SYSBIOAUX · A Systems Biology approach to disclose auxin synthesis in plants
FP7 — People (Marie Curie Actions)
- Duration
- 2012-03-01 → 2016-02-29
- EU contribution
- €100,000
- Participants
- 1
- Scheme
- MC-CIG
Lines connect the coordinator with its partners.
Results in brief
A Systems Biology approach to disclose auxin synthesis in plants
Plants utilize a very sophisticated network of phytohormones to control their growth and development. This regulatory network of interacting plant hormones is also paramount to integrate endogenous and exogenous stimuli and trigger adequate developmental responses, such as adapted growth velocities, tropisms, or initiation of chemical defense measures. In this framework, the substance class of auxins with its numerous precursors and derivatives plays an essential role. Auxins, and here especially the indole-3-acetic acid (IAA) as the most commonly occurring auxin in nature, are crucially involved in virtually every step of plant growth and development, including embryo and root patterning, organ formation, vascular tissue differentiation and growth responses to environmental cues. It is assumed that the main pathway for auxin formation in plants leads via the indole-3-pyruvic acid (IPyA)-pathway, involving a small family of tryptophan transaminases (TAA1, TARs) (Tao et al., 2008; Stepanova et al., 2008) and a bigger family of flavin containing monooxygenases, referred to as YUCCA enzymes (Mashiguchi et al., 2011; Won et al., 2011; Stepanova et al., 2011). Up to date, however, it cannot be completely excluded that a small number of alternative biosynthetic pathways also contribute to auxin biosynthesis in plants. Besides one Trp-independent pathway, at least two further Trp-dependent pathways for auxin biosynthesis have been proposed, each of them designated for an intermediate that is a hallmark of the pathway. These are the indole-3-acetaldoxime (IAOx)-pathway and the indole-3-acetamide (IAM)-pathway. The major objective of the SysBioAux project was to provide detailed insight into the occurrence and regulation of these possible routes for the production of IAA in the model plant Arabidopsis thaliana, and how they are interconnected with each other, in particular in terms of stress responses to external stimuli. In this respect, we based our experiments on a Systems Biology approach, including genomics, transcriptomics and metabolomics studies. Based on the results obtained in these experiments, we gained deeper insight into regulatory circuits through which transcript accumulation of a variety of IAA-biosynthesis related genes is controlled. Secondly, we conducted a number of transcriptomics and metabolomics studies, using both gain-of-function and loss-of-function mutants of auxin biosynthesis-related genes. It was possible to generate some novel higher-order mutants, which were also analyzed along with the already available mutants. On this broad basis of results, a model of the interconnection of the different auxin-biosynthetic pathways in Arabidopsis thaliana has been established. In addition, it was possible to carve out novel connections between auxin homeostasis and plant stress responses over the runtime of the project.
Data: CORDIS, © European Union
Project objective
Because plants have a sessile lifestyle, they must adjust to various external cues and coordinate their developmental program accordingly. To facilitate survival in often hostile environments, plants have evolved a notable developmental plasticity that allows them to shape their body and optimise their metabolism according to specific environmental demands. As with other multicellular organisms, the coordination of plant development relies on the communication across cellular boarders. In this context, plants employ a chemical-based network to control their developmental and physiological processes. Central to this network are a limited number of small molecules, called phytohormones. They are responsible for the adequate transcriptional reprogramming of tissues answering to external cues or for the maintenance of coordinated development. Although several molecules are known to function as plant hormones, plant shape is largely controlled by auxin. Over the past decades the knowledge of auxin action and signalling has greatly improved. By contrast, the synthesis of auxin is still not fully defined with respect to catalysed reactions and enzymes involved. Currently, it is assumed that a small number of alternative biosynthetic pathways contribute to auxin biosynthesis in plants. Due to prevailing knowledge gaps, extensive functional redundancy, and tissue and plant specific variations in expression patterns of the identified components, the relevance of each of these pathways is difficult to assess. The main focus of this project is to close the existing knowledge gaps and to decipher the pathways of auxin formation in plants. In addition, the cross-talk between the individual pathways and their regulation will be studied. To achieve these goals, a truly Systems Biology approach will be taken, encompassing genetics, transcriptomics, metabolomics, and bioinformatics workflows.
Original text from CORDIS.
Participants
- UNIVERSIDAD POLITECNICA DE MADRID · MadridCoordinatorSpain
Links
Data: CORDIS, © European Union