Molecular responses of Prunus avium (wild cherry) embryonic axes to temperatures affecting dormancy

Abstract

Seed dormancy and dormancy cycling are poorly understood at the molecular level, but are central to plant community development. This study focuses on the embryonic axes of deeply dormant seeds of Prunus avium (wild cherry). Rapid amplification of cDNA ends (RACE), differential display and quantitative PCR were used to recover and monitor expression of cDNAs. cDNAs similar to two dormancy-imposing genes were isolated; a serine/threonine protein-phosphatase 2C homologous to ABSCISIC ACID INSENSITIVE 1 and 2 (Pa-PP2C1), and the transcription factor ABSCISIC ACID INSENSITIVE 3 (Pa-ABI3). Two germination-associated cDNAs were recovered; aconitase (Pa-ACO1) and eukaryotic translation initiation factor 3 subunit 8 (Pa-eIF3 SUBUNIT 8). Cold-treatment reduced expression of Pa-PP2C1 and Pa-ABI3, consistent with roles in establishing primary dormancy; neither was induced by imposition of secondary dormancy. Expression of these genes was distinct from expression of Pa-ACO1 and Pa-eIF3-SUBUNIT 8. Results were consistent with a role for ABI1/ABI2 and ABI3 homologues in primary dormancy of P. avium embryonic axes, but not secondary dormancy as control of germination appeared overridden by the tissues surrounding the embryo.