Article filters

Search Papers

Title / Keyword

Author Affiliation

Type of scientific article

Knowledge area

Volume

Year

Spanish | English

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

Home
All the articles

<em>Trichoderma</em> spp. condiospores production and its application with <em>Streptomyces</em> spp. for the management of <em>Mycosphaerella fijiensis</em> in banana. Figure 1 - Total area under the disease progress curve (AUDPC) of black Sigatoka in “Gran Enano” banana through applications of <em>Trichoderma</em> spp.

Figure 1 - Total area under the disease progress curve (AUDPC) of black Sigatoka in “Gran Enano” banana through applications of Trichoderma spp.

Hrp proteins as bioinducers for the biocontrol of bacterial diseases in tomato and pepper plants in greenhouse. Figure 2 - Biological effectiveness of different biological treatments for the control of X. <em>euvesicatoria</em>, strain BV865 in ancho chili pepper plants, San Luis variety, under greenhouse conditions, depending on the amount of necrotic, chlorotic and total spots per plant. PS=Healthy plant; PE=Diseased plant; AG=Actigard<sup>®</sup> (0.003 g mL<sup>−1</sup>); MG= Messenger Gold<sup>®</sup> (0.003 g mL<sup>−1</sup>); BF= BioFensa (1 μg mL<sup>−1</sup>). Different letters in each response variable indicate significant differences according to the LSD test (p≤0.05). Bars in the rectangle indicate ± the standard error.

Figure 2 - Biological effectiveness of different biological treatments for the control of X. euvesicatoria, strain BV865 in ancho chili pepper plants, San Luis variety, under greenhouse conditions, depending on the amount of necrotic, chlorotic and total spots per plant. PS=Healthy plant; PE=Diseased plant; AG=Actigard^® (0.003 g mL⁻¹); MG= Messenger Gold^® (0.003 g mL⁻¹); BF= BioFensa (1 μg mL⁻¹). Different letters in each response variable indicate significant differences according to the LSD test (p≤0.05). Bars in the rectangle indicate ± the standard error.

Hrp proteins as bioinducers for the biocontrol of bacterial diseases in tomato and pepper plants in greenhouse. Figure 1 - Biological effectiveness of different biological treatments for the control of P. <em>syringae</em> pv. <em>tomato</em>, strain DC3000 (bacterial speck) in tomato plants under greenhouse conditions, depending on the amount of necrotic, chlorotic and total spots per plant. PS=Healthy plant; PE=Diseased plant; AG=Actigard<sup>®</sup> (0.003 g mL<sup>−1</sup>); MG= Messenger Gold<sup>®</sup> (0.003 g mL<sup>−1</sup>); BF= BioFensa (1 μg mL<sup>−1</sup>). Different letters in each response variable indicate significant differences according to the LSD test (p≤0.05). Bars in the rectangle indicate ± the standard error.

Figure 1 - Biological effectiveness of different biological treatments for the control of P. syringae pv. tomato, strain DC3000 (bacterial speck) in tomato plants under greenhouse conditions, depending on the amount of necrotic, chlorotic and total spots per plant. PS=Healthy plant; PE=Diseased plant; AG=Actigard^® (0.003 g mL⁻¹); MG= Messenger Gold^® (0.003 g mL⁻¹); BF= BioFensa (1 μg mL⁻¹). Different letters in each response variable indicate significant differences according to the LSD test (p≤0.05). Bars in the rectangle indicate ± the standard error.

Figure 2 - Behavior of the area under the disease progress curve (AUDPC) of black Sigatoka in Gran Enano banana through applications of Trichoderma spp.

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 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 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.

Etiology of rhizome rot of asparagus (<em>Asparagus officinalis</em>) in Atenco, Mexico State. Figure 2 - F. proliferatum isolations used for the pathogenicity tests via different inoculation methods. A) Concatenated phylogenetic tree of isolates ON738483 (PISIR), ON738484 (P3DR) and ON973801 (P5DR) with the primers ITS 4-ITS5, EF688-EF1521, TUB T1-BT2B. B) Rhizome colonization by isolate P1SIR, C) Mycelial growth of <em>Fusarium</em> on the front and back of PDA medium after 7 days of growth, D) Macro and microconidia at 40X. E) Rhizome colonization by isolation P3DR, F) Mycelial growth of <em>Fusarium</em> on the front and back of PDA medium after 7 days of growth, G) Macro and microconidia at 40X. H) Rhizome colonization by isolate P5DR, I) Mycelial growth of <em>Fusarium</em> on the front and back of PDA medium after 7 days of growth, J) Macro and microconidia at 40X

Figure 2 - F. proliferatum isolations used for the pathogenicity tests via different inoculation methods. A) Concatenated phylogenetic tree of isolates ON738483 (PISIR), ON738484 (P3DR) and ON973801 (P5DR) with the primers ITS 4-ITS5, EF688-EF1521, TUB T1-BT2B. B) Rhizome colonization by isolate P1SIR, C) Mycelial growth of Fusarium on the front and back of PDA medium after 7 days of growth, D) Macro and microconidia at 40X. E) Rhizome colonization by isolation P3DR, F) Mycelial growth of Fusarium on the front and back of PDA medium after 7 days of growth, G) Macro and microconidia at 40X. H) Rhizome colonization by isolate P5DR, I) Mycelial growth of Fusarium on the front and back of PDA medium after 7 days of growth, J) Macro and microconidia at 40X

