Abstract
An Arabidopsis accession Cvi exhibits relatively strong seed dormancy compared to commonly used accessions such as Col and Ler. Primary dormancy of after-ripened Cvi depends largely on the seed coat; removal of the seed coat induced the growth of embryos (germination) upon imbibition. It is known that cold treatment of the imbibed seeds (stratification) breaks seed dormancy, however, we found that long-term cold imbibition of Cvi seeds induced secondary dormancy. Interestingly, the secondary dormant seeds did not germinate even after the removal of the seed coat. Inhibition of ABA biosynthesis by fluridone partially prevented the secondary dormancy induction, suggesting that ABA is involved in this response. However, it appears that ABA levels do not always correlate with seed dormancy status if seed dormancy and ABA levels were compared among accessions. To understand the molecular mechanisms that regulate seed dormancy status and its relationship with endogenous ABA levels, now we are conducting QTL mapping using an embryo-dormant accession that contain elevated endogenous ABA levels.
