World Applied Sciences Journal 15 (7): 978-984, 2011 ISSN 1818-4952 © IDOSI Publications, 2011 Corresponding Author: Ibrahim Elkhalil Benzohra, Laboratory of Plant Protection, University of Mostaganem, Mostaganem, Algeria. 978 Identification of Pathotypes and Physiological Races in Ascochyta rabiei (Pass.) Labr., The Agent of Ascochyta Blight in Chickpea (Cicer arietinum) in Algeria Ibrahim Elkhalil Benzohra, Boubekeur Seddik Bendahmane, 1 1 Mohamed Labdi and Mokhtar Youcef Benkada 2 1 Laboratory of Plant Protection, University of Mostaganem, Mostaganem, Algeria 1 INRAA/URO, Algerian National Institute of the Agricultural Research, 2 Western Research Unity, Sidi Bel Abbes, Algeria Abstract: Pathogenic determination of sixteen Ascochyta rabiei isolates obtained from 7 different provinces of western north of Algeria. The pathotypes and physiological races were determinated using 7 differential chickpea lines (ILC1929, F8, ICC1903, ILC 247, ILC 249, ILC 482, ILC 3279 and ICC 3996). All isolates were classified into 3 pathotypes and 6 physiological races according to their aggressiveness and virulence, respectively. We found only 1 isolate (6.25%) from pathotype I (least aggressive), 12 isolates (75%) from pathotype II (moderate aggressive) and 3 isolates (18.75%) from pathotype III (highly aggressive). Just 4 races of A. rabiei were determinated in this region (races 1, 4, 5 and 6). Races 1 and 2 were established in pathotype I, race 4 was represented by the pathotype II and pathotype III included the two races 5 and 6, which were virulent isolates. Key words: Ascochyta rabiei Cicer arietinum Pathotypes Physiological Races Aggressiveness Virulence INTRODUCTION The use of resistant chickpea cultivars is the most Chickpea (Cicer arietinum L.) is the third most ascochyta blight since the application of fungicide is important grain legume in the world after common bean not economical [8]. However, breeding of resistant (Phaseolus vulgaris L.) and pea (Pisum sativum L.) [1]. It chickpea cultivars against ascochyta blight is more is one of the major protein sources in developing difficult because of the variation in pathogenicity of countries such as Algeria and grows even on poor, sandy A. rabiei [9]. Thus, determination of pathotypes or soil [2]. physiological races is essential for breeding One of the greatest biotic stress reducing potential resistant chickpea cultivars. This determination is based yields in chickpea is ascochyta blight caused by on their reaction on a set of differential chickpea Ascochyta rabiei Pass. (Labr.) (teleomorph, Didymella genotypes [10]. rabiei v. Arx. syn. Mycosphaerella rabiei Kovachevski) The pathogenic variability in A. rabiei was first [3]. The fungus is recognized in many countries of the reported in India in 1969 [11]. Subsequently, Vir world including the Mediterranean region, Middle East and Grewal [12] found 2 races (race 1 and race 2) and Indian subcontinent [4]. The disease may cause total and 1 biotypes of race 2 in India. Reddy and yield loss if the environmental conditions are favorable Kabbabeh [13] reported 6 physiological races of [5]. A. rabiei from Syria and Lebanone using 6 differential In Algeria, data of several years of prospection chickpea lines. Jan and Wiese [14] identified 11 showed the presence and the extension of ascochyta pathotypes of A. rabiei in the Palouse region of blight with falls of output which can go up to 100% [6]. the USA. Singh and Reddy [15], using 3 differential Mabsoute et al. [7] announced that in Algeria like in the lines, reported that there were 6 races in Syria. other Maghreb countries, the ascochyta blight remains Udupa and Weigand [16] classified the isolates as 3 the major constraint of chickpea. pathotypes I, II and III according to their aggressiveness effective and economical management strategy for