Detection and molecular characterization of a 16SrII group phytoplasma associated with ‘witches broom’ disease in cactus (<em>Opuntia</em> sp.). Figure 2 - RFLP analysis of the 16S rDNA of phytoplasmas amplified using primers R16F2n/R16R2 and digested with five restriction enzymes: EcoRI, HaeIII, KpnI, MseI and RsaI M: molecular marker 100 pb (Promega, USA); A) Positive control ‘Candidatus Phytoplasma asteris’ (I-B); B) Symptomatic sample of cactus from this study (Accession number: 0N413680); C) Restriction patterns <em>in silico</em>, generated from the sequences of gene 16S rDNA of the Cactus witches’-broom phytoplasma 16SrII-C (Accession number: AJ293216.2) of the reconnaissance sites for 17 restriction enzymes.

Figure 2 - RFLP analysis of the 16S rDNA of phytoplasmas amplified using primers R16F2n/R16R2 and digested with five restriction enzymes: EcoRI, HaeIII, KpnI, MseI and RsaI M: molecular marker 100 pb (Promega, USA); A) Positive control ‘Candidatus Phytoplasma asteris’ (I-B); B) Symptomatic sample of cactus from this study (Accession number: 0N413680); C) Restriction patterns in silico, generated from the sequences of gene 16S rDNA of the Cactus witches’-broom phytoplasma 16SrII-C (Accession number: AJ293216.2) of the reconnaissance sites for 17 restriction enzymes.

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 2 - Inhibition of <em>Rhizoctonia solani</em> using plant <em>Agave striata</em> and <em>Fouquieria splendens</em> 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.

All the Articles

Open access
Review Article

Viruses and viroids in tomato (Solanum lycopersicum) and plant growth promoting rhizobacteria as a management alternative

byErika Janet Zamora Macorra , Norma Ávila Alistac*, Erika Lagunes Fortiz , Sergio de los Santos Villalobos

Received: 30/August/2023 – Published: 28/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2023-7

Abstract Viruses and viroids cause several diseases in tomato (Solanum lycopersicum) worldwide, generating important economic losses. About 312 viruses and seven viroids have been associated, of which more than 28 are present in Mexico. Therefore, the use of Plant Growth-Promoting Rhizobacteria (PGPR) can be an effective alternative for the management of viruses and viroids. The genera Pseudomonas, Bacillus, Azospirillum, Anabena and Stenotrophomonas have been implemented against main viruses reported in tomato: Cucumber mosaic virus (CMV), Tobacco mosaic virus (TMV), Tomato chlorotic spot virus (TCSV), Tomato mottle virus (ToMoV), Tomato spotted wilt virus (TSWV), Tomato yellow leaf curl virus (TYLCV), Potato virus Y (PVY), Groundnut bud necrosis virus (GBNV), with benefits in decreased incidence and severity up to 80 % and yield increase over 40 %. In Mexico, only Bacillus has been used. The use of PGPR is a strategy that could mitigate the impact of viral and viroid diseases and can be integrated into integrated management.

Show Figures and/or Tables

Figure 1. States of the Mexican Republic where viruses and viroids were detected in tomato (See Table 1)

Figure 2. Main forms of transmission of viruses and viroids in tomato. A) Transmission by seed; B) Mechanical transmission, due to the use of work tools, manipulation of plants; C) Transmission by insect vectors.

Figure 3. Symptoms associated with viruses and viroids in tomatoes. A and B) Mosaic, leaf reduction, and mild to severe leaf distortion associated with Tomato brown rugose fruit virus; C and D) Stunting, fruit deformation, and purple discoloration in leaves caused by Mexican papita viroid; E) Yellow mosaic symptom associated with Pepino mosaic virus; F) Symptoms of stunting, deformation, and severe mosaic associated with Begomovirus; G and H) Symptoms of concentric rings and slight fruit deformation associated with Tomato spotted wilt virus; I) Mosaic in leaves caused by Tobacco mosaic virus

Figure 4. Forms of application and mechanisms of action of Plant Growth-Promoting Rhizobacteria (PGPR) used to protect tomatoes from viral infections.

Table 1. Main viruses reported in tomato (<em>Solanum lycopersicum</em>) in Mexico and the world

Table 1. Main viruses reported in tomato (Solanum lycopersicum) in Mexico and the world

Table 2. Viroids that affect tomato (<em>Solanum lycopersicum</em>) in the world

Table 2. Viroids that affect tomato (Solanum lycopersicum) in the world

Table 3. Plant growth-promoting rhizobacteria species used for virus management in tomato.

