Pleiotropic changes in Arabidopsis f5h and sct mutants revealed by large-scale gene expression and metabolite analysis

Abstract

Hydrocinnamic acid esters, lignin, flavonoids, glucosinolates, and salicylic acid protect plants against UV exposure, oxidative stress, diseases, and herbivores. Through the phenylpropanoid pathway, certain Brassicaceae family members, including Arabidopsis thaliana and Brassica napus, accumulate large amounts of the anti-nutritive sinapoylcholine (sinapine) in the seed. We successfully down-regulated activities of key enzymes in the pathway including F5H and SCT and achieved reduction of sinapine and lignin in B. napus seeds. Despite this success, it was unclear how multiple agronomic traits were affected in the transgenic plants. Here, we report altered large-scale gene expression of new alleles of f5h and sct mutants of A. thaliana and resultant accumulation of sinapoylglucose, disinapoylglucose, quercetin-3-O-rhamnoside, salicylic acid glucoside, and total indolyl glucosinolates in the two mutants. Expression of several flowering genes was altered in these mutants when grown under drought and NaCl treatments. Furthermore, both mutants were more susceptible to fungal infection than the wild type. Microarray experiments identified distinctive spatial and temporal expression patterns of gene clusters involved in silique/seed developmental processes and metabolite biosynthesis in these mutants. Taken together, these findings suggest that both f5h and sct mutants exhibit major differences in accumulation of diverse metabolites in the seed and profound changes in global large-scale gene expression, resulting in differential pleiotropic responses to environmental cues. Electronic supplementary material The online version of this article (doi:10.1007/s00425-009-1007-2) contains supplementary material, which is available to authorized users.

Molecular Characterization of Ferulate 5‐Hydroxylase Gene from Kenaf (Hibiscus cannabinus L.)

“…For example, phenylpropanoid-derived compounds such as sinapate and flavonoids were detected at high levels in Arabidopsis flowers [33]. In addition, disruption of AtF5H led to a limited production of lignin, which resulted in a dwarf floral architecture in the f5 h mutant [34]. Therefore, F5H is an important enzyme in flower development.…”

The Arabidopsis tt19‐4 mutant differentially accumulates proanthocyanidin and anthocyanin through a 3′ amino acid substitution in glutathione S‐transferase

“…There may be an intermediate interacting with quercetin in the upper flavonoid pathway that is glutathionated or bound by TT19 and impacts vacuole formation. Analysis of vacuole ultrastructure and extractable and unextractable PA in the fah mutant, which also accumulates Q3R and is reduced in a sinapoyl anthocyanin (Huang et al . 2009), may reveal whether sinapic acid actually plays this role in TT19 function.…”

The role of the secondary cell wall in plant resistance to pathogens

“…It was further proven that comt mutants accumulated soluble 5-hydroxyferuloyl-malate and that this compound promoted sexual oomycete reproduction in vitro (Quentin et al, 2009). Arabidopsis f5h1 mutants showed an increased susceptibility to the fungal pathogen S. sclerotiorum and to the vascular fungus Verticillium longisporum (Huang et al, 2009; König et al, 2014). The f5h1 mutants have similar amounts of lignin as compared to wild type, but lack S units in the lignin and are sinapate ester deficient (Meyer et al, 1998; Vanholme et al, 2012b; König et al, 2014).…”