EARLY BUD-BREAK1 (EBB1) defines a conserved mechanism for control of bud-break in woody perennials

Abstract

Bud-break is an environmentally and economically important trait in trees, shrubs and vines from temperate latitudes. Poor synchronization of bud-break timing with local climates can lead to frost injuries, susceptibility to pests and pathogens and poor crop yields in fruit trees and vines. The rapid climate changes outpace the adaptive capacities of plants to respond through natural selection. This is particularly true for trees which have long generation cycle and thus the adaptive changes are significantly delayed. Therefore, to devise appropriate breeding and conservation strategies, it is imperative to understand the molecular underpinnings that govern dormancy mechanisms. We have recently identified and characterized the poplar EARLY BUD-BREAK 1 (EBB1) gene. EBB1 is a positive regulator of bud-break and encodes a transcription factor from the AP2/ERF family. Here, using comparative and functional genomics approaches we show that EBB1 function in regulation of bud-break is likely conserved across wide range of woody perennial species with importance to forestry and agriculture.

Keywords: climate change; dormancy; phenology.

Figure 1.

Phylogeny and expression of EBB1 orthologs. (A) Orthologs of poplar EBB1 were identified through homology searches. Arabidopsis orthologs were also included. Phylogenetic tree was constructed using Mega 4.1. Numbers in the branches show percent bootstrap support out of 1,000 iterations. (B) Expression of Vitis ortholog. Expression values are based on microarray data. Abbreviations used for the names of the genes in different species are as follows: Md-Malus domestica; Pa=Picea abies; Pta=Populus tremula X alba; Vv=Vitis vinifera.

Figure 2.

Expression of EBB1 homologs in spruce (Picea abies). (A) Clustering was based on RNA-seq expression data and using the congenie.org's exHeatmap tool. The hierarchical clustering was performed using the Ward's method and Euclidean distances with default parameters. (B) Expression of the 3 EBB1 spruce orthologs in buds during bud-break. BB=bud -break (see Supplemental materials for details).