) on the diameter of the inhibition halo.
Materials and Methods. Statistical analysis was performed with a completely randomized factorial design with fixed effects to compare the 72 treatments using the Kruskal-Walis test.
Results. All terms were found to be significant, the main effects of technique, resins, volume and fungi on the diameter of the inhibition halo, but also the double, triple and quadruple interactions.
Conclusion. B. linanoe resin showed higher inhibition for C. cassiicola and F. oxysporum, in the two techniques (agar well and agar disc technique or Kirby Bauer technique), this makes it the resin type with the highest biocontrol potential.
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Table 1. Minimum Inhibitory Dose (MID) of Jatropha curcas, Bursera linanoe resins and Mixture of (J. curcas and B. linanoe) against the fungi associated with roselle diseases
Table 2. Clusters of the 72 treatments after using the Kruskal-Wallis test.
Diversity and taxonomy of Fusarium solani isolated of wilted Agave tequilana var. azul plants
by Viviana Montaño Becerrra, Norma Alejandra Mancilla Margalli, Cristina Chávez Sánchez, Martin Eduardo Avila Miranda
Accepted: 16/September/2024 – Published: 25/October/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2310-5
Abstract Background/Objective. The objective of this work was to identify 24 strains of F. solani isolated from agave with wilt, with respect to the new phylogenetic species; determine their molecular similarity to F. solani f. spp.; determine their genetic diversity and their pathogenic capacity in agave, bean and corn.
Materials and Methods. Sequences of the ITS1-5.8S-ITS2 fragment of 24 agave isolates and those of F. solani f. spp., were compared with GenBank and FUSAROID-ID. Amplified 18S rRNA sequences were aligned with sequences reported of F. solani f. spp. phaseoli and batatas, defining the presence of introns. Genetic diversity was determined with the DNA RepPCR marker. Representative strains were tested against agave, bean and maize seedlings, evaluating their pathogenicity as root rot severity.
Results. Isolates morphologically identified as F. solani, GenBank placed them as F. solani or included in the FSSC, three strains were identified as Xenoacremonium sp. FUSAROID-ID defined that the sequences of F. solani were highly similar to those of Neocosmospora martii, N. pseudoradicicola, N. solani and N. falciformis. The ITS1-5.8S-ITS2 sequences and absence of introns in its SSU indicated that none is F. solani f. sp. phaseoli. Isolates obtained from agave were pathogenic to A. tequilana and a criollo corn cv, but not to Fusarium-resistant corn. No agave isolates were pathogenic to beans.
Conclusions. Four phylogenetic species of FSSC cause root rot in agave; F. solani isolates from agave did not affect Fusarium-resistant corn. It is safe to intercrop beans in agave.
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Figure 1. Appearance of plants from which the Fusarium solani strains were isolated A) Agave tequilana var. azul plant, with symptoms of agave wilt. B) Typical reddish necrotic tissue in the crown and the base of the stem.
Figure 2. Microphotograph of the main morphological characteristics used to identify Fusarium solani isolations obtained from necrotic tissue in the crown or base of the stem of Agave tequilana var. azul plant. A). Long conidiophores with only one microconidium. B) Fusarium macroconidia.
Figure 3. Appearance of fungal cultures after five days of growing in PDA at 28 °C. A) FsDr strain, identified molecularly as Xenoacremonium sp.and B) Fusarium solani FsP strain. C) Microphotograph of mycelium and conidiophore of the FsDr strain without macroconidia
by Diana Angelina Urias Lugo, Octavio Ernesto Martínez Ereva, Cecilia de Los Ángeles Romero Urías, Carlos Ramiro Ibarra Sarmiento, Sylvia Adriana Estrada Díaz, Rubén Félix Gastélum, Karla Yeriana Leyva Madrigal, Guadalupe Arlene Mora Romero
Accepted: 22/September/2024 – Published: 24/October/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-01
Abstract Background/Objective. The present work reports the in vitro effect of aqueous extracts (2, 4 and 6% w/v) of root, seed and leaf of Datura discolor obtained in two times (3 and 6 minutes) at High Pressure Processing, against Sclerotium rolfsii, Sclerotinia sclerotiorum and Colletotrichum gloeosporioides.
