Phytophthora Alni - Classification

Classification

P. alni was discovered in 1993 in Southern Britain. It has subsequently been reported in many European countries including the Netherlands, Germany, France, Sweden, Belgium, Austria and Hungary and has recently been found in Alaska. P. alni consists of three subspecies, the most commonly isolated and most virulent subspecies P. alni alni (also referred to as the 'standard form') and two less commonly isolated subspecies P. alni uniformis (also called the Swedish variant) and P.alni multiformis (which contains the Dutch, German and UK variants). A recent genetic analysis has suggested that P. alni alni. was generated on many separate occasions by the hybridization of either P. alni uniformis with P. alni multiformis or their ancestors. The same analysis suggests that P. alni uniformis may have P. cambivora as an ancestor. P. alni multiformis may have been generated by autopolyploidization (the spontaneous duplication of chromosome number within a species) or by a hybridisation of two unknown species a long time ago in evolutionary terms (ancient reticulation).