Awake1, an ABC-type transporter, reveals an essential role for suberin in the control of seed dormancy. Awake-1

In order to further understand the mechanisms by which seed dormancy control takes place in Arabidopsis, we conducted a forward genetic screen to isolate mutants that fail to enter dormancy in response to variation in temperature during seed set. We show that, for the first of these mutants, designated awake1, thematernal allele is required for entry into strongly dormant states and that awake1 mutants show seed phenotypes shown previously to be associated with the loss of suberin in the seed. We identify awake1 as an allele of ABCG20, an ATP-binding cassette transporter-encoding gene required for the transport of fatty acids during suberin deposition, and show that furthersuberin-deficient mutants have seed dormancy defects. Seed coat suberin composition is affected by temperature during seed maturation, but this response appears to be independent of ABCG20. We conclude that seed coat suberin is essential for seed dormancy imposition by low temperature and that the exclusion of oxygen and water from the seed by the suberin and tannin layers is important for dormancy imposition.