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Publikationen - Molekulare Signalverarbeitung

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Publikation

Gasperini, D.; Greenland, A.; Hedden, P.; Dreos, R.; Harwood, W.; Griffiths, S.; Genetic and physiological analysis of Rht8 in bread wheat: an alternative source of semi-dwarfism with a reduced sensitivity to brassinosteroids J. Exp. Bot. 63, 4419-4436, (2012) DOI: 10.1093/jxb/ers138

Over the next decade, wheat grain production must increase to meet the demand of a fast growing human population. One strategy to meet this challenge is to raise wheat productivity by optimizing plant stature. The Reduced height 8 (Rht8) semi-dwarfing gene is one of the few, together with the Green Revolution genes, to reduce stature of wheat (Triticum aestivum L.), and improve lodging resistance, without compromising grain yield. Rht8 is widely used in dry environments such as Mediterranean countries where it increases plant adaptability. With recent climate change, its use could become increasingly important even in more northern latitudes. In the present study, the characterization of Rht8 was furthered. Morphological analyses show that the semi-dwarf phenotype of Rht8 lines is due to shorter internodal segments along the wheat culm, achieved through reduced cell elongation. Physiological experiments show that the reduced cell elongation is not due to defective gibberellin biosynthesis or signalling, but possibly to a reduced sensitivity to brassinosteroids. Using a fine-resolution mapping approach and screening 3104 F2 individuals of a newly developed mapping population, the Rht8 genetic interval was reduced from 20.5 cM to 1.29 cM. Comparative genomics with model genomes confined the Rht8 syntenic intervals to 3.3 Mb of the short arm of rice chromosome 4, and to 2 Mb of Brachypodium distachyon chromosome 5. The very high resolution potential of the plant material generated is crucial for the eventual cloning of Rht8.
Publikation

Brandt, R.; Salla-Martret, M.; Bou-Torrent, J.; Musielak, T.; Stahl, M.; Lanz, C.; Ott, F.; Schmid, M.; Greb, T.; Schwarz, M.; Choi, S.-B.; Barton, M. K.; Reinhart, B. J.; Liu, T.; Quint, M.; Palauqui, J.-C.; Martínez-García, J. F.; Wenkel, S.; Genome-wide binding-site analysis of REVOLUTA reveals a link between leaf patterning and light-mediated growth responses Plant J. 72, 31-42, (2012) DOI: 10.1111/j.1365-313X.2012.05049.x

Unlike the situation in animals, the final morphology of the plant body is highly modulated by the environment. During Arabidopsis development, intrinsic factors provide the framework for basic patterning processes. CLASS III HOMEODOMAIN LEUCINE ZIPPER (HD‐ZIPIII) transcription factors are involved in embryo, shoot and root patterning. During vegetative growth HD‐ZIPIII proteins control several polarity set‐up processes such as in leaves and the vascular system. We have identified several direct target genes of the HD‐ZIPIII transcription factor REVOLUTA (REV) using a chromatin immunoprecipitation/DNA sequencing (ChIP‐Seq) approach. This analysis revealed that REV acts upstream of auxin biosynthesis and affects directly the expression of several class II HD‐ZIP transcription factors that have been shown to act in the shade‐avoidance response pathway. We show that, as well as involvement in basic patterning, HD‐ZIPIII transcription factors have a critical role in the control of the elongation growth that is induced when plants experience shade. Leaf polarity is established by the opposed actions of HD‐ZIPIII and KANADI transcription factors. Finally, our study reveals that the module that consists of HD‐ZIPIII/KANADI transcription factors controls shade growth antagonistically and that this antagonism is manifested in the opposed regulation of shared target genes.
Publikation

Calderón Villalobos, L. I. A.; Lee, S.; De Oliveira, C.; Ivetac, A.; Brandt, W.; Armitage, L.; Sheard, L. B.; Tan, X.; Parry, G.; Mao, H.; Zheng, N.; Napier, R.; Kepinski, S.; Estelle, M.; A combinatorial TIR1/AFB–Aux/IAA co-receptor system for differential sensing of auxin Nat. Chem. Biol. 8, 477-485, (2012) DOI: 10.1038/nchembio.926

The plant hormone auxin regulates virtually every aspect of plant growth and development. Auxin acts by binding the F-box protein transport inhibitor response 1 (TIR1) and promotes the degradation of the AUXIN/INDOLE-3-ACETIC ACID (Aux/IAA) transcriptional repressors. Here we show that efficient auxin binding requires assembly of an auxin co-receptor complex consisting of TIR1 and an Aux/IAA protein. Heterologous experiments in yeast and quantitative IAA binding assays using purified proteins showed that different combinations of TIR1 and Aux/IAA proteins form co-receptor complexes with a wide range of auxin-binding affinities. Auxin affinity seems to be largely determined by the Aux/IAA. As there are 6 TIR1/AUXIN SIGNALING F-BOX proteins (AFBs) and 29 Aux/IAA proteins in Arabidopsis thaliana, combinatorial interactions may result in many co-receptors with distinct auxin-sensing properties. We also demonstrate that the AFB5–Aux/IAA co-receptor selectively binds the auxinic herbicide picloram. This co-receptor system broadens the effective concentration range of the hormone and may contribute to the complexity of auxin response.
Bücher und Buchkapitel

Vaira, A. M.; Gago-Zachert, S.; Garcia, M. L.; Guerri, J.; Hammond, J.; Milne, R. G.; Moreno, P.; Morikawa, T.; Natsuaki, T.; Navarro, J. A.; Pallas, V.; Torok, V.; Verbeek, M.; Vetten, H. J.; Family - Ophioviridae (King, A. M. Q., et al., eds.). 743-748, (2012) DOI: 10.1016/B978-0-12-384684-6.00060-4

This chapter focuses on Ophioviridae family whose sole member genus is Ophiovirus. The member species of the genus include Citrus psorosis virus (CPsV), Freesia sneak virus(FreSV), Lettuce ring necrosis virus (LRNV), and Mirafiori lettuce big-vein virus (MiLBVV).The single stranded negative/possibly ambisense RNA genome is divided into 3–4 segments, each of which is encapsidated in a single coat protein (43–50 kDa) forming filamentous virions of about 3 nm in diameter, in shape of kinked or probably internally coiled circles of at least two different contour lengths. Ophioviruses can be mechanically transmitted to a limited range of test plants, inducing local lesions and systemic mottle. The natural hosts of CPsV, ranunculus white mottle virus (RWMV), MiLBVV, and LRNV are dicotyledonous plants of widely differing taxonomy. CPsV has a wide geographical distribution in citrus in the Americas, in the Mediterranean and in New Zealand. FreSV has been reported in two species of the family Ranunculacae from Northern Italy, and in lettuce in France and Germany. Tulip mild mottle mosaic virus (TMMMV) has been reported in tulips in Japan. LRNV is closely associated with lettuce ring necrosis disease in The Netherlands, Belgium, and France, and FreSV has been reported in Europe, Africa, North America and New Zealand.
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