Garlic (Allium sativum) is an important crop worldwide and it is widely grown and used in different industries to manufacture food, pharmaceutical, and insecticidal products. (Shang et al., 2019, ...Velsankar et al., 2020). According to what was reported by SIAP in 2020, more than 87 ha of the crop were lost in Mexico due to various problems, including the diseases that attack this crop such as basal rot, white rot and root rot, among others. During the 2019 fall/winter season, garlic plants of Perla and Piedra Blanca cultivars were collected from Aguascalientes and Zacatecas states in San Antonio Tepezala, Rincon de Romos, and Calera municipalities. The commercial fields encompassed 10 ha with 20% disease incidence and 35% severity, approximately. The sampling focused on diseased plants with symptoms of root rot, foliar wilt, stunting, and small bulbs. The roots of 25 plants were cleaned, and portions of the diseased tissue were cut and disinfected in sodium hypochlorite at 1% for three minutes. They were rinsed twice with sterile water and dried with paper towels. The plant tissue was plated onto potato dextrose agar (PDA) and incubated at 25°C in the dark for 72 hours. Pure cultures were obtained after observing mycelial growth using monosporal culture. We obtained 16 isolates including three identified as Fusarium oxysporum, one as Fusarium solani and another 12 as Clonostachys rosea. The latter isolates were white at the beginning before turning yellow. The mycelia had a felt-like cotton texture. The conidia formed verticillate and penicillate conidiophores. The primary conidia were abundant, hyaline, smooth, and sub-globous. They were 5.1-7.7 X 8.3-8.9 µm (n=50) long and 2.0-2.9 X 3.2-3.5 µm wide (n=50). The conidiophore stipe length ranged from 70 to 180 µm, and the base width was 3.3-5.4 µm. Secondary conidiophores were penicillate and stiped with a length of 58 to 106 µm; the base measured 3.3-6.1µm. The secondary conidia measured 4.1-5 X 5.3-5.6 µm long and 2-2.3 X 2.6-2.9 µm wide (n=50) (Sun et al., 2020). The identity of six isolates was molecularly confirmed by DNA extraction and PCR reactions using ITS1/ITS4 primers and gene TEF 1α EF1-728F/TEF 1α EF1-986R. The resulting products were sequenced and compared with the National Center for Biotechnology Information (NCBI) database using BLAST. The results showed Clonostachys rosea at 99.56 and 100% with access numbers MN548399 and KX185000. The sequences were deposited at Genbank database under access number OK263088 and OL700031. Pathogenicity tests were carried out with the following procedure. A conidial suspension of five isolates (5×105 conidia/ml) in sterilized water was prepared from 1-week-old colonies. The garlic cloves were planted after being disinfected with sodium hypochlorite at 1% in sterilized soil. When the healthy garlic plants were 30 days old, we inoculated a spore suspension in soil through irrigation, to 10 plants. Likewise,10 control plants were inoculated with sterile distilled water. After 25 days, the plants were wilted and had dry leaves; their root system showed light-brown lesions and rot. These plants were stunted versus the control healthy plants. The inoculated strain was recovered and was morphologically and molecularly identified as C. rosea, thus confirming its pathogenicity towards garlic. There are reports of C. rosea causing root rot to Fabaceae crops such as Glycine max L. and Vicia faba L., (Bienapfl et al., 2012; Afshari and Hemmati, 2017) in addition to affecting orchid crops (Gastrodia elata) in Korea (Lee et al., 2020). This is the first report of C. rosea causing root rot on garlic (Allium Sativum) in Mexico, thus presenting a potential risk to this crop.
The horizontal transmission of lymphocystis disease virus (LCDV) through contaminated water and feed (using artemia as vehicle) and the associated immune gene expression profiles in Senegalese sole ...post-larvae were investigated. All specimens analyzed were positive for LCDV DNA detection at 1-day post-challenge (1 dpc) with the highest viral levels in specimens infected through the immersion route. However, the percentage of LCDV-positive animals and number of viral DNA copies dropped progressively at 2 and 7 dpc. The histological analysis identified structural changes in the skin, muscle and gills of sole post-larvae LCDV-challenged by immersion. In situ hybridization confirmed a wide distribution of LCDV in the skin, gut, surrounding vessels in trunk muscle and head kidney in the immersion route, while the signals were restricted to the liver and lamina propria in the feeding treatment. Expression analysis using a set of 22 genes related to innate immune defense system demonstrated clear differences in the time-course response to LCDV as function of the infection route. Most antiviral defense genes, the proinflammatory cytokines, the complement c3, g-type lysozyme and T-cell markers cd4 and cd8a were rapidly induced in the feeding-infected post-larvae, and they were remained activated at 2 dpc. In contrast, in the immersion-infected post-larvae the induction of most defensive genes was delayed, with a low intensity at 2 dpc. All these data demonstrate that LCDV can horizontally infect Senegalese sole post-larvae through the water or feed although with different patterns of histopathological disorders, virus distribution and route-specific expression profiles.
