Plant Pathol. J. 27(2) : 128-137 (2011) DOI: 10.5423/PPJ.2011.27.2.128 pISSN 1598-2254 eISSN 2093-9280 The Plant Pathology Journal © The Korean Society of Plant Pathology Diversity of Macrophomina phaseolina Based on Morphological and Genotypic Characteristics in Iran Valiollah Mahdizadeh, Naser Safaie* and Ebrahim Mohammadi Goltapeh Department of Plant Pathology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran (Received on September 6, 2010; Accepted on April 17, 2011) Fifty two Macrophomina phaseolina isolates were re- covered from 24 host plant species through the 14 Iranian provinces. All isolates were confirmed to species using species-specific primers. The colony characteri- stics of each isolate were recorded, including chlorate phenotype, relative growth rate at 30°C and 37°C, aver- age size of microsclerotia, and time to microsclerotia formation. The feathery colony phenotype was the most common (63.7%) on the chlorate selective medium and represented the chlorate sensitive phenotype of the Iranian Macrophomina phaseolina population. Mean- time, inter simple sequence repeats (ISSR) Markers were used to assess the genetic diversity of the fungus. Unweighted pair-group method using arithmetic means (UPGMA) clustering of data showed that isolates did not clearly differentiate to the specific group according to the host or geographical origins, however, usually the isolates from the same host or the same geographic origin tend to group nearly. Our results did not show a correlation between the genetic diversity based on the ISSR and phenotypic characteristics. Similar to the M. phaseolina populations in the other countries, the Iranian isolates were highly diverse based on the phenotypic and the genotypic characteristics investigated and needs more studies using neutral molecular tools to get a deeper insight into this complex species. Keywords : charcoal rot, chlorate phenotype, ISSR The causal agent of charcoal rot, Macrophomina phaseolina (Tassi) Goidanich, is a soil- and seed-borne pathogen of over 500 host plant species (Dhingra and Sinclair, 1978) and it causes significant damage in Iran to soybean (Raeyatpanah and Forootan, 1993; Raeyatpanah et al., 2002) and sunflower (Razavi and Pahlavani, 2004). The high levels of morphological variability of M. phaseolina across different hosts and geographical regions suggest that this species may be divided into subgroups (Aboshosha et al., 2007; Beas-Fernandez et al., 2006; Hawatema and Hameed, 2006; Karunanithi et al., 1999; Mayek-Perez et al., 1997; Mihail and Taylor, 1995; Omar et al., 2007). However, grouping of isolates by formae specialis, subspecies, or physiological race was challenged due to variation in the morphology of isolates from a single host (Dhingra and Sinclair, 1972). Molecular markers are powerful tools for assessing genetic variation and elucidating genetic relationships within and among species (Chakravarthi and Naravaneni, 2006). Different molecular methods have been used for differen- tiating M. phaseolina populations including Restriction Fragment Length Polymorphism (RFLP) of rDNA-ITS regions (Aghakhani and Dubey, 2009; Almeida et al., 2003; Purkayastha et al., 2006; Su et al., 2001), Random Ampli- fied Polymorphic DNA (RAPD) (Aboshosha et al., 2007; Aghakhani and Dubey, 2009; Almeida et al., 2003; Almeida et al., 2008; Babu et al., 2010; Das et al., 2006; Jana et al., 2003; Omar et al., 2007; Purkayastha et al., Rajkumar and Kuruvinashetti, 2007; Su et al., 2001; 2006; Zade et al., 2009), Amplified Fragment Length Polymorphism (AFLP) (Brooker et al., 2008; Mayek-Perez et al., 2001; Reyes-Franco et al., 2006; Saleh et al., 2010; Vandemark et al., 2000), Universal Rice Primer PCR (URP-PCR) (Jana et al., 2005b), Inter simple sequence repeats (ISSR) (Jana et al., 2005a; Purkayastha et al., 2008), Repetitive Sequence- Based Polymerase Chain Reaction (Rep-PCR) (Purkayastha et al., 2008) and SSR (Baird et al., 2010). Inter simple sequence repeat (ISSR) markers are powerful tools which can be utilized to access the variation in the flanking regions of microsatellite loci that are dispersed throughout all genomes (Zietkiewicz et al., 1994). In this study we used some conventional techniques and ISSR markers to assess the morphologic and genetic variability among 52 isolates of M. phaseolina from different hosts and origins within Iran and identifying insights to host specialization. Material and Methods Fungal isolates. Isolates of M. phaseolina were recovered from 24 different host species showing typical symptoms *Corresponding author. Phone) +982148292346, FAX) +982148292200 E-mail) nsafaie@modares.ac.ir Open Access