Open access
Review Article

Weeds and ruderal plants as potential sources of inoculum for vegetable diseases in northern Sinaloa

byRubén Félix Gastélum , Gabriel Herrera Rodríguez , Karla Yeriana Leyva Madrigal , Guadalupe Arlene Mora Romero

Received: 31/July/2023 – Published: 28/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2023-4

Abstract Weeds and ruderal plants of the families Cucurbitaceae and Solanaceae are addressed as potential sources of inoculum for the development of viral diseases such as Tomato apex necrosis virus (ToANV), zucchini (Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Papaya ring spot virus (PRSV-W) and Cucumber mosaic virus (CMV). Reference is made to weeds and ruderal plants as potential sources of inoculum, including wild sunflower for powdery mildew (Golovinomyces spadiceus), wild tobacco for foliar blight (Alternaria spp.), black nightshade for leaf spot (Curvularia moehlemvekiae), Johnson grass for foliar blight (Alternaria sp.), and wild castor bean for foliar blight (Alternaria ricini) and wild melon for downy mildew (Pseudoperonospora cubensis). Future lines of multidisciplinary research focusing on the determination of pathogenicity in cultivated plants of viruses and fungi associated with wild plants and vice versa are proposed; the spatial-temporal distribution of wild plants that may serve as sources of inoculum, as well as the of potential insect vectors of viral diseases, should also be studied. The implementation of modern molecular techniques, such as High Throughput Sequencing, for the detection of phytopathogens is important. All this will contribute to the implementation of environmentally friendly strategies for disease control in agricultural crops in Sinaloa, for the benefit of the vegetable growers

Show Figures and/or Tables

Figure 1. Symptoms induced by <em>Tomato apex necrosis virus</em> (ToANV). A) Necrosis in young growth of tomato; B) Necrosis in tomato fruit; C) interveinal chlorosis in leaves of husk tomato; D) Yellowing in wild husk tomato (Physallis sp.); E) Slight yellowing and deformation of initial leaves in black nightshade (Solanum nigrum); F) Initial symptoms of interveinal chlorosis; G) Intense chlorosis and vein greening of wild tobacco (Nicotiana glauca) leaves; H) General yellowing in black nightshade (Solanum asureum).

Figure 1. Symptoms induced by Tomato apex necrosis virus (ToANV). A) Necrosis in young growth of tomato; B) Necrosis in tomato fruit; C) interveinal chlorosis in leaves of husk tomato; D) Yellowing in wild husk tomato (Physallis sp.); E) Slight yellowing and deformation of initial leaves in black nightshade (Solanum nigrum); F) Initial symptoms of interveinal chlorosis; G) Intense chlorosis and vein greening of wild tobacco (Nicotiana glauca) leaves; H) General yellowing in black nightshade (Solanum asureum).

Figure 2. Symptoms induced by the virus Zucchini yellows mosaic virus (ZYMV). A) Yellowing in Zucchini squash var. Grey leaf; B) Symptoms of deformation of the fruit of the same host caused by the same virus.

Figure 3. Symptoms induced by the virus Zucchini yellows mosaic virus (ZYMV). A) Yellowing in Zucchini squash var. Grey leaf; B) Symptoms of deformation of the fruit of the same host caused by the same virus.

Table 1. Viruses causing diseases in cucurbits and tomato in Sinaloa and other parts of the world

Open access
Phytopathological note

Cellulase and chitinase production by Fusarium oxysporum f.sp. cubense race 1 in submerged culture

byDulce Jazmín Hernández Melchor , Ronald Ferrera Cerrato , Clemente de Jesús García Ávila , Alejandro Alarcón*

Received: 09/July/2023 – Published: 29/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2307-2

Abstract Background/Objective. Fusarium has the capability to produce hydrolytic enzymes that can be used in the food and alcohol industries to break down natural organic compounds. This work studied the ability of Fusarium oxysporum f. sp. cubense race 1 (FocR1) to produce cellulases and chitinases enzymes in submerged culture using different carbon sources.

Materials and Methods. Five strains of FocR1 (CNRF-MIC17188, CNRF-MIC17189, CNRF-MIC17190, CNRF-MIC17191, and CNRF-MIC17192) were used in submerged culture for the degradation of three substrates [filter paper, newspaper, and chitin (Sigma®)], from where the radial growth rate (RGr) and the quantitative analysis of enzyme activities (FPase, CMCase and chitinase) were evaluated.

Results. The RGr of the five FocR1 strains oscillated in a range of 0.043 to 0.051 cm h-1. At 7 and 14 days, the five FocR1 strains produced cellulases and chitinases using the three substrates. Based on the statistical analysis, the strains CNRF-MIC17191 and CNRF-MIC17192 showed best results about enzymatic activities.

