دراسة الخصائص المظهرية والجزيئية للفطر Sclerotinia sclerotiorum(Lib.)De Bary في محافظة بابل وظروف إنتاجه للأجسام الثمرية

Morphological and Molecular Study of Sclerotinia sclerotiorum (Lib.)De Bary in Babylon Governorate and conditions of its Apothecium Production

The study included isolation and diagnosing the fungi Sclerotinia sclerotiorum (Lib.) de Bary based on the morphological ,  microscopic and molecular properties using PCR techniques using the Primer 18S rRNA and determination  the gene oxalate acetylhydrolase which is responsible on the production of oxalic acid gene in the fungi .

 The fungi was propagated using wheat grain medium to obtain a maximum number sclerotia of the following experiments. Some environmental conditions were studied i.e. temperature ,light, darkness in producing apothecium.

Dimensions of sclerotia were studied and the correlation coefficient between the length  and the width and their production  of Sclerotia, Ascus and Ascospores, in addition to the pattern of sclerotia distribution grown on PSA.

 was calculated respect of salinity at 100 meq./l as NaCl effect on the germination, vegetative growth and their production of sclerotia grown on PSA medium was studied .

Environmental factors expressed by temperature at 10,15,20  and 25 ⁰C  and light and darkness affected the stipes ,and apothecium of the sclerotia .The temperatures 10,15 and 20 ⁰C were suitable for apothecium production in the presence of light otherwise there is no complete growth of apothecium in the absence of light which is remaining as stipes ,elongating in the dark conditions .Whereas at temperature of 25 ⁰C no apothecium in the presence of light and no stipes growth as well was noticed .

There was a significant correlation between the width of sclerotia and the number of stipes, and between the area of sclerotia and the number of  stipes, between the area of sclerotia and the diameter of the sclerotia. There are no correlation between length and width of sclerotia, length and width of Ascus or length of ascospore, indicating their importance in the morphology and microscopic taxonomy .The diameter of Sclerotinia was 6-24m/length and 1-12m in width, the average number of stipes were 3-26 and 3-5m in length, and the number of apothecium 3-26, and 2-6 m in diameter, the length of Ascus was 15-31 m and 2-13m, 3-7m and 2-5m in width.

The number of sclerotia produced from single spore was different and produced more than 7.1 sclerotia .In the case of more than one spore in the petri dish i.e. two, three , four and five single spores gave 4.4 ,3.9 ,5.7 ,5.4 sclerotia respectively .the criteria correlated with distrbution pattern of the sclerotia in the petri dish recording occurrence of in compatibility in the case of ring more than one spore .

The single spore obtained was used in the study of vegetative growth in the presence of single and many spores in the petri dish, and also to study the pattern distribution of sclerotia grown on PSA.

The effect of NaCl at 100 meq.l^-1 quarter and double of this concentration as well as the sterilized distilled water (as control treatment) on the spores germination  ,vegetative growth and its production of  sclerotia on PSA was also investigated

Results also revealed a fluctuation in the vegetative growth of the fungi in presence of NaCl especially  at the first hours from incubation .The reduction in the growth rate was obvious at 100 meq.l^-1 NaCl gave higher growth considering this case as a kind of the resistance. In the presence of salinity at different levels produced less number of Sclerotinia compared with sterilized distilled water. Different concentrations of salinity  caused a less number of sclerotia compared with sterilized  distilled water ,and was significantly different  in the distilled water where the mean  sclerotia number was 9.35 .The salinity concentrations at  0.145 , 0.580 and 1.160 gave  3.45 , 3.80 and 2.50 sclerotia respectively