Ascochyta blight of chickpea in Australia: identification, pathogenicity and mating type

Abstract

The aetiology of blight of chickpea in South Australia was studied following sporadic disease outbreaks over several years that had been tentatively identified as Phoma blight. Nine fungal isolates from diseased chickpeas were tested for pathogenicity in the glasshouse, of which two caused symptoms resembling those of Ascochyta blight. The two aggressive isolates were identified as Ascochyta rabiei based on morphological characteristics of cultures and RAPD analysis. This was further confirmed by successful mating to international standard isolates, which showed that the two Australian isolates were MAT1‐1. These isolates are accessioned as DAR 71767 and DAR 71768, New South Wales Agriculture, Australia. This is the first time that A. rabiei has been positively identified in commercial chickpeas in the southern hemisphere. The pathogen was found (in 1992) in only one of 59 seed samples harvested throughout Australia between 1992 and 1996 and tested using International Seed Testing Association methods. The teleomorph has not been found in Australia and results to date suggest that only one mating type is present. This suggests that quarantine restrictions on imported chickpea seed should be retained to prevent the introduction of the opposite mating type.

An Update on Genetic Resistance of Chickpea to Ascochyta Blight

“…Labr., is an important disease of chickpea in many countries (India, Bangladesh, Algeria, Israel, Italy, Morocco, Nepal, Spain, Pakistan, Syria, Iran, USA, Australia and Canada) where cool and humid weather prevails during the flowering to podding stage [1][2][3][4][5][6][7]. AB severely reduces the yield of chickpea and can cause complete yield losses under favorable conditions [8][9][10][11].…”

Advances in winter pulse pathology research in Australia

“…However, extensive losses from AB occurred in Australian commercial crops in 1998 and 1999 and retrospective seed testing found its presence in the country since 1992 (Galloway and MacLeod 2003a;Khan et al 1999). At that time all Australian chickpea cultivars were susceptible to A. rabiei Nasir et al 2000) and yield losses exceeded 50% with many crops completely destroyed (Kimber et al 2006a) leading to substantial economic losses (Lindbeck et al 2006).…”

“…While low numbers of ascospores have been reported from infested chickpea stubble (Galloway and MacLeod 2003a), all Australian isolates are of one mating type (Khan et al 1999;Phan et al 2003a) and limited molecular diversity has been found among the Australian population of A. rabiei (Gomez 2000;Phan et al 2003b). Current research suggests it is likely that multiple entries of the pathogen have occurred, perhaps from origins where a single mating type existed.…”

Genetic relationships among Chickpea (Cicer arietinum L.) genotypes based on the SSRs at the quantitative trait Loci for resistance to Ascochyta Blight

“…The use of resistant cultivars will also help to stabilize chickpea production. Breeding for resistance to ascochyta blight in chickpea has been limited by several factors, including the high pathogenic variability of the fungus and the limited sources of good resistance (Khan et al 1999;Singh and Reddy 1993).…”