Materials and Methods. Extracts of roots, seeds and leaves of D. discolor were prepared in a 1:10 w/v ratio with distilled water. Two continuous treatments of high pressure (600 MPa) with pressure maintained for 3 min and another with pressure (600 MPa) maintained for 6 min were considered. The extracts were evaluated against S. rolfsii, S. sclerotiorum and C. gloeosporioides. The experiments were performed in Petri dishes with PDA medium. The efficiency of the extracts was evaluated by obtaining the percentage of inhibition.
Results. The results show variable percentages of inhibition of the extracts in the different anatomical parts of the plant and concentrations; The leaf extracts at 6%, regardless of the extraction time, show effectiveness against the three pathogens, with inhibition of 99 and 100%, 55 and 56%, and 43 and 36% for S. rolfsii, S. sclerotiorum and C. gloeosporioides at 3 and 6 minutes respectively.
Conclusion. The effectiveness of leaf extract at 6%, six months after its preparation, is similar to the observed with fresh extracts. These results pave the way for future research focused on the sustainable management of phytopathogens. Studies on the biological effectiveness of the extracts in the greenhouse and field are suggested.
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Figure 1. Effect of Datura discolor aqueous leaf extract obtained High Pressure Processing for 6 minutes. A-D Sclerotium rolfsii, E-H Sclerotinia sclerotiorum, I-L Colletotrichum gloeosporioides. Chemical control = tebuconazole or carbendazim 1 ppm).
Table 1. In vitro inhibition of the mycelial growth of Sclerotium rolfsii, Sclerotinia sclerotiorum and Colletotrichum gloeosporioides. The treatments shown are with aqueous extracts of 2, 4 and 6% Datura discolor root, seed and leaf, obtained by High Pressure Processing in two times 3 and 6
Tobamovirus fructirugosum an emerging disease: review and current situation in Mexico
by Ubilfrido Vásquez Gutiérrez, Juan Carlos Delgado Ortiz, Gustavo Alberto Frías Treviño, Luis Alberto Aguirre Uribe, Alberto Flores Olivas
Accepted: 11/September/2024 – Published: 15/October/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2401-7
Abstract Background/Objective. Tobamovirus fructirugosum species (ToBRFV) is considered a worldwide quarantine pest that limits the production of Solanum lycopersicum and Capsicum annum, currently present in three countries of the American continent. The objective of this work was to deepen in the genetic variability of ToBRFV with respect to the different isolates, the physico-molecular and symptomatic characterization, the traditional and more current methods implemented for diagnosis, the range of virus reservoir hosts, and the epidemiology. Results. ToBRFV was generated from a mutation resulting from genetic recombination with TMV, considered the main progenitor and ToMMV secondary progenitor. Phylogenetic analyses report the existence of five clades with respect to the genetic diversity of ToBRFV. The first primers for detection were designed in 2015 that encode replication, movement and capsid proteins. Serological methods can be used for preventive diagnosis, while molecular and NGS can confirm virus infection even at low concentrations in the plant. Sixteen weed families and host crops are reported from 47 countries. To achieve an effective strategy, it is necessary to reduce inoculum sources, develop compounds that inhibit mechanical transmission and develop tolerant genotypes. Conclusion. ToBRFV is distributed nationally and represents a phytosanitary risk for Mexico; the exhaustive analysis of the study of diagnostic techniques, host range, dissemination, epidemiology and control strategies, contributes to the knowledge of ToBRFV.
