Photocontrol of Axillary Bud Outgrowth by MicroRNAs: Current State-of-the-Art and Novel Perspectives Gained From the Rosebush Model

Abstract

Shoot branching is highly dependent on environmental factors. While many species show some light dependence for branching, the rosebush shows a strict requirement for light to allow branching, making this species an excellent model to further understand how light impinges on branching. Here, in the first part, we provide a review of the current understanding of how light may modulate the complex regulatory network of endogenous factors like hormones (SL, IAA, CK, GA, and ABA), nutrients (sugar and nitrogen), and ROS to control branching. We review the regulatory contribution of microRNAs (miRNAs) to branching in different species, highlighting the action of such evolutionarily conserved factors. We underline some possible pathways by which light may modulate miRNA-dependent regulation of branching. In the second part, we exploit the strict light dependence of rosebush for branching to identify putative miRNAs that could contribute to the photocontrol of branching. For this, we first performed a profiling of the miRNAs expressed in early light-induced rosebush buds and next tested whether they were predicted to target recognized regulators of branching. Thus, we identified seven miRNAs (miR156, miR159, miR164, miR166, miR399, miR477, and miR8175) that could target nine genes (CKX1/6, EXPA3, MAX4, CYCD3;1, SUSY, 6PFK, APX1, and RBOHB1). Because these genes are affecting branching through different hormonal or metabolic pathways and because expression of some of these genes is photoregulated, our bioinformatic analysis suggests that miRNAs may trigger a rearrangement of the regulatory network to modulate branching in response to light environment.

Detection of Transcription Factors Related to Axillary Bud Development after Exposure to Cold Conditions in Hexaploid Chrysanthemum morifolium Using Arabidopsis Information

“…Thus, control of axillary bud formation and growth is important because axillary buds are needed or not needed depending on the use of the chrysanthemum. Numerous reports on genes or plant hormones involved in axillary bud formation and growth have been found in rice and Arabidopsis [1][2][3].…”

“…In Arabidopsis, a variety of TFs have been identified as being critical for axillary bud formation and regulation, and the signaling hierarchy of each TF has been identified [3]. It has also been discovered that miRNAs regulate TFs necessary for axillary bud development [2]. Among the TFs that have been shown to be important for axillary bud formation in Arabidopsis, it has been reported that axillary bud formation is suppressed by the lateral suppressor-like gene [4] in an antisense transgenic chrysanthemum [5].…”