Two calcium dependent protein kinases are differently regulated by light and have different activity patterns during seedling growth in Pharbitis nil

Abstract

In this study using biochemical approaches we identified two calcium-dependent protein kinases (CDPKs) named PnCDPK52 and PnCDPK56 in soluble protein extracts from seedlings of Pharbitis nil. Both enzymes phosphorylated the specific substrate histone III-S in the presence of Ca 2? and cross-reacted with antibodies against the CDPK. PnCDPKs exhibited quite different activity and protein levels during germination and successive stages of seedling growth. PnCDPK52 protein level was high in seeds and during germination, whereas PnCDPK56 increased in the next stages of seedling growth, being the dominant enzymes in mature seedlings, of the light-and dark-grown plant. In all cases both activity and accumulation of protein PnCDPK56 was higher in dark grown plants whereas exposure to light reduced both factors. When etiolated cotyledons were exposed to light, the activity of PnCDPK56 was reduced to the basal level within 5 h. Conversely, increasing activity of PnCDPK56 in cotyledons of green plants shifted to darkness was extremely rapid, reaching the maximum level after just 1 h of darkness and then gradually decreased. Further lengthening of the darkness to 16 h resulted in a strong increase in activity at 12 h. These data indicate that at least two isoforms of CDPK are involved in germination and seedling growth of P. nil. The differences in PnCDPKs strongly argue for the pleiotropic role of these isoforms. It seems that PnCDPK52 is associated with the germination process and PnCDPK56 with seedling growth. Moreover it suggests that activity of PnCDPK56 is controlled by light via the photoreceptor-dependent pathway.

Improvement of a Genetic Transformation System and Preliminary Study on the Function of LpABCB21 and LpPILS7 Based on Somatic Embryogenesis in Lilium pumilum DC. Fisch

“…Calcium ions are the major second messenger in plants, and the calcium signaling pathway has been extensively studied [ 47 , 48 ]. Recent studies have shown that CaCl 2 (calcium chloride) can promote the induction of embryogenic calli (EC) and the germination of somatic embryos.…”

In Search of Monocot Phosphodiesterases: Identification of a Calmodulin Stimulated Phosphodiesterase from Brachypodium distachyon

“…Calcium-dependent cellular processes are regulated through intracellular Ca 2+ -binding proteins, of which the best-studied are calmodulin (CaM), calmodulin-like proteins (CMLs) and calcium-dependent protein kinases (CDPKs). These proteins bind Ca 2+ ions through the EF hand motif, a conserved helix-loop-helix structure that binds a single Ca 2+ ion, thereby causing a change in the conformation that, in turn, can activate target proteins or cause self-activation [31][32][33][34]. Since it was reported that CaM/Ca 2+ affects the activity of group I animal PDEs and the PDE domain of the ATKUP5 [17,35] and that a protein sequence analysis revealed that BDPDE1 also contains a predicted CaM-binding site between amino acids 50 and 70, we investigated the possible interactions of CaM and CaM-like isoforms with plant PDE using fluorescence spectroscopy.…”

The ecological hazard of artificial lighting in greenhouses

“…In the next step, we ignore the needs of all species of fauna and flora, we design lighting systems adjusted to our eyesight. Finally, we are surprised why some animal species die in automobile accidents [1], birds die after crashing into skyscrapers [2,3] and the greenhouse plants grow slower [4][5][6] than we expect? After all, we provided white light with a high colour rendering index or selectable colour temperature -but in pursuit of economic efficiency, we have forgotten about nature.…”