Sources of resistance to ascochyta blight in wild species of lentil (Lens culinaris Medik.)

Cultivated lentil (Lens culinaris Medik. subsp. culinaris) has a relatively narrow genetic base and many commercial cultivars are susceptible to ascochyta blight caused by Ascochyta lentis Vassilievsky. A total of 375 accessions of six wild species of lentil received from ICARDA and 18 cultivated genotypes were screened for resistance to A. lentis under both field and greenhouse conditions in Saskatoon, Canada. A mixture of three monoconidial isolates of A. lentis was used as an inoculum and the level of infection rated using the Horsfall-Barratt scale (0-11). Accessions with resistance to A. lentis were observed in all wild species except for L. culinaris subsp. tomentosa (Ladiz.) Ferguson et al. showing no resistant accessions. Several consistently resistant accessions were found among entries of L. ervoides (Brign.) Grande and L. nigricans, (M. Bieb.) Godr., both of which belong to the secondary gene pool and a few in L. culinaris subsp. orientalis (Boiss.) Ponert and L. culinaris subsp. odemensis (Ladiz.) Ferguson et al. belonging to the primary gene pool. Some accessions of L. ervoides exhibited lower disease ratings and AUDPC values than the resistant control cv. 'Indianhead.' Thirteen accessions, previously reported as resistant to Syrian isolates of A. lentis were also resistant to the Canadian isolates; some also had resistance to anthracnose. The highest frequency of resistance was found in accessions of L. ervoides which originated from Syria and Turkey. These wild accessions represent a useful and untapped source for improving disease resistance in lentil.