Are protein disulfide isomerases effectively involved in the rose senescence phenomenon?

•Two rosa hybrid protein disulfide isomerases influence cut flowers of rose responses to ethylene and senescence with the probable effect on protein folding protection in a short-vase life rose variety. Noteably, these two genes, especially RhPDIA6, may be involved in the aging process in roses. Flowers are key organs in many ornamental plants, and various phases of flower development impact their economic value. Previously, a senescence associated expressed sequence tag (EST) was isolated and identified by cDNA-AFLP, RhAC, by comparing two long- and short-vase life rose cultivars treated by ethylene. Protein sequence alignment of At3g54960 revealed that there are two probable proteins PDIA6 and PDI with the utmost similarity (67%) in Rosa chinensis genome. In the present study, the first comprehensive genome-wide exploration of the PDI gene family in Rosa chinensis was conducted. Full-length cDNAs of RhPDIA6 and RhPDI, 1994 and 1397 bp, respectively, were obtained by the homology method and confirmed by sequence analysis and structural features. Forty one RcPDIs were unevenly distributed on seven chromosomes of R. chinensis. Phylogenetic and sequence alignment analyses divided the RcPDIs into two clads and seven subfamilies. Chromosomal distribution, gene structure and motif composition were subsequently investigated and indicated that the motif VEFYAPWCGHCKKLAPEYEK was conserved and C-G-HC array was observed in all of the RhPDI sequences and most them were localized on Chr3. Promoter sequences analysis showed a total of thirty nine different motifs in the promoter region of PDI genes in rose, of which light-responsive elements and hormonal-responsive elements were the most present with sixteen and fifteen motifs, respectively. Protein interaction revealed that RhPDI and RhPDIA6 were related to other protein disulfide isomerases and oxidases. RhPDI and RhPDIA6 expression patterns were analyzed in two varieties of Rosa hybrida (Marroussia and Cool water) under ethylene treatment at two developmental stages of flowers (bud and open) in petals, sepal, and stamen after 24 and 48 h In addition to inducing the expression of both genes by ethylene in all studied tissues, it was found that in Cool water (with short-vase life) the expression of both genes was higher. This study is the first to establish the role of two PDI genes in the aging of cut rose flower parts.