Genomic organization and expression properties of the MtSucS1 gene, which encodes a nodule-enhanced sucrose synthase in the model legume Medicago truncatula

Abstract

We have isolated and sequenced a sucrose synthase (SucS) cDNA from the model legume Medicago truncatula. This cDNA (MtSucS1) contains an ORF of 2418 bp, coding for a protein of 805 amino acids with a molecular mass of 92.29 kDa. The deduced amino acid sequence shows significant homology to other plant sucrose synthases, in particular to the nodule-enhanced sucrose synthases from pea and broad bean. Northern analysis revealed that the corresponding gene shows a ten-fold higher expression level in root nodules than in uninfected root, stem and leaf tissues. SucS protein was detected in root nodules from a variety of legumes, including M. truncatula. Whereas only one SucS isoform was detectable in root nodules, an additional sucrose synthase of slightly larger molecular weight was present in uninfected root, stem and flower tissues of M. truncatula. From our expression and sequence data we infer that the MtSucS1 gene encodes a nodule-enhanced sucrose synthase in M. truncatula. Southern hybridization data indicate that MtSucS1 is a single-copy gene. An analysis of a genomic MtSucS1 sequence revealed that the gene consists of 14 exons with the start codon being located on exon II. As is common for SucS genes, the MtSucS1 gene contains a large intron of 747 bp in the 5' untranslated region. The transcriptional start of MtSucS1 was mapped and putative regulatory elements in the MtSucS1 promoter were identified.

TILLING Mutants of Lotus japonicus Reveal That Nitrogen Assimilation and Fixation Can Occur in the Absence of Nodule-Enhanced Sucrose Synthase

“…1). This is the same number of genes reported for Arabidopsis (Baud et al, 2004) and rice (Huang et al, 1996;Harada et al, 2005) and extends the understanding of the gene family in legumes, where several isoforms have been reported in Medicago truncatula (Hohnjec et al, 1999) and pea (Barratt et al, 2001). As in Arabidopsis, the encoded SUS proteins appear to fall into three distinct groups of isoforms, each group containing two proteins (Fig.…”

“…3) showed a clear legume cluster of Suc synthase isoforms as well as a monocot (rice SUS5 and SUS6) and a dicot (LjSUS5 and LjSUS6 and AtSUS5 and AtSUS6) cluster in the ''New Group'' (Komatsu et al, 2002). The first three Suc synthase isoforms of M. truncatula (MtSucS1, MtSucS2, and MtSucS3) are closely related to the three pea Suc synthase isoforms and share a similar expression pattern with them (Hohnjec et al, 1999). There are, however, some distinct differences in expression patterns between the L. japonicus genes and those in other legumes.…”

The Root Hair “Infectome” of Medicago truncatula Uncovers Changes in Cell Cycle Genes and Reveals a Requirement for Auxin Signaling in Rhizobial Infection

“…Several other genes that had not been previously linked to infection were identified. The sucrose synthase gene SUCS1 (Mtr.22018.1.S1_s_at: Medtr4g124660), which is expressed in nodules and required for nitrogen fixation (Baier et al, 2007) and is required for colonization by arbuscular mycorrhizal fungi (Hohnjec et al, 1999;Baier et al, 2010), had increased expression in skl after S. meliloti inoculation. SWEET13, which encodes a sugar transporter (Chen et al, 2012), and a gene involved in actin nucleation ABIL1 (Mtr.20281.1.S1_at: Medtr7g116710), which had very low expression in root hairs in the absence of Nod factorproducing rhizobia, were also induced by S. meliloti.…”

Identification and Characterization of the Duplicate Rice Sucrose Synthase Genes OsSUS5 and OsSUS7 Which Are Associated with the Plasma Membrane

“…Phylogenetic analyses were conducted using MEGA version 4 (Tamura et al, 2007) and the neighbor-joining method. The accession numbers of the sequences used to construct the phylogenetic tree are as follows: AtSUS1-AtSUS6 from Arabidopsis, At5g20830, At5g49190, At4g02280, At3g43190, At5g-37180, and At1g73370, respectively (Baud et al, 2004); Ag-SUS from Alnus glutinosa, X92378 (van Ghelue et al, 1996); BoSUS1-BoSUS4 from Bambusa oldhamii, AF412036, AF-412038, AF412037, and AF412039, respectively; BvSBSS1 and BvSBSS2 from sugar beet, AY457173 and EF660856, respectively (Hesse and Willmitzer, 1996;Klotz and Haagenson, 2008); ClSUS from Citrullus lanatus, AB018561; Cpss1 and Cpss2 from Craterostigma plantagineum, AJ131999 and AJ132000, respectively (Kleines et al, 1999); CrSUS from Chenopodium rubrum, X82504 (Godt et al, 1995); CitSUS1 and CitSUSA from citrus, AB022092 and AB022091 (Komatsu et al, 2002); DcSUS1 and DcSUS2 from carrot, X75332 and Y16091 (Sebkova et al, 1995;; GhSUS from Gossypium hirsutum, U73588; GmSUS from soybean, AF030231; HvSUS1 and HvSUS2 from barley, X65871 and X69931 (Sánchez de la Hoz et al, 1992); LeSUS1 and Le-SUS2 from tomato, L19762 and AJ011319 (Chengappa et al, 1999;Wang et al, 1993); MsSUS from Medicago sativa, AF049487; MtSUS1 from Medicago truncatula, AJ131943 (Hohnjec et al, 1999); MySUS from the tropical epiphytic CAM orchid Mokara Yellow, AF530568 (Li et al, 2004); OgSUS from the tropical epiphytic orchid Oncidium goldiana, AF530567; OsSUS1-OsSUS7 from rice, LOC_Os03g28330, LOC_Os06g 09450, LOC_Os07g42490, LOC_Os03g22120, LOC_Os04g 24430, LOC_Os02g58480, and LOC_Os04g17650, respectively (Hirose et al, 2008;Huang et al, 1996;Wang et al, 1992); PdSUS1 and PdSUS2 from Potamogeton distinctus, AB193515 and AB193516; PtSUS from Populus tremuloides, AY341026; PvSS from bean, AF315375 (Silvente et al, 2003); PsSUS1-PsSUS3 from pea, AJ012080, AJ001071, and AJ311496, respectively (Barratt et al, 2001;Craig et al, 1999); SoSusy2 from Saccharum officinarum, AY118266; StSUS2-StSUS4 from potato, AY205302, U24088, and U24087, respectively (Fu and Park, 1995;Salanoubat and Belliard, 1987); TaSUS1 and TaSUS2 from Triticum aestivum, AJ001117 and AJ000153; TgSUS1 and TgSUS2 from tulip, X96938 and X96939 (Balk and de Boer, 1999); VfSUS from fava bean, X69773; Vrvss1 from mung bean, D10266 …”