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Búsquedas previas al 2023, Núm. 3. En la sección Volúmenes 30 - 41 (2012 - 2023).

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<em>Bipolaris oryzae</em> associated agent at the leaf spot disease in <em>Cocos nucifera</em> hybrid “Brazilian Green Dwarf”. Figure 1 - Leaves with symptoms of leaf spot in hybrid coconut tree “Brazilian Green Dwarf”. A) Brown oval spots and yellow halo, B) palm leaves with multiple oval spots and C) view of the nursery with plants with leaf spot.

Figure 1 - Leaves with symptoms of leaf spot in hybrid coconut tree “Brazilian Green Dwarf”. A) Brown oval spots and yellow halo, B) palm leaves with multiple oval spots and C) view of the nursery with plants with leaf spot.

Resistance to <em>Phytophthora capsici</em> in manzano chili grafted onto CM-334, grown in infested soil, with applications of auxins and <em>Trichoderma harzianum</em>. Figure 1 - Arbitrary scale for evaluating the incidence and severity caused by <em>P. capsici</em> in ‘Dali’ hybrid manzano chili (<em>Capsicum pubescens</em>) plants grown in pots with <em>P. capsici</em>-infested soil. Chapingo, Mexico, 2020–2021.

Figure 1 - Arbitrary scale for evaluating the incidence and severity caused by P. capsici in ‘Dali’ hybrid manzano chili (Capsicum pubescens) plants grown in pots with P. capsici-infested soil. Chapingo, Mexico, 2020–2021.

Figure 2 - Root of non-grafted vs. CM-334-grafted manzano chili hybrid grown in hydroponics and greenhouse conditions in Chapingo, Mexico (2017–2019). A) Maruca, B) Maruca grafted, C) Jhos, D) Jhos grafted, E) Dali, F) Dali grafted.

Figure 4 - Area under the disease progress curve (AUDPC) of P. capsici in manzano chili plants grown in Chapingo, Mexico, from 2020 to 2021. dat: days after transplantation. D: non-grafted ‘Dali’ hybrid, d: days (application frequency). ^zSame letters indicate no statistically significant differences (Fisher’s LSD, P≤0.05).

Figure 5 - Morphological characterization of P. capsici in diseased plants. A) cottony growth, B y C) bipapillate sporangium of P. capsici in manzano chili in Chapingo, Mexico.

Etiology of brown rot in strawberry (<em>Fragaria x nanassa</em>) in the State of Mexico. Figure 5 - Pathogenicity tests on strawberry fruit inoculated with a concentration of 2×10<sup>6</sup> conidia mL<sup>−1</sup> of <em>Pilidium concavum</em>. A) Fruit with a wound inoculated with the fungus. B) Wounded fruit showing symptoms 72 hours post-inoculation (hpi). C) Sporodochia of the fungus on the wounded fruit. D) Unwounded fruit inoculated with the fungus. E) Unwounded fruit showing symptoms 96 hours post-inoculation. F) Sporodochia of the fungus on the unwounded fruit. G) Control inoculated with sterile distilled water, showing no symptoms at 96 hours post-inoculation.

Figure 5 - Pathogenicity tests on strawberry fruit inoculated with a concentration of 2×10⁶ conidia mL⁻¹ of Pilidium concavum. A) Fruit with a wound inoculated with the fungus. B) Wounded fruit showing symptoms 72 hours post-inoculation (hpi). C) Sporodochia of the fungus on the wounded fruit. D) Unwounded fruit inoculated with the fungus. E) Unwounded fruit showing symptoms 96 hours post-inoculation. F) Sporodochia of the fungus on the unwounded fruit. G) Control inoculated with sterile distilled water, showing no symptoms at 96 hours post-inoculation.

Biological effectiveness of <em>Agave striata</em> and <em>Fouquieria splendens</em> extracts against <em>Pythium aphanidermatum</em> and <em>Rhizoctonia solani in vitro</em>. Figure 1 - Inhibition of <em>Pythium aphanidermatum</em> with methanolic <em>Agave striata</em> and <em>Fouquieria splendens</em> extracts using the poisoned medium method.

