Figure 1.

A conceptual model of transcription factor-mediated control on biomass recalcitrance-related properties such as xylem development, secondary cell wall formation, lignin and other cell wall components. The model is based on current knowledge from bioenergy crop types such as Populus, Pinus, Eucalyptus and Panicum spp. as well as the plant model Arabidopsis thaliana presented in several recent publications (Hussey et al., 2013; Ko et al., 2014; Shen et al., 2012; Wang et al., 2011; Zhong et al., 2010, 2011). Transcription factors (activators or repressors) reported to be control lignin biosynthesis pathway are indicted in red circles. Additional unidentified transcription factors relating to each of these properties are indicated by a ‘?’ symbol embedded within circles of respective colours. The bottom panel of the figure reflects the phenotypic properties of lignocellulosic biomass such as stem development, secondary wall formation under the influence of reported transcription factors.