Polyamines and Adventitious Root Formation in the Juvenile and Mature Phase of English Ivy

Root histogenesis in herbaceous and woody explants cultured in vitro. A critical review

“…It is well known that exogenously applied natural or synthetic auxins favour rooting, and there is evidence that this hormone is the most effective inducer of the process (Lyndon, 1990 (Geneve et al, 1988 (Mohnen, 1994 (Coleman and Greyson, 1977). Figure 1 shows some examples of the stages through which a hypothetical tissue progresses to a final rooting response.…”

“…It is generally believed that determination occurs in the rooting process well before meristemoids are formed, as clearly shown for Convolvulus (Christianson and Warnick, 1985;Warnick, 1992), English ivy (Geneve et al, 1988), and tobacco Mohnen, 1994). According to this hypothesis, the meristemoid is born with a rooting 'nature' and is canalized toward root development from the beginning of its formation.…”

Patterns of adventitious root formation in English ivy

“…Also, the usual pattern of root formation in juvenile petiole cuttings was altered to the indirect pattern by using DFMA, a specific inhibitor of arginine decarboxylase. Previous studies with the debladed petiole rooting system have demonstrated a significant reduction in endogenous putrescine and spermidine levels after DFMA treatment (Geneve and Kester 1991). The reversal of this effect by additional putrescine suggested that putrescine was required for juvenile petioles to form roots via the direct pattern of root formation (Table 1).…”

“…The in vitro debladed petiole system for evaluating root formation in the juvenile and mature phases of English ivy has been described in detail, previously (Geneve et al 1988). Leaves from the two phases were collected from plants grown in a greenhouse.…”

“…In English ivy, it has also been determined that easy-to-root juvenile cuttings form roots predominantly through the direct rooting pattern, while difficult-to-root mature phase cuttings form roots via the indirect pattern (Girouard 1967a,b, Geneve et al 1988. The objective of the current study was to use an in vitro system for rooting debladed petioles of English ivy (Geneve et al 1988) to determine if the easy-to-root condition was strongly linked to the direct pattern of root formation and to better understand the cells involved in the initial stages of adventitious root formation.…”