JXB Advance Access originally published online on May 23, 2005
Journal of Experimental Botany 2005 56(417):1943-1950; doi:10.1093/jxb/eri189
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
RESEARCH PAPER |
Is root growth under phosphorus deficiency affected by source or sink limitations?
International Rice Research Institute, Crop, Soil, and Water Sciences Division, Los Banos, Laguna, The Philippines
* To whom correspondence should be addressed. Fax: +63 2 580 5699. E-mail: m.wissuwa{at}cgiar.org
Reduced net photosynthesis (Pn) and decreasing shoot and root biomass are typical effects of phosphorus deficiency in plants. Lower biomass accumulation could be the result of reduced Pn (source limitation), but may also be due to direct negative effects of low P availability on growth (sink limitation). Because of the principal importance of root growth for P uptake, this study specifically examined the question whether source or sink limitations were responsible for reduced root growth rates under P deficiency. Rice plants were grown in nutrient solutions with four levels of P supply and at two light treatments and the effect of Pxlight treatments on growth and carbohydrate distribution was observed. Plants had up to 70% higher Pn when grown with natural (high) light compared with low light. Higher Pn, however, did not lead to additional growth under P deficiency, suggesting that assimilate supply from source leaves to roots was not a limiting factor under P deficiency. This was supported by observations that root starch concentrations increased in P-deficient roots. The comparison of two genotypes with different tolerance to P deficiency showed that the more tolerant one preferentially distributed P to roots where the additional P stimulated root growth and, ultimately, P uptake. The results therefore suggest that source limitation is of little importance under P deficiency. Even at highly sub-optimal tissue P concentrations of below 0.7 mg P g–1 dry weight, plants were able to produce enough assimilates to sustain growth rates that were directly limited by low P availability.
Key words: Light intensity, phosphorus efficiency, phosphorus uptake, photosynthesis, Pup1 locus, QTL, rice
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  N. C. Collins, F. Tardieu, and R. Tuberosa Quantitative Trait Loci and Crop Performance under Abiotic Stress: Where Do We Stand? Plant Physiology, June 1, 2008; 147(2): 469 - 486. [Full Text] [PDF]
|
|
|
|
 |
|
 J. P. Hammond and P. J. White Sucrose transport in the phloem: integrating root responses to phosphorus starvation J. Exp. Bot., January 1, 2008; 59(1): 93 - 109. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Bucciarelli, J. Hanan, D. Palmquist, and C. P. Vance A Standardized Method for Analysis of Medicago truncatula Phenotypic Development Plant Physiology, September 1, 2006; 142(1): 207 - 219. [Abstract] [Full Text] [PDF]
|
|