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Doctoral thesis2020Open access

Molecular Regulation of Bud Phenology and Vegetative Phase Change in Populus Trees

Sane, Shashank

Abstract

Trees are sessile organisms that have evolved to survive and thrive in changing growth conditions. As a survival strategy they undergo massive morphological changes that can be quantified. Post germination, during the transition from juvenility to maturity, many plants undergo well defined phase changes, for instance in vegetative morphology and in the capacity of the plant to produce reproductive organs. These phases reflect underlying changes in gene regulation within the plants. Along with aging, trees being perennials have to survive across several years being exposed to seasonal cycles. Extreme winter conditions make it particularly difficult for trees to survive due to cold induced damages and drought. Trees sense the coming of the winter and cease the growth of their meristematic tissues and undergo bud formation. This too is under the control of an underlying genetic machinery. Earlier studies on the annual weed Arabidopsis thaliana has already uncovered the co-ordination between changing environmental conditions and the changes in the cellular machinery it triggers. In this thesis, I have used this already available knowledge and studied the effects of the aging related miR156 and miR172 genes in regulating phase change and apical bud phenology in the model tree Populus tremula x tremuloides. In addition to that I have also studied the function of the GIGANTEA gene in the same photoperiodically regulated control of growth cessation and bud set.

Keywords

juvenile to reproductive phase shift, growth cessation, bud set, bud burst, photoperiod, aging, circadian clock, miR156, miR172, GIGANTEA

Published in

Acta Universitatis Agriculturae Sueciae
2020, number: 2020:3
ISBN: 978-91-7760-524-9, eISBN: 978-91-7760-525-6
Publisher: Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences