Characterization of an ethylene receptor family with differential expression in rose (Rosa hybrida L.) flowers

To analyze differences in flower longevity and ethylene sensitivity, we iso lated Rosa hybrida gene fragments with sequence similarity to the Arabidops is thaliana ethylene receptor gene-family. A rose gene (RhETR1) highly simi lar to AtERS1 had been previously sequenced. Here, we report the isolation of three additional partial rose genes (RhETR2-4) belonging to different su b-groups of ethylene receptor genes. RhETR2 clusters with AtETR1, RhETR4 wi th AtERS1 and RhETR1, whereas RhETR3 shows high sequence similarity to AtET R2 and AtERS2. Expression analysis of RhETR2 and RhETR3 revealed that they are differentially expressed. RhETR2 is expressed at a constitutive level t hroughout newer development whereas RhETR3 expression increases in senescin g flowers of the cultivar 'Bronze' which has a short floral life while it r emains at low levels in the long-lasting flowers of the cultivar 'Vanilla'. Expression of both genes was increased by ABA and ethylene treatment, but transcript abundance differed between rose cultivars with different posthar vest performance. These results indicate that differences in flower life am ong rose cultivars could be due to differences in receptor levels.