Molecular identification of the pathogen causing bacterial leaf streak disease of maize and standardization of inoculation technique

Bacterial leaf streak is an emerging disease of maize in Punjab. The disease is occurring frequently in Punjab during the last 3–4 years. During Kharif 2014, maize growing areas of Punjab were surveyed for the occurrence of this disease. The pathogen associated with the disease was isolated. It produced yellow slimy colonies on King's B medium. It was identified as Acidovorax avenae subsp. avenae based on production of single band of 470bp in all twenty five cultures after amplification of genomic DNA with rDNA based primers AaarDNAf and AaarDNAr. Further sequencing and matching PCR product of three isolates Aaa1, Aaa2 and Aaa25 confirmed the pathogen to be Acidovorax avenae subsp. avenae. For developing artificial epiphytotics of the disease, four inoculation methods were tested in field during 2014. Whorl prick inoculation method was the most effective in producing disease symptoms followed by pin prick inoculation and cotton swab inoculation.