First Report of Ascochyta rabiei Causing Ascochyta Blight of Cicer pinnatifidum

In July 2005, small (2 to 5 mm), elongated, dark brown spots on the stems of Cicer pinnatifidum Jaub. & Spach. were observed on plants grown in the rocky hills of the Kahramanmaras Province. To understand this phenomenon, field trips to Kahramanmaras, Adiyaman, and Sanliurfa provinces were conducted in the summer of 2006. C. pinnatifidum plants exhibiting symptoms similar to Ascochyta rabiei (Pass.) Lab. were collected during May and June. The plants had flowers and pods with seeds at the time of collection. Ascochyta blight symptoms on stems were not extensive. None of the plants had leaf symptoms, but one plant had lesions on its pods. Twelve plants exhibiting Ascochyta blight symptoms were taken to the laboratory, and necrotic parts were used for isolation of the fungi on potato dextrose agar (PDA). After 3 to 5 days of culturing on PDA, characteristic beige-to-dark brown colony development of A. rabiei from explants was observed and five isolates from different locations were recovered. The fungal colony growth was slow and limited conidia formed on PDA. The isolates were also cultured on chickpea meal agar (CMA) and Czapek Dox Agar (CDA) media. Abundant conidia formation occurred only on CMA, 10 to 12 days after culturing. Conidia were one-celled similar to that of A. rabiei of chickpea and single-spore isolations were done. C. pinnatifidum and chickpea cv. Gokce (C. arietinum L.) were inoculated with spore suspensions of 5 × 10⁵ spores per ml (2). Ten- to twelve-day-old seedlings were used for inoculation in the experiments. Brown-black lesions at the crown region on C. pinnatifidum seedlings were observed 9 to 10 days after inoculation, and characteristic Ascochyta blight symptoms on stems developed on chickpea cv. Gokce. The fungus was reisolated from the infected seedlings. For molecular characterization, mating type of the isolates was determined by PCR using A. rabiei specific Tail1, Com1, and Sp21 primers (1). A single band of Mat 1.2 specific 500- bp product was amplified by PCR from five of the A. rabiei isolates of C. pinnatifidum. This confirmed that the isolates from C. pinnatifidum are A. rabiei. References: (1) M. P. Barve et al. Fungal Genet. Biol. 39:151, 2003. (2) M. S. A. Khan et al. Plant Pathol. 48:230, 1999.