Comparison of phytohormone levels and transcript profiles during seasonal dormancy transitions in underground adventitious buds of leafy spurge

Abstract

Leafy spurge (Euphorbia esula L.) is an herbaceous perennial weed that maintains its perennial growth habit through generation of underground adventitious buds (UABs) on the crown and lateral roots. These UABs undergo seasonal phases of dormancy under natural conditions, namely para-, endo-, and ecodormancy in summer, fall, and winter, respectively. These dormancy phases can also be induced in growth chambers by manipulating photoperiod and temperature. In this study, UABs induced into the three phases of dormancy under controlled conditions were used to compare changes in phytohormone and transcriptome profiles. Results indicated that relatively high levels of ABA, the ABA metabolite PA, and IAA were found in paradormant buds. When UABs transitioned from para- to endodormancy, ABA and PA levels decreased, whereas IAA levels were maintained. Additionally, transcript profiles associated with regulation of soluble sugars and ethylene activities were also increased during para- to endodormancy transition, which may play some role in maintaining endodormancy status. When crown buds transitioned from endo- to ecodormancy, the ABA metabolites PA and DPA decreased significantly along with the down-regulation of ABA biosynthesis genes, ABA2 and NCED3. IAA levels were also significantly lower in ecodormant buds than that of endodormant buds. We hypothesize that extended cold treatment may trigger physiological stress in endodormant buds, and that these stress-associated signals induced the endo- to ecodormancy transition and growth competence. The up-regulation of NAD/NADH phosphorylation and dephosphorylation pathway, and MAF3-like and GRFs genes, may be considered as markers of growth competency.

Vernalization shapes shoot architecture and ensures the maintenance of dormant buds in the perennial Arabis alpina

“…NINE‐CIS‐EPOXYCAROTENOID DIOXYGENASE 3 ) shown to be associated with bud dormancy in several species (Fig. i; Destefano‐Beltrán et al , ; Zheng et al , ; Chao et al , ; Singh et al , ). We also detected the dehydrin coding genes EARLY RESPONSIVE TO DEHYDRATION 10 and 14 and RESPONSIVE TO ABA 18 , which are induced by ABA and suggested to prevent water dehydration during tree winter dormancy (Fig.…”

Modulation of Dormancy and Growth Responses in Reproductive Buds of Temperate Trees

“…Even though diverse anatomical and physiological particularities are found, differentiated vegetative and reproductive meristems cease growth in a well defined stage and form a bud surrounded by protective scales in a similar fashion in different tree species. However, in spite of growth cessation and dormancy, overwintering buds do not remain in a completely inactive state, as verified by extensive transcriptomic and hormonal changes observed during bud development ( Howe et al, 2015 ; Chao et al, 2017 ). In fact, three major processes including dormancy, cold acclimation , and flowering converge spatially and temporally in a reproductive bud, where they play an active and relevant role in bud dynamics and determine plant survival and growth resumption under favorable conditions.…”

Bud Dormancy in Perennial Fruit Tree Species: A Pivotal Role for Oxidative Cues

“…In fruit trees, increases in bud ABA content have been reported at the beginning of endodormancy in the fall ( Götz et al, 2014 ; Wang et al, 2016 ; Tuan et al, 2017 ; Li et al, 2018 ) followed by a rapid drop in response to cold ( Leida et al, 2012 ) or dormancy-breaking agents ( Seif El-Yazal et al, 2014 ; Zheng et al, 2015 ), accompanied by changes in the expression of genes related to ABA biosynthesis and degradation. Several studies showed that the expression of 9- cis -epoxycarotenoid dioxygenases ( NCED ), involved in ABA synthesis, is activated during dormancy induction and maintenance ( Fennell et al, 2015 ; Wang et al, 2016 ; Chao et al, 2017 ; Li et al, 2018 ). In addition, after chilling requirements are satisfied, ABA levels decrease under the control of ABA 8′-hydroxylase (encoded by CYP707A ), which is up-regulated during dormancy release ( Zhang et al, 2015 ; Wang et al, 2016 ; Tuan et al, 2017 ; Li et al, 2018 ).…”