•Feed and water immersion were effective to horizontally transmit LCDV to sole post-larvae.•Histopathological changes and LCDV distribution were route-specific.•Both LCDV infection routes triggered a wide defensive response although with temporal and intensity differences.
A new genetic variation and potential new haplotype of Bactericera cockerelli was identified based on the analysis of the mitochondrial region Cytochrome Oxidase subunit I of two populations from ...greenhouses in Villa Unión, Durango and Saltillo, Coahuila, Mexico. A variation was found in the base 247 of a 500 bp amplified of the mtCOI gene, this change implies the substitution of an adenine (A) to a Guanine (G), this mutation was detected in the insects collect from greenhouses and in their progeny obtained under laboratory conditions. This genetic variant has a great potential to be a new haplotype of B. cockerelli, therefore, it was designated Mexico Haplotype 1 (MXH1) with GenBank accession number KX130767. A total of ten insects from the original collection and then from laboratory cages were evaluated for Lso infection and all tested negative.
Phytotoxicity caused by secondary metabolites of botanical extracts is a drawback in agriculture. The objective of this study was to evaluate the phytotoxic effects of methanolic extracts of ...Crotalaria longirostrata and Argemone mexicana on the germination and physiological variables of tomato seedlings. The results indicated that high doses of both extracts (Clong500 and Amex500) inhibited tomato seed germination, while their mixture (Cl50 + Am50) promoted germination by 100%. At 30 days after transplanting (dat), the plant height increased by 15.4% with a high dose of C. longirostrata (Clong500) compared to the control. At 30 dat, the vigor index displayed a notable increase with Cl50 + Am50, reaching 29.5%. The root length increased with the mean dose of A. mexicana (Amex95) at 10, 20, and 30 dat (59.7%, 15.1%, and 22.4%, respectively). The chlorophyll content increased with Amex95 by 66.1% in 10 dat, 22.6% at 20 dat, and 19.6% at 30 dat. On the other hand, Amex95 had a higher nitrogen content throughout the trial. Amex95 produced the greatest increase in root dry weight by 731.5% and 209.4% at 10 and 20 dat. The foliage dry weight increased by 85.7% at 10 dat with Amex95 and up to 209.7% with Amex50 at 30 dat. The present investigation reveals the ability of the extracts to stimulate tomato growth at low and medium doses, though at high doses they exhibit allelopathic effects.
Tomato brown rugose fruit virus (ToBRFV) is considered an emerging disease and a viral pandemic for tomato consumers. The objectives of this research were to analyze the biological and ...physicochemical characteristics of ToBRFV in tomato and tobacco plants, as well as to evaluate its natural host range. Inoculant seeds were recovered from ToBRFV-infected tomato samples in Coahuila, Mexico, and confirmed by RT-PCR. In the first greenhouse experiment, tomato plants of the F1 hybrid variety 172–300 (Yüksel), infected with ToBRFV, were used to evaluate viral inclusions (VI), dilution endpoint (DEP), the incubation period (IP), and latency period (LP). In a greenhouse experiment, Nicotiana longiflora plants were inoculated with ToBRFV to determine the in vitro longevity (IVL) and thermal inactivation (TI) of the virus in sap. Finally, the inoculation of tomato plants grown in open fields was carried out to evaluate transmission to natural hosts. The plants tested for possible ToBRFV reservoirs near the inoculum source were inspected and confirmed by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The results indicate that the VIs on tomato leaves manifested as X-bodies and rounded, stacked plaques within epidermal cells. The DEP required to induce the infection in plants was from a ToBRFV concentration of 1 × 10−5.5, the IP of ToBRFV occurred 9 to 12 days post-inoculation, and LP could be detected one day after inoculation. The TI of ToBRFV in N. longiflora plants occurred at 85 °C for 30 min. Ipomoea purpurea, Mirabilis jalapa, Clematis drummondii, and Solanum tuberosum were newly identified hosts of ToBRFV. The results found contribute to a better understanding of the impact of ToBRFV, managing and preventing the spread of ToBRFV in diverse environments.
Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of Liberibacter asiaticus Jagoueix et al. and Liberibacter americanus Teixeira et al., causal agents of the critical yellow dragon disease ...or Huanglongbing (HLB), which affects citrus production worldwide. Recently, green synthetic nanoparticles have emerged as a potential alternative to control of agricultural insect pests. The insecticide effect of silver nanoparticles (AgNPs) on 2nd instar nymphs of D. citri under laboratory and greenhouse conditions was evaluated. Mortality was recorded 24, 48, and 72 h after application on D. citri nymphs under both laboratory and greenhouse conditions. The laboratory results showed that AgNPs caused 97.84 and 100% mortality at 32 and 64 ppm, respectively, 72 h after treatment. In the greenhouse, AgNPs caused 78.69 and 80.14% mortality using 64 and 128 ppm 72 h after application. This research is the first to evaluate the green synthesis AgNPs on D. citri and are a promising strategy to control the pest.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Las especies de Crotalaria están ampliamente distribuidas en climas tropicales y subtropicales, describiéndose más de 700 especies; de las cuales, la mayoría son consideradas malezas o especies ...invasoras. Las plantas de este género presentan una amplia diversidad metabólica de compuestos bioactivos en semillas, raíces, tallos, hojas y flores; a partir de extractos acuosos, etanol, metanol, éter etílico, cloroformo y diclorometano, que muestran efecto directo o indirecto relacionado con actividades antidiarreicas, antiinflamatorias, cardiodepresores y como hepatoprotectores. También se ha demostrado la eficacia de extractos vegetales en la agricultura como manejo alternativo sobre agentes patógenos como bacterias, hongos, insectos, nematodos, en el control de malezas y su función como fuente de nutrientes. Por lo anterior, en la presente revisión se recopiló las características distintivas del género Crotalaria, así como su composición nutrimental, compuestos fitoquímicos, su implementación en el control de enfermedades y usos alternativos en la agricultura.
La enfermedad del permanente del tomate o zebra chip cau- sada por “Candidatus Liberibacter solanacearum” (Ca. L. solanacearum), es de gran importancia en las regiones productoras de tomate en ...México, la cual causa pérdidas de entre el 60 y 100% de la producción. El objetivo del trabajo fue evaluar el efecto de seis fosfitos (FOS), ácido salicílico y acibenzolar s-metil sobre el crecimiento del cultivo de tomate y la severidad de Ca. L. solanacearum. Las plantas de tomate se infectaron con Ca. L. solanacearum mediante el confinamiento con adultos de B. cockerelli portadores de esta bacteria. Como respuesta se evaluaron la disminución de la severidad de la enfermedad y nueve parámetros agronómicos. La aspersión de fosfitos redujo la severidad de los síntomas de la enfermedad ocasionada por Ca. L. solanacearum, mejorando las variables altura de planta, peso del fruto, peso de planta y peso de raíz. En cambio, la aspersión de ácido salicílico y acibenzolar s-metil no redujeron los efectos de la enfermedad en el cultivo de tomate.
Abstract In August and September 2014, different avocado orchards (Persea americana Mill. Var. Hass) were sampled in four municipalities (Tancítaro, Uruapan, San Juan Nuevo Parangaricutiro and ...Peribán) of the “Franja aguacatera” in Michoacan State, Mexico. Samples were collected from avocado trees showing symptoms of the “Tristeza del aguacate” disease. Strains of Pythium sp. were obtained consistently from symptomatic tissue isolated in the selective medium V8®-Agar-PARPH. Morphological identification was made through taxonomic keys, and molecular identification was obtained by sequencing Internal Transcribed Spacer (ITS) gene. Koch's postulates were corroborated by pathogenicity tests carried out on P. americana seedlings with six true leaves, identifying the strain of P. sp. amazonianum as the causal agent of the “Tristeza del aguacate” disease. This is the first report that associates the “Tristeza del aguacate” with P. sp. amazonianum in Michoacan, Mexico.
Candidatus Liberibacter solanacearum (CLso) es una bacteria fitopatógena Gram-negativa, limitada al floema en solanáceas y no cultivable in vitro. Es transmitida de manera vertical y horizontal por ...el psílido Bactericera cockerelli. En México se asocia como responsable de la enfermedad "permanente del tomate", "punta morada de la papa" (Zebra chip) y "variegado del chile". Los síntomas causados por la bacteria varían según el cultivar y la etapa de crecimiento del hospedante pero consisten principalmente en amarillamientos y deformación de la lámina foliar, debido a la alimentación del vector y la colonización del patógeno. Las infecciones ocasionadas por CLso reducen la calidad del producto y el valor comercial en el mercado. La presencia de esta bacteria ha sido detectada en los estados de Coahuila, Sinaloa y Guanajuato, México a través de técnicas moleculares; mientras que el control de la enfermedad se encuentra enfocado en el vector, mediante prácticas culturales y la aplicación de agentes químicos y biológicos. Por lo anterior el objetivo del trabajo es puntualizar la situación actual de la distribución de CLso en México, los métodos de diagnóstico y las estrategias para el manejo integrado de la enfermedad y el vector.
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