Courses
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Plant Anatomy
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Our research
in plant anatomy and development focuses on two fundamental questions of plant
developmental biology.
1. What are the basic mechanisms of histogenesis?
Histogenesis encompasses the
developmental specification of vascular, dermal and ground tissue systems
(radial pattern formation), patterns of cell proliferation and enlargement
within each tissue system, and the differentiation of specialized cell types.
We are particularly interested in the formation of primary vascular pattern
during shoot and leaf development. While dermal and ground tissues are derived
from precursors within the shoot apical meristem, vascular tissue pattern is
formed de novo from ground tissue precursors. We have combined
anatomical approaches with the use of molecular markers of procambium identity
and cell cycling to study the developmental relationship between vascular
pattern formation and distinctive spatial and temporal patterns of cell
division in Arabidopsis.
2. How are histogenic mechanisms altered during the
evolution of structural adaptions?
One of the best-known
examples of such alteration is the concomitant appearance of Kranz anatomy and
photosynthetic biochemistry during the evolution of C4 species from their C3
ancestors. The evolution of Kranz anatomy requires alteration of vein spacing,
modifications of patterns of cell division and cell enlargement within
photosynthetic ground tissues, and specialization of mesophyll (PCA, primary
carbon assimilation) and bundle sheath (PCR, photosynthetic carbon reduction)
cells. This suite of anatomical characteristics has evolved repeatedly during
the diversification of flowering plants. We are currently studying the
convergence of structure, physiology and biochemistry in several families of
dicotyledons. We are particularly interested in the evolutionary modification
of vein pattern and spacing in the genus Flaveria (Asteraceae).
Department of Botany
University of Toronto
contact: Dr. Nancy G. Dengler