Functional diversification of duplicated chalcone synthase genes in anthocyanin biosynthesis of Gerbera hybrida

Abstract

SummaryChalcone synthase (CHS) is the key enzyme in the first committed step of the flavonoid biosynthetic pathway and catalyzes the stepwise condensation of 4-coumaroyl-CoA and malonyl-CoA to naringenin chalcone. In plants, CHS is often encoded by a small family of genes that are temporally and spatially regulated. Our earlier studies have shown that GCHS4 is highly activated by ectopic expression of an MYB-type regulator GMYB10 in gerbera (Gerbera hybrida).The tissue-and development-specific expression patterns of three gerbera CHS genes were examined. Virus-induced gene silencing (VIGS) was used to knock down GCHS1 and GCHS4 separately in gerbera inflorescences.Our data show that GCHS4 is the only CHS encoding gene that is expressed in the cyanidin-pigmented vegetative tissues of gerbera cv Terraregina. GCHS3 expression is pronounced in the pappus bristles of the flowers. Expression of both GCHS1 and GCHS4 is high in the epidermal cells of gerbera petals, but only GCHS1 is contributing to flavonoid biosynthesis.Gerbera contains a family of three CHS encoding genes showing different spatial and temporal regulation. GCHS4 expression in gerbera petals is regulated post-transcriptionally, at the level of either translation elongation or protein stability.

Molecular and functional characterization of two isoforms of chalcone synthase and their expression analysis in relation to flavonoid constituents in Grewia asiatica L

“…The differential transcript levels of Ga CHSs in different organs was in agreement with the earlier studies on CHS multigene family of Glycine max and Gerbera hybrida [57,63]. The variable expression patterns indicate the efficient selection of Ga CHS isoforms.…”

“…It has been observed that CHS shows wide substrate specificity range as it could accept both aliphatic and aromatic CoA esters to produce various reaction products including the unnatural aromatic polyketide [55]. The differential enzyme activity of different CHS isoforms with different substrates has also been reported in Humulus lupulus [56], Gerbera hybrida [57], Emblica officinalis [58] and others. The differential enzyme activity of Ga CHS2 towards different substrates indicates its evolutionary expansion possibly due to gene duplication “Fig 6”.…”

Functional Promiscuity of Two Divergent Paralogs of Type III Plant Polyketide Synthases

“…It has extended primarily from the model plants to various economically important species, including apple (Malus domestica), grape (Vitis vinifera), potato (Solanum tuberosum), strawberry (Fragaria spp. ), and tomato (Solanum lycopersicum; Deng et al, 2014). However, the limited availability of these beneficial compounds from their natural sources makes flavonoids prime candidates to be synthesized in engineered microbes like Escherichia coli and Saccharomyces cerevisiae .…”

“…To persist over long periods of evolutionary time, nearly all plant genes are represented within most plant genomes as small to large gene families (Han et al, 2006). For instance, in many angiosperms, CHS is encoded by a multigene family with members ranging from two (Zea mays), three (Gerbera hybrida), six (Ipomoea purpurea), seven (Pisum sativum), eight (Physcomitrella patens), nine (Glycine max), and even 10 in some species like Petunia hybrida (Jiang et al, 2006;Deng et al, 2014). These gene families emerge as a result of selective gene duplication and subsequent nucleotide substitution events.…”

Outer‐sphere residues influence the catalytic activity of a chalcone synthase from Polygonum cuspidatum

“…The chalcone synthase (CHS) superfamily of type III polyketide synthases (PKSs) are crucial enzymes responsible for the formation of numerous structurally diverse and biologically significant secondary metabolites, and some of the metabolites can serve as antibiotics, anticancer drugs, and immunosuppressants . CHS and homologous members of type III PKSs are usually homodimers of 40–45 kDa subunits, and they perform a complete series of decarboxylation, condensation, cyclization, and aromatization reactions in a single active site .…”