Conclusion. The five strains of FocR1 can be exploited as a commercial source of cellulases and chitinases, as well as potential candidates for bioconverting complex C-sources for further utilization in industrial processes

Show Figures and/or Tables

Figure 1. Radial growth rate (RGr) of <em>Fusarium oxysporum</em> f.sp. cubense Race 1 (FocR1) strains in PDA medium, at 192 h. Different letters on bars are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 1. Radial growth rate (RGr) of Fusarium oxysporum f.sp. cubense Race 1 (FocR1) strains in PDA medium, at 192 h. Different letters on bars are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 2. Quantitative enzymatic activity of five strains of <em>Fusarium oxysporum</em> f.sp. cubense Race 1 (FocR1) using newspaper as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 2. Quantitative enzymatic activity of five strains of Fusarium oxysporum f.sp. cubense Race 1 (FocR1) using newspaper as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 3. Quantitative enzymatic activity of five strains of <em>Fusarium oxysporum</em> f.sp. cubense Race 1 (FocR1) using filter paper as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 3. Quantitative enzymatic activity of five strains of Fusarium oxysporum f.sp. cubense Race 1 (FocR1) using filter paper as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 4. Quantitative enzymatic activity of five strains of <em>Fusarium oxysporum</em> f.sp. cubense Race 1 (FocR1) using chitin as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Figure 4. Quantitative enzymatic activity of five strains of Fusarium oxysporum f.sp. cubense Race 1 (FocR1) using chitin as substrate, at 7 and 14 days. A) Cellulase activity (FPase). B) Carboxymethyl cellulase (CMCase). C) Chitinase activity. Different letters over the bars in the three graphs are significantly different (Tukey; p≤0.05). Means ± standard error, n=3.

Open access
Phytopathological note

Diagrammatic scale to quantify the severity of Ascochyta blight in broad bean crops

byErnesto Alonso López Reyes , Álvaro Castañeda Vildózola*, Jesús Ricardo Sánchez Pale , Alejandra Contreras Rendón , Juyma Mayvé Fragoso Benhumea , Rómulo García Velasco

Received: 15/September/2022 – Published: 26/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2209-4

Abstract Background/Objective. The objective of this study was to design and validate a diagrammatic severity scale of brown spot on broad bean.

Materials and Methods. We collected 120 leaflets with different level of brown spot damage from commercial crops in the Toluca Valley, which were visually selected based on the expressed symptomology. Sixty leaflets were scanned for evaluation with the software APS PRESS ©Assess 2.0 to determine the real severity value for each leaflet.

Results. The damage values allowed us to generate a diagrammatic scale consisting of six different classes: 0(0.0), 1(0.1-6.0), 2(6.1-10.0), 3(10.1-15.0), 4(15.1-40.0), 5(> 40.1-100). The leaflets were visually examined by evaluators who had no prior experience. The results from each evaluator were analyzed with a simple linear regression, obtaining r2 values from 0.0042 to 0.8748, β0 de 0.51 a 9.11, y β1 de 0.132 a 0.925. Using a scale, r2 values were obtained 0.9143 to 0.985, β0 de 0.001 a 0.911 y β1<0.001.

Conclusion. The generated diagrammatic severity scale was validated and reproducible, showing high reliability.

Show Figures and/or Tables

Figure 1. Diagrammatic scale of brown spot severity (Ascochyta fabae) in broad bean. zLower limit-average-upper limit.

Figure 2. Distribution of residuals (estimated severity-real severity) of the brown spot evaluations (Ascochyta fabae) in broad bean leaflets. A) Scaled evaluation. B) Unscaled evaluation.

Table 1. Values of the Intercept (β0), slope of the line (β1), coefficient of determination (r²) and margin of error (1-r²) of the simple linear regression equation in visual estimations of the severity in of brown spot in broad bean (Ascochyta fabae), with 20 unscaled evaluators and 10 scaled evaluators

Open access
Phytopathological note

Biostimulant effect of native Trichoderma strains on the germination of four varieties of basil

byJuanita Guadalupe Hollman Aragón , Mirella Romero Bastidas*, Pablo Misael Arce Amezquita , Alejandro Palacios Espinosa

Received: 15/March/2023 – Published: 19/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2303-1

Abstract Objetive/antecedents. Trichoderma is an efficient tool as biostimulant in basil crop. However, only few species have been studied in specific cultivars. Therefore, the objective of this research was to evaluate the biostimulant efficacy of native Trichoderma strains on the germination and growth of four varieties of basil.

Materials and Methods. Seven strains of Trichoderma (T. asperellum, atroviride, viride, longibrachiatum, harzianum, koningii and Trichoderma sp.), a commercial Trichoderma (T. harzianum), synthetic fertilizer (T17) and the control were used in the study. 30 seeds of the Purple Ruffles, Lemon, Siam Queen and Nufar varieties were treated with a spore suspension of each Trichoderma. 48 h later, the seeds were sown and incubated at 28 °C with a 12 h light/dark photoperiod. The variables evaluated were; Rate and percentage of germination, biomass and length of seedlings.

Results. T. atroviride presented the greatest biostimulant effect on germination (95%). While T. asperellum registered an increased efficiency in biomass (≥ 0.120 g) and length (≥ 1.0 cm) of the plant in the four varieties. The action of commercial T. was lower in all cases.

Conclusion. This study demonstrated that the native strains of Trichoderma have a biostimulant effect on plants and are more effective than commercial species.

