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Mitigating Chili Plant Wilt: Synergy of Arbuscular Mycorrhizal Fungi and Silver Nanoparticles
by Hilda Karina Sáenz Hidalgo ,Esteban Sánchez Chávez ,Nuvia Orduño Cruz ,Mahendra Rai ,Víctor Olalde Portugal ,Graciela Dolores Ávila Quezada*
Accepted: 15/November/2024 – Published: 13/December/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-8
Abstract Background/Objective. The chilaca pepper (Capsicum annuum) is significantly impacted by the attack of the oomycete Phytophthora capsici, which causes chili wilt. Current methods for controlling this disease have been inefficient. Therefore, the search for more environmentally friendly alternatives is of great importance. In pursuit of this objective, we assessed the potential of arbuscular mycorrhizal fungi (AMF) and silver nanoparticles (AgNPs) to try to reduce or postpone chili pepper wilt.
Materials and Methods.Growth parameters were measured in inoculated and non-inoculated chili pepper plants with AMF from a commercil consortium TM-73 (Biotecnología Microbiana) and the protective effects of AMF and AgNPs (NanoID®) against P. capsici as evaluated using a severity scale for wilt symptoms. Plant response to pathogen infection was assessed by measuring the activities of antioxidant enzymes: PER, SOD, CAT and H2O2.
Results. The results indicated that AMF application improved the growth parameters of C. annuum, while the plant-pathogen interaction induced an antioxidant enzymatic response. AMF maintained wilt symptoms at or below 80%, preventing plant death. Meanwhile, AgNPs (50ppm) delayed plant mortality compared to the control treatment.
Conclusion. The combined use of AMF and AgNPs offer options for future research in the disease management for chili peppers.
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Figure 1. Mycorrhizal structures in chilaca pepper roots inoculated with AMF: A, B, C) Hyphae (H) and Vesicles (V), d) Arbuscules (A).
Figure 2. Percentage of severity of the disease caused by P. capsici in chilaca peppers. Severity was evaluated with a scale for 12 days after the inoculation of the pathogen.
Figure 3. Comparison of averages of the area under the curve of the scale of severe diseases caused by P. capsici in chilaca peppers. Standard error 5%. Different letters in each column indicate a significant difference (p ≤0.05).
Figure 4. Superoxide dismutase (SOD) activity in chilaca pepper plants inoculated with P. capsici treated with AMF and AgNPs. Same letters in each column indicate there were no significant differences (p >0.05).
Figure 5. Concentration of H2O2 in chilaca pepper plants inoculated with P. capsici treated with AMF and AgNPs. Same letters in each column indicate there were no significant differences (p >0.05).
Figure 6. Catalase (CAT) activity in chilaca peppers inoculated with P. capsici treated with AMF and AgNPs. Same letters in each column indicate there were no significant differences (p > 0.05).
Figure 7. Peroxidase (PER) activity in chilaca pepper plants inoculated with P. capsici treated with AMF and AgNPs. Same letters in each column indicate there were no significant differences (p >0.05).
Figure 8. Effect on the enzyme activity in chilaca pepper plants inoculated with P. capsici. Superoxide Dismutase (SOD), Catalase (CAT), Peroxidase (PER).
Table 1. Scale of severity of wilting by P. capsici in C. annuum.
Table 2. Effect of AMF in the development of the chilaca pepper (Capsicum annuum).
by Francisco Palemón Alberto ,Santo Ángel Ortega Acosta* ,Erubiel Toledo Hernández ,Cesár Sotelo Leyva ,Guadalupe Reyes García ,Elizabeth Tecomulapa Acatitlán
Accepted: 15/November/2024 – Published: 04/December/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-21
Abstract Background/Objective. Diseases of agricultural crops affect the yields and quality of products. Synthetic chemical compounds are generally used to control them; these cause harmful impacts to the environment, as well as to human health. In this sense, beneficial microorganisms can be used in agriculture as biocontrol agents, and contribute to obtaining food in sufficient and safe quantities. The fungus Irpex lacteus has been reported as a potential biocontrol agent. The objective of this research work was to evaluate the in vitro mycoparasitic capacity of the endophytic fungus I. lacteus P7B against 22 fungi and one oomycete associated with plant diseases.
