CHANGES IN CHLOROPHYLL CONTENT DURING PATHOGENESIS IN COMMON BEAN – RUST PATHOSYSTEM

Abstract

Common bean rust is a disease of economic importance in bean production areas. When disease intensity is high the pathogen Uromyces appendiculatus can cause up to 100% yield loss. The aim of present study is to investigate the changes in chlorophyll content during pathogenesis in common bean after inoculation with U. appendiculatus. The investigation is carried out in greenhouse conditions. Plants of cultivar “Skitiya” were inoculated with spore suspension of the pathogen. Starting from the day after inoculation (DAI), daily for 15 days, leaf samples of inoculated and non-inoculated plants were used to determine chlorophyll content spectrophotometrically. The results show that no differences between non-inoculated and inoculated plants were observed in term of chlorophyll ‘a’ (chl a) and chlorophyll ‘b’ (chl b) content during first three DAI. In fourth and fifth DAI the values of the indexes decreases but still not significantly. White small spots appear on abaxial and adaxial leaf surface in 6th DAI which indicate that latent period is six days. At the same time chl a is 174,03 mg/m3 and chl b is 40,43 mg/m3 in inoculated leaves which is significantly lower than non-inoculated leaves. First pustules with infection type (IT)=5,6 (0.5-0.8 mm and >0.8mm in diameter) occur 11 DAI and chl a is 114,23 mg/m3 and chl b is 34,63 mg/m3. The differences between inoculated and non-inoculated leaves are statistically significant. The pustules are fully developed 13 DAI. The results demonstrate that infection of U. appendiculatus cause reduction of chlorophyll content in leaves of common bean during pathogenesis process, and more specifically during incubation period.