Molecular characterization of a low-molecular-weight glutenin cDNA clone from Triticum durum

Abstract

A full-length, low-molecular-weight (LMW) glutenin cDNA clone, pTdUCD1, has been isolated from a Triticum durum cv 'Mexicali' wheat cDNA library. The complete sequence was determined and compared to the LMW glutenin genes that have been isolated from hexaploid wheat, Triticum aestivum. This cDNA codes for a protein of 295 amino acids (33,414 daltons) including a 20-amino acid signal peptide as deduced from the DNA sequence. Northern analysis showed that this cDNA hybridizes to a family of related sequences ranging in length from 1,200 to 1,000 nucleotides. This gene is similar but not identical to previously published LMW glutenin gene sequences. The most striking characteristic of all cloned LMW glutenin genes is the conservation of eight cysteine residues, which could be involved in potential secondary or tertiary structure, disulfide bond interactions. This paper presents a structural map defining distinct regions of the LMW glutenin gene family.

Seed-storage-protein loci in RFLP maps of diploid, tetraploid, and hexaploid wheat

“…This possibility was however, ruled out in the present study. Low-M glutenin clone pTdUCD1 has less than 70% homology with the gliadin genes at the nucleotide-sequence level and does not hybridize with them (Cassidy and Dvorak 1991). Restriction fragments that hybridized with the clone and mapped at the XGlu-2 locus did not hybridize with the gliadin clone while those that mapped at the XGli-B3 locus and hybridized with the gliadin clone did not hybridize with the low-M glutenin clone.…”

“…The final wash was 0.2;SSC at 65°C for 30 min for wheat clones and 0.5;SSC at 65°C for 30 min for heterologous clones. The following clones were used in the mapping of seed-storage-protein loci: hordein ( -gliadin) clone pcP387 , -gliadin clone pTU1 (D'Ovidio et al 1992), high-M glutenin clone pDY10A/KS- (Anderson et al 1989), low-M glutenin clone pTdUCD1 (Cassidy and Dvorak 1991), and triticin clone Tri25-11 (Singh et al 1993). Probes used for the mapping of the remaining loci were as described by Dubcovsky et al (1996).…”

“…The C subunits have an M ranging from 30 to 40 kDa and constitute a minor group (Payne and Corfield 1979;Pogna et al 1994). The B and C low-M glutenin subunits are distantly related to -gliadins (Colot et al 1989;Cassidy and Dvorak 1991). Another minor group are the D subunits which are highly acidic and are related to -gliadins (Jackson et al 1983;Masci et al 1993).…”

“…Low-M glutenin genes that have been cloned are sufficiently different at the nucleotide sequence level from the gliadin genes so that they do not hybridize with them (Cassidy and Dvorak 1991;. Hence, mapping of DNA restriction fragments hybridizing with cloned gliadin or low-M glutenin genes provides a convenient strategy to ascertain whether a mapped storage protein was coded by a glutenin or gliadin gene.…”

Length variation of i-type low-molecular-weight glutenin subunit genes in diploid wheats

“…A number of typical LMW-GS genes have been isolated from wheat and its relatives [10][11][12][13][14][15][16][17]. The general structure of a typical LMW-GS consists of four structural domains including a signal peptide of 20 amino acids, a short N-terminal domain (13 amino acids) that usually contains the first cysteine residue, a highly variable repetitive domain rich in glutamine codons and a conserved This article was submitted by the authors in English.…”