Materials and Methods. The P7B isolate, previously detected as a mycoparasite, was used and molecularly identified by amplification and sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA, using primers ITS1/ ITS4.The confrontations of the mycoparasite (P7B) against the phytopathogenic microorganisms were carried out in PDA culture medium. Three replicates were used for each microorganism, in addition to the controls, which consisted of placing the microorganisms individually.
Results. Molecular analyses determined that isolate P7B corresponded to Irpex lacteus (GenBank: PP922180). The results of the in vitro assays indicated that I. lacteus P7B inhibited all the phytopathogenic agents with which it was confronted, 100% inhibition by I. lacteus occurred approximately in 14 days, except for Rhizopus spp., this was at 23 days after the confrontations.
Conclusion. The present study demonstrates that the fungus I. lacteus presented 100% in vitro mycoparasitic capacity against the various fungi and an oomycete evaluated, so future work could focus on evaluating its mycoparasitic activity under field conditions.
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Figure 1. Effect of the confrontation in dual culture in PDA under in vitro conditions between I. lacteus P7B against fungi and an oomycete associated to plant diseases.
Figure 3. Effect of the confrontation in dual culture in PDA under in vitro conditions between I. lacteus P7B against fungi and an oomycete associated to plant diseases. P7B = Irpex lacteus. CC47GRO = Corynespora cassiicola. COLTOR1 = Colletotrichum gloeosporioides. PAP-4= Phytophthora sp. C4 = Macrophomina sp. RIZOPAP = Rhizopus sp. Dac = Days after confrontation.
Figure 3. Effect of the confrontation in vitro of I. lacteus P7B against fungi and an oomycete. A= Macrophomina sp. (isolate C4) control; B= Macrophomina sp. (isolate C4) confronted with I. lacteus P7B, a degradation of sclerotia and hyphae can be observed. C = Alternaria sp. (isolate AL1) control; D = Alternaria sp. (isolate AL1) confronted with I. lacteus P7B, in which a degradation of conidia and hyphae can be observed. E = Rhizopus sp. (isolate RIZOPAP) control; F = Rhizopus sp. (isolate RIZOPAP) confronted with I. lacteus P7B, shows degraded sporangia. Images captured with anoptic microscope with 10X (A, B, E and F), and 40X objective lens (C and D).
Table 1. Microorganisms used in the evaluation for the confrontation with Irpex lacteus P7B from the collection of pyhtopathogenic fungi of the Plant Physiology and Biotechnology Laboratory, FCAA-UAGro.
by Estefanía Fonseca Chávez ,Irvin Alonso Molina Marañón ,Luz Irela Lugo Zambrano ,Juan Carlos Martínez Álvarez ,Guadalupe Arlene Mora Romero ,Jesús Damián Cordero Ramírez ,Karla Yeriana Leyva Madriga*
Accepted: 13/November/2024 – Published: 04/December/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-14
Abstract Background/Objective. Biological control offers new strategies for disease management in agriculture. In the present study, the antifungal activity of volatile organic compounds (VOCs) emitted by rhizobacteria, was evaluated in the growth and infective capacity of four isolates of E. turcicum obtained from symptomatic corn plants, in northern Sinaloa.
Materials y methods. The fungal isolates were characterized morphologically and molecularly, and their pathogenicity was corroborated in a detached leaf assay. The ability of VOCs to inhibit mycelial growth and infection of maize leaves by E. turcicum was evaluated in in vitro assays, in divided Petri dishes. Bacterial hydrogen cyanide production was qualitatively determined.
Results. The mycelial growth of E. turcicum was reduced by VOCs of at least one rhizobacteria, registering inhibitions between 22% and 63%. Leaves infection was reduced between 63% and 98% in the presence of rhizobacterial VOCs. Hydrogen cyanide production was detected in strains B3 and B9.
Conclusion. Strain B95 was more effective in reducing mycelial growth and infection by E. turcicum. The production of hydrogen cyanide could be involved in its antagonistic effect. In-plant tests are required to corroborate its effectiveness, as well as characterize its volatile profile.
