Biology subjects

Delory, B. M.

Publications and source records attributed to Delory, B. M..

3 recordsLinked to original sources

bioRxiv2020

Barley shoot biomass responds strongly to N:P stoichiometry and intraspecific competition, whereas roots only alter their foraging

Background and AimsPlants respond to various environmental stimuli, and root systems are highly responsive to the availability and distribution of nutrients in the soil. Root system responses to the limitation of either nitrogen (N) or phosphorus (P) are well documented, but how the early root system responds to (co-) limitation of one (N or P) or both (N and P) in a stoichiometric framework is not well known despite its relevance in agriculture. In addition, how plant-plant competition (here intra-specific) alters plant responses to N:P stoichiometry is understudied. Therefore, we aimed to investigate the effects of N:P stoichiometry and competition on root system responses and overall plant performance. MethodsPlants (Hordeum vulgare L.) were grown in rhizoboxes for 24 days in the presence or absence of competition (three vs. one plant per rhizobox), and fertilized with different combinations of N:P (low N+low P, low N+high P, high N+low P, and high N+high P). Key ResultsShoot biomass was highest when both N and P were provided in high amounts. In competition, shoot biomass decreased on average by 22%. Interestingly, N:P stoichiometry and competition had no clear effect on root biomass. However, we found distinct root responses in relation to biomass allocation across depths. Specific root length depended on the identity of limiting nutrient (N or P) and presence/absence of competition. Plants rooted deeper when N was the most limiting compared to shallower rooting when P was the most limiting nutrient. ConclusionsOverall, our study sheds light on the early plant responses to plant-plant competition and stoichiometric availability of two macronutrients most limiting plant performance. With low N and P availability during early growth, higher investments in root system development can significantly trade off with aboveground productivity, and strong intra-specific competition can further strengthen such effects.

plant biology↗

bioRxiv2019

Developmental plasticity of Brachypodium distachyon in response to P deficiency: modulation by inoculation with phosphate-solubilizing bacteria

BackgroundMineral P fertilisers must be used wisely in order to preserve rock phosphate, a limited and non-renewable resource. The use of bio-inoculants to improve soil nutrient availability and trigger an efficient plant response to nutrient deficiency is one potential strategy in the attempt to decrease P inputs in agriculture. MethodA gnotobiotic co-cultivation system was used to study the response of Brachypodium distachyon to contrasted P supplies (soluble and poorly soluble forms of P) and inoculation with P solubilizing bacteria. Brachypodiums responses to P conditions and inoculation with bacteria were studied in terms of developmental plasticity and P use efficiency. ResultsBrachypodium showed plasticity in its biomass allocation pattern in response to variable P conditions, specifically by prioritizing root development over shoot productivity under poorly soluble P conditions. Despite the ability of the bacteria to solubilize P, shoot productivity was depressed in plants inoculated with bacteria, although the root system development was maintained. The negative impact of bacteria on biomass production in Brachypodium might be attributed to inadequate C supply to bacteria, an increased competition for P between both organisms under P-limiting conditions, or an accumulation of toxic bacterial metabolites in our cultivation system. Both P and inoculation treatments impacted root system morphology. The modulation of Brachypodiums developmental response to P supplies by P solubilizing bacteria did not lead to improved P use efficiency. ConclusionOur results support the hypothesis that plastic responses of Brachypodium cultivated under P-limited conditions are modulated by P solubilizing bacteria. The considered experimental context impacts plant-bacteria interactions. Choosing experimental conditions as close as possible to real ones is important in the selection of P solubilizing bacteria. Both persistent homology and allometric analyses proved to be useful tools that should be considered when studying the impact of bio-inoculants on plant development in response to varying nutritional context.

plant biology↗

bioRxiv2019

Call for participation: Collaborative benchmarking of functional-structural root architecture models. The case of root water uptake.

Three-dimensional models of root growth, architecture and function are becoming important tools that aid the design of agricultural management schemes and the selection of beneficial root traits. However, while benchmarking is common in many disciplines that use numerical models such as natural and engineering sciences, functional-structural root architecture models have never been systematically compared. The following reasons might induce disagreement between the simulation results of different models: different representation of root growth, sink term of root water and solute uptake and representation of the rhizosphere. Presently, the extent of discrepancies is unknown, and a framework for quantitatively comparing functional-structural root architecture models is required. We propose, in a first step, to define benchmarking scenarios that test individual components of complex models: root architecture, water flow in soil and water flow in roots. While the latter two will focus mainly on comparing numerical aspects, the root architectural models have to be compared at a conceptual level as they generally differ in process representation. Therefore defining common inputs that allow recreating reference root systems in all models will be a key challenge. In a second step, benchmarking scenarios for the coupled problems are defined. We expect that the results of step 1 will enable us to better interpret differences found in step 2. This benchmarking will result in a better understanding of the different models and contribute towards improving them. Improved models will allow us to simulate various scenarios with greater confidence and avoid bugs, numerical errors or conceptual misunderstandings. This work will set a standard for future model development.

plant biology↗