Figure 1 - Inhibition of Pythium aphanidermatum with methanolic Agave striata and Fouquieria splendens extracts using the poisoned medium method.

Diversity and antibiotic resistance in bacteria associated with symptoms of bacterial infection in Costa Rican crops. Figure 2 - Cladograma construido con el método del vecino más cercano a partir de 70 secuencias parciales del gen ARNr 16S de bacterias aisladas de lesiones en plantas y secuencias de cepas de referencia. Se evaluó la topología del árbol realizando 1 000 remuestreos y se utilizó la secuencia de <em>Bacillus</em> subtilis como grupo externo. Los símbolos en el exterior del árbol indican los aislamientos clasificados como resistentes a Estreptomicina, Tetraciclina y Gentamicina y sus combinaciones (círculos) y aquellos con Reacción hipersensible positiva (triángulos)Cladogram constructed using the nearest neighbor method from 70 partial sequences of the 16S rRNA gene of bacteria isolated from plant lesions and sequences of reference strains. The tree topology was assessed through 1,000 resamplings, with the sequence of <em>Bacillus</em> subtilis used as an outgroup. Symbols on the outer part of the tree indicate isolates classified as resistant to Streptomycin, Tetracycline, and Gentamicin, as well as their combinations (circles), and those with a positive Hypersensitive Reaction (triangles).

Figure 2 - Cladograma construido con el método del vecino más cercano a partir de 70 secuencias parciales del gen ARNr 16S de bacterias aisladas de lesiones en plantas y secuencias de cepas de referencia. Se evaluó la topología del árbol realizando 1 000 remuestreos y se utilizó la secuencia de Bacillus subtilis como grupo externo. Los símbolos en el exterior del árbol indican los aislamientos clasificados como resistentes a Estreptomicina, Tetraciclina y Gentamicina y sus combinaciones (círculos) y aquellos con Reacción hipersensible positiva (triángulos)Cladogram constructed using the nearest neighbor method from 70 partial sequences of the 16S rRNA gene of bacteria isolated from plant lesions and sequences of reference strains. The tree topology was assessed through 1,000 resamplings, with the sequence of Bacillus subtilis used as an outgroup. Symbols on the outer part of the tree indicate isolates classified as resistant to Streptomycin, Tetracycline, and Gentamicin, as well as their combinations (circles), and those with a positive Hypersensitive Reaction (triangles).

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Scientific Article

Identification of species and physiological races of Xanthomonas isolated from tomato (Solanum lycopersicum) and chili pepper (Capsicum annuum) in Sinaloa, Mexico

byLaura Belén Tapia de la Barrera , Manuel Alonzo Báez Sañudo , Raymundo Saúl García Estrada , Juan Manuel Tovar Pedraza , José Armando Carrillo Fasio

Received: 10/February/2022 – Published: 31/July/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2210-2

Abstract Bacterial spot of tomato and chili pepper, caused by four species of Xanthomonas and various races, is one of the diseases with the greatest impact on horticulture worldwide. The aim of this study was to identify the species and physiological races of Xanthomonas present in tomato (Solanum lycopersicum) and chili pepper (Capsicum annuum) crops in Sinaloa, Mexico. For this purpose, samples with typical symptoms of bacterial spot were collected in commercial fields of the different municipalities in the state of Sinaloa. Ninety-three bacteria were isolated on semi-selective medium as nutrient agar and yeast extract-dextrose. A total of 47 bacteria were identified as Xanthomonas by a combination of morphological, pathogenic, biochemical, physiological, and molecular tests. In addition, to characterize the morphological race of each strain, differential tomato (four) and chili pepper (six) lines were used. Molecular diagnostic using specific primers indicated that 83% corresponded to X. euvesicatoria, 10.6% to X. perforans, and 6.4% to X. vesicatoria. At the physiological race level, races T1, T2, T3, and T5 were detected in tomato; while the Xanthomonas races detected in chili pepper were P0, P3, P6, P8 and P10. This information updates previous data on the distribution of races of Xanthomonas that infect chili peppers in Sinaloa, since races P6 and P10 are reported for the first time.