Show Figures and/or Tables

Figure 1. Biostimulating action of native <em>Trichoderma</em>s in the percentage of germinated seeds of four varieties of basil

Figure 1. Biostimulating action of native Trichodermas in the percentage of germinated seeds of four varieties of basil

Figure 2. Main <em>Trichoderma</em> treatments with the highest positive (1st. and 2nd. photo from the left) or negative response (3rd. photo on the right) in the growth of four basil cultivars

Figure 2. Main Trichoderma treatments with the highest positive (1st. and 2nd. photo from the left) or negative response (3rd. photo on the right) in the growth of four basil cultivars

Table 1. Morphometric parameters of basil Var. Purple Ruffles seedlings against the effect of different <em>Trichoderma</em> isolates

Table 1. Morphometric parameters of basil Var. Purple Ruffles seedlings against the effect of different Trichoderma isolates

Table 2. Morphometric parameters of basil Var. Lemon against the effect of different <em>Trichoderma</em> isolates.

Table 2. Morphometric parameters of basil Var. Lemon against the effect of different Trichoderma isolates.

Table 3. Morphometric parameters of basil Var. Siam Queen against the effect of different <em>Trichoderma</em> isolates

Table 3. Morphometric parameters of basil Var. Siam Queen against the effect of different Trichoderma isolates

Table 4. Morphometric parameters of basil Var. Nufar against the effect of different <em>Trichoderma</em> isolates

Table 4. Morphometric parameters of basil Var. Nufar against the effect of different Trichoderma isolates

Open access
Review Article

Current situation of viticulture in Costa Rica and management strategies for downy mildew (Plasmopara viticola)

byDaniel Castrillo Sequeira , Rodrigo Jiménez Robles , Milagro Granados Montero*

Received: 18/September/2023 – Published: 27/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2309-3

Abstract Viticulture is one of the oldest agricultural activities, and its exploitation has traditionally been limited to temperate climate zones, where the european grapevine (Vitis vinifera) and wine originate. Given the effects of climate change, more areas lose the capacity to grow this crop, and the tropics are presented as potential regions for this market. In Costa Rica, viticultural activity has been reported since the mid20th century, however, technical information on the crop is scarce. Downy mildew, caused by the oomycete Plasmopara viticola, represents one of the diseases with the greatest economic impact for viticulture worldwide, as well as the most limiting phytosanitary problem in Costa Rica. Under high humidity conditions, the development of the pathogen is accelerated, and the host remains susceptible throughout the crop cycle, which makes proper management of epidemics difficult. Chemical control is the most common management strategy around the world, however, the appearance of P. viticola populations with resistance to fungicides has been observed in most grape vine-growing areas, hence the search for more ecological alternatives is a necessity. Currently, Costa Rica does not have integrated management strategies that allow sustainable production, and there is only one registered product for protection against this pathogen. This situation justifies paying more attention to the investigation of this pathosystem

Show Figures and/or Tables

Figure 1. Location of the main grapevine plantations in Costa Rica

Figure 2. Life cycle of the <em>Plasmopara viticola</em> in the grapevine (<em>Vitis vinifera</em>)

Figure 2. Life cycle of the Plasmopara viticola in the grapevine (Vitis vinifera)

Figure 3. Symptoms and characteristic signs of downy mildew in the grapevine (<em>Vitis vinifera</em>), caused by the oomycete <em>Plasmopara viticola</em>. A. Chlorosis and foliar necrosis. B. Sporulation on the reverse of leaves with necrotic lesions. C. Sporulation on young fruits. D. Leaf necrosis and poor filling of fruits

Figure 3. Symptoms and characteristic signs of downy mildew in the grapevine (Vitis vinifera), caused by the oomycete Plasmopara viticola. A. Chlorosis and foliar necrosis. B. Sporulation on the reverse of leaves with necrotic lesions. C. Sporulation on young fruits. D. Leaf necrosis and poor filling of fruits

Figure 4. Tactics (advantages and disadvantages) documented for the management of downy mildew in the vine (<em>Vitis vinifera</em>), caused by the oomycete <em>Plasmopara viticola</em>.

Figure 4. Tactics (advantages and disadvantages) documented for the management of downy mildew in the vine (Vitis vinifera), caused by the oomycete Plasmopara viticola.

Table 1. List of active ingredients available for oomycete control, divided according to the FRAC mode of action and chemical group, modified from Hollomon (2015)

Open access
Scientific Article

Induction of defense response mediated by inulin from dahlia tubers (Dahlia sp.) in Capsicum annuum

byJulio César López Velázquez , Soledad García Morales , Joaquín Alejandro Qui Zapata*, Zaira Yunuen García Carvajal , Diego Eloyr Navarro López , Rebeca García Varela

Received: 10/May/2023 – Published: 29/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2305-2

Abstract Background/Objective. Phytophthora capsici is the causal agent of chili wilt. Among the strategies for its control is the use of resistance inducers. Fructans are molecules with interesting biological properties, including the ability to induce resistance mechanisms in some plants. In this work, the protective effect of four concentrations inulin from dahlia tubers on chili infected with P. capsici was evaluated.

Materials and Methods. The concentration that showed the highest protection was chosen to evaluate the induction of defense response through the enzymatic activity of β-1,3 glucanases, peroxidases and the production of total phenolic compounds.

Results. Inulin showed a protective effect against infection at concentrations of 100 to 300 μM, as symptoms decreased and seedlings showed improved vegetative development. It was observed that inulin at 200 μM concentration was able to induce an effective defense response associated with increased activity of β-1,3 glucanases and peroxidases through a local and systemic response in seedlings. This response was differentiated between seedlings treated with inulin and seedlings infected with P. capsici.

