Proanthocyanidins in Cereals and Brassicaceae: A Cross-Species Approach on their Roles for Seed-Coat Biophysical Properties, Dormancy and Germination

Project: Research

Description

The aim of this project is to determine the mechanisms by which condensed tannins, or proanthocyanidins (PAs), present in the seed coat of many plant species determine coat-imposed seed dormancy as well as the speed and uniformity of seed germination. PAs are polymerised flavan-3-ols that are synthesized from flavonoid precursors in the integument, a maternal tissue which on maturation and cell death becomes the testa, or true seed coat. There are a number of hypotheses to explain the mechanisms through which PAs promote seed dormancy and inhibit germination. These include possible roles in determining the biophysical properties of the testa, including its mechanical strength/resistance and permeability to oxygen or plant hormones, and also the possibility that mobile PA precursors or metabolites may directly suppress embryo germination upon imbibition. In previous projects we have developed materials and techniques that will allow us to directly test these various hypotheses in an eudicot and a monocot species. These include mutant and trangenic lines of cress (Lepidum sativum) and wheat (Triticum aestivum) with complete or partial lesions in the later steps of PA biosynthesis and also methods to directly measure puncture force, extensibility and permeability of the testa and other outer seed layers of our target species. These methods require a suitably large seed size which is met by the species under study and we have verified the feasibility of our techniques. In addition, we propose to investigate the processes in seed maturation during which PAs assembled in the vacuoles of integument cells become associated with the cell wall, and how this results in changes to its biophysical properties. We further propose to investigate how the PA-related biophysical properties are altered at different ambient temperatures during seed imbibition and how this affects embryo growth, coat dormancy and germination speed and uniformity.
StatusActive
Effective start/end date1/01/1531/12/17

Funding

Biotechnology&BioSci Research BBSRC: £688,344

Publications

ID: 22799137