Abstract:
Blister blight, a leaf disease caused by the fungus Exobasidium vexans Massee, is
an economically important disease in tea lands. This disease cause heavy crop
losses in the cultivation of tea.
Tea Research Institute has developed Exobasidium vexans resistant and susceptible
cultivars using conventional plant breeding programme. The study was carried out at
TRI, using Exobasidium vexans resistant & susceptible selection as determined by
the Pathology division from phase I & II stage of the conventional plant breeding
programme in order to confirm the possibility of using chemical markers to detect
blister blight resistant cultivars.
Nine selections from phase II and seven selections from phase I were selected.
These selections included both blister blight resistant & susceptible cultivars, from
the field No. 12, St.Coombs estate, Thalawakelle. Extraction of the samples for the
analysis of individual catechins was done by maceration of samples in 70%(v/v)
boiling methanol. Analysis of caffeine and catechins were carried out using high
performance liquid chromatography (HPLC).
The results of phase I, revealed that there is no significant correlation between the
Epigallocatechin (EG C ) content in the tea plant with the blister blight resistance. The
results from phase I also revealed that there may be possibility of using Epicatechin
(E C ) levels together with Epigallocatechin gallate(EGCG) levels in the tea plant to
select blister blight resistant & susceptible tea varieties.
According to the results from phase II, EG C content & EC G contents of phase II
selections had no correlation to blister blight disease resistance. The EC & E G C G
contents of phase II selections indicated that there could be a correlation between
E C & EG CG contents of the tea plant and blister blight leaf disease resistance as in
the case of phase I selections.
Results obtained from this study confirmed the previous work carried out at TRI, in
order to use chemical compounds as an indicator for the blister blight resistance &
susceptibility.
Further investigations need to be carried out to confirm the possibility of using
chemical markers to detect blister blight resistant varieties of an early stages of the
breeding programme.
