Abstract
Abstract
Up to now, edaphic or soil algae of Siwa Oasis have never been demonstrated before. Soil samples of the investigated four regions of Siwa Oasis were cultured on Chu No.10 nutritive medium. Overall, 19 soil algal taxa were detected throughout the areas of study. These were assigned to four systematic algal divisions, of which 10 Cyanophyta taxa followed by 6 Chlorophyta taxa, 2 Xanthophyta taxa and one Euglenophyta taxon. The heterocystous, nitrogen- fixing taxa were demonstrated in considerable numbers (seven/ ten cyanophytes). At time of isolation (12 days-exponential phase), the pure fresh uni-algal cultures of Amorphonostoc paludosum Kossinsk, Aphanizomenon elenkinii Kisselev and Anabaena naviculoides Hollerb (isolated from Siwa Oasis) were selected to study their taxonomical (successive growth stages) and molecular characters. Current molecular study showed that, the used scot polymorphism resolves the problematic taxonomy of Anabaena and Aphanizomenon genera. The recorded morphological and life cycle data (that daily based on microscopic examination to the successive growth stages of the studied three nostocales species) were support the genetic results and indicated that, Anabaena and Aphanizomenon significantly different. Fresh isolated cultured Amorphonostoc and Anabaena genera are traditionally separated based on morphological characteristics and life cycle differences. Therefore, combining of taxonomical, life cycle and molecular evidences for the fresh cultured genera proved to be reliable and successful approaches for the analyses of cyanophytes polymorphisms.

Key words: Key words: Morphology of cyanophytes, Nostocales polymorphism, Uni-micro-algal cultures, Molecular genetics of cyanophytes, Start Codon Targeted (SCoT) marker techniques.