A Phenylurea Cytokinin, CPPU, Elevated Reducing Sugar and Correlated to Andrographolide Contents in Leaves of Andrographis paniculata (Burm. F.) Wall. Ex Nees

Abstract

Cytokinins are phytohormones that play multiple roles to control plant growth and development. In this study, leaf biomass and the production of andrographolide compounds in a medicinal plant Andrographis paniculata were significantly increased after exogenously treating with the synthetic cytokinin cytokinin-1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) at 0 (water), 5, or 10 mg L and observed the results for 24 h, 48 h, and 7 days of treatment. It was found that CPPU could significantly enhance new axillary bud formation and further promote branching 4.6-5.6-fold higher, resulting in higher fresh weight (FW) and dry weight (DW) than the control. Application of CPPU at 5 mg L significantly promoted the highest contents of total reducing sugar at 2.5-fold in leaves and at 1.5-fold in roots. Although treatments of CPPU significantly affected the increasing contents of chlorophyll and carotenoid (1.2-1.6-fold), CPPU at 10 mg L slightly caused leaf stress and chlorophyll reduction. Interestingly, 5 mg L CPPU could enhance andrographolide content, an active anti-infectious compound in Andrographis paniculata (2.2-fold higher than the control) that reached the highest content at 24 h after treatment. This study suggested that CPPU should be suitable for field application to promote leaf yields and induce the production of useful pharmaceutical compounds in Andrographis paniculata.

The Mode of Cytokinin Functions Assisting Plant Adaptations to Osmotic Stresses

“…Recent findings posit the role of cytokinins (CKs) in mediating cellular responses to drought acclimation [4]. Exogenous application of cytokinins improves plant soluble sugar contents which in turn act as osmolytes to help plants tolerate osmotic stresses [5]. Moreover, CKs play a crucial role in delaying senescence, reducing oxidative damage and upholding plant growth under osmotic stresses.…”

Ethylene represses the promoting influence of cytokinin on cell division and expansion of cotyledons in etiolated Arabidopsis thaliana seedlings

“…Cytokinins are broadly classified as either purine-type or phenyl-urea-type and we tested one of each, benzyl-aminopurine (BA) and 4PU-30, respectively, both synthetic. Phenyl-urea cytokinins are of interest because of their chemical stability and independence of nucleotide metabolism ( Worakan et al, 2017 ). Either of these cytokinins modestly promoted cotyledon expansion.…”

A synthetic cytokinin influences the accumulation of leaf soluble sugars and sugar transporters, and enhances the drought adaptability in rice

“…CPPU (N-2-(chloro-4-pyridyl)-N-phenyl urea), a phenyl-urea-based synthetic cytokinin, is a competitive inhibitor of cytokinin oxidase/dehydrogenase (CKX) that helps the plants to retain enhanced cytokinin concentration (Kopečný et al 2010;Nisler et al 2016). The previous studies of our laboratory indicated the positive impact of cytokinin spray (at 5 mg⋅L −1 CPPU) on the process of photosynthesis in rice under drought stress (Gujjar et al 2020), the contents of soluble sugars in a medicinal plant, Andrographis paniculata (Worakan et al 2017), and the adaptability of rice to salinity stress (Gashaw et al 2014).…”