Correlation between selected morphological and biochemical parameters in a hybrid tea population with the blister blight disease

Abstract

Tea is produced from the plant species Camellia sinensis. Blister blight is a major leaf disease caused by the fungus Exobasidium vexans in tea resulting in significant yield losses, debilitation and death of tea bushes . Copper and systemic fungicides are currently used to control the disease resulting in high costs and potential residues in tea. In addition, there is a possibility of developing fungi resistance in tea plants to fungicides. Therefore, developing cultivars with resistance towards Blister blight is considered as the most suitable approach to control the disease. In the present study, the correlation between morphological and biochemical parameters was investigated with Blister blight disease with an aim to develop resistant cultivars. Twenty (20) tea samples including 18 accessions produced by crossing two parent cultivars: TRI 2043 (highly resistant to Blister blight) and TRI 3055 (highly susceptible to Blister blight) and the two parent cultivar samples were used in this study. The morphological analysis was carried out with reference to the guidelines given in the descriptors for tea by the International Plant Genetic Resources Institute (IPGRI) in 1997 and the descriptor list of the International Union for the Protection of New Varieties of Plants (UPOV) for tea (2008). Biochemical parameters were analysed following spectrophotometric methods and HPLC methods. Total anthocyanin, caffeine, polyphenol, gallic acid, epigallocatechin, catechin, epicatechin, epigallocatechin gallate and epicatechin gallate contents were determined. Results obtained for morphological and biochemical parameters were statistically analysed using the Minitab software under two categories; calculating the correlation between morphological and biochemical parameters and plotting a dendrogram for morphological and biochemical parameters separately. The Pearson correlation method was used to calculate the correlation between parameters. From the morphological parameters, a positive relationship was observed in the number of average pubescence on young leaf with the Blister blight resistance. Total anthocyanin content showed a positive relationship and epicatechin showed a low negative relationship with the Blister blight resistance. Accession 26 showed a very high total anthocyanin content (0.123 ± 0.065%), a moderate epicatechin content (0.792 ± 0.168%) and a high resistance to Blister blight disease, indicating its potential to be developed as a resistant cultivar. The experiment was duplicated, and the same results were obtained both times. Based on the results, it can be concluded that anthocyanin content can be suggested as a biochemical marker in tea crop improvement programs.