Abstract
The main objective of this research was to examine the effects of exogenous salicylic acid (SA) and to study the seasonal variation of the chlorophyll a fluorescence parameters and antioxidant enzymatic activities in desiccation-tolerant moss species Syntrichia ruralis (Hedw.) Web. and Mohr. Aqueous 0.001 M SA solution was sprayed on the moss cushions collected from semi-arid sandy grassland, Hungary in three seasons (spring, summer, autumn). These cushions were kept under the observation for 10 Days. Chlorophyll a fluorescence parameters, i.e., maximum photochemical quantum yield of PS II (Fv/Fm), effective photochemical quantum yield of PS II (ΦPSII), non-photochemical quenching (NPQ), and antioxidant enzymatic activities, i.e., ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (POD), and protein content were determined. The results showed the increase of Fv/Fm in spring and autumn season while ΦPSII was reduced significantly during spring and summer season after treatment with SA compared to control. SA-treated mosses showed higher values of non-photochemical quenching (NPQ) during the spring and autumn season than in summer. Activities of enzyme APX and CAT were found to increase in SA-treated except POD activity. In SA-treated moss cushions, lower protein content was found. It can be concluded that seasonal variation has been observed in chlorophyll fluorescence and antioxidant system after long term of desiccation in S. ruralis species that could be because of SA and might be due to fluctuations in conditions of their habitat, duration of light intensity, temperature and precipitation.
Highlights
Bryophytes are the experimental model organisms that contribute to study of evolution of plant hormones
Water content was expressed as a percentage of that at full turgor
In the case of Salicylic acid (SA) treated, the trend of the water content increased at 12 h and steadily decreased as the time progressed, while in the case of control samples the trend was variable
Summary
Bryophytes are the experimental model organisms that contribute to study of evolution of plant hormones. Phytohormones are low-molecular-weight molecules that activate an effective defense response against both biotic and abiotic environmental stresses and responsible for growth and development. Only auxins, cytokinins, and abscisic acid has been earlier investigated. There is limited information related to the occurrence, metabolism, and function of plant hormones in mosses [1]. Most of the previous investigations concerning the effect of phytohormones on bryophyte were focused on the model moss Physcomitrella patens (Hedw.) Bruch and Schimp., and Funaria hygrometrica (Hedw.), and few reports are conducted on the other bryophytes. Salicylic acid (SA) can inhibit the later stages of bud formation in F. hygrometrica in a dose-dependent manner
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