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Title: Whole plant phenotypic variability in nitrogen and phosphorus response of Brachypodium distachyon

Author
item POIRE, RICHARD - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item CHOHOIS, V - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item SIRAULT, XAVIER - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item Vogel, John
item WATT, MICHELLE - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item FURBANK, ROBERT - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Journal of Integrative Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2014
Publication Date: 3/25/2014
Citation: Poire, R.R., Chohois, V., Sirault, X.R., Vogel, J.P., Watt, M., Furbank, R.T. 2014. Whole plant phenotypic variability in nitrogen and phosphorus response of Brachypodium distachyon. Journal of Integrative Plant Biology. DOI: 10.1111/jipb.12198.

Interpretive Summary: Nitrogen and phosphorous are two nutrients necessary for plant growth. The efficiency with which plants utilize these nutrients is of considerable importance to farmers because nitrogen and phosphorous are the most important components of added fertilizers. The model grass Brachypodium distachyon is an experimental tool that allows researchers to rapidly test hypothesis relevant to grains and grasses used as biomass crops. We examined the response of several different accessions of B. distachyon to various concentrations of nitrogen and phosphorous to develop dose response curves. Phenotypes measure include: leaf area and biomass, root length and biomass, tissue phosphorus and nitrogen content, and photosynthetic parameters. This work provides a baseline and starting point for future studies geared toward determining the genetic basis of nutrient use efficiency in the grasses.

Technical Abstract: This work evaluates the phenotypic response of the model grass (Brachypodium distachyon) to nitrogen and phosphorus nutrition. Reference line Bd21-3 was grown in sand under controlled conditions using 11 phosphorus and 11 nitrogen application rates. We established a dose-response curve for both nitrogen and phosphorus nutrition by characterising plant growth and development above and below ground using a range of destructive and non-destructive techniques. Leaf area and biomass, root length and biomass, and tissue phosphorus and nitrogen contents increased with nutrient concentration. Shoot biomass at harvest varied from 54 mg to 920 mg over the nitrogen range supplied and from 34 mg to 650 mg over the range of phosphorus supplied. Shoot biovolume, estimated from digital imaging, correlated with destructive harvest (R²>0.92) regardless of nutrient treatment and was used to calculate relative growth rates. Leaf photochemical efficiency did not respond to low nitrogen but was strongly reduced by low phosphorus. Root and shoot biomass responded similarly to both nutrients, such that shoot to root ratios did not change with treatments. Higher nutrient supply promoted nodal root axis growth whereas primary seminal root growth did not respond. The same phenotyping approach was applied to a set of four accessions to investigate the ability of these methods to detect genetic variation in nutrient response of Brachypodium. This study illustrates the great potential of applying phenomics techniques to monitor the genetic variation of a model plant to better understand crop physiology.