Expression of the C 4 Me1 Gene from Flaveria bidentis Requires an Interaction between 5' and 3' Sequences

Abstract

The efficient functioning of C4 photosynthesis requires the strict compartmentation of a suite of enzymes in either mesophyll or bundle sheath cells. To determine the mechanism controlling bundle sheath cell-specific expression of the NADP-malic enzyme, we made a set of chimeric constructs using the 5[prime] and 3[prime] regions of the Flaveria bidentis Me1 gene fused to the [beta]-glucuronidase gusA reporter gene. The pattern of GUS activity in stably transformed F. bidentis plants was analyzed by histochemical and cell separation techniques. We conclude that the 5[prime] region of Me1 determines bundle sheath specificity, whereas the 3[prime] region contains an apparent enhancer-like element that confers high-level expression in leaves. The interaction of 5[prime] and 3[prime] sequences was dependent on factors that are present in the C4 plant but not found in tobacco.

An Untranslated cis-Element Regulates the Accumulation of Multiple C4 Enzymes in Gynandropsis gynandra Mesophyll Cells

“…The evolution of C 4 photosynthesis from the C 3 ancestral state requires mechanisms generating increased abundance as well as cell specificity of a large number of enzymes (Marshall et al, 1997;Patel et al, 2004;Gowik et al, 2004;Wiludda et al, 2012). A recent study has suggested that the evolution of increased abundance can be complex, with multiple sequences within promoters and 59 UTRs contributing to the expression of C 4 genes (Wiludda et al, 2012).…”

“…As these studies focused on a number of genes isolated from phylogenetically distinct C 4 species, they suggest that the mechanisms regulating genes of the C 4 pathway vary both within and between independent C 4 lineages. In the majority of cases, different sequences generate increased abundance and cell specificity for the same gene (Marshall et al, 1997;Akyildiz et al, 2007;Kajala et al, 2012;Wiludda et al, 2012), suggesting that the evolution of these two traits is not coordinated. Most mechanisms identified to date are also unique to each C 4 lineage studied, although a homologous mechanism has been co-opted to generate BS specificity for multiple genes encoding malic enzyme within maize (Zea mays) and Gynandropsis gynandra (formerly designated as Cleome gynandra; Brown et al, 2011).…”

The Gene for the P-Subunit of Glycine Decarboxylase from the C4 SpeciesFlaveria trinervia: Analysis of Transcriptional Control in TransgenicFlaveria bidentis(C4) and Arabidopsis (C3)

“…It has been shown that mesophyll-specific expression of C 4 cycle genes is mainly regulated at the transcriptional level (Schaffner and Sheen, 1992;Stockhaus et al, 1994;Rosche et al, 1998;Sheen, 1999), whereas bundle-sheath-specific expression is controlled at both transcriptional and posttranscriptional levels (Long and Berry, 1996;Marshall et al, 1997;Sheen, 1999;Patel et al, 2006).…”

Evolution of C4 Photosynthesis inFlaveria Species1

“…leaves, respectively (Marshall et al, 1997). Thus, at least two chloroplastic forms of NADP-ME might be expected to occur in Flaveria spp.…”