The effect of ethephon on physiology and coumarin-related compounds in leaves of two chamomile cultivars (Matricaria chamomilla L.)

Abstract

Seven-week-old leaf rosettes were treated with 0.3- or 0.7-mM ethephon (ET) and analyzed at four different time points (24, 48, 72, 96 h). The intensity of ET influence was assessed by monitoring the physiological, photosynthetic, and stress-related parameters. Another aim was to compare the responses of two cultivar differ in ploidy level. ET treatment negatively affected chlorophylls and total carotenoid content. Hydrogen peroxide and superoxide radical level was the most elevated after 72 h for diploids and 96 h for tetraploid after 0.7-mM ET. Among physiological parameters, the lower concentration appeared to be less stressful in both cultivars. The levels of total phenols and flavonoids in control plants were comparable within cultivars, but the elevation (maximum in 48-h and 72-h variants in 0.7-mM ET, respectively) was more apparent in tetraploids. Significant differences between treatments were in diploid in case of total phenols and in tetraploid in case of flavonoids. Enhanced phenylalanine ammonia-lyase activity resulted in a moderate increment of all monitored coumarin-related compounds, with one exception for (Z)-2-β-d-glucopyranosyloxy-4-methoxycinnamic acid, where a declining trend occurred. Strong accumulation for umbelliferone over the time was monitored. Overall, the effect of the lower ET concentration was less stimulatory. Due to increment in monitored secondary metabolites, we can conclude that used concentration of ET did not act as a stimulant of secondary metabolite synthesis. Comparative study of two cultivars indicated that diploid cultivar react to treatment more pronouncedly.