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A group of scientists from five countries, including Russia, researched a genetic regulation of stem cells in the stem of plants and discovered a previously unknown mechanism for controlling the growth of wood by the plant hormone auxin, according to the newspaper “Science in Siberia” . Proteins-regulators of the response to auxin coordination gene WOX4 is a key to maintain stem cells of the stem plants. The results of the study are not only for the fundamental biology, but also for the solution of the economic and environmental problems, as the mechanism will allow in the future to influence the quality and volume of wood. Details published in the journal Nature Communications.
An international team of scientists from the Center for Organic Studies (Germany), the Institute of Gregor Mendel (Austria), the FITZ Institute of Cytology and Genetics, the Novosibirsk State University (Russia), the Wageningen University (the Netherlands) and the Institute of Molecular and cellular plant biology, Polytechnic University of Valencia (Spain) showed a key role in the formation of cambium (stem cell niches in the stalk of plants) protein-regulators of the response to auxin. The researchers also developed on the basis of the spatial coordination of gene activity in stem tissues. Was not previously known, are some of the way the stability of cambium through the plant hormone auxin and through the protein-regulator of WOX4, these areas were considered parallel. In their work the authors showed that between them there is a direct relationship.
“Because we were able to distinguish between different types of cells in Kambia, our work is an important step in the regulation of the functioning of this tissue. cell niche of the cambium, which provides the existence of the woods, makes up the significant part of the biomass of our planet, “commented the results of its head. Thomas Rowed.
Amazing the cambium and the king of the phytohormones auxin
From the cambium – the stem cells of the stem plants. The originality of the cambium in that it is at the same time as “born” two types of vascular tissues: xylem or wood, the pith of the trunk and phloem (bark) to the outside.
The xylem provides the upward flow of water and dissolved nutrients, and phloem – the downward movement of sugars and starches, necessary for the growth and development of plant cells. Formed vascular tissue consists of dead cells, constantly incrementing the volume by dividing stem cells of the cambium. It is important that the xylem and phloem are formed throughout the life of the plant, and not only in the embryonic period. If “dies” is cambium dies and the trunk of the tree.
Studies were conducted on rethoville tal (Arabidopsis thaliana), it has no wood as, the plant has got the advantage of the small size, short life cycle, well-studied genome. It is on this plant earlier, scientists have found that the auxin is a kind of king of plant hormones. It regulates many processes, including the ability of plants to turn to the sun, respond to gravity, and also controls the development of the organs of plants – seeds, roots, leaves and stems.
Genetic engineering experiments helped to establish the relationship between proteins that control the development of cambium, and AUX-in
Communications regulation division of cambium with the plant hormone auxin has been established for quite some time, but at the level of the control gene activity. During the experiments, the scientists – participants of the international collaboration from Germany, Belgium, Holland and Spain had a difficult work to create transgenic plants, which were visualized basic proteins-regulators (WOX4, ARF and others) that control the formation and further differentiation of cambium – formation from it protoplena and protocolary. Proteins could be observed in the studied tissues under the confocal microscope: fluorescently. Likewise, the authors looked at the distribution of auxin – it used a sensor which is sensitive to the concentration of this hormone, and its presence in tissues could also be judged by the glow under a microscope.
Transgenic plants are those that have been modified DNA using genetic engineering methods. The purpose of these modifications is to introduce uncharacteristic for plant genetic design, which can be useful for the purpose of the study. For example, such modification can be a specific protein “Shine” when you study under a fluorescence microscope.
Using transgenic plants, scientists were able to establish the activity of protein-regulators of the response to auxin in the cage of the cambium, of which later formed xylem (wood). Visualization of regulatory proteins, we have established that in the same cells synthesized and WOX4 protein, and one of the factors response to auxin, namely, ARF5. Other proteins-regulators of the response to the auxin – ARF3 and ARF4 are also active in Kambia, but not specifically because they work and in other tissues of the stem.
To prove that active in the cells of the cambium proteins WOX4, ARF5 and sensor response to auxin “playing in the same team”, the researchers conducted a thorough study of the activity of regulatory proteins in mutant plants. Each mutant plant is one of the most studied genes are corrupted, and hence protein encoded by this gene. Mutants of key regulators of cambium development had significant differences in the thickness of a layer of cambium. The mutant genes of arf5 and wox4 are the opposite patterns of arf5 mutant a layer of stem cells in the stem.
Scientists represent genes and fusion proteins with them same letters, but different font. Genes in italic and small letters, and are in plain text and capital letters. In the case of mutant genes are indicated in italics and lowercase letters.
Interestingly, a higher level of WOX4 protein (compared to a normal plant) was recorded in the mutant gene arf5. This suggests that when ARF5 protein is not synthesized, it does not affect the expression (reading process of genetic information and its implementation) WOX4 gene and, as a consequence, gene expression increases. Taken together, these facts are allowed to the ARF5.
The contribution of Novosibirsk bioinformatics
ARF5 and WOX4 or the first directly affects the second? Novosibirsk scientists have shown that the effect of ARF5 on the regulation of WOX4 protein synthesis may be direct, predicting, two, the website of the transcription factor ARF5 in the area of the WOX4 gene. In vitro binding ARF5 with one of the sites was confirmed.
The website “landing” – a section of non-coding DNA sequences, joined by a transcription factor (protein regulator), and then starts the process of genetic information and protein synthesis. Sites “landing” may be a few, and the probability of binding of the transcription factor.
“During genetic engineering experiments, our colleagues came to the conclusion that a transcription factor (TF) of response to the auxin – ARF5 affects the activity of another TF named WOX4. must “sit” on the DNA in the central part of the gene, WOX4 We were able to detect by using bioinformatics methods, analyzing data on how to “look” known sites “landing” for ARF5 in other genes In our case, the website “landing” was a sequence of eight nucleotides, and we localized the two versions in close proximity to the genome of WOX4, “said the postgraduate student, FITZ” Institute of Cytology and Genetics “and the University of Wageningen (Holland), the engineer of the laboratory of computer transcriptomic and evolution ary bioinformatics at Novosibirsk state University. Darya Novikova.
An international group of authors clarified the role of auxin in plant growth in width, in particular to increase timber. It was found that the activity of stem cells of the stem three factors governed the response to the auxin – ARF3, ARF4 and ARF5. Their distribution in the plant tissues, as well as other regulators of cambium development.