Susceptibility of chilli selected cultivars to foliar and seed infecting bacteria

Abstract

Phytobacteria are potent threat to sustainable chilli (Capsicum annuum L.) production all over the world. In past, bacterial infections were reported in chilli plantations of Pakistan but data is still scanty and sporadic. Therefore, this study was planned to evaluate the chilli germplasm resistance against local putative bacterial isolates. Chilli infected disease samples were collected from Mianwali, Taxila, Chakwal, Islamabad and Rawalpindi during 2021-22. In addition, seeds of different chilli cultivars were also investigated for bacterial infection. In total, six putative isolates were obtained viz., GP, ISL, TAX, CM, and AAR from infected leaf samples while 1 (APO) from infected seeds. On basis of biochemical and pathogenicity assays, two putative isolates; GP (Xanthomonas vesicatoria) and APO (Pseudomonas syringae) isolates were screened for further analysis. Detached leaf and seedling inoculations assays showed that hot pepper and Gola Peshawari were found resistant against GP and APO respectively. Out of three cultivars (TAX, Sky Star, and Golden Hot), TAX cultivar showed resistance against GP isolate and Sky star show resistance against APO isolate in seedling inoculation assay. GP and APO isolates sensitivity against copper sulphate and antibiotics viz., erythromycin, penicillin, streptomycin and tetracycline was also assessed by gel diffusion and plate poisoning method respectively. It was observed that tetracycline and streptomycin were effective against GP and APO respectively while bacterial strains APO and GP showed resistance against copper sulphate. Our data showed that Xanthomonas vesicatoria and Pseudomonas syringae are prevailing in chilli field plantations and seeds. Chilli germplasm must be screened against these bacteria before cultivation to avoid future disease spread.