Regresar

Molecular characterization and screening of Xanthomonas oryzae pv. oryzae, isolated from Pakistan for pbkp_rediction of bacterial leaf blight-resistant basmati rice

Abstract:

Bacterial leaf blight (BLB) is a devastating disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo), severely affects grain quality and reduces yield in all rice-growing areas of Pakistan. The pathogen is highly dynamic and quickly evolves itself when encountered with new resistant genes, hence, the knowledge about existing virulence range within the pathogen population and availability of corresponding resistance gene source is of immense importance. The present study focused on molecular dissection and evaluating the effectiveness of different resistance gene combinations against Xoo isolates collected from seven major rice-growing districts of Punjab Pakistan. Phenotypic characterization of collected Xoo isolates has shown that all of them were rod-shaped Gram-negative bacteria. However, oryzae species and oryzae pathovar were confirmed in only 22 out of 50 isolates using multiplex PCR. Analysis of loop-mediated isothermal amplification validated the lineage and close relatedness of Pakistani Xoo isolates with the already reported Asian Xoo population. Pathogenicity test on susceptible rice variety Super Basmati has shown that out of twenty-two tested Xoo isolates, four isolates from three different districts fell into the most virulent category with an average lesion length of ≥15 cm. Pathotyping of selected resistant rice lines against Xoo isolates distributed 22 isolates into nine pathotypes based on their interaction with R genes. Current molecular and phenotypic profiling of isolated Pakistani Xoo isolates may serve as a valuable reference for global comparison to manage BLB disease of rice in real-time.