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Phytochromes and shade-avoidance responses in plants   总被引:28,自引:0,他引:28  
BACKGROUND AND AIMS: The ability to detect and respond to the impending threat of shade can confer significant selective advantage to plants growing in natural communities. This Botanical Briefing highlights (a) the regulation of shade-avoidance responses by endogenous and exogenous factors and (b) current understanding of the molecular components involved in red to far-red ratio signal transduction. SCOPE: The Briefing covers: (a) the shade-avoidance syndrome in higher plants; (b) the adaptive significance of shade avoidance in natural light environments; (c) phytochrome regulation of shade-avoidance responses; (d) the role of blue light signals in shade avoidance; (e) gating of rapid shade-avoidance responses by the circadian clock; (f) potential signalling components and future perspectives.  相似文献   
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Light signals received by phytochromes in plants may be transduced through protein phosphorylation. Ca(2+) as second messenger was involved in phytochrome-mediated cellular events. Our experiments with Cucumis sativus cotyledons, treated with red (R) and far-red (FR) light, showed a stimulatory effect on in vitro protein phosphorylation of histone, added as exogenous substrate to the cotyledon extracts, and also modified the phosphorylation of endogenous polypeptides. The effect of light treatments was mimicked by the addition of Ca(2+) to the phosphorylation buffer, indicating phytochrome- and Ca(2+)-dependence on activity of some protein kinases (PKs). In-gel kinase assays were performed to characterize the PKs involved at the cotyledon stage of cucumber plants. Three proteins of about 75, 57 and 47kDa with PK activity were detected between M(r) markers of 94 and 45kDa. All three were able to phosphorylate histone and undergo autophosphorylation. However, only the 75 and 57kDa proteins autophosphorylated and phosphorylated the substrate in a Ca(2+)-dependent manner, and were inhibited when calmodulin (CaM) antagonists were added to the incubation buffer. Western-blot analysis with polyclonal antibodies directed against calcium-dependent protein kinase of rice (OsCDPK11) or Arabidopsis (AtCPK2) recognised 57 and 75kDa polypeptides, respectively. These results indicate the presence in cucumber cotyledons of at least two proteins (ca. 75 and 57kDa) with activity of PKs that could be calcium-dependent protein kinases (CDPKs). Both CDPKs could be modulated by phytochromes throughout FR-HIR and VLFR responses.  相似文献   
3.
Plants possess photoreceptors to perceive light which controls most aspects of their lives. Three photoreceptor families are well characterized: cryptochromes (crys), phototropins (phots), and phytochromes (phys). Two putative families have been identified more recently: Zeitlupes (ZTLs) and UV-B photoreceptors (ULI). Using Arabidopsis thaliana and Oryza sativa photoreceptor sequences as references, we have searched for photoreceptor encoding genes in the major phyla of plant kingdom. For each photoreceptor family, using a phylogenetic tree based on the alignment of conserved amino acid sequences, we have tried to trace back the evolution and the emergence of the diverse photoreceptor ancestral sequences. The green alga Chlamydomonas contains one cry and one phot sequence, probably close to the corresponding ancestral sequences, and no phy-related sequence. The putative UV-B photoreceptors seem to be restricted to the Brassicacae. Except for mosses and ferns, which contain divergent photoreceptor numbers, the composition of the diverse photoreceptor families is conserved between species. A high conservation of the residues within domains is observed in each photoreceptor family. The complete phylogenic analysis of the photoreceptor families in plants has confirmed the existence of crucial evolutionary nodes between the major phyla. For each photoreceptor class, a major duplication occurred before the separation between Mono- and Eudicotyledons. This allowed postulating on the putative ancestral function of the photoreceptors. [Reviewing Editor: Dr. Rudiger Cerff]  相似文献   
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植物光敏色素入核机理的研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
光敏色素是植物感受外界环境变化的重要光受体,它对植物的生长发育具有重要的调控作用。在介绍植物光敏色素分子结构的基础上,对不同光敏色素的入核机理以及核内定位进行了综述,并根据最新研究进展对光敏色素入核机理进行了展望。  相似文献   
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