The occurrence of free and bound cytokinins in clubroots and Plasmodiophora brassicae infected turnip tissue cultures

Abstract

This paper deals with the quantitative determination of free and bound cytokinins in clubroot tissue and in Flasmodiophora brassicae Woron. infected Brassica campesiris L, callus tissue. The fractions were separated in a butanol soluble fraction containing the free cytokinins such as zeatin and zeatin riboside and a water soluble fraction containing the bound cytokinins.The butanol fraction was extensively purified and analysed by high pressure liquid chromatography (HPLC), The butanol fraction contained cytokinins which cochromatographed with zeatin and zeatin riboside and not with dihydrozeatin, Zeatin and zeatin riboside were quantitatively determined by HPLC, Recovery of the cytokinins varied between 30-50%, Clubs contained 50-160 ng zeatin and 210-300 ng zeatin riboside per g dry weight. Callus tissue contained 133 ng zeatin and 169 ng zeatin riboside per g dry weight.Clubs, callus as well as healthy tissue contain large amounts of bound cytokinins. Upon treatment of the water soluble fraction first with alkaline phosphatase and then with {i-glucosidase biologically active fractions were found which coeluted with zeatin and zeatin riboside on Sephadex LH2(i in 20% ethanol. Evidence is presented for a novel cytokinin in the water soluble fraction which yields free zeatin and glucose-6-phosphate after treatment with P-glucosidase,

Flow of cytokinins through the environment

“…However, these organisms do provide an alternative source of cytokinins and their contribution to the total cytokinin pool, especially in the soil should not be overlooked considering the large interface between plants and the physical environment. Examples from this review have highlighted the importance of both iP-and cZ-type cytokinins that often occur as the predominant cytokinin form in ferns (Arthur et al 2007), seaweeds , microalgae (Ö rdög et al 2004), fungi (Dekhuijzen 1980;van Staden and Nicholson 1989), bacteria (Maruyama et al 1986) and insects (McDermott et al 1996;Mapes and Davies 2001;Dorchin et al 2009), suggesting that tRNA degradation could be an important source of cytokinins in these organisms. The physiological role of cZ conjugates in plants and their interaction with other cytokinins should be determined considering their widespread distribution and frequency in which they are identified in lower order plants and microorganisms.…”

“…This abnormal outgrowth is caused by a hormonal imbalance with cytokinin levels 2-3 9 higher in the infected tissue compared to healthy tissue with cZ and cZR occurring in higher levels than tZ and tZR (Dekhuijzen 1980). There is evidence for the direct biosynthesis of tZ from adenine by P. brassicae (Müller and Hilgenberg 1986) although the cytokinin biosynthetic pathway in fungi has yet to be elucidated.…”

What can we learn from clubroots: alterations in host roots and hormone homeostasis caused by Plasmodiophora brassicae

“…It was shown that the amount of free and bound cytokinins was two to three times higher in clubs than in control roots (Dekhuijzen 1980). Dekhuijzen (1981) also showed that the contents of bound and free cytokinins were different in the host cytoplasm and plasmodia of the pathogen.…”

Concentrations of indole‐3‐acetic acid in plants of tolerant and susceptible varieties of Chinese cabbage infected with Plasmodiophora brassicae Woron.

“…the fungus causes abnormal tissue proliferation, Indole-3-acetonitrile (IAN) is then hydrolyzed which is the result of an altered metabolism of auxins to IAA by the enzyme nitrilase (Mahadevan & (Butcher, EI-Tigani & Ingram, 1974;Kavanagh & Thimann, 1964;Rausch & Hiigenberg, 1980). In Williams, 1981) and cytokinins (Dekhuijzen, 1980). intact tissue indole-3-acetaldoxime can be directly Whereas cytokinins were found to occur and to be converted to indoIe-3-acetonitriie (Ludwig-Miiller synthesized in plasmodia (Dekhuijzen 1981;MCiller & Hilgenberg, 1990) without indole glucosinoiates as & Hilgenberg, 1986), changes in auxin metabolism intermediates.…”