Characteristic of the gene candidate SecARS encoding alkylresorcinol synthase in Secale.

BACKGROUND: Alkylresorcinols (ARs) are compounds belonging to the class of phenolic lipids. A rich source of ARs are cereal grains such as rye, wheat, triticale or barley. ARs found in plants are characterized by a variety of biological properties such as antimicrobial, antifungal and cytotoxic activity. Moreover, they are proven to have a positive influence on human health. Here, we aimed to find and characterize the gene with ARs synthase activity in the species Secale cereale. METHODS AND RESULTS: Using BAC library screening, two BAC clones containing the gene candidate were isolated and sequenced. Bioinformatic analyses of the resulting contigs were used to examine the structure and other features of the gene, including promoter, intron, 3'UTR and 5'UTR. Mapping using the FISH procedure located the gene on the 4R chromosome. Comparative analysis showed that the gene is highly similar to sequences coding for type III polyketide synthase. The level of gene expression in various parts of the plant was investigated, and the biochemical function of the gene was confirmed by heterologous expression in yeast. CONCLUSIONS: The conducted analyses contributed to a better understanding of the processes related to ARs synthesis. Although the research concerned the rye model, the knowledge gained may help in understanding the genetic basis of ARs biosynthesis in other species of the Poaceae family as well.

Calreticulin localizes to plant intra/extracellular peripheries of highly specialized cells involved in pollen-pistil interactions.

Calcium (Ca2+) plays essential roles in generative reproduction of angiosperms, but the sites and mechanisms of Ca2+ storage and mobilization during pollen-pistil interactions have not been fully defined. Both external and internal Ca2+ stores are likely important during male gametophyte communication with the sporophytic and gametophytic cells within the pistil. Given that calreticulin (CRT), a Ca2+-buffering protein, is able to bind Ca2+ reversibly, it can serve as a mobile store of easily releasable Ca2+ (so called an exchangeable Ca2+) in eukaryotic cells. CRT has typical endoplasmic reticulum (ER) targeting and retention signals and resides primarily in the ER. However, localization of this protein outside the ER has also been revealed in both animal and plant cells, including Golgi/dictyosomes, nucleus, plasma membrane/cell surface, plasmodesmata, and even extracellular matrix. These findings indicate that CRT may function in a variety of different cell compartments and specialized structures. We have recently shown that CRT is highly expressed and accumulated in the ER of plant cells involved in pollen-pistil interactions in Petunia, and we proposed an essential role for CRT in intracellular Ca2+ storage and mobilization during the key reproductive events. Here, we demonstrate that both CRT and exchangeable Ca2+ are localized in the intra/extracellular peripheries of highly specialized plant cells, such as the pistil transmitting tract cells, pollen tubes, nucellus cells surrounding the embryo sac, and synergids. Based on our present results, we propose that extracellularly located CRT is also involved in Ca2+ storage and mobilization during sexual reproduction of angiosperms.

Proteinaceous toxins of Stagonospora nodorum, the causal agent of triticale leaf and glume blotch.

S. nodorum is an economically important necrotrophic pathogen of cereals and grasses worldwide. In past several years appeared in literature quite a number of reports on existence of proteinaceous effectors produced by the fungus which induce necrosis in cereal host tissue. These host specific toxins induce necrosis by interacting with specific, dominant host genes. Up to the present research on S. nodorum toxin resistance was conducted only with wheat. Because wheat chromosomes are present in triticale genome, it is highly likely that mechanism used by S. nodorum for necrosis induction in triticale is the same as in wheat. Simple pilot experiment conducted in our laboratory, confirms that mechanism of necrosis induction via proteinaceous toxins is similar for both, wheat and triticale.

[Myosin VI: the unique motor protein of the actin cytoskeleton]. / Miozyna VI: unikalne bialko motoryczne cytoszkieletu aktynowego.

Myosins are actin-based motor proteins that use energy derived from ATP hydrolysis to generate force and move along actin filaments. Myosin VI is a unique motor protein because it moves towards the "minus" end of actin filament, which is the opposite direction to all of the other myosins studied so far, and therefore is thought to have unique properties and cellular functions. Localization and functional studies indicate that myosin VI plays a role in a variety of different intracellular processes, such as endocytosis and secretion as well as cell division, differentiation, and cell migration. These various functions of myosin VI are mediated by interaction with a range of different binding partners. In this review, we describe the structure, kinetic properties and functions proposed for myosin VI, and present current hypotheses on the mechanisms of functioning of this unique protein in vivo.

[Calreticulin--the structure, cell localizations and functions in animals and plants]. / Kalretikulina--budowa, lokalizacja komórkowa oraz proponowane funkcje u zwierzat i roslin.

Calreticulin (CRT) is an ubiquitously expressed Ca2+ binding protein in endoplasmic reticulum (ER) of eukaryotic cells. A highly conserved structure between CRTs from different species of animals and plants confirms an important role of the protein in living cells. CRT has been found in different cellular compartments, suggesting to play a role in many cellular processes both inside and outside the ER. Although, the basic CRT functions like regulation of Ca2 homeostasis and molecular chaperoning in ER might be the key to explain the multi-process property of the protein. The plant CRT sequence shares the same structural domain features identified for animal CRT and seems to have similar properties. However, the current knowledge about CRT expression and physiological role in plants is still very limited. Therefore in this work, we focus on these less-well-characterized functions of CRT in plants.