South-western Australia was a part of Gondwanaland, and some of the most ancient parts of the Earth’ crust can be found here. Other parts of the landscape originated more recently from calcareous marine deposits . Therefore, the soils of Western Australia are amongst the most heavily leached and nutrient-impoverished in the world. Moreover, the soils on lateritic profiles tightly bind phosphate, so that, phosphorus (P) is also poorly available to plants that are not adapted to these conditions. The old, climatically buffered ancient landscape (OCBIL) of south-western Australia is also one of the world’s hotspots of higher plant species diversity . Therefore, this environment offers a unique opportunity to study plant adaptations to nutrient-poor conditions [3, 4].
A relatively large proportion of species from the P-poor environments in Western Australia cannot produce an association with mycorrhizal fungi, but, instead, produce cluster roots or dauciform roots [5, 6]. These specialised roots are an adaptation both in structure and in functioning; they release large amounts of exudates, in particular carboxylates . Cluster-root-bearing Proteaceae in Western Australia occur on the most P-impoverished soils, whereas the mycorrhizal Myrtaceae tend to inhabit the less P-impoverished soils in this region .
The functioning of cluster roots in Proteaceae and Fabaceae has received considerable attention. Dauciform roots in Cyperaceae have been explored less [9, 10], but they appear to function in a similar manner . The growth of specialised cluster or dauciform roots in species of the Cyperaceae, Fabaceae and Proteaceae is stimulated when plants are grown at a very low P supply, and suppressed when leaf P concentrations increase [5, 7]. These specialised roots are all short-lived structures, and they release large amounts of carboxylates during an ‘exudative burst’ at rates that are considerably faster than reported for non-specialised roots of a wide range of species. The carboxylate release plays a pivotal role in mobilisation of P from P-sorbing soil .
Because the world P reserves are being depleted whilst vast amounts of P are stored in fertilised soils, there is a growing need for crops with a high efficiency of P acquisition. Some Australian native species have traits that would be highly desirable for future crops. The possibilities of introducing P-acquisition efficient species in new cropping and pasture systems are currently being explored [12, 13]. In addition, possible strategies to introduce traits associated with a high P-use efficiency into future crop species are considered promising.
High P-use efficiency in Proteaceae includes a highly efficient and proficient mobilisation of P from senescing leaves . In addition, many species operate at extremely low leaf P concentrations exhibiting rates of photosynthesis similar to crop plant; expressed per unit leaf P, their rates of photosynthesis are extraordinarily high [4, 14]. I will explore what traits these species have that allow them to exhibit high rates of photosynthesis at very low leaf P concentrations.
I was born on a farm in the Netherlands in 1950 and completed my undergraduate degree in biology (1976), with a bachelor’s degree in biochemistry, followed by research projects in plant physiology and microbiology. I finished my PhD degree (1979) at the University of Groningen in the Netherlands, working on (cyanide-resistant) plant respiration and effects of flooding. My PhD supervisors were Dr Rinie Hofstra, and Professors Pieter Kuiper and Rienk Brouwer.
After completion of my PhD, I did postdoctoral work at the University of Western Australia, with Professor John Pate, Melbourne University, with Dr Michael Dalling, and the Research School of Biological Science at the Australian National University, with Professor Barry Osmond, working on various aspects of the metabolism and transport of carbon and nitrogen in wheat, white lupins, and a range of other species. After two years as a postdoctoral fellow back in Groningen, I was offered the chair in Ecophysiology at Utrecht University (in 1985).
While in Utrecht, I continued work on plant respiration and started a new program on the physiological basis of variation in plant growth rate and productivity. Twenty eight fascinating theses have come to fruition under my supervision during that great time.
My teaching activities in ecophysiology have led to the completion of a textbook, Plant Physiological Ecology, Springer, New York, just before I moved to UWA. The textbook was translated in both Chinese and Persian. The second, completely revised edition of this book appeared in 2008.
For three years, after my move to UWA, I maintained a fractional appointment at Utrecht University, to promote exchange of students between Utrecht University and UWA and to build collaborative research programs.
PS* This seminar is free and open to the public & no RSVP required.
Hans Lambers, Head of School /Winthrop Professor, School of Plant Biology, The University of Western Australia
Blakers Lecture Room, Ground Floor, Mathematics Building, The University of Western Australia
: 6488 7565
Wed, 31 Oct 2012 16:00
Wed, 31 Oct 2012 17:00
Askale Abebe <[email protected]>
Fri, 12 Oct 2012 10:58
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