Diagnosis of Sclerotinia sclerotiorum by using PCR and determination of oxalic acid produced under different ecological and chemical conditions.


Series of Laboratory experiments were conducted in Biol.Dept.College of Education for Pure Science , Kerbala Univ. from Jan. ,2012 till Jan. ,2013.Fungal strain of Sclerotinia sclerotiorum was diagnosed for first time in Iraq of using Polymerase Chain Reaction (PCR).It was found that this strain was compatible with (MCG)strain at the frequent of 475 bp in the region of Enterbacterial Repetitive Intergenic (ERIC). In vitro produced Oxalic acid by this fungi was determined which plays an important role in virulent , activity and ability in the infection which are affected by Ecological and Chemical factors . These factors included temperature at 20,25,30 and 35 oC and pH at 3.5,5.5,7.5 and 9.5 and mineral nutrients (NH4)2SO4 , CaCO3 and K2SO4 at concentrations of 0, 103,104 and 105 mg/l of each. Oxalic acid was also determined under different concentrations of Gibberellic acid( GA3) and Salicylic acid (SA) at 0,150,200 and 250 mg /l of each. Results showed a reduction in oxalic acid produced by this fungi when temperature increased more than 25 oC giving the least value (0.0 )mg at 30 oC . The pH affected the production of oxalic acid significantly , the best pH was 5.5 giving 6.43 mg oxalic acid wherase, pH 7.5 and 9,5 gave 1.77 and 1.52 mg oxalic acid respectively . A significant difference in oxalic acid content under high concentrations of nutrient elements was detected . A reduction of oxalic acid due to (NH4)2SO4 at 104mg/l was observed giving 2.95 mg oxalic acid followed by K2SO4 giving 4.55 mg at the same concentration . Meanwhile, no oxalic acid was produced under the effect of CaCO3 at all used concentrations . Results also revealed a reduction in oxalic acid produced by this fungi under GA3 and SA effects at all concentrations used giving 0.0 mg at 250 mg /l GA3 .