Plants constantly monitor their light environment in order to grow and develop optimally, in part through use of the phytochromes, which sense red/far-red light. A phytochrome binding protein, PKS1 (phytochrome kinase substrate 1), was identified that is a substrate for light-regulated phytochrome kinase activity in vitro. In vivo experiments suggest that PKS1 is phosphorylated in a phytochrome-dependent manner and negatively regulates phytochrome signaling. The data suggest that phytochromes signal by serine-threonine phosphorylation.
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http://dx.doi.org/10.1126/science.284.5419.1539 | DOI Listing |
FEBS Lett
January 2025
Allgemeine Botanik, Karlsruhe Institute of Technology, Joseph Kölreuter Institut für Pflanzenwissenschaften (JKIP), Karlsruhe, Germany.
Phytochromes are biliprotein photoreceptors found in bacteria, fungi, and plants. The soil bacterium Agrobacterium fabrum has two phytochromes, Agp1 and Agp2, which work together to control DNA transfer to plants and bacterial conjugation. Both phytochromes interact as homodimeric proteins.
View Article and Find Full Text PDFPlant Physiol
January 2025
School of Life Science, Ningxia University, Yinchuan 750021, Ningxia, China.
Cold stress severely impacts the quality and yield of grapevine (Vitis L.). In this study, we extend our previous work to elucidate the role and regulatory mechanisms of Vitis amurensis MYB transcription factor 4a (VaMYB4a) in grapevine's response to cold stress.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing 100193, China.
Light serves as an energy source for cell division and expansion during fruit development. Cell expansion significantly influences fruit size and is closely linked to endoreduplication, a unique cell cycle variation characterized by DNA replication without cytokinesis. Paradoxically, under conditions of ample photosynthates, light signaling suppresses cell expansion.
View Article and Find Full Text PDFJ Exp Bot
December 2024
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi-110067, India.
Stomata, the small pores on the surfaces of leaves and stems, are crucial for gas exchange in plants and also play a role in defense against pathogens. The stomatal movement is not only influenced by surrounding light conditions but also by the presence of foliar pathogens. To put it more crisply, certain light wavelengths such as blue or strong red light, cause stomatal opening, which tragically makes it easier for bacteria to enter through opened stomata and causes disease progression in plants.
View Article and Find Full Text PDFChemistry
January 2025
NMR-supported Structural Biology, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany.
Phytochromes perceive subtle changes in the light environment and convert them into biological signals by photoconversion between the red-light absorbing (Pr) and the far-red-absorbing (Pfr) states. In the primitive bacteriophytochromes this includes refolding of a tongue-like hairpin loop close to the chromophore, one strand of an antiparallel β-sheet being replaced by an α-helix. However, the strand sequence in the cyanobacterial phytochrome Cph1 is different from that of previously investigated bacteriophytochromes and has a higher β-sheet propensity.
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