Transformation of Brassica oleracea with an S-locus gene from B. campestris changes the self-incompatibility phenotype

Summary An SLG gene derived from the S-locus and encoding and S-locus-specific glycoprotein of Brassica campestris L. was introduced via Agrobacterium-mediated transformation into B. oleracea L. A self-incompatible hybrid and another with partial self-compatibility were used as recipients. The transgenic plants were altered in their pollen-stigma interaction and were fully compatible upon self-pollination. Reciprocal crosses between the transgenic plants and untransformed control plants indicated that the stigma reaction was changed in one recipient strain while the pollen reaction was altered in the other. Due to interspecific incompatibility, we could not demonstrate whether or not the introduced SLG gene confers a new allelic specificity in the transgenic plants. Our results show that the introduced SLG gene perturbs the self-incompatibility phenotype of stigma and pollen.     

The use of acetylated cytochrome c in detecting superoxide anion production in rabbit alveolar macrophages

Polymorphonuclear phagocytes have been shown to undergo marked alteration in oxidative metabolism during phagocytosis. These alterations, collectively known as the "respiratory burst", include increased glucose oxidation through the hexose monophosphate shunt (1), increased oxygen consumption (1), and increased superoxide (O-2)3 (2) and H2O2 production (3). Similar metabolic events have also been shown to occur in the rabbit alveolar macrophage (AM). There is consistent evidence that the macrophage undergoes increased oxygen consumption (4-6) and hexose monophosphate shunt activity (4-9) upon phagocytosis. There are conflicting data, however, concerning the ability of the macrophage to produce O-2. Some studies suggest that macrophages are incapable of producing measurable amounts of O-2 upon phagocytosis (7, 10-12). Other studies, however, suggest that macrophages are indeed capable of producing substantial amounts of O-2 during phagocytosis (8, 13-15). This study was designed to resolve the discrepancies in the literature concerning O-2 production in macrophages.     

Brassica S-Proteins Accumulate in the Intercellular Matrix along the Path of Pollen Tubes in Transgenic Tobacco Pistils

A tobacco plant transformed with a Brassica oleracea SLG-22 gene was analyzed by immunocytochemical methods to determine the localization of the transgene-encoded protein product. Immunolabeling was observed in the pistil along the path followed by pollen tubes after pollination. S-antigen accumulated in the intercellular matrix of the transmitting tissue of the style and its continuation in the basal portion of the stigma and outside a few special cells of the placental epidermis of the ovary. This pattern of S-antigen distribution closely resembles that described for the S-associated glycoproteins of self-incompatible Nicotiana alata and differs from its distribution in B. oleracea.     

A plant receptor-like gene, the S-locus receptor kinase of Brassica oleracea L., encodes a functional serine/threonine kinase.

To investigate the catalytic properties of the Brassica oleracea S-locus receptor kinase (SRK), we have expressed the domain that is homologous to protein kinases as a fusion protein in Escherichia coli. Following in vivo labeling of cultures with 32P-labeled inorganic phosphate, we observed phosphorylation of the fusion protein on serine and threonine, but not on tyrosine. In contrast, labeling was not observed when lysine-524, a residue conserved among all protein kinases, was mutated to arginine, thus confirming that SRK phosphorylation was the result of intrinsic serine/threonine kinase activity.     

Distinct cis-acting elements direct pistil-specific and pollen-specific activity of the Brassica S locus glycoprotein gene promoter.

The promoter of the S Locus Glycoprotein (SLG) gene of Brassica is a tightly regulated promoter that is active specifically in reproductive organs. In transgenic tobacco, this promoter is active exclusively in cells of the pistil and in pollen. We transformed tobacco with truncated versions of the SLG13 promoter fused to the beta-glucuronidase reporter gene. We show that the promoter has a modular organization and consists of separable DNA elements that independently specify pistil- and pollen-specific expression. A 196-bp region (-339 to -143) is sufficient to confer stigma and style specificity to the marker gene. Two distinct, but functionally redundant, domains (-415 to -291 and -117 to -8) allow specific expression of the gene in pollen. The functional domains identified within the SLG13 promoter contain sequence elements that are highly conserved in different alleles of the SLG gene and in the S Locus Related SLR1 gene.     

Peroxidases in Relation to Removal of Dormancy and Germination of Apple Embryos

The changes in germination, peroxidase activity and isoperoxidase spectrum have been studied in apple embryos at 5°C (stratification) and at 20°C in the presence or absence of seed coats. The embryo dormancy is progressively released at 5°C, but not at 20°C. The peroxidase activity in embryos covered with seed coats is very low at 5°C as well as at 20°C which corresponds to a restricted number of isoenzymes. In isolated embryos the peroxidase activity increases significantly. This is due to an increase in both the number and the activity of the isoperoxidases and it is more pronounced at 20°C than at 5°C. The obtained results suggest that the soluble peroxidases are not involved in the process of the release of embryo dormancy. The variations observed are attributed to the growth process following germination, which can occur even at low temperature.