Genetic and Pathogenic Analyses of Colletotrichum gloeosporioides Isolates from Strawberry and Noncultivated Hosts

Abstract

Colletotrichum crown rot of strawberry in Florida is caused primarily by Colletotrichum gloeosporioides. To determine potential inoculum sources, isolates of Colletotrichum spp. from strawberry and various noncultivated plants growing in the areas adjacent to strawberry fields were collected from different sites. Species-specific internal transcribed spacer primers for C. gloeosporioides and C. acutatum were used to identify isolates to species. Random amplified polymorphic DNA (RAPD) markers were used to determine genetic relationships among isolates recovered from noncultivated hosts and diseased strawberry plants. Selected isolates also were tested for pathogenicity on strawberry plants in the greenhouse. In all, 39 C. gloeosporioides and 3 C. acutatum isolates were recovered from diseased strawberry crowns, and 52 C. gloeosporioides and 1 C. acutatum isolate were recovered from noncultivated hosts. In crown inoculation tests, 18 of the 52 C. gloeosporioides isolates recovered from noncultivated hosts were pathogenic to strawberry. Phylogenetic analysis using RAPD marker data divided isolates of C. gloeosporioides from noncultivated hosts into two separate clusters. One cluster contained 50 of the 52 isolates and a second cluster contained 2 isolates that were homothallic in culture. Isolates from strawberry were interspersed within the cluster containing the 50 isolates that were recovered from noncultivated hosts. The results are not inconsistent with the hypothesis that C. gloeosporioides isolates obtained from strawberry and noncultivated hosts adjacent to strawberry fields are from the same population and that noncultivated hosts can serve as potential inoculum sources for Colletotrichum crown rot of strawberry.

Análisis de la infección de Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. de frutos de aguacatero

“…Con el tiempo la lesión toma un aspecto seco y quebradizo, en forma de cráter, llegando a desprenderse. El síntoma de clavo se manifiesta como lesiones irregulares color café oscuro y hundidas que, en condiciones de humedad relativa elevada, coalescen (ZAMORA-MAGDALENO et al, 2001). La antracnosis ocasiona pérdidas sustanciales por el declive de frutos durante el almacenaje y la comercialización (FREEMAN et al, 1996) y se manifiesta con la presencia de manchas circulares café oscuras en el pericarpio y daños por ablandamiento y pudrición del mesocarpio (PRUSKY et al, 2001).…”

“…Los aislamientos puros se obtuvieron mediante resiembras constantes en PDA de punta de hifa, mientras que para la identificación del hongo se analizaron conidias con base en lo reportado por CANO et al (2004) y ROCA et al (2000. La producción de conidias se obtuvo a partir de cultivos monoconidiales, de donde se extrajeron tres discos con sacabocados estéril de 10 mm de diámetro mismos que se colocaron en 45 mL de medio líquido V8 al 20 % (CASCINO et al, 1990) y se incubaron en agitación orbital constante de 150 rpm (XIAO et al, 2004) a 25 ºC por cinco días (TALHINHAS et al, 2005). Las conidias se suspendieron en una solución amortiguadora de sodio-fosfato 10 mM (pH 7.2) (PRUSKY et al, 2001) y, posteriormente, se filtraron con gasa estéril para eliminar el micelio y los fragmentos de medio de cultivo.…”

“…Dicha sustancia se ha observado también en los apresorios y en el tubo germinativo de Colletotrichum sp. (ZAMORA-MAGDALENO et al, 2001). La capa mucilaginosa contiene enzimas, cutinasas y esterasas, que degradan la cutícula y permiten que el patógeno se adhiera fácilmente al hospedante (DICKMAN et al, 2003).…”

“…También, se ha reportado la síntesis de gloeosporona, terpeno perteneciente al grupo de las lactonas, que funciona como auto-inhibidor de la germinación de conidias y de apresorios de C. gloeosporioides (CASCINO et al, 1990;KIM et al, 1999). ZAMORA-MAGDALENO et al (2001) mencionan que, en las etapas iníciales de infección por antracnosis, no se observa el micelio del hongo invadiendo las células del parénquima del exocarpio y mesocarpio. Resultados semejantes se obtuvieron en este estudio, pues la invasión de las hifas se observó a partir de los 6 ddi, acompañada de la plasmólisis celular.…”

Reaction of dwarf cashew clones to Colletotrichum gloeosporioides isolates in controlled environment

“…The fact that isolates from host species other than cashew (LARS 905-909) were able to cause anthracnose in this plant is not a new observation for C. gloeosporioides. Several authors have reported cross-infections in controlled environmental conditions with Colletotrichum isolates from many fruit crops (Abang et al, 2006;Serra et al, 2008;Xiao et al, 2004). In some instances, isolates from different hosts had identical rDNA and similar mtDNA banding patterns (Alahakoon et al, 1994), while heterogeneity was observed within populations of C gloeosporioides on almond, apple, avocado, mango and strawberry, all of which possess a teleomorphic stage (Freeman et al, 1998).…”