1. Evolution of cold adaptations in the temperate Pooideae grasses
Flowering plants likely originated from tropical habitats and subsequently radiated into cooler and more seasonal areas due to climatic cooling and species migrations. To adapt to temperate climates, plants have evolved suites of traits and mechanisms that ensure survival and reproductive success during the winter freeze. Specifically, cold acclimation (increased freezing tolerance during exposure to low nonfreezing temperatures), a response to vernalization (becoming competent to flower after a prolonged cold exposure), and seasonal avoidance coupled with growth suppression and photoperiod insensitivity, are among the best-documented strategies that plants have evolved to survive during cool, short day winters of the temperate zones (Zhong et al. in prep).
2. Development and evolution of fused corolla tube (sympetaly) in asterids of the core eudicots
The emergence of phenotypic novelties is central to organismal diversification. In plants, the formation of tubular flower (i.e. fused corollas) is important for mutual interactions of plants and their pollinators, and hence speciation. Here, we find that orthologs of genes known to establish organ boundaries in free-petaled species have evolved a novel petal fusion function in species with fused petals (Zhong and Preston 2015). Specifically, silencing of organ boundary gene orthologs in petunia results in the loss of organ boundaries in some floral organs (e.g. sepals), but the establishment of organ boundaries in petals. Taken together, these data suggest that fused petals evolved through the changes in the organ boundary patterning pathways (Zhong et al. 2016).
3. Evolution of corolla symmetry in the plant order Lamiales
Flowers exhibit remarkable variation in form, affecting how pollinating insects recognize them, but the evolution of that form is not well understood. The mints and their relatives are a good group in which to study the evolution of floral shape, because there have been many changes from radial symmetry to bilateral symmetry and back. This project will test the hypothesis that (a) a major shift from radial symmetry to bilateral symmetry within the mint relatives correlates with extra copies of floral symmetry patterning genes, and changes in gene expression (Zhong and Kellogg 2015a,b); (b) a return to radial symmetry occurred by diversification of the same genes (Zhong et al. in revision).
Flowering plants likely originated from tropical habitats and subsequently radiated into cooler and more seasonal areas due to climatic cooling and species migrations. To adapt to temperate climates, plants have evolved suites of traits and mechanisms that ensure survival and reproductive success during the winter freeze. Specifically, cold acclimation (increased freezing tolerance during exposure to low nonfreezing temperatures), a response to vernalization (becoming competent to flower after a prolonged cold exposure), and seasonal avoidance coupled with growth suppression and photoperiod insensitivity, are among the best-documented strategies that plants have evolved to survive during cool, short day winters of the temperate zones (Zhong et al. in prep).
2. Development and evolution of fused corolla tube (sympetaly) in asterids of the core eudicots
The emergence of phenotypic novelties is central to organismal diversification. In plants, the formation of tubular flower (i.e. fused corollas) is important for mutual interactions of plants and their pollinators, and hence speciation. Here, we find that orthologs of genes known to establish organ boundaries in free-petaled species have evolved a novel petal fusion function in species with fused petals (Zhong and Preston 2015). Specifically, silencing of organ boundary gene orthologs in petunia results in the loss of organ boundaries in some floral organs (e.g. sepals), but the establishment of organ boundaries in petals. Taken together, these data suggest that fused petals evolved through the changes in the organ boundary patterning pathways (Zhong et al. 2016).
3. Evolution of corolla symmetry in the plant order Lamiales
Flowers exhibit remarkable variation in form, affecting how pollinating insects recognize them, but the evolution of that form is not well understood. The mints and their relatives are a good group in which to study the evolution of floral shape, because there have been many changes from radial symmetry to bilateral symmetry and back. This project will test the hypothesis that (a) a major shift from radial symmetry to bilateral symmetry within the mint relatives correlates with extra copies of floral symmetry patterning genes, and changes in gene expression (Zhong and Kellogg 2015a,b); (b) a return to radial symmetry occurred by diversification of the same genes (Zhong et al. in revision).