Plant Growth Regulators II: Cytokinins, their Analogues and Antagonists

Micropropagation of Hedychium coronarium J. Koenig through rhizome bud

“…However, the presence of an auxin, NAA, along with BA in the MS medium significantly increases the number of regenerated shoots as well as roots per explant. This may be attributed to the interaction and balance between cytokinin and auxin, which (1) control the various aspects of cellular differentiation and organogenesis and (2) usually require for the formation of adventitious shoot and root meristem in tissue culture (George et al 2008). A combination of BA and NAA was also found to be optimum in many other species of Zingiberaceae, which includes Kaempferia galanga (Shirin et al 2000) and Curcuma longa (Salvi et al 2002).…”

Assessing the response of indigenous loquat cultivar Mardan to phytohormones for in vitro shoot proliferation and rooting

“…IBA is the most common auxin, and is the strongest, most highly stable and least toxic rooting plant hormone among all auxins (Weisman et al, 1988;Hartmann et al, 2007). George et al (2008) also found that development and growth of roots is accelerated by auxins, which enhance cell division in the root zone. Root initiation is dependent on the interaction between external and internal factors, such as the type and level of endogenous PGRs.…”

“…Bennet et al (1994) reported that a decrease in fresh weight might arise because kinetin is less effective than BAP in prompting the enzyme activity involved in promoting vegetative growth. High concentrations of cytokinins cause senescence of tissues, possibly due to the production of ethylene, which consequently gives lower fresh weight (George et al, 2008).…”

“…Ozel and Arslan (2006) reported that they also raise the endogenous auxin levels in plants providing protection against catabolism and increasing interactions with growth inhibitors by conjugation. Plants with long roots and higher root numbers are produced, which is probably due to effect of endogenous hormones (George et al, 2008). Taiz and Zeiger (2002) also found that lower concentrations of auxin promote root growth but higher levels reduce growth due to the production of ethylene in the root zone, which acts as a growth inhibitor.…”

“…The current lack of certified germplasm repositories and seasonal fluctuations in supply require immediate application of in vitro techniques to overcome these problems of the fruit industry. Biotechnological tools for mass propagation of different tree species have been introduced recently, particularly in the last decade (Azad et al, 2005;George et al, 2008), and micropropagation protocols are available for many species and cultivars (Ruzic and Vujovic, 2008). However, propagation of woody plants in vitro is an intricate process.…”