Abstract
Quantitative trait loci (QTL) analyses for five groups of hormones, including cytokinins in Arabidopsis roots were performed using recombinant inbred lines (Ler×Cvi). Significant QTLs were detected for cytokinins, jasmonic acid and salicylic acid. Separate analysis of two sub-populations, viz., vegetative and flowering plants revealed that many of the QTLs were development-specific. Using near-isogenic lines, several significant QTLs were confirmed; three co-localized QTL regions were responsible for determining several cytokinin metabolites. Using a knock-out plant, a functional role of zeatin N-glucosyltransferase gene (UGT76C2) underlying a large-effect QTL for levels of tZ-N-glucosides and tZRMP was evaluated in the metabolism of cytokinins. Pleotropic effects of this gene were found for cytokinin levels in both roots and leaves, but significant changes of morphological traits were observed only in roots. Hormone QTL analysis reveals development-specific and organ-dependent aspects of the regulation of plant hormone content and metabolism.
Highlights
Plant hormones are naturally occurring organic substances that influence complex processes in plant development at extremely low concentrations
To identify the genetic loci affecting endogenous hormone levels in Arabidopsis roots, hormone levels were determined in 35-day-old-roots of a Ler×Cvi recombinant inbred lines (RILs) population
Normal distributions were found, the distribution ranges were skewed for several compounds, e.g. cis-zeatin riboside and jasmonic acid (JA)
Summary
Plant hormones are naturally occurring organic substances that influence complex processes in plant development at extremely low concentrations. Hormone concentrations may vary between different varieties [2] Such variations of plant hormones are obviously determined by genes involved in anabolic and catabolic pathways, transport facilitators and/or signalling components [4, 5]. Even allelic difference at a single locus can contribute to pleiotropic differences in growth and fitness [7]. Such allelic variations may induce changes in metabolic profiles, as shown by Chayut et al [8]; allelic variation of the melon’s Or gene (CmOr) resulted in an increase of beta-carotene accumulation in melon fruit. The quantitative variation of plant hormones within a species is expected to be due to genetic heterogeneity
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