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Figure 1. Phylogenetic analysis of ToBRFV sequences reported in NCBI. For the reconstruction of the phylogenetic tree, Molecular Evolutionary Genetics Analysis version 11 software was used with the Neighbor joining model and 10,000 replicates (Bootstrap). With a genetic distance of 0.02
Figure 2. Symptoms manifested in tomato plants by ToBRFV grown in greenhouse. A) Tomato plants at 180 days after sowing showing high incidence of ToBRFV; B) Irregularities in fruit ripening; C) Plants in a state of collapse due to severe ToBRFV infection; D) Presence of mosaic patterns, mottling, and blistering on leaves.
Figure 3. Rapid detection procedure for ToBRFV using Agdia® immunological strips. A) Selection of symptomatic tissue (young leaves); B) Macerated sample and positive reaction to ToBRFV, showing the control line and the test line (both in red color)
by Maria Magdalena Rivera Salas, José Basilio Heredia, Juan Manuel Tovar Pedraza, Cesar San Martín Hernández, José Benigno Valdez Torres, Isabel Cruz Lachica, Raymundo Saúl García Estrada
Accepted: 22/July/2024 – Published: 23/August/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2405-11
Abstract Background/Objective. Species of Bacillus are currently gaining interest because its ability to produce secondary metabolites with antifungal properties against various plant pathogenic fungi. The objective of this study was to optimize fermentation temperature and time for antifungal extract production by Bacillus amyloliquefaciens B17 and to verify its activity against plant pathogenic fungi Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea.
Materials and Methods. A central composite design (CCD) with two factors and five levels (fermentation temperature: 23.7, 25, 28, 31, and 32.2 °C and fermentation time: 25, 46, 95, 144, and 164.3 h) was used. Thirteen combinations of temperature and fermentation time were randomly performed. The thirteen crude extracts of B. amyloliquefaciens B17 were obtained from the cell-free fermentation broth by acid precipitation followed by alkaline solubilization. The response variable was the diameter of the inhibition halos generated by placing drops of the different crude extracts onto the medium already inoculated with a suspension of Gilbertella persicaria spores.
Results. The optimal conditions for the production of the extract with the greatest antifungal activity in B. amyloliquefaciens B17 were 26.8 °C and 158.6 h.
Conclusion. The optimized crude extract from B. amyloliquefaciens B17 exhibited a strong ability to inhibit mycelial growth and spore germination of Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea.
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Figure 1. Response surface plot for the inhibition halo diameter as a function of fermentation time and temperature
Table 1. Experimental results of the inhibition halos generated by the crude extracts of B. amyloliquefaciens obtained under different fermentation conditions.
Table 2. ANOVA and regression analysis for the response variable (diameter of the inhibition halo) generated by the crude extracts of B. amyloliquefaciens obtained under different fermentation conditions.
by Erick Ortega Piña, Daniel Leobardo Ochoa Martínez, Reyna Isabel Rojas Martínez, Alfredo Díaz Lara
Accepted: 26/July/2024 – Published: 12/August/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2402-8
Abstract Background/Objective. In broad bean (Vicia faba) crops established in Montecillo, Texcoco, State of Mexico, 100% of plants were observed with viral symptoms consisting of mosaic, mottling, leaf curling, wilting and a notable decrease in plant development. These symptoms led to a significant reduction in seed yield and quality. In this context, the present study was carried out with the objective of identifying the viral species associated with these symptoms.
Materials and Methods. The experimental strategy consisted of extraction of total RNA from leaves showing the aforementioned symptoms, followed by nextgeneration sequencing.
Results. In the results, the complete genomes of Orthotospovirus impatiensnecromaculae (before impatiens necrotic spot virus) and two isolates of the Potyvirus phaseoluteum (before bean yellow mosaic virus) were obtained. The phylogenetic analysis revealed that the isolate of O. impatiensnecromaculae (INSV CPMEX) shows significant divergences from those previously reported in other plant species. On the other hand, the two P. phaseoluteum isolates (BYMV CP1MEX and BYMV CP2MEX) proved to be different from each other, being related to isolates reported in Sudan and Iran.
Conclusion. This result suggests considerable genetic diversity among the viruses associated with viral symptoms in faba bean crops in the region, which underlines the importance of accurate identification for the management and control of these viral infections.
