Seminars

Plant growth and biomass production is the result of a complex interplay between intrinsic genetic factors and environmental conditions. The description and functional characterization of growth regulatory networks require an integrative, systems biology inspired approach involving genetics, phenotyping, ‘omics’-technologies and mathematical modeling. As model systems to understand growth we have chosen to work on leaf growth both in Arabidopsis and corn. Many genes, denominated Intrinsic Yield Genes or IYG, that promote leaf growth have been described and a detailed molecular and phenotypic analysis, using robotized imaging platforms, allowed for the identification of five different mechanisms that contribute to final leaf size. These mechanisms include i) the number of cells recruited to become part of the leaf initial; ii) cell cycle duration; iii) the developmentally controlled transition from cell proliferation to cell expansion; iv) the extent of cell expansion; and v) the activity of meristemoids. At least the latter three mechanisms are influenced by environmental cues.  The majority of the IYG’s have a role in the transition between cell proliferation and cell expansion (third mechanism) and form part of a chromatin remodeling complex that regulates the expression of genes involved in growth (Vercruyssen et al., 2014 The Plant Cell). The growth promoting chromatin remodeling complex is counteracted by a GA-DELLA mediated module that controls cell cycle exit (Dubois et al., 2013 Plant Phys). Although different in the details, there is a remarkable conservation of growth regulatory mechanisms between Arabidopsis and corn. Examples of how a thorough understanding of growth regulatory networks can be used to enhance leaf growth and biomass production in corn will be shown (Vanhaeren et al., 2014, eLife).