Flavonoids are thought to participate in protection of the photosynthetic apparatus against photoinhibition under excessive light. Flavone glycoside, scutellarin, is a main active ingredient extracted from Erigeron breviscapus, the plant used in Chinese medicine. Shade-developed leaves of E. breviscapus were transferred from shade to full sunlight to quantify a relationship between the concentration of leaf scutellarin and tolerance to high radiation stress or the recovery from photoinhibition. The maximal quantum yield of PSII photochemistry showed a diurnal fluctuation in both shaded and sunlit leaves throughout the day. It indicated dynamic photoinhibition in the leaves of Erigeron, i.e., higher photoinhibition at solar noon and lower one in the morning and late afternoon. The sun-developed leaves reached the higher scutellarin content and values of nonphotochemical quenching coefficient with a lower degree of photoinhibition than the shade-developed leaves. When the shade-developed leaves were transferred to full sunlight, the content of scutellarin was declining continuously for 10 d and then was increasing for 15 d. After 50 d, all leaves became the sun-developed leaves with their scutellarin contents of about 138.5 ± 5.2 mg g-1(dry mass, DM) which was significantly higher than that of the shade-developed leaves [107.8 ± 9.8 mg g-1(DM)]. During acclimatization, the degree of photoinhibition was negatively correlated with the scutellarin content. Our results demonstrated a synchronous fluctuation between the flavonoid content and degree of protection against photoinhibition., R. Zhou, W. H. Su, G. F. Zhang, Y. N. Zhang, X. R. Guo., and Obsahuje seznam literatury
A greenhouse study was performed in order to investigate the effects of three arbuscular mycorrhizal fungi (AMF) species on vegetative growth, water relations, and mineral composition parameters of snapdragon (Antirrhinum majus cv. Bells white) under irrigation from different water sources. Five irrigation treatments included using purely desalinized (fresh) water (DW), as a control, three different blends of DW with saline ground water from a well with increasing salinity, and one with 100% of saline well water. Inoculation with AMF enhanced growth rates and a relative water content of snapdragon plants grown under well-water irrigation. AMF also improved the leaf water potential and increased water-use efficiency of the plants. Shoot and root dry masses were higher in the AMF-treated plants than those in AMF-free plants. In both shoots and roots, concentrations of total P, Ca2+, N, Mg2+, and K+ were higher in the AMF-treated plants compared with AMF-free plants under salt-stress conditions. Shoot Cl- and Na+ concentrations were lower in the AMF-treated plants than those in the AMF-free plants grown under well-water irrigation. Snapdragon plants exhibited a high degree of dependency on AMF; it improved plant growth rates and leaf water relations, particularly, with increasing salinity of irrigation water., Y. I. El-Nashar., and Obsahuje bibliografii