Biochemical responses associated with bacterial blight of rice (Oryza sativa)

Abstract

Biochemical response of susceptible cultivar TN 1 and resistant near isogenic lines IRBB 13 and IRBB 21 of rice to Xanthomonas oryzae pv. oryzae (Xoo) was studied at different stages of infection. The activities of the defence related enzymes peroxidase (PO), phenylalanine ammonia lyase (PAL) and tyrosine ammonia lyase (TAL) were found to be significantly higher in the resistant isogenic lines, IRBB 13 and IRBB 21 than in the susceptible cultivar TN 1. Total phenols, ortho-dihydroxyphenols and flavonols content also exhibited a similar trend as that of the enzymes. After bacterial infiltration a significant increase in the levels of total phenols, o-dihydroxyphenols, flavonols, PO, PAL and TAL was observed. However, this increase was comparatively rapid and higher in resistant near isogenic lines when compared with the susceptible line. Total sugars, reducing sugars and starch content were significantly higher in the leaves of the susceptible variety TN 1 than in the resistant near isogenic lines IRBB 13 and IRBB 21.