Tissue expression analysis of FeMT3, a drought and oxidative stress related metallothionein gene from buckwheat (Fagopyrum esculentum).

Metallothionein type 3 (MT3) expression has previously been detected in leaves, fruits, and developing somatic embryos in different plant species. However, specific tissular and cellular localization of MT3 transcripts have remained unidentified. In this study, in situ RNA-RNA analysis revealed buckwheat metallothionein type 3 (FeMT3) transcript localization in vascular elements, mesophyll and guard cells of leaves, vascular tissue of roots and throughout the whole embryo.

Buckwheat (Fagopyrum esculentum Moench) FeMT3 gene in heavy metal stress: protective role of the protein and inducibility of the promoter region under Cu(2+) and Cd(2+) treatments.

The protective role in vivo of buckwheat metallothionein type 3 (FeMT3) during metal stress and the responsiveness of its promoter to metal ions were examined. Increased tolerance to heavy metals of FeMT3 producing Escherichia coli and cup1(Delta) yeast cells was detected. The defensive ability of buckwheat MT3 during Cd and Cu stresses was also demonstrated in Nicotiana debneyii leaves transiently expressing FeMT3.

Ubiquitous aspartic proteinase as an actor in the stress response in buckwheat.

The aspartic protease (FeAP9) gene from buckwheat resembles the exon-intron structure characteristic for typical aspartic proteinases, including the presence of the leader intron in the 5'-UTR. RT PCR experiments and gel protein blot analysis indicated that FeAP9 was present in all analyzed organs: developing seeds, seedlings, flowers, leaves, roots and stems. Using Real-time PCR, we found that FeAP9 expression is upregulated in buckwheat leaves under the influence of different abiotic stresses, including dark, drought and UV-B light, as well as wounding and salicylic acid.

Functional analysis of the buckwheat metallothionein promoter: tissue specificity pattern and up-regulation under complex stress stimuli.

To shed light on expression regulation of the metallothionein gene from buckwheat (FeMT3), functional promoter analysis was performed with a complete 5' regulatory region and two deletion variants, employing stably transformed tobacco plants. Histochemical GUS assay of transgenic tobacco lines showed the strongest signals in vascular elements of leaves and in pollen grains, while somewhat weaker staining was observed in the roots of mature plants. This tissue specificity pattern implies a possible function of buckwheat MT3 in those tissues.

Two types of aspartic proteinases from buckwheat seed--gene structure and expression analysis.

Two types of aspartic proteinase (AP) genes have been isolated from the cDNA library of developing buckwheat seeds. Analysis of their sequences showed that one of these, FeAP9, resembled the structure and shared high homology with the so-called typical plant APs characterized by the presence of a plant-specific insert (PSI), an element unique among APs. The other cDNA, FeAPL1, encoded an AP-like protein lacking that domain.

Isolation and computer analysis of the 5'-regulatory region of the seed storage protein gene from buckwheat (Fagopyrum esculentum Moench).

Using the modified rapid amplification of cDNA ends (5'-RACE) approach, a fragment containing the 955 bp long 5'-regulatory region of the buckwheat storage globulin gene (FeLEG1) has been amplified from the genomic DNA of buckwheat. The entire fragment was sequenced, and the sequence was analyzed by computer prediction of cis-regulatory elements possibly involved in tissue-specific and developmentally controlled seed storage protein gene expression. The promoter obtained might be interesting not only for fundamental research but also as a useful tool for biotechnological application.

Vicilin-like storage globulin from buckwheat (Fagopyrum esculentum Moench) seeds.

An 8S storage globulin from buckwheat seed, which resembles the structure and features common to the vicilin-like family of seed storage proteins, was analyzed for this paper. It was found that expression of the 8S globulin gene precedes that of the 13S globulin (the main buckwheat storage protein) and starts from an early stage of buckwheat seed development (9-11 days after flowering), continuing to accumulate throughout seed development to contribute approximately 7% of total seed proteins. This protein fraction might be more interesting for biotechnological application than the 13S buckwheat legumin consisting of 23-25 kDa subunits reported to be the major buckwheat allergen.

Characterization and evolutionary relationship of methionine-rich legumin-like protein from buckwheat.

We have isolated and characterized a full-length cDNA for legumin-like storage polypeptide from buckwheat seed (Fagopyrum esculentum Moench) and compared its deduced amino acid sequence with those from different representatives of dicots, monocots and gymnosperms. The cDNA sequence was reconstructed from two overlapping clones isolated from a cDNA library made on mRNA of buckwheat seed at the mid-maturation stage of development. Analysis of the deduced amino acid sequence revealed that this specific buckwheat storage polypeptide should be classified in the methionine-rich legumin subfamily present in the lower angiosperm clades, a representative of which was first characterized in Magnolia salicifolia (clone B 14).

Expression analysis of buckwheat (Fagopyrum esculentum Moench) metallothionein-like gene (MT3) under different stress and physiological conditions.

The buckwheat metallothionein-like (MT3) gene expression was studied throughout seed and leaf development, as well as under the influence of different external stimuli. MT3 mRNAs were detected from the early stage of seed development to the end of maturation, reaching the highest level during the mid-maturation stage. High MT3 mRNA level was noticed for both green and senescent leaves.

Characterization of an aspartic proteinase activity in buckwheat (Fagopyrum esculentum Moench) seeds.

The pepstatin A sensitive acidic proteolytic activity of total protein extracts of buckwheat seeds has been analyzed in developing, mature, and germinating seeds by activity measurements as well as by electrophoretic and immunochemical techniques. Immunoblot analysis using cross-reactive antibodies raised against barley phytepsin suggested that specific proteolytic activity could be attributed to a 47 kDa heterodimeric polypeptide, composed of two subunits: 31 and 16 kDa polypeptides. The analysis of time course expression revealed that the 47 kDa heterodimer accumulated during seed maturation starting from 12 days after pollination and was also present at the beginning of germination.