Abstract
A recent proteomic analysis of germinating Arabidopsis thaliana seeds demonstrates the effectiveness of functional genomics for investigating the complexity of developmental regulatory networks, such as the development of the embryo into a young plant.
In flowering plant development, seed germination is the transition of the quiescent embryo, which has developed from the fertilized ovule, into a new photosynthetically active plant. The visible sign that germination has been completed is the protrusion of the radicle, the precursor of the root, through the seed coat; germination sensu stricto begins, however, with water uptake by the seed (imbibition) and ends with the start of elongation the embryonic axis inside the seed [1]. Germination results from a combination of many cellular and metabolic events, coordinated by a complex regulatory network that includes seed dormancy, an intrinsic ability to temporarily block radicle elongation in order to optimize the timing of germination [2]. In the field of seed biology, germination mechanisms and their control by dormancy have been investigated in a wide range of species. Nonetheless, how these processes are coordinated, how they contribute to germination, and the regulatory network leading to completion of germination remain poorly understood.
The availability of the complete genome sequence of the model plant Arabidopsis thaliana [3], together with the development of high-throughput procedures for global analyses of gene function, has launched the 'post-genomic' era of plant biology. Systematic analyses of RNA and protein expression patterns, and of post-translational modifications, are now feasible for a large set of genes [4]. These can provide important clues about protein-protein interactions and gene functions in a complex developmental context. A recent proteome study of germinating Arabidopsis seeds [5] highlights the effectiveness of using this model organism to provide information on germination that may prove general to all plants.