Calmodulin (CaM) is a highly conserved calcium sensor protein associated with chilling tolerance in living organisms. It has four EF-hand domains for binding of four Ca2+, two of them located in the N-terminus, and the other two in the C-terminus. A notothenioid CaM gene fragment (CaMm), which only codes for N-terminus of CaM (with two EF-hand domains), was introduced into Nicotiana benthamiana. Effects of its overexpression on chilling tolerance in plants were explored. During 4◦C or 0◦C chilling treatment, both CaMm and CaM transgenic plants showed higher PSII maximum quantum yield, actual quantum yield, and soluble protein content, lower electrolyte leakage and malondialdehyde content than that of the control. The changes in these physiological indices were comparable between the CaMm and CaM transgenic plants during the treatments. These results indicate that the N-terminus of calmodulin is likely the key functional domain involved in the adaptive response to cold stress., T. J. Zhang, L. J. Pan, Q. Huang, L. H. Zhu, N. Yang, C. L. Peng, L. B. Chen., and Obsahuje seznam literatury
We investigated the photosynthetic characteristics of Chorispora bungeana under conditions of drought stress caused by different concentrations of polyethylene glycol-6000 (PEG; 0, 5, 20, and 40%) and various concentrations of exogenous glycine (0, 5, 10, and 20 mM) with 20% PEG. We showed that moderate and severe drought stress of PEG reduced the chlorophyll (Chl) content (both Chl a and b), maximal quantum yield of PSII photochemistry (Fv/Fm), actual photochemical efficiency of PSII in light (YII), and quantum yield of regulated energy dissipation (YNPQ), while Chl a/b and quantum yield of nonregulated energy dissipation (YNO) increased. The low and moderate drought stress increased Mg2+ and Fe3+ contents, while a decrease in Mg2+ and Fe3+ was found under severe drought stress. Compared to sole PEG stress, the addition of exogenous 10 mM glycine increased Chl, Mg2+ and Fe3+ contents, Fv/Fm, YII, and YNPQ, and reduced YNO. On the contrary, 20 mM glycine showed an opposite effect, except for YNO. Our results proved that Chl contents and fluorescence parameters are reliable indicators for drought tolerance of C. bungeana. We suggest that a proper glycine content can relieve the effect of drought stress on C. bungeana., N. Yang, C.-L. Wang, W.-P. He, Y.-Z. Qu, Y.-S. Li., and Seznam literatury