Repressed Expression of DC-ACS1 Gene in a Transgenic Carnation Supports the Role of its Expression in the Gynoecium for Ethylene Production in Senescing Flower

Abstract

DC-ACS1 is a gene for 1-aminocyclopropane-1-carboxylate (ACC) synthase which is expressed slightly in the gynoecium, but abundantly in petals of carnation (Dianthus caryophyllus L.) flowers. It is known that ethylene evolved from the gynoecium triggers the expression of DC-ACS1 and DC-ACO1 (the gene for carnation ACC oxidase), which results in an abundant ethylene production in petals. In a transgenic carnation (16-0-66 line) transformed with DC-ACS1 cDNA in sense orientation, the exogenous ethylene treatment caused the expression of DC-ACO1 in the gynoecium and petals, but not that of DC-ACS1. This suggests that the cosuppression of the expression of endogenous DC-ACS1 gene by the integrated transgene. DC-ACS1 transcript is absent in both gynoecium and petals of senescing 16-0-66 flowers, so that the flowers produce no ethylene; whereas DC-ACO1 transcript is present in the gynoecium but absent in the petals. These findings give further support on the role of the DC-ACS1 gene in the gynoecium for ethylene production by petals in senescing carnation flowers.

Expression and Regulation of Senescence-related Genes in Carnation Flowers with Low Ethylene Production during Senescence

“…Therefore, the low level of ethylene production during senescence in MS, 006-13, and 62-2 relative to WS was associated with longer vase life and lower loss of fresh weight, which delayed petal wilting. In general, autocatalytic ethylene production in normal carnation flowers begins in the gynoecia and is subsequently induced in the petals (Satoh and Waki, 2006;Shibuya et al, 2000;ten Have and Woltering, 1997). It is still unclear whether the low level of ethylene production by flowers of 006-13 and 62-2 is induced by ethylene from the gynoecia.…”

“…Three genes encoding ACS (DcACS1, DcACS2, and DcACS3) and 1 gene encoding ACO (DcACO1) have been identified (Henskens et al, 1994;Jones and Woodson, 1999;Park et al, 1992;Wang and Woodson, 1991). DcACS1 (previously called CARACC3) is expressed in gynoecia and petals and is the most abundantly expressed of all DcACS genes in petals (Jones and Woodson, 1999;Satoh and Waki, 2006). Its expression is enhanced by exogenous ethylene treatment, which induces ethylene production.…”

Effect of Age on the Auto-catalytic Ethylene Production and the Expression of Ethylene Biosynthetic Gene Dc-ACS1 in Petals of Long-life Carnations

“…Three ACC synthase genes (Dc-ACS1, Dc-ACS2 and Dc-ACS3) and one ACC oxidase gene (Dc-ACO1) have been identified, and their levels during flower senescence have been characterized 18,30 . Dc-ACS1 mRNA was the most abundant of all Dc-ACS genes in the petals 18,34 . Dc-ACS2 and Dc-ACS3 occur in the gynoecium but to a lesser extent 34 .…”

“…Dc-ACS1 mRNA was the most abundant of all Dc-ACS genes in the petals 18,34 . Dc-ACS2 and Dc-ACS3 occur in the gynoecium but to a lesser extent 34 . Ethylene responsiveness, auto-catalytic ethylene production, and the senescence process in the flower organs implicate ethylene perception and ethylene signaling.…”

Transgenics in Ornamental Crops:Creating Novelties in Economically Important Cut Flowers

“…Regarding control of senescence in carnation flowers by regulating ethylene production, two major contributing genes have been identified, viz. DC-ACS1 (encoding ACC synthase) and DC-ACO1 (encoding ACC oxidase) 90,91 . To enhance post-harvest longevity of carnation, regulation of ethylene-induced senescence is of utmost significance economically, as transgenic carnation with reduced ethylene production will lead to the complete elimination of costly and harmful chemicals used to lengthen the vase life 92 .…”