Activity-dormancy transition in the cambial meristem involves stage-specific modulation of auxin response in hybrid aspen

• Published in: Proceedings of the National Academy of Sciences - PNAS 2011-02, Vol.108 (8), p.3418-3423
• Main Authors: Baba, Kyoko, Karlberg, Anna, Schmidt, Julien, Schrader, Jarmo, Hvidsten, Torgeir R., Bako, Laszlo, Bhalerao, Rishikesh P., Sederoff, Ronald R.
• Format: Article
• Language: English
• Subjects: Auxins; Biological Sciences; Cambium - growth & development; Cell division; Dormancy; Forest Science; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation, Plant; Genes; Hormones; Hybridity; Indoleacetic Acids; Meristem - growth & development; Meristems; Plant growth; Plant growth regulators; Plant Growth Regulators - physiology; Plants; Proteins; Skogsvetenskap; Tissues; Trees; Trees - physiology
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1011506108

The molecular basis of short-day-induced growth cessation and dormancy in the meristems of perennial plants (e.g., forest trees growing in temperate and high-latitude regions) is poorly understood. Using global transcript profiling, we show distinct stagespecific alterations in auxin responsiveness of the transcriptome in the stem tissues during short-day-induced growth cessation and both the transition to and establishment of dormancy in the cambial meristem of hybrid aspen trees. This stage-specific modulation of auxin signaling appears to be controlled via distinct mechanisms. Whereas the induction of growth cessation in the cambium could involve induction of repressor auxin response factors (ARFs) and down-regulation of activator ARFs, dormancy is associated with perturbation of the activity of the SKP-Cullin-F-box TIR (SCF TIR ) complex, leading to potential stabilization of repressor auxin (AUX)/indole-3-acetic acid (IAA) proteins. Although the role of hormones, such as abscisic acid (ABA) and gibberellic acid (GA), in growth cessation and dormancy is well established, our data now implicate auxin in this process. Importantly, in contrast to most developmental processes in which regulation by auxin involves changes in cellular auxin contents, day-length-regulated induction of cambial growth cessation and dormancy involves changes in auxin responses rather than auxin content.