Conclusion. It was concluded that inulin has the ability to protect chili bell pepper from P. capsici by induction of resistance.

Show Figures and/or Tables

Figure 1. Evaluation of dahlia inulin in the protection of <em>P. capsici</em> infection in chili seedlings. a: Biological effectiveness test of dahlia inulin in chili seedlings, bar equivalent to 10 cm; b: Root damage, bar equivalent to 5 cm; c: Presence of the oomycete in chili roots, bar equivalent to 20 μm, arrows indicate oomycete presence. Treatments as follows: C: Control seedlings, treated with only sterile distilled water; P: Seedlings inoculated with <em>P. capsici</em>; I1+P: Seedlings inoculated with <em>P. capsici</em> and treated with 20 μM of inulin; I2+P: Seedlings inoculated with <em>P. capsici</em> and treated with 100 μM of inulin; I3+P: Seedlings inoculated with <em>P. capsici</em> and treated with 200 μM of inulin; I4+P: Seedlings inoculated with <em>P. capsici</em> and treated with 300 μM of inulin

Figure 1. Evaluation of dahlia inulin in the protection of P. capsici infection in chili seedlings. a: Biological effectiveness test of dahlia inulin in chili seedlings, bar equivalent to 10 cm; b: Root damage, bar equivalent to 5 cm; c: Presence of the oomycete in chili roots, bar equivalent to 20 μm, arrows indicate oomycete presence. Treatments as follows: C: Control seedlings, treated with only sterile distilled water; P: Seedlings inoculated with P. capsici; I1+P: Seedlings inoculated with P. capsici and treated with 20 μM of inulin; I2+P: Seedlings inoculated with P. capsici and treated with 100 μM of inulin; I3+P: Seedlings inoculated with P. capsici and treated with 200 μM of inulin; I4+P: Seedlings inoculated with P. capsici and treated with 300 μM of inulin

Figure 2. Evaluation of β-1,3 glucanase activity in roots (a) and leaves (b) of chili seedlings treated with dahlia inulin and inoculated with <em>P. capsici</em>. C: Control seedlings, treated with sterile distilled water; P: Seedlings inoculated with <em>P. capsici</em>; I: Seedlings treated with 200 μM of inulin; IP: Seedlings inoculated with <em>P. capsici</em> and treated with 200 μM of inulin. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control

Figure 2. Evaluation of β-1,3 glucanase activity in roots (a) and leaves (b) of chili seedlings treated with dahlia inulin and inoculated with P. capsici. C: Control seedlings, treated with sterile distilled water; P: Seedlings inoculated with P. capsici; I: Seedlings treated with 200 μM of inulin; IP: Seedlings inoculated with P. capsici and treated with 200 μM of inulin. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control

Figure 3. Evaluation of peroxidase activity in roots (a) and leaves (b) of chili seedlings. The treatments are described in figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control

Figure 4. Quantification of total phenolic compounds in roots (a) and leaves (b) of chili seedlings. The treatments are described in Figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control

Table 1. Growth parameters and protection induced by dahlia inulin in chili seedlings.

Open access
Scientific Article

Establishment of an efficient protocol for in vitro disinfection of seeds of seven Agave spp. species

byMaría Guadalupe Aguilar Rito , Amaury Martín Arzate Fernández*, Hilda Guadalupe García Núñez , Tomas Héctor Norman Mondragón

Received: 02/October/2023 – Published: 20/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2310-1

Abstract Background. Disinfection of Agave seeds is a crucial step in in vitro culture to prevent contamination, which can be caused by microorganisms such as bacteria, fungi and viruses that can affect seedling growth and reduce seed germination rate. Therefore, proper seed disinfection is essential to ensure vigorous and healthy plant growth. Objective. Generate an efficient seed disinfection protocol in seven species of Agave; Agave marmorata, A. karwinskii, A. potatorum, A. angustifolia, A. cupreata, A. horrida and A. salmiana to reduce pollution levels.

Materials and Methods. A total of 12 disinfection treatments with disinfectants and different combinations were evaluated. The disinfectants used were; 3 % Hydrogen Peroxide for 24 h, Commercial Sodium Hypochlorite 5 % (v/v) for 5 min, Calcium Hypochlorite 8 % (w/v) for 15 min, Copper Sulfate 30 % (v/v) for 10 min, Mercury Chloride II 0.1 % (w/v) for 10 min. Before each treatment was tested, the seeds were pre-washed with liquid soap and subjected to the treatments, Subsequently, they were sown in DM medium and the percentage of germination and contamination for each treatment was evaluated weekly for a period of 30 days. Additionally, the contaminating microorganisms found were identified.

Results. The best treatment for seed disinfection was 30 % copper sulfate (v/v) for 10 min, 0.1 % mercuric chloride II for 10 min and 3 % hydrogen peroxide for 24 h, obtaining 100 % disinfection. Four genera of fungi were identified: Monilinia sp., Aspergillus sp., Penicillium sp., and Alternaria alternata, a bacterium; Bacillus sp., and a yeast, Schizosaccharomyces sp.

