Characterization of Macrophomina phaseolina isolates affecting sunflower growth in El-Behera Governorate, Egypt

Thirty three Macrophomina phaseolina isolates were recovered from different regions where sunflower was grown in El-Behera governorate during the 2003 and 2004 growing seasons. Housh Eisa and Abo El-Matameer were the most affected regions as 33.3% and 30.3% of the total isolates were recovered, respectively. This was followed by Etay El-Barood, where 12.1% of the isolates were recovered. Occurrence of M. phaseolina in rest of the surveyed regions i.e., El-Dalangat, Kafr El-Dawar and El-Malumoudia was less than 10%. The recovered M. phaseolina isolates were characterized for pathogenicity, colony phenotype, protein banding pattern and the random amplified polymorphic DNA (RAPD). All the recovered isolates were pathogenic to both of the tested sunflower cultivars, Hl 1-008 and Hl 1-009, in the pathogenicity test. However, 27.8% of the isolates (combined data) were identified as highly, 28.1% intermediately and 44.1% lowly pathogenic phenotype. Five color phenotypes and six growth patterns were recognized on PDA, Czapek-Dox and Chlorate media. These were white, grey, black, dark green and brown colony color phenotypes; grey being the most frequent (30.3%). Colony growth patterns recognized were the dense, light, sparse dense, sparse, restricted and shy growth; dense being the most frequent (40.3%). Eleven isolates i.e., 33.3% of the total 33 M. phaseolina isolates analyzed, were Chlorate sensitive, while rest were Chlorate resistant. All the isolates showed the expression of 8-100 kDa polypeptides with 78.4% mean content and exhibited 6-20 polypeptide bands in this kDa range with 34.5% of the isolates were differentiated with unique bands. At the higher 101-300 kDa protein analysis, 27.4-51.3% of the isolates only contained polypeptides of this kDa range with little variation (2-6 bands) and less differentiation (6.7-21.7%). Moreover RAPD-PCR analysis using eight random oligonucleotide primers revealed DNA fingerprints 2-9 bands ranging from 350bp to 3kbp. However, no variations were revealed for number of bands between isolates with primers OPS-16 or OPA-2, while more variations were revealed with OPA-1, OPA-4, OPA-5, OPA-8, OPA-13 and OPR-14 primers. The stem type of M. phaseolina isolates exhibited higher pathogenicity as revealed from size of the lesions incited, plant death and plant head reduction in the pathogenicity tests as compared to the root type of isolates showing these values as 6.1 cm, 37.9% and 37.4%. However, no distinct colony phenotype or protein banding pattern was linked to any of the both types of isolates or even any of the high, intermediate and the low pathogenic phenotypes. However, the RAPD-PCR phylogenetic analysis did not reveal known genetic entities for the stem type and the root type of isolates, since it did revealed two clusters for the high pathogenic isolates and the low pathogenic isolates in the Dendrogram of the tested M. phaseolina isolates.