Inhibition of Carotenoid Synthesis by Fluridone and Norflurazon

Abstract

Fluridone {1-methyl-3-phenyl-5-[3-(trifluromethyl)phenyl]-4(1H)-pyridinone} and norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] inhibited carotenoid synthesis in wheat(Triticum aestivumL. ‘Maricopa’) seedlings and caused the accumulation of colorless carotenoid precursors, phytoene, and phytofluene. These data suggested that dehydrogenation reactions following phytoene formation were inhibited by the herbicides. Chlorophyll accumulated in the treated seedlings grown under 10 lux of light but was destroyed in seedlings illuminated with 16 klux of light. Seedlings illuminated with 16 klux of light lacked chloroplast ribosomes and normal ultrastructure whereas dark grown seedlings contained pastid ribosomes and had normal etioplast ultrastructure. The disruption of the chloroplasts and loss of chlorophyll was due to the absence of carotenoids in the treated plants, which would normally act to protect the chloroplasts from photodestruction.

The effects of gibberellic acid, fluridone, abscisic acid and paclobutrazol on anther culture of Brussels sprouts

“…The results suggest that both GA, and fluridone can be used to improve embryo production in anther culture of Brussels sprouts although the effect may depend on the cultivar used. This contrasts with the few studies with GA and fluridone which have shown an inhibition of somatic embryogenesis [6,8,211. However, work with excised zygotic embryos of Phaseolus coccineus [22] has shown that GA, can substitute for the suspensor in maintaining embryogenesis, although too much GA, applied to embryos with the suspensors attached, inhibited embrogenesis [22].…”

“…Both gibberellin (GA) and abscisic acid (ABA) appear to be involved in zygotic embryogenesis [18,201 which suggests they may also play important roles in the control of microspore embryogenesis. The two hormones usually have opposite and mutually antagonistic effects on plant growth and development, and whereas ABA has been used to improve somatic embryogenesis in various species, including wheat [4] and several conifers [e.g., 5, 231, the few studies with GA have shown an inhibition of somatic embryogenesis [6,81. In Pennisetum purpureum [21], GA, and fluridone (1 -methyl-3-phenyl-5-(3[trifluoromethyl]-phenyl)4-( 1 H) pyridone), a non-specific inhibitor of ABA biosynthesis [15], both inhibited somatic embryogenesis, whereas ABA promoted it.…”

The r�le of abscisic acid in root growth and gravireaction: A critical review

“…Fluridone, when applied to the developing maize kernels, inhibits carotenoid biosynthesis at, or just following, the stage at which phytoene is converted to phytofluene [13,172] . Fluridone produces a seedling which is a phenocopy of the vp-5 mutant [172] and possibly of other vp mutants which have blocks at steps following the conversion of phytofluene tõ -carotene [56] .…”

“…The plantlets which develop are white, unable to photosynthesise, and die after 12-14 days . They also suffer the effects of photobleaching and other photosensitive reactions [13] .…”

Analysis of fluorescence transients of DCMU-treated leaves of Triticum species to provide estimates of the densities of photosystem II reaction centres

“…This treatment gave second leaves the lower halves of which were devoid of chlorophyll. Norflurazon inhibits carotenoid biosynthesis [5] and results in the photodestruction of chlorophyll. Electron microscope preparations of the white parts of these leaves (kindly made by Dr. M.L.…”