Abstract
Induction of carbohydrate metabolism in relation to leaf blight (Bipolaris sorokiniana) was studied in healthy and infected leaves of barley (Hordeum vulgare). Two genotypes with varying sensitivity to leaf blight viz. PL 426 (susceptible) and BL 4 (resistant) in the absence of or following infection with leaf blight at different stages (0-20 days after infection) were used. Both acid and neutral invertase activities increased in response to leaf blight and might be linked with a defence mechanism against fungal infection. Low activities of sucrose synthase and sucrose phosphate synthase in infected leaves as compared to non infected leaves may be involved in retention of more sugars for utilization by the fungus for its own metabolic processes. The levels of total sugar, non-reducing sugar and starch were less in infected leaves as compared to non infected leaves. Irrespective of cultivar and stage of infection, activity of total amylase marginally increased with concomitant decline in starch content. The lower yield of infected host plants may be linked to reduced photosynthesis due to leaf blight leading to an alteration in the fluxes of carbon. Thus fungal infection represents a costly stress to the plant in terms of carbon production and utilization.
