gamma-Glutamyl transpeptidase (GGT) is the only enzyme known that can cleave the gamma-peptide bond between glutamate and cysteine in glutathione, and is therefore a key step in glutathione degradation. There are three functional GGT genes in Arabidopsis, two of which are considered here. GGT1 and GGT2 are apoplastic, associated with the plasma membrane and/or cell wall. RNA blots and analysis of enzyme activity in knockout mutants suggest that GGT1 is expressed most strongly in leaves but is found throughout the plant. A GGT1::GUS fusion construct showed expression only in vascular tissue, specifically the phloem of the mid-rib and minor veins of leaves, roots and flowers. This localization was confirmed in leaves by laser microdissection. GGT2 expression is limited to embryo, endosperm, outer integument, and a small portion of the funiculus in developing siliques. The ggt2 mutants had no detectable phenotype, while the ggt1 knockouts were smaller and flowered sooner than wild-type. In ggt1 plants, the cotyledons and older leaves yellowed early, and GSSG, the oxidized form of glutathione, accumulated in the apoplastic space. These observations suggest that GGT1 is important in preventing oxidative stress by metabolizing extracellular GSSG, while GGT2 might be important in transporting glutathione into developing seeds.

Eighteen L. inconspicuous accessions collected from different countries were evaluated for variations of seed weight, seed protein content, and electrophoretic patterns of the total seed proteins analyzed under reducing conditions. They exhibited a reasonable genetic variability for the evaluated traits. This genetic variability revealed that improvement through simple selection for these traits is possible. The variation between the seed size of this accessions was attributed to the development process or the life cycle of the plant, and the environmental condition to which the mother plant is exposed. On the other hand, the variation in protein content among the different accessions may be due to genotype and/or seasonal influences. The relationship between protein content and 100 seeds weight in the evaluated accessions was reversible, the accession showed the lowest quantity of the total seed proteins was the accession that exhibited highest weight of 100 seeds and nearly vice versa. Each accession gave a different electrophoretic pattern except the two accessions collected from Iran, exhibited an identical one. The difference in 100 seed weight and total protein content of these accessions indicated that they are not genetically identical. The variation in the electrophoregram of the evaluated accessions located in the bands with molecular weight more than 98 kDa, the heavy subunits of alpha-lathyrin subunits and the region molecular weight around 70 kDa. The results of cluster analysis based of SDS/PAGE under reduction conditions indicated that genetic diversity between Turkish, Syrian, and Iranian and Australian accessions is pronounced, and Turkish accessions are closer to both Syrian and Iranian accessions than the relation between Syrian and Iranian. This suggested that crosses between the Iranian and Syrian accessions could create more genetic variability than crosses with Turkish accessions. The distribution of Turkish and Syrian accessions between more than one clusters revealed that genetic diversity and geographic distribution were independent of each other. PCA showed that all accessions were separated on the first principal component, indicating that the accessions showed a good association, due, probably, to parallel evolution.Key words: 100 seeds weight, Protein analysis, multivariate analysis, germplasm characterization IZVLEČEK ANALIZA GENETSKE VARIABILNOSTI AKCESIJ GRAHORJA (Lathyrus inconspicuous (L.) S SDS POLIAKRILAMIDNO GELSKO ELEKTROFOREZOOsemnajst akcesij grahorja (L. inconspicuous L.), zbranih iz različnih držav, je bilo ovrednoteno glede na variabilnost mase semen, vsebnost semenskih proteinov in elektroforetskih vzorcev celokupnih semenskih proteinov analiziranih v reducirajočih razmerah, ob prisotnosti reducenta. Ovrednotene lastnosti so pokazale pričakovano genetsko variabilnost na osnovi katere je možna preprosta selekcija. Variabilnost v velikosti semen med akcesijami je bila odvisna od razvojnih procesov v življenskem ciklu rastlin in okoljskih dejavnikov, katerim je b...

The results in the present study emphasize that in Arabidopsis thaliana genome, gamma-GTase encoded by a gene family comprised of four genes. Three of these genes are functionally expressed while the fourth is a pseudogene. The three functional genes express different active protein isoforms that appeared to have different functions. Two genes (GGT1 and GGT2) are structurally similar and expresses proteins with the same molecular weight and both target to the same cellular compartment (plasma membrane). However, both demonstrated different tissue localization, physiological activities and different patterns of response to environmental stress. The majority of GGTI encoded by the first gene was localized in the rosette leaves, It is also expressed throughout the whole plant.

Cucurbita pepo ssp. pepo; zucchini group is a widely grown and economically important group belonging to genus Cucurbita, and being one of the easiest groups to cultivate in temperate climate with overwhelming production. Since, RAPD analysis provides a fast and reliable method for molecular characterization and investigation of the intraspecific genetic relationships; it had been used in this study to discriminate and clarify the genetic diversity between seven cultivars of C. pepo ssp. pepo originated worldwide. Seven out of 20 decamer arbitrary primers showed polymorphism in the RAPD profile. The polymorphism was investigated by 87 consistent amplification products. Some of those fragments were uniquely amplified in single cultivar. Thus, they can be used as molecular markers for cultivar identification. The results of Jaccard similarity and the phenogram ascertained the wide genetic base of the Egyptian landrace El-Escandrani with the lowest loading component of 0.400. Therefore, it could be recommended as a reservoir of alleles useful for breeding programs in parental crosses. The multivariate analysis using the principle component analysis separated all the cultivars on the first component indicating the high correlation between them. The strongest correlation was confirmed between the two MHTSQ hybrids with Mansoura cultivar from Italy, with a loading component of 0.85.