The model plant Arabidopsis thaliana and its use in flowering-time studies
The use of molecular genetics in the model plant Arabidopsisthaliana has proved to be a powerful approach for studying the floral transition. Arabidopsis thaliana, also known as Mouse-ear or Thale cress, is a member of the Brassicaceae family, and was chosen as a model organism for many reasons.
The major advantages of Arabidopsis for molecular-genetic experiments are its small size, diploid nature, short generation time, ability to produce large numbers of seeds and a small genome (Schmidt, 1998) . The subsequent determination of the full genome sequence facilitated gene isolation (AGI, 2000) , and enabled reverse genetics approaches aimed at isolating mutations in every gene (Alonso et al., 2003) .
Flowering time of Arabidopsis is influenced by many of the environmental stimuli that control flowering in other species, making it an ideal species in which to study the genetic control of these processes. Many accessions of Arabidopsis also show different flowering responses to environmental conditions. A combination of quantitative genetics and the isolation of induced mutations that delay or accelerate flowering has identified at least 80 genes involved in flowering-time control in Arabidopsis (Araki, 2001) .
Many of these genes have homologues in other plant species, and in some of these related roles in flowering time control have been demonstrated. The analysis of flowering time control in Arabidopsis therefore provides a starting point for understanding the regulation of flowering in other species (Mouradov et al., 2002; Hayama and Coupland, 2003).
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