Elucidating the Roles of Lysine Acetylation in the Regulation of Plant Metabolism

Chemical modifications on proteins enable cells to regulate protein functions in response to environmental cues by altering protein localization, molecular interactions or enzymatic activities. The lysine side chains within proteins is subject to several chemical modifications, such as the reversible acetylation, which removes the positive charge of the lysine residue, and which occurs in different sub-cellular compartments. Lysine acetylation is regulated by the antagonistic action of lysine acetyltransferases and deacetylases. While the function of lysine acetylation on nuclear histone proteins has been extensively studied, the role of non-nuclear acetylation has only started to be uncovered. Here I will present our latest research on this protein modification and its modifiers in plants.

Polyploidy and Plant Diversification

Polyploidy, or whole-genome duplication (WGD), has long been recognized as an important
speciation mechanism in plants. However, WGD has biological effects that extend far beyond
the generation of new species. WGD is a key integrator across levels of biological organization,
with effects that range from the molecular and subcellular levels to those of the ecosystem and
Tree of Life. The immediate impact of WGD is duplication of all nuclear genetic material, but
over time, the component subgenomes become fractionated to yield a composite of duplicated
and unduplicated loci. This loss of duplicate genes can begin to occur surprisingly quickly, in
perhaps only a few generations. Through gene loss and shifts in gene expression, polyploid
individuals originating from a single polyploidization event may become genetically and
phenotypically unique, together forming a morphologically, physiologically, and/or ecologically
polymorphic population, in contrast to classical views of allopolyploids as genetically identical
and chromosomally fixed F1 hybrids. This array of genetic and phenotypic novelty may provide
new variants that can potentially drive evolution in new directions, with consequences for the
tempo of diversification at macroevolutionary scales. Case studies in Tragopogon (Compositae)
will illustrate patterns of duplicate gene loss and shifts in gene expression in synthetic and
natural allopolyploids of recent origin. On longer timescales, signatures of ancient WGDs in
Compositae and across angiosperms are often associated with accelerated rates of species
diversification, suggesting a causal role of WGD in the diversification of these clades. Although
statistical support for co-localized WGD events and diversification rate shifts is low across all
angiosperms, many individual WGDs appear to be associated with the origins of novel features
and increased diversification, suggesting that features that arise via microevolutionary
processes may translate into key innovations on macroevolutionary timescales.