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Figure 1. Agarose gel to detect <em>Xanthomonas</em> spp. species. In the first lane (M) 100 pb marker; in the second lane, primers for X. euvesicatoria (E); third, X. vesicatoria (V), fourth lane with a specific stripe for X. perforans (P); fifth, X. gardneri (G) and sixth lane with universal primers for <em>Xanthomonas</em> spp. (X)

Figure 1. Agarose gel to detect Xanthomonas spp. species. In the first lane (M) 100 pb marker; in the second lane, primers for X. euvesicatoria (E); third, X. vesicatoria (V), fourth lane with a specific stripe for X. perforans (P); fifth, X. gardneri (G) and sixth lane with universal primers for Xanthomonas spp. (X)

Table 1. Specific primers for the identification of <em>Xanthomonas</em> species in strains obtained from tomato and chili pepper in Sinaloa, Mexico

Table 1. Specific primers for the identification of Xanthomonas species in strains obtained from tomato and chili pepper in Sinaloa, Mexico

Table 2. Reaction mixture for PCR for the identification of <em>Xanthomonas</em> species

Table 2. Reaction mixture for PCR for the identification of Xanthomonas species

Table 3. Classification of <em>Xanthomonas</em> spp. races in chili pepper (<em>Capsicum annuum</em>) by susceptibility and hypersensitivity reactions.

Table 3. Classification of Xanthomonas spp. races in chili pepper (Capsicum annuum) by susceptibility and hypersensitivity reactions.

Table 4. Classification of physiological <em>Xanthomonas</em> races in tomato by susceptibility and hypersensitivity reactions.

Table 4. Classification of physiological Xanthomonas races in tomato by susceptibility and hypersensitivity reactions.

Table 5. Species and races of <em>Xanthomonas</em> isolated from chili pepper and tomato from Sinaloa from November, 2016 to March, 2017.

Table 5. Species and races of Xanthomonas isolated from chili pepper and tomato from Sinaloa from November, 2016 to March, 2017.

Open access
Scientific Article

Alternatives for the gray mold (Botrytis cinerea) control in cape gooseberry (Physalis peruviana) crop

byYimmy Alexander Zapata Narváez*, Andrés Díaz Garcia , Camilo Rubén Beltrán Acosta

Received: 10/February/2022 – Published: 31/July/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2302-5

Abstract The effect of the field applications of three bioproducts (based on Trichoderma koningiopsis, Rhodotorula mucilaginosa, and Bacillus amyloliquefaciens), the alternation of the biostimulant Kendal® and the Swinglea glutinosa extract and the rotations of two fungicides (based on Azoxystrobin-Difenoconazole and Thiram- Pyrimethanol), on the incidence of gray mold in cape gooseberry postharvest was evaluated. For this purpose, the fruit was harvested weekly in the field, arranged in wet chambers with fruits with and without calyx, and incubated for seven days at 20 °C in laboratory conditions to promote the development of B. cinerea and determine the efficacy in its control. In addition, the populations of the microbial antagonists were monitored between applications by collecting the leaflets and washing them in 0.1% Tween 80 and sowing aliquots in specific culture media. In fruits with calyx, the lowest incidence of the gray mold, with averages of 48 and 51%, occurred with the applications of the bioproducts based on T. koningiopsis and R. mucilaginosa, respectively. In contrast, the incidence did not exceed 1.4% in fruits without calyx in all treatments. Furthermore, the population of microbial antagonists in the phyllosphere remained constant between applications, with counts of 1x103 CFU g-1 for T. koningiopsis and 1x105 CFU g-1 for R. mucilaginosa and B. amyloliquefaciens.

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Figure 1. Top, healthy cape gooseberry (<em>Physalis peruviana</em>) fruits. Below, fruits with signs of gray mold (<em>Botrytis cinerea</em>) in the field, showing the presence of the mycelia and conidia of <em>Botrytis cinerea</em> with a grayish tome on the calyx and the berry inside.

Figure 1. Top, healthy cape gooseberry (Physalis peruviana) fruits. Below, fruits with signs of gray mold (Botrytis cinerea) in the field, showing the presence of the mycelia and conidia of Botrytis cinerea with a grayish tome on the calyx and the berry inside.

