Ethylene-insensitive related phenotypes exist naturally in a genetically variable population of Dianthus barbatus

Abstract

Within the genetically variable population of Dianthus barbatus’’Dagan’’, we identified genetic lines with flowers possessing ethylene insensitivite-related phenotypes. The phenotypes are: Caf + , with a fresh-looking corolla attached to a mature ovary; Inr – , with flowers whose petals do not inroll during flower senescence; and Rfi + , whose flower petals inroll, but recover from inrolling. The frequencies of Caf + , Inr - and Rfi + were 33%, 25% and 75% in the population inspected, respectively. These relatively high frequencies were probably due to continuous selection over the years for flowers with open and long-lasting corollas. By examining the distribution of the genetic lines which express two of these phenotypes, we determined that Caf + , Inr – and Rfi + are independent traits. However, these traits might be associated with male sterility. Exposure of a random sample of the population to exogenous ethylene, followed by examination of the resulting inrolling and wilting, revealed five different ethylene response groups. In one group ethylene enhanced both inrolling and wilting, and most genetic lines within this group exhibited a Caf – phenotype. In two other groups ethylene enhanced either the inrolling or the wilting, and both of the Caf + and Caf – phenotypes were included. Two other groups were completely non-responsive to ethylene, but in one of them the flower life span was twice as long as in the other, and all the genetic lines exhibited the Caf + phenotype. We concluded that the Caf + phenotype is most-likely related to ethylene insensitivity and that the inrolling and wilting are controlled by ethylene, probably via different pathways.