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Figure 1. Detection of Orthotospovirus impatiensnecromaculae and Potyvirus phaseoluteum in broad bean plants using RT-PCR. A) Product of RT-PCR of a 438 bp fragment of the L segment that codifies the viral replicase of O. impatiensnecromaculae: MPM= Molecular weight marker 100 bp PROMEGA, negative control (-). Lanes 1, 3, 4, 9, 10, 13, 14 and 15 broad bean plant samples with symptoms of mosaic, mottling, leaf curling and wilting. B) Product of RT-PCR of a 319 bp fragment of the ORF of the P. phaseoluteum that codifies for the nucleocapsid MPM= Molecular weight marker 100 bp PROMEGA, negative control (-). Lanes 1, 2, 3, 4, 9, 10, 13, 14 and 15 broad bean plant samples with symptoms of mosaic, mottling, leaf curling and wilting. The sequences of the amplicons obtained had a 99% coverage and 99% identity with P. phaseoluteum and O. impatiensnecromaculae isolates deposited in the GenBank, respectively
Figure 2. Phylogenetic tree of the Potyvirus phaseoluteum CP1MEX and BYMV CP2MEX isolates using the General-Time- Reversible model and the maximum likelihood method with 500 bootstrap replicates.
Table 1. Primers designed to verify the presence of Potyvirus phaseoluteum (Pp) and Orthotospovirus impatiensnecromaculae (Oi) in broad bean foliar tissue with symptoms of mosaic, mottling, leaf curling, wilting and growth reduction.
by Yeison David López Galé, Mauricio Fernando Martínez, Lizeth Paola Palacios Joya, Nubia Murcia Riaño, Mario Augusto García Dávila
Accepted: 16/July/2024 – Published: 08/August/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2311-1
Abstract Background/Objective. The level of resistance to Phytophthora cinnamomi in avocado germplasm can be evaluated indirectly through inoculation of the pathogen by wounding the stem. The objective of this work was to compare the conventional graft development method and the etiolated graft method to determine levels of indirect resistance to P. cinnamomi through the stem wound inoculation technique.
Materials and Methods. In the study, three isolates of P. cinnamomi and two avocado genotypes with different levels of resistance to the pathogen were used, Duke-7 (medium resistant) and Hass (susceptible). Clonal multiplication of the genotypes was carried out with buds grafted on rootstocks propagated by Antillean avocado seeds. Inoculation was performed on the shoot at a height of 8 cm and the growth of the lesions was measured for 24 days. With the data, the Area Under the Disease Progress Curve (AUDPC) and the Coefficients Variation (CV) are calculated. The information was analyzed with a completely randomized experimental design with a 2*2*3 factorial arrangement (Method*Genotype*Isolation).
Results. The analysis of variance for the AUDPC showed no differences between methods (p=0.1881); However, there were differences between genotypes, isolates and between the genotype*method and genotype*isolation interactions (p≤0.05). With the conventional method, the development of the outbreaks was late (141-159 days) and the size of the lesions was highly variable (CV=38.9-64.4%), being able to discriminate partial degrees of aggressiveness between isolates, but not levels of resistance between genotypes. The etiolated and greened shoots in the nursery, on the contrary, presented rapid growth (101-107 days) and greater uniformity in the lesions generated by the pathogen (CV=11.1-24.2%).
Conclusion. The development of etiolated shoots in avocado grafts is proposed as a rapid alternative method that can guarantee greater uniformity in the development of lesions within the experimental units of a treatment, thus achieving greater reliability when evaluating and selecting preliminarily. avocado genotypes with indirect resistance attributes to P. cinnamomi.
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Figure 1. Propagation and shoot development process in avocado grafts. A) Conventional graft development method, B) etiolated graft development method. Yellow dots and lines indicate the location where the wound was made and P. cinnamomi was inoculated.
