Complementation of the embryo-lethal T-DNA insertion mutant of AUXIN-BINDING-PROTEIN 1 (ABP1) with abp1 point mutated versions reveals crosstalk of ABP1 and phytochromes.
The function of the extracytoplasmic AUXIN-BINDING-PROTEIN1 (ABP1) is largely enigmatic. We complemented a homozygous T-DNA insertion null mutant of ABP1 in Arabidopsis thaliana Wassilewskia with three mutated and one wild-type (wt) ABP1 cDNA, all tagged C-terminally with a strepII-FLAG tag upstream the KDEL signal. Based on in silico modelling, the abp1 mutants were predicted to have altered geometries of the auxin binding pocket and calculated auxin binding energies lower than the wt. Phenotypes linked to auxin transport were compromised in these three complemented abp1 mutants. Red light effects, such as elongation of hypocotyls in constant red (R) and far-red (FR) light, in white light supplemented by FR light simulating shade, and inhibition of gravitropism by R or FR, were all compromised in the complemented lines. Using auxin- or light-induced expression of marker genes, we showed that auxin-induced expression was delayed already after 10 min, and light-induced expression within 60 min, even though TIR1/AFB or phyB are thought to act as receptors relevant for gene expression regulation. The expression of marker genes in seedlings responding to both auxin and shade showed that for both stimuli regulation of marker gene expression was altered after 10-20 min in the wild type and phyB mutant. The rapidity of expression responses provides a framework for the mechanics of functional interaction of ABP1 and phyB to trigger interwoven signalling pathways.
Leibniz Universität Hannover, Institut für Gartenbauliche Produktionssysteme, Abt. Molekulare Ertragsphysiologie, Herrenhäuser Str. 2, D-30419 Hannover, Germany Al Azhar Indonesia University, Department of Biology, Sisingamangaraja, Jakarta 12110, Indonesia.
Yunus
Y
Effendi
University of Bonn, Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, Beringstr. 4, D-53115 Bonn, Germany.
Noel
N
Ferro
Leibniz Universität Hannover, Institut für Gartenbauliche Produktionssysteme, Abt. Molekulare Ertragsphysiologie, Herrenhäuser Str. 2, D-30419 Hannover, Germany.
Corinna
C
Labusch
University of Fribourg, Department of Biology - Plant Biology, Chemin de Museé 10, CH-1700 Fribourg, Switzerland.
Markus
M
Geisler
Leibniz Universität Hannover, Institut für Gartenbauliche Produktionssysteme, Abt. Molekulare Ertragsphysiologie, Herrenhäuser Str. 2, D-30419 Hannover, Germany scherer@zier.uni-hannover.de.
Günther F E
GF
Scherer
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D001692:Biological Transport; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D008027:Light; D010834:Phytochrome / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017354:Point Mutation; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
D004269:DNA, Bacterial; D007210:Indoleacetic Acids; D010940:Plant Proteins; D011956:Receptors, Cell Surface; C036483:T-DNA; C083846:auxin-binding protein 1; D010834:Phytochrome
AUXIN-BINDING PROTEIN1 (ABP1); Arabidopsis thaliana.; abp1 mutants; early auxin-regulated genes; early light-regulated genes; gravitropism; hypocotyl elongation; phototropism; phytochrome; shade avoidance