Abstract
The effects of plant growth regulators (PGRs) were studied on growth, total flavonoid, gibberellins (GA) and salicylic acid (SA) contents of Taraxacum officinale (dandelion), a widely used medicinal plant in Korea. All the four PGRs used; gibberellic acid (GA3), kinetin (Kn), salicylic acid (SA) and ethephon (2- chloroethylphosphonic acid) were applied at the rates of 0.5 and 1.0 mM. GA3 markedly enhanced fresh shoot weight, while 0.5 mM of kinetin application significantly enhanced dry root mass as compared to control. SA enhanced both shoot and root attributes, while ethephon decreased plant growth. Endogenous bioactive GA1 and GA4 content and SA content enhanced with the application of GA3, SA and kinetin, but declined with ethephon. The flavonoid content of dandelion significantly increased with SA treatment, but was not altered with the application of other PGRs. The current study demonstrated the favorable effect of GA3, kinetin and SA on growth, bioactive GAs, SA and flavonoid contents of dandelion. These investigations offered interesting information as PGRs were never tested for plant growth and development of dandelion. It also reports the presence of both early C-13 hydroxylation and non C-13 hydroxylation pathways of GA biosynthesis in dandelion for the first time.
Highlights
Dandelion (Taraxacum officinale Wigg.) is known for its medicinal importance for a long time (Ahmad et al, 2000) and widely used as choleretic, diuretic and anticarcinogenic
The current study demonstrated the favorable effect of GA3, kinetin and salicylic acid (SA) on growth, bioactive GAs, SA and flavonoid contents of dandelion
All growth parameters were promoted by GAs, kinetin and SA, while ethephon showed an opposite effect on the growth attributes of dandelion
Summary
Dandelion (Taraxacum officinale Wigg.) is known for its medicinal importance for a long time (Ahmad et al, 2000) and widely used as choleretic, diuretic and anticarcinogenic. Flavonoids and sesquiterpeniods isolated from the whole plant have been known to carry anti-oxidant and anti-cancerous activity (Hansel et al, 1980; Williams et al, 1996). Flavonoids metabolism in plant plays substantial role in the formation of red and purple anthocyanin pigments. While the nonpigmented flavonoid compounds play central roles in the biology of plants, serving as signals for pollinators and for other beneficial organisms, participating in plant hormone signaling, facilitating pollen-tube germination, protecting plants from UV-B and functioning as phytoalexins and allelopathic compounds (Taylor and Grotewold, 2005; Cushnie and Lamb, 2005). The exogenous application of flavonoids reports plant growth regulation (Yoshiokaa et al, 2004; Peer and Murphy, 2007)
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