IDENTIFICATION AND FUNCTIONAL ANALYSIS OF ABA-INSENSITIVE3 FROM ROSA CANINA

Abstract

ABA-insensitive 3 (ABI3), initially identified in Arabidopsis thaliana, is intermediary in regulating ABA- esponsive genes during seed dormancy inception and seed germination developmental program. In order to study whether the ortholog of ABI3 from Rosa canina was functional, we isolated the ortholog by a ombination of degenerate polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE). It encodes 718 amino acids with a predicted molecular mass of 79.9kDa and a theoretical isoelectric point of 5.78. The predicted amino acid sequence of the RcABI3 is most closely related to the ABI3 orthologs identified in Prunus avium (PaABI3 and PaVP1). Expression analysis revealed that RcABI3 was expressed in seeds and rotocorm-like bodies (PLBs), but not in roots, stems, leaves and flowers. On a cellular level, we localized the RcABI3::GFP fusion protein to the nucleus in onion epidermal cells, which was consistent with the nuclear localization of PsABI3 in Pisum sativum. The RcABI3 is able to restore the Arabidopsis abi3-6 mutant seed ormancy ability and almost completely rescue the ABA sensitivity during seed germination, which suggest that it is a functional ABI3 ortholog. These results suggest that RcABI3 is appropriate for application in genetic engineering strategies aimed at regulating seed dormancy and germination in R. canina or even in Rosa plants