Figure 2. Micrographs of histological sections of Hass and Duke-7 avocado stems developed by the conventional method and the etiolation method (40X). (MP) Medullary parenchyma, (X1) Primary xylem, (X2) Secondary xylem, (CP) Cortical parenchyma, (P) Periderm, (E) Epidermis.
Figure 3. Macroscopic and microscopic characteristics of P. cinnamomi isolate A-Ag- 041. (A) Colony growth on PDA culture medium, (B) mycelium (hyphae), (C) chlamydospores, (D) sporangium.
Mixed viral infections in vegetable crops: biochemical and molecular aspects
by Mario Sánchez Sánchez, Irasema Vargas Arispuro, Juan Manuel Tovar Pedraza, Cristóbal González Pérez Pedraza, Emmanuel Aispuro Hernández, Eber Addí Quintana Obregón, Miguel Ángel Martínez Téllez
Accepted: 10/July/2024 – Published: 06/August/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2404-3
Abstract Mixed viral infections refer to the coinfection of two or more viruses in the plant, which regularly lead to exacerbated symptoms on leaves and fruits. The dynamics of coinfections may follow either a synergistic, antagonistic, or neutral interaction that impacts the severity of the symptoms and infection. Mixed viral infections occur due to the convergence of fundamental characteristics reviewed in this manuscript. The virus‒host plant interrelationship influences the establishment and spread patterns of mixed viral infections. Attention should be drawn to potential changes in the dynamics of transmission and prevalence of plant viral diseases due to the effect of anthropogenic and natural alterations to complex agroecological systems or their components, including hosts, reservoirs, vectors, ecological niches, and the emergence of new virus strains
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![Figure 1. Symptom transition in the lower, middle, and upper leaves of tomato plants agroinoculated with the infectious cloned DNA-A and DNA-B components of isolates of TYLCV from Costa Rica (ToYMoV-[CR:Gre:GR1:90]) and Tomato leaf curl Sinaloa virus (ToLCSiV-[CR:Lib:L1:02]) from Costa Rica and the infectious clone of the genomic DNA of TYLCV from the Dominican Republic (TYLCV-[DO]) individually or in all combinations. (A) TYLCV; (B) non-inoculated tomato plant; (C) ToYMoV and ToLCSiV; (D) ToYMoV and TYLCV; (E) ToLCSiV and TYLCV; (F) ToYMoV, ToLCSiV and TYLCV. Plants were photographed 21 d after agroinoculation (with permission of Maliano <em>et al.,</em> 2022)](img/RMF/Volumenes/NumNormales/V4232024/RMF2404-3/Figure1.jpg)
Figura 2. Plant components involved in viral mixed infections. Normal communication processes between plant cells involve the interrelation of structures such as plasmodesmata (A) and nucleus (B), the former are conducted in the cell walls that allow the passage of molecules between cytoplasm. In the presence of a viral infection (C), the cell counteracts the action through well-defined biochemical pathways such as inhibition of plasmodesmata function and intracellular trafficking (D), production of specific response metabolites (They can occur before and during the development of the viral infection), (E) or increase in the production of proteins involved in detoxification processes (F). In other hand, after a successful internalization by two viruses occurs synergistic effect of mixed viral infection (G).
Figure 1. Symptom transition in the lower, middle, and upper leaves of tomato plants agroinoculated with the infectious cloned DNA-A and DNA-B components of isolates of TYLCV from Costa Rica (ToYMoV-[CR:Gre:GR1:90]) and Tomato leaf curl Sinaloa virus (ToLCSiV-[CR:Lib:L1:02]) from Costa Rica and the infectious clone of the genomic DNA of TYLCV from the Dominican Republic (TYLCV-[DO]) individually or in all combinations. (A) TYLCV; (B) non-inoculated tomato plant; (C) ToYMoV and ToLCSiV; (D) ToYMoV and TYLCV; (E) ToLCSiV and TYLCV; (F) ToYMoV, ToLCSiV and TYLCV. Plants were photographed 21 d after agroinoculation (with permission of Maliano et al., 2022)
