Diversity and cis-element architecture of the promoter regions of cellulose synthase genes in Eucalyptus

Abstract

Lignocellulosic biomass from fast-growing plantation trees is composed of carbohydrate-rich materials deposited into plant cell walls in a coordinated manner during wood formation. The diversity and evolution of the transcriptional networks regulating this process have not been studied extensively. We investigated patterns of species-level nucleotide diversity in the -2 -promoters of cellulose synthase (CesA) genes from different Eucalyptus tree species and assessed the possible roles of DNA sequence polymorphism in the gain or loss of ciselements harboured within the promoters. Promoter regions of three primary and three secondary cell wall-associated CesA genes were isolated from 13 Eucalyptus species and were analysed for nucleotide and cis-element diversity. Species-level nucleotide diversity (π) ranged from 0.014 to 0.068 and different CesA promoters exhibited distinct patterns of sequence conservation. A set of 22 putative cis-elements were mapped to the CesA promoters using in silico methods. Forty two percent of the mapped cis-element occurrences contained singleton polymorphisms which resulted in either the gain or loss of a cis-element in a particular Eucalyptus species. The promoters of Eucalyptus CesA genes contained regions that are highly conserved at the species (Eucalyptus) and genus (with Arabidopsis and Populus) level, suggesting the presence of regulatory modules imposing functional constraint on such regions. Nucleotide polymorphisms in the CesA promoters more frequently created new cis-element occurrences than disrupted existing cis-element occurrences, a process which may be important for the maintenance and evolution of cellulose gene regulation in plants.

Isolation and characterization of the 4-coumarate:coenzyme A ligase (4CL1) promoter from Eucalyptus camaldulensis

“…The control mechanisms of lignifications in Eucalyptus have been studied at the level of gene expression regulatory elements. For example, the SND2 promoter (Botha et al 2011) and the cellulose synthase (CesA) promoter (Creux et al , 2013 from Eucalyptus have been functionally characterized. In this study, the promoter region of the 4CL1 gene from E. camaldulensis was isolated and characterized by expression analysis of promoter-GUS fusion construct in transgenic tobacco plants.…”

Perfil transcricional da xilogênese em <i>Eucalyptus grandis</i>

“…Os outros fatores de transcrição que foram identificados e correlacionados aos genes de E. grandis, foram descritos em artigos que consideraram a rede de regulação da parede celular secundária de Arabidopsis (Kumar et al, 2016;Taylor-Teeples et al, 2015). Como por exemplo, o IRX11 pertencente à família dos IRX (irregular xylem), a qual foi relacionada na literatura à via de biossíntese das xilanas (Chiniquy et al, 2013;Shinya et al, 2016 (Ambavaram et al, 2011;Mckinley et al, 2016;Mendu et al, 2011), além serem funcionalmente conservados em diversas espécies vegetais, inclusive em Eucalyptus (Creux et al, 2013 (Brown et al, 2009), e esses três genes UXS, IRX10 e GATL apresentaram níveis de expressão alterados em híbridos de eucalipto com teores maiores de lignina (Shinya et al, 2016). Desta maneira, a presença e expressão diferencial desses genes corrobora a regulação gênica existente para a diferenciação dos elementos traqueais.…”