VIRULENCE AND GENETIC VARIABILITY OF NEOCOSMOSPORA VASINFECTA CAUSING ROOT ROT IN CHICKPEA
H. Ali, K. Pervaiz Akhtar, T. Mahmud Shah, N. Iqbal
Since chickpea (Cicer arietinum) root rot caused by Neocosmospora vasinfecta is widespread in Khushab, Jhang and Layyah, three regions of the Pujab province (Ali et al., 2011), a study was conducted to assess the virulence and genetic diversity of a number of fungal isolates which, upon isolation on chickpea seed meal agar, yielded white cottony colonies within 7-10 days at 25°C. Virulence assays of seven such isolates were carried out in pots in a glasshouse and a growth-room using the susceptible genotypes JG62 and Aug424, as described by Sharma et al. (2005) and Infantino et al. (2006), All tested isolates were virulent on both genotypes with variable reaction from least to highly aggressive. Four out of five isolates from Khushab and the only isolate from Layyah were aggressive. For genetic diversity analysis, eight RAPD and nine URP markers (Kang et al., 2002) were used. Analysis showed that the seven N. vasinfecta isolates fall into three distinct clades, with URP markers allowing a better definition of genetic variability than RAPD. Virulence and genetic diversity tests proved that the seven isolates fall into three distinct groups. Cluster analysis was performed based on the un-weighted pair group method with arithmetic means (UPGMA) using the Genstat software (10th Edition). No overlap between genetic and virulence groups was detected, nor a correlation was found between these two variables and the geographical origin of the isolates. This preliminary study will form the basis for a comprehensive future work on more isolates and may lead to identify N. vasinfecta-resistant genotypes, potentially forming part of an efficient strategy to manage chickpea root rot.