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ROBERTO CARLOS VAZQUEZ EUAN ROSA GRIJALVA ARANGO BARTOLOME HUMBERTO CHI MANZANERO MIGUEL ALONSO TZEC SIMA IGNACIO RODRIGO ISLAS FLORES CECILIA MONICA RODRIGUEZ GARCIA LETICIA PERAZA ECHEVERRIA ANDREW CHRISTOPHER JAMES GILBERTO MANZO SANCHEZ BLONDY BEATRIZ CANTO CANCHE (2012)
Sigatoka disease is the most important threat for banana production worldwide. Many species of Mycosphaerella have been described from banana but, to date, the three species Mycosphaerella fijiensis, M. musicola and M. eumusae are the only species found to be pathogenic to banana. Reliable identification by classical methods requires expertise because these fungi produce similar symptoms and they are morphologically similar. For studies of ecology, genetic diversity and epidemiology their differentiation is crucial. Several laboratories have developed molecular protocols to differentiate these fungi. Currently, a number of primers targeting ribosomal sequences, actin, tubulin and histone 3 genes are available for diagnosis of the Sigatoka complex. In the present work, we report a direct colony-polymerase chain reaction (DC-PCR) approach to rapidly distinguish M. fijiensis and M. musicola strains in multiplex PCR reactions. This is the most economical and the fastest procedure reported so far for diagnosis of these two Mycosphaerella species, which are distributed in banana-growing regions in the world; the DC-PCR technique was also found to be amenable for the identification of mating type of M. fijiensis isolates. This DC-PCR may also be applicable to prepare DNA templates for basic PCR-based analyses in other fungi.
Maarten van Ginkel (1999)
Workshop held on September 20 - 24, 1999 at CIMMYT, Mexico.
Blotches Disease resistance Fungal diseases Genetic control Mycosphaerella Plant diseases Plant response Research projects Selection Septoria Soft wheat Triticum Plant breeding CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA
Idiomorphs mat1-1 and mat1-2 from Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana, were isolated. Degenerate oligos were used to amplify the HMG box of themat1-2 idiomorph from M. fijiensis, showing homology with the HMG box of Mycosphaerella graminicola. Using a DNA walking strategy, anchored on the DNA lyase gene towards the HMG box, a 9-kb-long region of mat1-2 was obtained. A 5-kb fragment from the mat1-1 region was obtained by long-range PCR using primers on the flanking regions, which have close to 100% identity between both idiomorphs. High-identity (77-89%), inverted regions within both idiomorphs were found, which suggest unique inversion events, which have not been found before, and that could have been significant in the evolution of this species. The predicted genes showed the conserved introns in both idiomorphs as well as an additional intron within the alpha box. The implications for theevolution of species in the Mycosphaerella complex on banana are discussed.
Anthracnose, caused by Colletotrichum truncatum (syn. C. capsici), has become a common disease of tropical crops, severely affecting the quantity and quality of fruit and seed and, therefore, reducing their market value. For years, chemical control has been extensively used for managing this disease. However, the appearance of isolates that are resistant to the most commonly employed fungicides is increasingly widespread. Twenty C. truncatum isolates from pepper, papaya, and physic nut were rested in vitro against four fungicides to determine their sensitivity. All evaluated isolates were resistant to azoxystrobin and thiabendazole and susceptible to cyprodinil + fludioxonil and mancozeb. To determine the molecular mechanism conferring thiabendazole resistance, the TUB-2 gene was characterized, revealing a glutamic acid to alanine substitution at position 198 in 6 of the 20 isolates that were tested. This work confirms the emergence of benzimidazole-based fungicide resistance in C. truncatum populations and highlights the need for monitoring fungicide sensitivity as an essential activity for the development of effective control schemes.