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Figure 1. Characterization of Exserohilum turcicum isolates. A-C) Morphological characteristics of representative isolate Bac7-2. A) Frontal view of the culture in PDA; B) Reverse view of the culture in PDA; C) Conidium; D) Maximum Likelihood phylogram inferred from the combined matrix of the markers act+ITS+rpb2 from Exserohilum.
Figure 2. Pathogenicity test. A) Detached leaf system used to confirm the pathogenicity; B) Symptoms caused by the Exserohilum turcicum isolates in the detached maize leaves.
Figure 3. Effect of the bacterial volatile organic compounds on the mycelial growth of Exserohilum turcicum in divided Petri dishes.
Figure 4. Effect of the bacterial volatile organic compounds on the infective capacity of Exserohilum turcicum on detached maize leaves.
Figure 5. Detection of volatile hydrocyanic acid emitted by rhizobacteria.
Table 1. Effect of the bacterial volatile organic compounds (VOCs) on the mycelial growth of Exserohilum turcicum in divided plates.
Table 2. Effect of the bacterial volatile organic compounds (VOCs), in the infective capacity of Exserohilum turcicum in detached maize leaves.
by Jesús Eduardo Ramírez Méndez ,Francisco Daniel Hernández Castillo ,Gabriel Gallegos Morales ,Diana Jasso Cantú ,Roberto Arredondo Valdés ,Marco Antonio Tucuch Pérez*
Accepted: 09/November/2024 – Published: 23/November/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-23
Abstract Background/Objective. Pythium aphanidermatum and Rhizoctonia solani are pathogens that affect agricultural crops. The objective of this study was to evaluate some Agave striata and Fouquieria splendens methanolic extracts, from the Chihuahuan Desert, against those fungi, in search for biological control alternatives.
Materials and Methods. Pathogens from chili plants were isolated and identified using morphological and molecular methods. Methanolic extracts from both plants were prepared, and the antioxidant capacity (AC), the total polyphenol content (TPC), and the antifungal compounds via HPLC-MS were assessed. The antifungal effectiveness was tested at concentrations of 3.9-2000 mg L-1 using a poisoned medium assay, where fungi structural damage was observed.
Results. The F. splendens and A. striata extracts exhibited 55% and 68% AC, as well as 61 mg/g and 112 mg/g TPC, respectively. Both extracts contained caffeic acid and quercetin, while F. splendens also exhibited eriodyctiol, kaempferol, and luteolin; A. striata contained pinocembrin and theaflavin B. F. splendens attained 100% inhibition of P. aphanidermatum at 250 mg L-1, and of R. solani at 500 mg L-1, whereas A. striata achieved 100% inhibition at 1000 mg L-1 in both cases. The extracts produced lysis in P. aphanidermatum oogonia and mycelial fragmentation in R. solani.
Conclusion. The F. splendens and A. striata methanolic extracts demonstrate promising antifungal activity against P. aphanidermatum and R. solani, suggesting that these natural compounds might be useful as a biological alternative for pathogen control in agricultural crops.
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Figure 1. Inhibition of Pythium aphanidermatum with methanolic Agave striata and Fouquieria splendens extracts using the poisoned medium method.
Figure 2. Inhibition of Rhizoctonia solani using plant Agave striata and Fouquieria splendens extracts using the poisoned medium method.
Figure 3. Effect of plant extracts on Pythium aphanidermatum oogonia at 100X. A, B and C) Fouquieria splendens, D, E and F) Agave striata, and G) Negative control.
Figure 4. Effect of plant extracts on mycelial Rhizoctonia solani structures at 40X and 100X. A, B, C) Fouquieria splendens, D, E, F) Agave striata, and G), H) Negative control.
Table 1. Phytochemical compounds identified in methanolic Agave striata and Fouquieria splendens extracts characterized by reverse-phase liquid chromatography (HPLC-MS).
Table 2. Antioxidant Capacity and Capacity of Total Polyphenols of methanolic Agave striata and Fouquieria splendens extracts.
Table 3. Inhibitory concentration at 50% (IC50) of methanolic Agave striata and Fouquieria splendens extracts on Pythium aphanidermatum and Rhizoctonia solani.
by Fannie Isela Parra Cota ,Isabeli Bruno ,Mónica García Montelongo ,Sebastián González Villarreal ,María Fernanda Villarreal Delgado ,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)