| 1. |
- Canales, Javier, et al.
(författare)
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Gene expression profiling in the stem of young maritime pine trees : detection of ammonium stress-responsive genes in the apex
- 2011
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Ingår i: Trees. - : Springer Science and Business Media LLC. - 0931-1890 .- 1432-2285. ; 26:2, s. 609-619
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Tidskriftsartikel (refereegranskat)abstract
- The shoots of young conifer trees represent an interesting model to study the development and growth of conifers from meristematic cells in the shoot apex to differentiated tissues at the shoot base. In this work, microarray analysis was used to monitor contrasting patterns of gene expression between the apex and the base ofmaritime pine shoots. A group of differentially expressed genes were selected and validated by examining their relative expression levels in different sections along thestem, from the top to the bottom. After validation of the microarray data, additional geneexpression analyses were also performed in the shoots of young maritime pine treesexposed to different levels of ammonium nutrition. Our results show that the apex ofmaritime pine trees is extremely sensitive to conditions of ammonium excess or deficiency, as revealed by the observed changes in the expression of stress-responsivegenes. This new knowledge may be used to precocious detection of early symptoms of nitrogen nutritional stresses, thereby increasing survival and growth rates of young treesin managed forests.
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| 2. |
- Pacheco-Villalobos, David, et al.
(författare)
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The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium
- 2016
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Ingår i: The Plant Cell. - : American Society of Plant Biologists. - 1040-4651 .- 1532-298X. ; 28:5, s. 1009-1024
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Tidskriftsartikel (refereegranskat)abstract
- The long-standing Acid Growth Theory of plant cell elongation posits that auxin promotes cell elongation by stimulating cell wall acidification and thus expansin action. To date, the paucity of pertinent genetic materials has precluded thorough analysis of the importance of this concept in roots. The recent isolation of mutants of the model grass species Brachypodium distachyon with dramatically enhanced root cell elongation due to increased cellular auxin levels has allowed us to address this question. We found that the primary transcriptomic effect associated with elevated steady state auxin concentration in elongating root cells is upregulation of cell wall remodeling factors, notably expansins, while plant hormone signaling pathways maintain remarkable homeostasis. These changes are specifically accompanied by reduced cell wall arabinogalactan complexity but not by increased proton excretion. On the contrary, we observed a tendency for decreased rather than increased proton extrusion from root elongation zones with higher cellular auxin levels. Moreover, similar to Brachypodium, root cell elongation is, in general, robustly buffered against external pH fluctuation in Arabidopsis thaliana. However, forced acidification through artificial proton pump activation inhibits root cell elongation. Thus, the interplay between auxin, proton pump activation, and expansin action may be more flexible in roots than in shoots.
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