Show Figures and/or Tables

Figure 1. A. salmiana seed germination. A) root emergence and elongation. (14 dap) B) Elongation of the plumule. (21 dap) C) Diferenciation of the root cotyledons and development. (30 dap) D) Full germination and development. (14-30 dap) E) Normal, completely developed A. salmiana seedlings. (50 dap); dap days after planting

Figure 2. Bacterial and fungal strains found in the seeds of Agave spp. A) <em>Schizosaccharomyces sp.</em> B) <em>Bacillus</em> sp. C) Penicilllium sp. D) <em>Alternaria alternata</em>. E) <em>Aspergillus sp.</em> F) <em>Monilinia sp.</em>

Figure 2. Bacterial and fungal strains found in the seeds of Agave spp. A) Schizosaccharomyces sp. B) Bacillus sp. C) Penicilllium sp. D) Alternaria alternata. E) Aspergillus sp. F) Monilinia sp.

Table 1. Agave species and seed collection data

Table 2. Disinfection treatments evaluated in seven Agave species

Table 3. Analysis of variance for the variables contamination and germination, evaluating 12 disinfection treatments and seven agave species.

Table 4. Analysis of variance for the variables contamination and germination, evaluatinMeans comparison for the variables contamination and germination in seven agave species, according to Tukey’s test (p<0.05).g 12 disinfection treatments and seven agave species.

Table 5. Contaminant microorganisms found in the Agave seeds after applying the treamtnets

Open access
Scientific Article

Bacillus sp. A8a reduces leaf wilting by Phytophthora and modifies tannin accumulation in avocado

byEdgar Guevara Avendaño , Itzel Anayansi Solís García , Alfonso Méndez Bravo , Fernando Pineda García , Guillermo Angeles Alvarez , Carolina Madero Vega , Sylvia P. Fernández Pavía , Alejandra Mondragón Flores , Frédérique Reverchon*

Received: 17/September/2023 – Published: 08/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2309-2

Abstract Background/Objective. The objective was to assess the biocontrol capacity of Bacillus sp. A8a in avocado (Persea americana) plants infected by Phytophthora cinnamomi.

Materials and Methods. A greenhouse experiment was implemented with four treatments: 1) control plants; 2) plants infected with P. cinnamomi; 3) plants inoculated with Bacillus sp. A8a; 4) plants infected with P. cinnamomi and inoculated with Bacillus sp. A8a. We evaluated several morpho physiological variables during the experiment, which lasted 25 days after infection (dai). Moreover, we analyzed tannin density in stems at 25 dai to determine the plant defense response against the disease.

Results. Inoculation with strain A8a reduced wilting symptoms by 49 % at 25 dai, compared with non-inoculated plants. No differences were detected in morpho physiological variables between treatments. However, a greater tannin accumulation was registered in the xylem of infected plants, whilst plants inoculated with strain A8a displayed a larger tannin density in the cortex.

Conclusion. Our results confirm the biocontrol activity of Bacillus sp. A8a in avocado plants and suggest that tannin differential accumulation in the cortex of plants inoculated with the bacteria may contribute to the enhanced tolerance of avocado plants against Phytophthora root rot.

Show Figures and/or Tables

Figure 1. Effect of the inoculation of <em>Bacillus</em> sp. A8a and <em>P. cinnamomi</em> in avocado trees at 1, 4, 7, 13 and 25 dai (days after infection). A) Percentage of wilting caused by <em>P. cinnamomi</em>; B) tree height (cm); C) stem diameter (cm). Bars show the average of the data (n = 6, treatments C and Pc; n = 3, treatments B and BPc) ± s.d. Different letters indicate significant differences (two-way ANOVA, P ≤ 0.05). In Figure 1A, (+) indicates significant differences between times, compared with (-), for the Pc treatment (ANOVA, P ≤ 0.05). D) Representative photographs of the aerial parts and root systems of avocado trees at 25 dai, in the four treatments. C: control; Pc: infected with <em>P. cinnamomi</em>; B: inoculated with <em>Bacillus</em> sp. A8a; BPc: infected with <em>P. cinnamomi</em> and inoculated with <em>Bacillus</em> sp. A8a.

Figure 1. Effect of the inoculation of Bacillus sp. A8a and P. cinnamomi in avocado trees at 1, 4, 7, 13 and 25 dai (days after infection). A) Percentage of wilting caused by P. cinnamomi; B) tree height (cm); C) stem diameter (cm). Bars show the average of the data (n = 6, treatments C and Pc; n = 3, treatments B and BPc) ± s.d. Different letters indicate significant differences (two-way ANOVA, P ≤ 0.05). In Figure 1A, (+) indicates significant differences between times, compared with (-), for the Pc treatment (ANOVA, P ≤ 0.05). D) Representative photographs of the aerial parts and root systems of avocado trees at 25 dai, in the four treatments. C: control; Pc: infected with P. cinnamomi; B: inoculated with Bacillus sp. A8a; BPc: infected with P. cinnamomi and inoculated with Bacillus sp. A8a.

