Genetic variability of Brazilian isolates of Alternaria alternata detected by AFLP and RAPD techniques

Abstract

The Alternaria brown spot (ABS) is a disease caused in tangerine plants and its hybrids by the fungusAlternaria alternata f. sp. citri which has been found in Brazil since 2001. Due to the recent occurrence in Brazilian orchards, the epidemiology and genetic variability of this pathogen is still an issue to be addressed. Here it is presented a survey about the genetic variability of this fungus by the characterization of twenty four pathogenic isolates of A. alternata f. sp. citri from citrus plants and four endophytic isolates from mango (one Alternaria tenuissima and three Alternaria arborescens). The application of two molecular markers Random Amplified Polymorphic DNA (RAPD) and Amplified Fragment Length Polymorphism (AFLP) had revealed the isolates clustering in distinct groups when fingerprintings were analyzed by Principal Components Analysis (PCA). Despite the better assessment of the genetic variability through the AFLP, significant modifications in clusters components were not observed, and only slight shifts in the positioning of isolates LRS 39/3 and 25M were observed in PCA plots. Furthermore, in both analyses, only the isolates from lemon plants revealed to be clustered, differently from the absence of clustering for other hosts or plant tissues. Summarizing, both RAPD and AFLP analyses were both efficient to detect the genetic variability within the population of the pathogenic fungus Alternaria spp., supplying information on the genetic variability of this species as a basis for further studies aiming the disease control.

Diversity among Isolates of the Tangerine Pathotype of <i>Alternaria alternata</i>

“…Clustering by host has also been reported [13]. The authors cited describe the formation of four distinct groups and obtained an ample profile using AFLP markers.…”

“…In sexual fungi, such as the tangerine pathotype of A. alternata, in which sexual reproduction is rare or not observed in nature [13] genetic recombination mechanisms are pre- [42] used RAPD markers in isolates of A. brassicicola and found high genetic variability as well as variability with regard to mycelial growth and sporulation.…”

“…The effectiveness of disease control strategies depends on the understanding of the pathogen and its population dynamics [13]. In this context, the study of variability in fungal populations is an important research tool.…”

Cultural, morphological, pathogenic and molecular characterization of Alternaria mali associated with Alternaria leaf blotch of apple

“…All the primers showed 100% polymorphism, except U2 with 85.71% polymorphism (Table 6). DNA based molecular markers that are selectively neutral and randomly distributed in a genome are important tools in studies on genetic diversity of pathogen populations (Dini-Andreote et al, 2009). In absence of defined differential set availability, molecular markers offer an appropriate alternative to detect and characterize genetic variability in A. mali.…”

Variabilidade genética de Colletotrichum guaranicola usando marcadores AFLP

“…Duarte et al (1995) (Vós et al 1995) foi utilizada para análises moleculares em diversos microrganismos fitopatogênicos (o`neill et al 1997;talhinhas et al 2002;Peres et al 2003;Dini-andreote et al 2009) permitindo a análise de um grande número de locos por reação com reprodutibilidade dos resultados (Ferreira e Grattapaglia 1996) e pode ser aplicada também a estudos de segregação de genes, visando determinar as bases genéticas e moleculares de fenômenos biológicos em fungos fitopatogênicos, virulência e em estudos taxonômicos (o`neill et al 1997;Silva-Mann et al 2005;Rodrigues 2010).…”