biological sciences HONOURs 2014 - The University of Sydney

48 PLANT AND ECOSYSTEM
FUNCTIon
Research Interests
My mission is to understand how plants function and interact
with the wider world. My research is organised into two basic
themes. The first is how plants are affected by and cope with
their environment. The scope of this research includes the
internal activities of plants - that is the chemical and physical
processes associated with life (photosynthesis, respiration, gas
exchange, nutrient uptake). The second major theme is the role
of plants in ecosystem processes (ecosystem cycles of carbon,
nitrogen, phosphorus and energy, and major interaction process
such as competition).
Honours projects
1. The metabolic footprint of plants. Planet Earth bears
the metabolic footprint of plants. This is because plants use
planet Earth as a substrate for chemical reactions and as
a resting place for waste products. In contrast to the wellknown
metabolic footprint of plants on the atmosphere, the
below-ground metabolic footprint of plants is poorly known.
We know that >10% of carbon fixed via photosynthesis may
be exuded from roots as a diverse soup of organic molecules.
This enormous flux of carbon belowground provides fuel for
soil microbes and is a major player in global CO 2
balance, yet it
Associate Professor
Charles Warren
Room 225A, Heydon-
Laurence Building A08
T: (02) 9351 2678
E: charles.warren@
sydney.edu.au
is still treated as a “black box”. The aim of this project is to go beyond the “black box” view by
characterising the molecules that exude from roots and their function.
2. Ecosystem cycles of nitrogen. Our understanding of ecosystem cycles of nitrogen and plant
nitrogen nutrition are changing very rapidly. For 100 years it was accepted that plants could take
up only nitrate and ammonium, 20 years ago it was shown that plants could also take up amino
acids, a couple of years ago it was shown plants could also take up oligopeptides. In recent
months my lab has made the next major breakthrough. In contrast to the consensus view that
the pool of non-peptide small organic nitrogen is dominated by protein amino acids, we found
that soil contains at least 100 nitrogen-containing compounds from 12 compound classes. The
exciting next steps are to discover what role these other organic compounds have in ecosystem
nitrogen cycles and plant nutrition.