The Regulation of Ornithine Decarboxylase Gene Expression by Sucrose and Small Upstream Open Reading Frame in Tomato (Lycopersicon esculentum Mill)

Abstract

We identified a near-full-length cDNA clone encoding ornithine decarboxylase (ODC) from tomato (Lycopersicon esculentum Mill). It contained a small upstream open reading frame (uORF) within its 5' untranslated region. An in vitro translation assay demonstrated that the uORF repressed expression of downstream ORF. Neither nucleotide nor predicted peptide sequence of the uORF was responsible for the repression. The presence of upstream AUG codon was shown to be responsible. ODC expression appeared to be organ specific. The ODC gene was expressed in roots, hypocotyls and sink leaves but not in source leaves. ODC transcripts were observed in apical meristem of primary roots, and were distributed in cells of cortex layer preferentially. ODC expression responded immediately to sucrose availability via the sucrose-specific pathway independent of hexokinase. Sucrose induction of ODC gene was seen in roots, hypocotyls and flowers but not in mature leaves. Moreover, only the root apical meristem responded to sucrose availability. These observations indicate that the spatial pattern of ODC expression is closely associated with cell proliferation and that sucrose sensing plays a major role in the spatial pattern of ODC expression. Also, the differential regulation of ODC and arginine decarboxylase gene expression by factors modulating plant growth suggests that they would have different physiological roles in plant development.

Differential distribution of transcripts from genes involved in polyamine biosynthesis in bean plants

“…Our transcription results correlate with those from D. stramonium (Michael et al 1996), where odc mRNA accumulates to a greater extent in highly branching and fast growing transformed root cultures as compared to leaves or stems, where cell division is limited. Studies on tomato have shown similar results for odc (Kwak and Lee 2001), higher expression levels were detected in roots followed by stems, whereas lower levels were found in young and mature leaves. Alabadí and Carbonell (1998) found that unpollinated ovaries in tomato at 1 d post-anthesis showed a high level of odc mRNA, which gradually decreased with time.…”

Effect of Salt Stress on the Regulation of Maize (Zea mays L.) Genes Involved in Polyamine Biosynthesis

“…Zmodc transcript was detected only in leaves (Figure 3d). Results from Datura stramonium (Michael et al 1996), Lycopersicon esculentum (Alabadi and Carbonell 1998;Kwak and Lee 2001) and Capsicum annuum (Zainal et al 2002) support the idea that odc expression pattern is organ-specific and closely related to cellular proliferation. The adc transcript was detected in higher levels in leaves, followed by stem and barely observed in roots (Figure 3b).…”

Lysine Decarboxylase Catalyzes the First Step of Quinolizidine Alkaloid Biosynthesis and Coevolved with Alkaloid Production in Leguminosae

“…The ODC transcript levels in plants such as tomato (Solanum lycopersicum) (Kwak and Lee, 2001), soybean (Delis et al, 2005), and devil's trumpet (Michael et al, 1996) showed high transcript levels in developing tissues and expanding cells, such as those in hypocotyls and roots. The transcripts of L. angustifolius L/ODC accumulated coincidently with the production of QAs, exclusively in the young leaves of the bitter cultivar ( Figure 4A); this suggests that L/ODC is specifically involved in the biosynthesis of QAs.…”