Gene expression in opening and senescing petals of rose (Rosa hybrida L.)

Roses are one of the most important cut flowers which are available in more color and sizes throughout the year. Senescence is a programmed event responding to external (environmental) and internal (developmental) signals; it requires de novo gene expression and protein synthesis, and is controlled in a highly coordinated manner. In order to know about molecular mechanisms and complex nets involved in aging regulating pathways, a cDNA-amplified fragment length polymorphism (cDNA-AFLP) analysis was performed to identify and isolate senescence-associated genes (SAGs) in rose petals of two cultivars ‘Black magic’ and ‘Marroussia’ with different longevities. The transcription profiles of plants at different developmental stages (flowering and senescent) were compared. About 1,600 cDNA fragments, ranging in size from 250 to 1,200 bp, were reproducibly detected. This allowed the identification of 22 differentially expressed cDNAs corresponding to genes belonging to different functional categories related to senescence, signal transduction pathway, carbohydrate metabolism, energy and other catabolic events such as protein, lipid and cell wall degradation. SAGs-encoded proteins are likely to participate in response to the two isolated fragments; RhCG (Rosa hybrida CG) and RhAA (Rosa hybrida AA) are more similar to putative protein associated to the senescence of Pisum sativum and Picea abies, respectively. There was no information for two fragments in the database. Reverse Northern blot demonstrated the credibility of the result of cDNA-AFLP. Study of expression pattern of the fragments showed an increase of expression level in almost all of them.