Biology subjects

Knipfer, T.

Publications and source records attributed to Knipfer, T..

3 recordsLinked to original sources

bioRxiv2026

Phenological stage influences how white lupin (Lupinus albus) root exudate metabolites respond to phosphorus supply

The composition and quantity of root exudates are strongly influenced by physiological and environmental conditions, reflecting dynamic changes in plant metabolism. Although many studies report that root exudate metabolite profiles vary with plant phenology, few have disentangled the effects of phenological stage from those of nutrient availability. We collected root exudates from white lupin (Lupinus albus) grown in a fine phosphorus (P) gradient (5, 10, 20, 30 and 50 {micro}M P) in hydroponics at three developmental stages, performed untargeted metabolomics using GC-MS, and measured 10 above and belowground traits. Our results show that plant phenological stage exerts a stronger influence on exudate metabolomic profiles than variation in P supply. During leaf development, exudates were dominated by metabolites associated with carbon metabolism, whereas flowering was characterized by compounds related to secondary metabolism and cell wall turnover. Phosphorus influenced exudate profiles only at the flowering stage, with distinct profiles observed at 5 and 10 {micro}M P compared with 20-50 {micro}M P. These findings provide new insights into the temporal regulation of root exudation and demonstrate that plant developmental stage is a primary determinant of metabolic responses to phosphorus availability and, potentially, rhizosphere functioning under nutrient limitation. HighlightRoot exudate quantity and composition in white lupin is shaped more by plant phenological stage than phosphorus supply, with phosphorus effects emerging only during flowering.

plant biology↗

bioRxiv2026

Phosphorus limitation enhances root exudation and mineral bioweathering across diverse soil process domains

AimsHarnessing rhizosphere processes offers a valuable opportunity to optimize nutrient use efficiency in agroecosystems. In nutrient-limited soils, plants discharge part of photosynthate surplus via root exudation, including carboxylates, which may enhance mineral dissolution and nutrient mobilization. We aimed to assess how plant responses to nutrient limitation translated into changes in exudate profiles, and how these exudates, in turn, drive bioweathering across soils of contrasting mineralogy and weathering degree. MethodsWe conducted a hydroponic experiment with Lupinus albus grown in a phosphorus (P) gradient over seven weeks. We measured plant biomass and root traits, performed a metabolomics analysis and quantified seven carboxylates in root exudates using gas chromatography-mass spectrometry. To assess bioweathering across contrasted soil domains, we conducted batch dissolution tests with exudates using three soil horizons--each with distinct physicochemical properties: enriched in organic matter, iron oxides, or primary silicates. ResultsAt the intermediate level of P supply, shoot biomass was comparable to that under high P, but plants produced more root biomass and a higher total carboxylate exudation rate. Despite low carboxylate concentrations (<100 ppb), exudates promoted the dissolution of Ca, Mg, Si, Fe, P and K in all soils. Yet, the degree of element released varied among soil types. ConclusionThese findings highlight the importance of root exudates in enhancing mineral dissolution, with effects dependent on soil physicochemical properties. The results suggest that managing agroecosystems under moderate nutrient limitation could be a sustainable strategy to increase root-to-shoot ratios, enhance bioweathering and nutrient release in rhizosphere.

biochemistry↗

bioRxiv2023

Leaf hydration status under drought is predominantly linked to stomatal regulation and leaf roll but not osmotic adjustment in Canadian hard red spring wheat (Triticum aestivum) cultivars

For wheat (Triticum aestivum), sustained crop yield at limited soil water has been linked to osmotic adjustment (OA) as one of the main drivers to minimize drought-induced reductions in leaf hydration status and growth. Canada Western Red Spring (CWRS) cultivars are typically grown in rainfed areas in northern regions with milder climates, but ongoing climate change has increased the frequency and intensity of drought event questioning how successful they are in tolerating drought. The extent of OA and its relation to stomatal behavior, leaf roll, and kernel development under periods of drought remain elusive for CWRS. For several commercially used Canada Western Red Spring (CWRS) wheat cultivars ( Superb, Stettler, AAC Viewfield), OA was not found to be a mechanism contributing to drought tolerance. In contrast, we found that sustained kernel weight during periods of relatively low soil water content was linked to tight stomatal behavior (i.e., efficient transition from onset to full stomatal closure) and early leaf roll (i.e., reductions in flag leaf width). Moreover, leaf hydration status ({Theta}RWC) marked the onset of drought-induced losses in kernel weight in all three cultivars. In conclusion, CWRS wheat lacks OA but leaf stomatal behavior and leaf rolling aid in securing leaf hydration status and kernel weight under drought. One-sentence summarySelect wheat cultivars maintain leaf hydration status and yield by early leaf roll and rapid stomatal closure in the absence of osmotic adjustment and isohydric behavior.

plant biology↗