Development and validation of ELISA technique for early detection of rhizome rot in golden spice turmeric from different agroclimatic zones

•Lacunae in early detection of rhizome rot causes losses of yield and quality of turmeric.•Polyclonal antibody with high affinity and specificity for Pythium aphanidermatum was raised.•Indirect ELISA was established for early detection of rhizome rot in turmeric.•Validation of ELISA was done by correlating antigenic load with antibody titres.•ELISA detected rhizome rot at early stage regardless of location and antigenic load.

Early and precise diagnosis of diseases in turmeric (Curcuma longa L.) permits early treatment which can enhance yield and quality of Indian spices. In the present study, polyclonal antibody (pAb) raised against the protein extract from Pythium aphanidermatum was established for the detection of rhizome rot using serological assays. The fungal proteins were recognized by ELISA with high sensitivity (50 ng) and the proteins ranging from 15 to 95 kDa showed immuno-reactivity in Western blot using the developed pAb. Correlation coefficient between infected samples at various stages from different agroclimatic zones with antibody titres was taken as the primary endpoint for standardization of the protocol. Highest positive correlation (r = 0.999) was observed in stage I and II infected samples of North-western zone, whereas low negative correlation (r = −0.284) was found in stage III infected samples of Western zone with developed pAb. Linear positive correlations (R2) exist between antigenic proteins at all the stages of infection and the developed pAb titres. Hence, the developed pAbs could be used to detect the presence of the fungal pathogen at an early stage. These serological approaches allow us to develop a rapid, sensitive, specific and accurate diagnostic kit for early detection of rhizome rot in turmeric.