The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium

0461670 - ÚEB 2017 RIV US eng J - Journal Article
Pacheco-Villalobos, D. - Diaz-Moreno, S.M. - van der Schuren, A. - Tamaki, T. - Kang, Y.H. - Gujas, B. - Novák, Ondřej - Jaspert, N. - Li, Z. - Wolf, S. - Oecking, C. - Ljung, K. - Bulone, V. - Hardtke, Ch. S.
The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium.
Plant Cell. Roč. 28, č. 5 (2016), s. 1009-1024. ISSN 1040-4651. E-ISSN 1532-298X
R&D Projects: GA MŠMT(CZ) LO1204
Institutional support: RVO:61389030
Keywords : MEMBRANE H+-ATPASE * PLANT PLASMA-MEMBRANE * ACID-GROWTH THEORY
Subject RIV: EB - Genetics ; Molecular Biology
Impact factor: 8.726, year: 2016

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.
Permanent Link: http://hdl.handle.net/11104/0261264