Figure 2. Leaf water potential in avocado trees at 1, 4, 7, 13 and 25 dai. A) Leaf water potential (MPa) at 5:00 am; B) foliar water potential at 14:00 pm. Bars show the average of the data (n = 3 ± s.d.). Different letters indicate significant differences between treatments at the same time. The water potential measured at 1, 4 and 25 dai was analyzed with a oneway ANOVA and Tukey’s test (P ≤ 0.05). Non-parametric data recorded at 7 y 13 dai were analyzed with KruskalWallis and Wilcoxon rank sum tests ( P ≤ 0.05).

Figure 3. Tannin accumulation in crosssections of the cortex (C), outer xylem and inner xylem of avocado stems from the four treatments at 25 dai. A – C: Control treatment. A. A few tanniniferous cells (T) are observed interspersed in the tissue. B. Tanniniferous cells (T) are observed in the ray parenchyma. Vessels (V) and rays (r) are indicated. C. A few tanniniferous cells (T) are observed in the axial parenchyma and in some radial parenchyma (r). Ph = secondary phloem. Scale: A - C. 30 μm. Figures D – F: treatment Pc. D. Abundant tanniniferous cells (T) are observed. E. Tanniniferous cells (T) are in the radial as well as in the axial parenchyma. V = vessels. F. Tanniniferous cells (T) are mostly concentrated in the radial cells. Scale: D. 60 μm. E and F. 30 μm. Figures G – I: treatment B. G. Cross-section through the secondary phloem (Ph) and cortex (C). Some tanniniferous cells are interspersed amid parenchyma cells full with starch (asterisks). H. A long radial chain of vessels (V) can be observed in the center of the image. Only a few tanniniferous cells (T) are observed in the radial parenchyma. I. Tanniniferous cells (T) are even scarcer than in the outer xylem. Scale: G. 25 μm. H and I. 30 μm. Figures J – L: treatment BPc. J. Tanniniferous cells (T) are observed. K. Grouped or solitary vessels (V) and some tanniniferous cells (T) are observed in the radial parenchyma. L. Few tanniniferous cells (T) are observed in the axial parenchyma. Vessels (V) are grouped in radial chains or in groups of four. Scale: J - L. 35 μm.

Table 1. Photosynthetic rate, stomatal conductance and transpiration in avocado trees infected with <em>P. cinnamomi</em> and inoculated with <em>Bacillus</em> sp. A8a

Table 1. Photosynthetic rate, stomatal conductance and transpiration in avocado trees infected with P. cinnamomi and inoculated with Bacillus sp. A8a

Table 2. Percentage of the area occupied by tanniniferous cells at 25 dai in differ ent stem sections of avocado trees infected by <em>P. cinnamomi</em> and inocu lated with <em>Bacillus</em> sp. A8a.

Table 2. Percentage of the area occupied by tanniniferous cells at 25 dai in differ ent stem sections of avocado trees infected by P. cinnamomi and inocu lated with Bacillus sp. A8a.

Open access
Phytopathological note

Characterization of endophytic bacteria growth-promoting in potato plants (Solanum tuberosum)

byRosa María Longoria Espinoza*, Cristal Leyva Ruiz , Gloria Margarita Zamudio Aguilasocho , Rubén Félix Gastélum

Received: 02/October/2023 – Published: 23/January/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2310-4

Abstract Background/Objective. The purpose of this research was to evaluate the in vitro plant growth-promoting activity of endophytic bacteria isolated in tissue from Atlantic variety potato plants from the municipality of Guasave, Sinaloa, Mexico.

Materials and Methods. The bacterial population was isolated in Lb agar culture medium; two bacterial isolates were obtained from the root and two from the stem, all four Gram positive. The bacterial population of the tissue samples was expressed as (CFU/g-1). The phosphate solubilization capacity, production of chitinases and siderophores were qualitatively evaluated.

Results. Partial sequencing of the 16S rDNA gene was performed, allowing the identification of associated bacterial species within the Firmicutes. 100% of the strains were identified as Bacillus sp. with identities greater than 97%: B. cereus, B. tropicus, B. thuringiensis, B. fungorum. The B. thuringiensis and B. cereus strains showed positive activity in promoting plant growth in vitro through phosphate solubilization, production of chitinases and siderophores. B. cereus and B. tropicus presented inhibitory capacity greater than 50% for Sclerothium rolfsii.

Conclusion. It is relevant to continue research carried out in the laboratory, in order to determine its potential in the field, improving the production of potato crops.

Show Figures and/or Tables

Figure 1. Neighbor-Joining Dendogram from the sequences of the gene that codifies the 16S subunit of the rDNA of endophytic bacteria.

Table 1. Related characteristics in promoting plant growth <em>in vitro</em> of bacteria isolated from tissue (root, stem) in potato plants collected in plots of Ejido El Gallo, Municipality of Guasave, Sinaloa, Mexico.

Table 1. Related characteristics in promoting plant growth in vitro of bacteria isolated from tissue (root, stem) in potato plants collected in plots of Ejido El Gallo, Municipality of Guasave, Sinaloa, Mexico.

Table 2. Antagonistic activity against phytopathogenic fungi represented in percentage; of bacteria isolated from tissue (root, stem) in potato plant collected in plots of Ejido El Gallo, Municipality of Guasave, Sinaloa, Mexico.

Page 6 of 8