Genome-wide de novo identification and expression profiling of the BURP-containing gene family in a hybrid poplar indicate their crucial roles in poplar developmental gradient, response to abiotic stresses and fungal pathogens

Abstract

Abstract BURP domain-containing proteins are a plant-specific protein family with diverse functions in plant development and response to stress. Overexpression of certain BURP genes were confirmed to improve crop yield or resistance to abiotic stress in multiple plant species. However, detailed expression profiling of BURP genes has never been reported for wood plant. In this study we report the characterization and organ-specific expression profiling of 27 PdPapBURP genes identified in the de novo genome of an important Chinese hybrid poplar cultivar ‘Shanxin yang’ (Populus davidiana × P. alba var. pyramidalis). Constitutive expression profile suggested that 11 BURP genes had important roles in poplar secondary growth, nine were important for root maintenance and seven were specifically active in the young developing tissues of poplar. Organ-specific expression profiling of PdPapBURP genes under each treatment among salt, alkali, desiccation stress, the infecting of five major soil-borne plant fungal pathogens and the inducing of three stress-related plant hormone demonstrated differential regulation pattern of each PdPapBURP gene. Regulation patterns of PdPapBURP gene expression showed highest diversity in poplar root during fungal infection. Comparative motif analysis with previously reported BURP proteins suggested particular importance of the motifs specific to the PG1-β phylogenic subclass for poplar development and short repeated peptide sequences were one of the important structural bases for stress-resistant/stress-responsive functions of BURP proteins. This study is a thorough discovery of BURP genes in hybrid poplar. Our results present important information for understanding the growth and stress-response mechanisms of woody plants involving the BURP genes and provide profound insights into improving woody plant growth and stress/pathogen resistance.