Plant Hormones Isolated from “Katahdin” Potato Plant Tissues and the Influence of Photoperiod and Temperature on Their Levels in Relation to Tuber Induction

Endogenous cytokinin dynamics in micropropagated tulips during bulb formation process influenced by TDZ and iP pretreatment

“…During induction (S4) the free bases and ribosides of tZ and iP were the most abundant active CKs. These findings are generally consistent with reported rises in active CK contents (especially cZR) in potato plants under tuber-inducing conditions, after 4 days exposure to short photoperiods (Malkawi et al 2007). The increase in cZR contents observed in the cited study was followed by a rapid decline just before stolon swelling, the first tuber formation symptom (after 8 days under inductive conditions).…”

“…They found that levels of cis-and trans-Z differ during the ontogenesis of Arabidopsis, ratios of cis-to trans-CKs increased in mature leaves and seeds (at an active growth cessation). A similar CK profile has also been detected in potato plants during the tuberization process, which is associated with dormancy development (Malkawi et al 2007), as in tulip bulb formation (Podwyszyńska et al 2004). Our results correspond also with observed increases in cZR levels in shoot apices of Brassica napus plants during prolonged exposure to low temperature, when the shoot meristems switch from vegetative to reproductive morphogenetic programs and form flowers instead of leaves (Tarkowská et al 2012).…”

“…These PGRs play crucial roles in regulating diverse plant development and physiological processes, including cell proliferation and differentiation, seed germination, apical dominance, flower and fruit development, leaf senescence, and transduction of nutritional signals. However, little is known about their roles in storage organ formation (Sarkar et al 2006;Malkawi et al 2007). Naturally occurring CKs are adenine derivatives carrying an isoprene-derived or aromatic side chain at the N 6 -amino group.…”

“…Furthermore, under natural conditions, low temperatures during the winter induce both flower and daughter bulb development (Le Nard and De Hertogh 1993), and ZR levels may apparently be upregulated by specific inductive factors (e.g. low temperature for bulb/flower development in tulip and flower induction in oilseed rape (Tarkowská et al 2012), or short photoperiods for tuberization in potato, according to Malkawi et al (2007).…”

The endogenous plant hormones and ratios regulate sugar and dry matter accumulation in Jerusalem artichoke in salt-soil

“…Application of exogenous ZT was also reported to increase speed of tuber induction either in in vitro system or by direct application to stolons of developing potato (Malkawi et al, 2007).…”