Isolation and functional characterization of an Ethylene Response Factor (RhERF092) from rose (Rosa hybrida)

Abstract

Improper post-harvest handling results in significant losses to cut rose flowers. The phytohormone ethylene plays a key role in the growth of rose and flower opening. In this study we isolated and characterized an Ethylene Response Factor (RhERF092) from rose (Rosa hybrida) cv. “Samantha” and investigated its role in flower opening and development. RhERF092 was originally detected in a microarray experiment with a significant increase in its expression in rose petals after 1 h of ethylene treatment. Sequence analysis showed the presence of a canonical AP2/EREBP domain and a C-terminus trans-activation domain. Phylogenetic analysis showed that RhERF092 is an orthologue of the Arabidopsis ERF1 (AT3G23240) belonging to subgroup IX of the ERF gene family. Confocal laser scanning microscopy showed RhERF092: GFP expression in the nucleus. Basal expression of RhERF092 is highest expression at stage 0 of flower opening which gradually decreases and remains constant till senescence. Ectopic expression of RhERF092 in Arabidopsis caused various ethylene-related aberrations in plant development including stunted growth, abortion of apical dominance, production of lateral tillers from rosette nodes, branches from the aerial nodes, and sterile inflorescence. Arabidopsis 35SRhERF092 plants were found to be sensitive to the ethylene precursor ACC with significantly reduced hypocotyl and root system with significant reduction in the expression of genes involved in cell proliferation, cell expansion and cell cycle such as ARGOS, ARGOS-LIKE, SIM, JAGGED, AN3, CYCD3-1, and CYCD3-2as compared to WT plants. Taken together these results indicate that RhERF092 regulates ethylene-specific responses in rose and Arabidopsis. The rose Ethylene Response Factor RhERF092 is a transcription factor that regulates essential ethylene-related development of rose flowers and mediates abiotic stress responses in Arabidopsis.