Abstract
Flavonoids represent a class of secondary metabolites with diverse functions in plants including ultraviolet protection, pathogen defense, and interspecies communication. They are also known as modulators of signaling processes in plant and animal systems and therefore are considered to have beneficial effects as nutraceuticals. The rol1-2 (for repressor of lrx1) mutation of Arabidopsis (Arabidopsis thaliana) induces aberrant accumulation of flavonols and a cell-growth phenotype in the shoot. The hyponastic cotyledons, aberrant shape of pavement cells, and deformed trichomes in rol1-2 mutants are suppressed by blocking flavonoid biosynthesis, suggesting that the altered flavonol accumulation in these plants induces the shoot phenotype. Indeed, the identification of several transparent testa, myb, and fls1 (for flavonol synthase1) alleles in a rol1-2 suppressor screen provides genetic evidence that flavonols interfere with shoot development in rol1-2 seedlings. The increased accumulation of auxin in rol1-2 seedlings appears to be caused by a flavonol-induced modification of auxin transport. Quantification of auxin export from mesophyll protoplasts revealed that naphthalene-1-acetic acid but not indole-3-acetic acid transport is affected by the rol1-2 mutation. Inhibition of flavonol biosynthesis in rol1-2 fls1-3 restores naphthalene-1-acetic acid transport to wild-type levels, indicating a very specific mode of action of flavonols on the auxin transport machinery.
Highlights
Flavonoids represent a class of secondary metabolites with diverse functions in plants including ultraviolet protection, pathogen defense, and interspecies communication
Flavonols can compete with the auxin transport inhibitor 1-N-naphthylphthalamic acid for binding to proteins involved in auxin transport
To characterize the role of flavonoids in the establishment of the rol1-2 mutant phenotype, modification of flavonoid biosynthesis in rol1-2 was taken as an approach
Summary
Flavonoids represent a class of secondary metabolites with diverse functions in plants including ultraviolet protection, pathogen defense, and interspecies communication. Rol1-2 myb111 double mutants showed a strong reduction in flavonol levels in the shoot but not the root compared to the wild type or rol1-2 (Fig. 3A). It was speculated that mutations in the FLS1 gene, coding for the most active FLS protein of Arabidopsis, should result in a suppressed rol1-2 shoot phenotype but not inhibit anthocyanin accumulation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have