YENY LIZZET COUOH UICAB IGNACIO RODRIGO ISLAS FLORES NUVIA EUGENIA KANTUN MORENO MIGUEL ALONSO TZEC SIMA SANTY PERAZA ECHEVERRIA LIGIA GUADALUPE BRITO ARGAEZ LETICIA PERAZA ECHEVERRIA ROSA GRIJALVA ARANGO ANDREW CHRISTOPHER JAMES CECILIA MONICA RODRIGUEZ GARCIA (2012)
ABC transporters are membrane proteins that use the energy released from the hydrolysis of ATP to drive the transport of compounds across biological membranes. In some plants, pathogenic fungi ABC transporters play a role as virulence factors by mediating the export of plant defense compounds or fungal virulence factors. Mycosphaerella fijiensis, the causal agent of black Sigatoka disease in banana, is the main constraint for the banana industry worldwide. So far, little is known about molecular mechanism that it uses to infect the host. In this study, degenerated primers designed from fungal ABC transporters known to be involved in virulence were used to isolate homologs from M. fijiensis.Here, we reported the full cloning of MfAtr4 a putative ortholog of MgAtr4, an ABC transporter of the related Mycosphaerella graminicola with a function in virulence. Similarities and differences with its presumed ortholog MgAtr4 are described, and the putative function of MfAtr4 are discussed. Analysis of MfAtr4 gene expression in field banana samples exhibiting visible symptoms of black Sigatoka disease indicated a higher expression of MfAtr4 during the first symptomatic stages in comparison to the late necrotrophic phases, suggesting a role for MfAtr4 in the early stages of pathogenic development of M. fijiensis.
BRISIA ALEJANDRA AGUILAR BARRAGAN OLGA ELIZABETH ODRIOZOLA CASAS GLORIA MARGARITA MACEDO RAYGOZA TETSUYA OGURA GILBERTO MANZO SANCHEZ ANDREW CHRISTOPHER JAMES KAY IGNACIO RODRIGO ISLAS FLORES MIGUEL JUAN BELTRAN GARCIA (2014)
Mycosphaerella fijiensis (Morelet) requires numerous applications of fungicides per year. However this has led to fungicide resistance in the field. The present study evaluated the activities of six fungicides against the mycelial growth by determination of EC50 values of strains collected from fields with different fungicide management programs: Rustic management (RM) without applications and Intensive management (IM) more than 25 fungicide application/year. Results showed a decreased sensitivity to all fungicides in isolates collected from IM. Means of EC50 values in mg L-1 for RM and IM were: 13.25 ± 18.24 and 51.58 ± 46.14 for azoxystrobin, 81.40 ± 56.50 and 1.8575 ± 2.11 for carbendazim, 1.225 ± 0.945 and 10.01 ± 8.55 for propiconazole, 220 ± 67.66 vs. 368 ± 62.76 for vinclozolin, 9.862 ± 3.24 and 54.5 ± 21.08 for fludioxonil, 49.2125 ± 34.11 and 112.25 ± 51.20 for mancozeb. A molecular analysis for β-tubulin revealed a mutation at codon 198 in these strains having an EC50 greater than 10 mg L-1 for carbendazim. Our data indicate a consistency between fungicide resistance and intensive chemical management in banana fields, however indicative values for resistance were also found in strains collected from rustic fields, suggesting that proximity among fields may be causing a fungus interchange, where rustic fields are breeding grounds for development of resistant strains. Urgent actions are required in order to avoid fungicide resistance in Mexican populations of M. fijiensis due to fungicide management practices.
Maarten van Ginkel (1987)
En los últimos 25 años, se ha dedicado más atención a las enfermedades del trigo causadas por Septoria. Los dos agentes patógenos del género Septoria que tienen mayor repercusión en la producción mundial del trigo son Septoria tritici y Septoria nodorum. Se estima que las pérdidas anuales de rendimiento causadas en todo el mundo por las dos enfermedades ascienden a 9 millones de toneladas métricas. El fitomejoramiento para obtener resistencia ocupa un lugar preeminente en muchos programas de investigación y mejoramiento de cultivos en todo el mundo. En esta introducción, se hace hincapié en sintetizar los informes científicos más importantes para el manejo de los dos principales agentes patógenos del género Septoria. Los datos obtenidos en las investigaciones se traducen en conceptos y procedimientos. Entre los temas que aquí se desarrollan se cuentan la biología de estos hongos, el proceso de Infección, la recolección y manejo del material infectado, el aislamiento y conservación, la producción de inoculo, la inoculación artificial, la evaluación de los daños, su epidemiología, la especialización de estos agentes patógenos, el fitomejoramiento para obtener resistencia y los métodos químicos y de cultivo para combatir estos patógenos. En esta obra se trata un tema o un grupo de métodos alternativos, y luego se recomiendan una o más técnicas o métodos. Dicha información se dirige a los científicos especializados en el cultivo del trigo de países desarrollados o en desarrollo, que no estén familiarizados con estas enfermedades.