Pathophysiology of Fusarium oxysporum f. Sp. Dianthi in carnation (Dianthus caryophyllus L.)

The bio-chemical changes occurred in the carnation after inoculation with F. oxysporum f.sp. dianthi was studied under in vitro. Carnation plants inoculated with fourteen isolates of F.oxysporum f.sp.dianthi and monitored for their ability to production of fungal pectin-degrading enzymes viz., Pectin Methyl Esterase (PME), Polygalacturonase (PG) and Pectin Trans Eliminase (PTE) involved in development of disease symptoms. Production of pectinolytic enzymes in carnation plants were assessed from 2 days up to 8 days after inoculation at 48h intervals. The accumulation of these enzymes increased in two days after inoculation and attained a peak at six days after inoculation and slowly declined thereafter in all the inoculated plants. Among the fourteen isolates, YRPFOD2 had maximum ability to increase the activity of pectinolytic enzymes viz., Pectin Methyl Esterase (0.49 μ mole hydrogen ion / min / ml), Polygalacturonase (16.11% reduction in viscosity) and Pectin Trans Eliminase (57.59 % reduction in viscosity) after six days of inoculation in infected plants.