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Changes in resource partitioning between and within organs support growth adjustment to neighbor proximity in Brassicaceae seedlings.

ABSTRACT: In shade-intolerant plants, the perception of proximate neighbors rapidly induces architectural changes resulting in elongated stems and reduced leaf size. Sensing and signaling steps triggering this modified growth program have been identified. However, the underlying changes in resource allocation that fuel stem growth remain poorly understood. Through ¹⁴CO₂ pulse labeling of Brassica rapa seedlings, we show that perception of the neighbor detection signal, low ratio of red to far-red light (R:FR), leads to increased carbon allocation from the major site of photosynthesis (cotyledons) to the elongating hypocotyl. While carbon fixation and metabolite levels remain similar in low R:FR, partitioning to all downstream carbon pools within the hypocotyl is increased. Genetic analyses using Arabidopsis thaliana mutants indicate that low-R:FR-induced hypocotyl elongation requires sucrose transport from the cotyledons and is regulated by a PIF7-dependent metabolic response. Moreover, our data suggest that starch metabolism in the hypocotyl has a growth-regulatory function. The results reveal a key mechanism by which metabolic adjustments can support rapid growth adaptation to a changing environment.

SUBMITTER: de Wit M

PROVIDER: S-EPMC6196536 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Changes in resource partitioning between and within organs support growth adjustment to neighbor proximity in Brassicaceae seedlings.

de Wit Mieke M George Gavin M GM Ince Yetkin Çaka YÇ Dankwa-Egli Barbara B Hersch Micha M Zeeman Samuel C SC Fankhauser Christian C

Proceedings of the National Academy of Sciences of the United States of America 20181001 42

In shade-intolerant plants, the perception of proximate neighbors rapidly induces architectural changes resulting in elongated stems and reduced leaf size. Sensing and signaling steps triggering this modified growth program have been identified. However, the underlying changes in resource allocation that fuel stem growth remain poorly understood. Through 14CO2 pulse labeling of Brassica rapa seedlings, we show that perception of the neighbor detection signal, low rat ...[more]

PMID: 30275313

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Project description:The communities of marine bacteria that assemble around living microphytoplankton are predictably dominated by three taxonomic groups, each of which specializes in the use or transport of different components of the available metabolite pool: Rhodobacterales transport small and polar metabolites, Flavobacteriia use carbohydrate-rich polymers, and Gammaproteobacteria use compounds from both classes. The consistent ecological pattern involving these three taxa is widespread throughout the surface ocean, yet whether it reflects the outcome competition or niche partitioning of the phytoplankton-derived compounds is not clear. Addressing this question requires better knowledge than currently exists of the metabolites that link microbial autotrophs and heterotrophs in the surface ocean. Here we used two untargeted biological screening strategies that leverage bacterial proficiency for scavenging dilute substrates from chemically complex mixtures to characterize metabolite uptake by heterotrophic bacteria. In the first, expression patterns of transporters and diagnostic catabolic genes were analyzed in model marine bacteria grown individually in co-culture with the diatom Thalassiosira pseudonana. In the second, the ability of bacteria to draw down exometabolites from the culture medium was detected by novel approaches in mass spectrometry (MS) and nuclear magnetic resonance (NMR) analysis. These methods identified diverse chemical currencies mediating carbon transfer including low molecular weight metabolites (nucleosides, amino acids, organic acids, monomeric sugars, peptides, and sulfonates) and components of polysaccharides (chrysolaminarin, chitin oligomers, and alginate-like oligosaccharides). Bacterial utilization of bioreactive metabolites in the absence of competition indicated low resource overlap among strains and a dominance of resource partitioning over resource competition among the bacterial groups that process a major fraction of marine net primary production. NMR assay is reported in the current study <a href='https://www.ebi.ac.uk/metabolights/MTBLS1544' rel='noopener noreferrer' target='_blank'>MTBLS1544</a>UPLC-MS assay is reported in <a href='https://www.ebi.ac.uk/metabolights/MTBLS1751' rel='noopener noreferrer' target='_blank'>MTBLS1751</a>

Project description:BackgroundThe link between biodiversity and ecosystem processes has firmly been established, but the mechanisms underpinning this relationship are poorly documented. Most studies have focused on terrestrial plant systems where resource use can be difficult to quantify as species rely on a limited number of common resources. Investigating resource use at the bulk level may not always be of sufficient resolution to detect subtle differences in resource use, as species-specific nutritional niches at the biochemical level may also moderate diversity effects on resource use.Methodology/principal findingsHere we use three co-occurring marine benthic echinoderms (Brissopsis lyrifera, Mesothuria intestinalis, Parastichopus tremulus) that feed on the same phytodetrital food source, to determine whether resource partitioning is the principal mechanism underpinning diversity effects on resource use. Specifically we investigate the use of phytodetrital pigments (chlorophylls and carotenoids) because many of these are essential for biological functions, including reproduction. Pigments were identified and quantified using reverse-phase high performance liquid Chromatography (HPLC) and data were analysed using a combination of extended linear regression with generalised least squares (GLS) estimation and standard multivariate techniques. Our analyses reveal no species-specific selectivity for particular algal pigments, confirming that these three species do not partition food resources at the biochemical level. Nevertheless, we demonstrate increased total resource use in diverse treatments as a result of selection effects and the dominance of one species (B. lyrifera).ConclusionOverall, we found no evidence for resource partitioning at the biochemical level, as pigment composition was similar between individuals, which is likely due to plentiful food availability. Reduced intra-specific competition in the species mixture combined with greater adsorption efficiency and differences in feeding behaviour likely explain the dominant use of resources by B. lyrifera.

Dataset Information

Changes in resource partitioning between and within organs support growth adjustment to neighbor proximity in Brassicaceae seedlings.

Publications

Changes in resource partitioning between and within organs support growth adjustment to neighbor proximity in <i>Brassicaceae</i> seedlings.

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