AOBPreview originally published online on February 12, 2009
Annals of Botany 2009 103(6):901-911; doi:10.1093/aob/mcp021
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Putting the P in Ptilotus: a phosphorus-accumulating herb native to Australia
1 School of Plant Biology, The University of Western Australia M081, 35 Stirling Hwy, Crawley, WA, 6009, Australia
2 Future Farm Industries Cooperative Research Centre, The University of Western Australia M081, 35 Stirling Hwy, Crawley, WA, 6009, Australia
3 Faculty of Organic Agricultural Sciences, University of Kassel, Kassel, Germany
4 Centre for Land Rehabilitation, School of Earth and Environment, The University of Western Australia MO87, 35 Stirling Hwy, Crawley, WA, 6009, Australia
* For correspondence. E-mail megan.ryan{at}uwa.edu.au
Received: 8 August 2008 Returned for revision: 8 October 2008 Accepted: 5 January 2009 Published electronically: 12 February 2009
Background and Aims: Ptilotus polystachyus (green mulla mulla; ptilotus) is a short-lived perennial herb that occurs widely in Australia in arid and semi-arid regions with nutrient poor soils. As this species shows potential for domestication, its response to addition of phosphorus (P) and nitrogen (N) was compared to a variety of the domesticated exotic perennial pasture herb Cichorium intybus (chicory), ‘Puna’.
Methods: Pots were filled with 3 kg of an extremely nutrient-deficient sterilized field soil that contained 3 mg kg–1 mineral N and 2 mg kg–1 bicarbonate-extractable P. The growth and P and N accumulation of ptilotus and chicory in response to seven rates of readily available phosphorus (0–300 mg P pot–1) and nitrogen (N) (0–270 mg N pot–1) was examined.
Key Results: Ptilotus grew extremely well under low P conditions: shoot dry weights were 23, 6 and 1·7 times greater than for chicory at the three lowest levels of P addition, 0, 15 and 30 mg P pot–1, respectively. Ptilotus could not downregulate P uptake. Concentrations of P in shoots approached 4 % of dry weight and cryo-scanning electron microscopy and X-ray microanalysis showed 35–196 mM of P in cell vacuoles in a range of tissues from young leaves. Ptilotus had a remarkable tolerance of high P concentrations in shoots. While chicory exhibited symptoms of P toxicity at the highest rate of P addition (300 mg P pot–1), no symptoms were present for ptilotus. The two species responded in a similar manner to addition of N.
Conclusions: In comparison to chicory, ptilotus demonstrated an impressive ability to grow well under conditions of low and high P availability. Further study of the mechanisms of P uptake and tolerance in ptilotus is warranted.
Key words: Phosphorus, nitrogen, hyperaccumulation, X-ray microanalysis, cell vacuole, Australian native plant, toxicity, domestication, phytoremediation, Ptilotus polystachyus, Cichorium intybus
CiteULike 
Connotea 
Del.icio.us What's this?
Related articles in Ann Bot:
- ContentSnapshots
Ann Bot 2009 103: i.[Extract] [Full Text]