Table 1. Treatments evaluated for the control of gray mold (<em>Botrytis cinerea</em>) in the cape gooseberry crop.

Table 1. Treatments evaluated for the control of gray mold (Botrytis cinerea) in the cape gooseberry crop.

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Scientific Article

Biodegradables films with fungistatic activity for the postharvest control of Fusarium solani in Hass avocado fruit

byWendy Abril Flores Pérez , Nemesio Villa Ruano , Efraín Rubio Rosas*

Received: 31/January/2022 – Published: 23/August/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2303-4

Abstract Little is known on the use of biodegradable films for the control of diseases in crops of agricultural importance. Consequently, the objective of this work was to determine the efficacy of chitosan hybrid films impregnated with thyme essential oil on Hass avocado fruits previously infected with Fusarium solani isolated from the northeastern highlands of Puebla, Mexico. The native strain of F. solani was morphologically and molecularly identified and the fungistatic activity of three chitosan films supplemented with 0.7% (FT1), 1.0% (FT2) and 1.3% (FT3) of thyme essential oil was evaluated in situ on the growth of F. solani in avocado fruits. Texture, transmittance and opacity of the films were obtained by scanning electron microscopy and UV-Vis spectrometry, respectively. Overall, it was recorded that films with a higher concentration of thyme essential oil (1-1.3% w/v) presented lower transmittance in the UV light range and higher opacity. Avocado fruits infected with F. solani simultaneously treated with FT2 and FT3 reduced the appearance of symptoms while preserved firmness, as well as fiber, fat, reducing sugars, and protein content (p < 0.01). In the same context, these materials promoted the conservation of the content of the nutraceuticals linoleic acid, oleic acid, palmitic acid and palmitoleic acid for 21 days. These results suggest that the hybrid films generated in the present study have the ability to control fusariosis caused by this fungus, prolonging the shelf life of Hass avocado fruit.

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Figure 1. Morphology of Fusariun solani. A) Radial growth observed from the obverse of Petri dish in PDA after 7 days. B) Radial growth observed from the reverse of Petri dish. C) Macroconida observed at 50X without staining. D) Microconidia observed at 50X stained with cotton blue.

Figure 2. Phylogenetic tree of <em>Fusarium solani</em> with concatenated sequences of ITS and EF-1α. The strain <em>F. solani</em> isolated from the northeast highland of Puebla is remarked in bold font.

Figure 2. Phylogenetic tree of Fusarium solani with concatenated sequences of ITS and EF-1α. The strain F. solani isolated from the northeast highland of Puebla is remarked in bold font.

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Scientific Article

Biofilm of epiphytic algae and fungi in forest plantations of pinabete (Abies guatemalensis) in Guatemala

byAndrés Villalobos*, Ana Lucía Dubón , María Renée Álvarez , Sergio Osorio , Margarita Palmieri

Received: 31/January/2022 – Published: 23/August/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2301-2

Abstract In recent years, a new pest has been reported in Guatemalan fir (Abies guatemalensis) plantations, a biofilm of microorganisms known as “green algae”. The objective of this research was to identify the algae and fungi that make up the biofilm growing on Guatemalan fir leaves. Leaf samples were collected from three locations where the biofilm has been reported, and the algae and fungi present on the leaves were isolated. Microorganisms were cultured in vitro and identified by light microscopy; in the case of fungi, DNA extraction and amplification of the ITS region were also performed. Four algae of the genera Desmococcus, Klebsormidium and the class Trebouxiophyceae, and 11 fungi of the genera Alternaria, Aspergillus, Fusarium, Mucor, Trichoderma and Ulocladium were identified from 120 leaves of 15 trees. It was concluded that the biofilm affecting Guatemalan fir plantations in Guatemala is composed of several species of epiphytic algae and fungi, which may vary according to the locality. The factors affecting the richness of microorganisms in the biofilm and their symbiotic relationship still need to be addressed

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Multidiscipline, a basic component of innovation in the biological control of plant pathogens

byEnrique Galindo

Received: 03/August/2023 – Published: 24/August/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2308-1

Abstract

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