Biology subjects

Salter, W. T.

Publications and source records attributed to Salter, W. T..

8 recordsLinked to original sources

bioRxiv2026

Field-based dissection of stomatal anatomy and conductance reveals stable QTL under drought and heat in wheat

Stomatal traits balance carbon gain with water loss, yet their breeding potential in wheat remains underexploited. This study investigated physiological and anatomical stomatal responses alongside yield across two years of large-scale field trials under water-limitation and delayed sowing-induced heat exposure. Across both seasons, stomatal conductance (gs) declined under stress, reflecting strong environmental constraint on gas-exchange (water-limitation:-26.9%; heat:-13.8%). Partitioning responses by leaf surface and genotype identified the adaxial surface as the dominant contributor to gs variation and the most stress responsive. Despite increases in theoretical anatomical gas-exchange capacity (gsmax), gs-efficiency declined, indicating partial decoupling between structural potential and realised conductance. Drought reduced stomatal size while increasing density whereas heat increased size, suggesting stress-specific anatomical plasticity. Moderate-to-high heritability was observed for anatomical traits (Water-limitation: 0.13-0.57; Heat: 0.42-0.71), contrasting with lower and less stable heritability for gs (water-limitation: 0.13-0.41; heat: 0.13-0.50). Genome-wide-association-mapping identified 169 putative QTLs, predominantly for anatomical traits, including stable and co-localised pleiotropic loci. Fourteen sets of closely positioned markers were detected across seasons or studies, with stable regions on chromosomes 2B, 3B and 7B emerging as key loci. Focusing on stable loci controlling adaxial stomatal anatomy offers a realistic strategy to enhance wheat photosynthetic efficiency and climate resilience. HighlightAdaxial stomatal traits dominate gas exchange responses to heat and drought in wheat, with stable anatomical QTL identified on chromosomes 2B, 3B and 7B. Their stability across environments supports their relevance for crop improvement in water-limited and high temperature systems.

physiology↗

bioRxiv2025

QTL for Heat-Induced Stomatal Anatomy Underpin Gas Exchange Variation in Field-Grown Wheat

Stomata are central to leaf gas exchange, governing carbon uptake, water loss, and ultimately, crop performance. However, the contribution of integrated stomatal anatomy and physiology to wheat heat tolerance remains poorly understood, particularly under realistic field conditions and across divers germplasm. This study explored the role of stomatal anatomical and physiological traits in shaping wheat responses to heat stress. Across two years of multi-environment field trials encompassing 200 genotypes in season 1 and 50 genotypes in season 2, we examined stomatal conductance (g), anatomical traits including stomatal size and density, and the stomatal conductance operating efficiency (gse) across leaf surfaces, along with grain yield. Timely and delayed sowing treatments were used to expose key developmental stages (anthesis) to contrasting temperature regimes. Early sowing supported higher gs and gse, while delayed sowing impaired stomatal function despite similar theoretical anatomical capacity (gsmax), revealing a decoupling of structural potential and physiological performance under stress. The adaxial surface consistently exhibited higher gs, stomatal density, and gsmax than the abaxial surface, highlighting its dominant role in leaf gas exchange. Later sowing induced plastic shifts in anatomy, including smaller, denser stomata, particularly on the adaxial surface, suggesting an adaptive response to thermal stress. Significant genotypic variation was observed for gs, gse, gsmax, and stomatal anatomical traits, with moderate heritability indicating genetic control. 125 putative QTL were identified for multiple stomatal traits across environments, including several stable loci on chromosomes 2B and 5B, and numerous closely clustered QTL for anatomical traits on chromosome 7B, highlighting key genomic regions underlying stomatal anatomy. In contrast, QTL for gs and gse were fewer and season-specific, highlighting the environmentally sensitive nature of physiological stomatal regulation. 42 of the QTL identified were consistent with previously reported QTL for stomatal traits in wheat. Together, these findings elevate the role of stomatal traits, supporting an integrated breeding strategy that combines selection for favourable stomatal anatomy with efficiency physiological regulation. Incorporating traits like gse into selection frameworks may enhance yield stability and resilience in heat-prone environments, advancing the development of climate-resilient wheat ideotypes. ScopeThis manuscript examines how stomatal anatomical and physiological traits integrate to shape wheat responses to heat stress under field conditions, addressing a central challenge in understanding the roles of stomata in a warming climate. Using multi-environment field trials across two growing seasons and encompassing 200 wheat genotypes, we quantify stomatal conductance (gs), anatomical traits, and stomatal operating efficiency (gse), across adaxial and abaxial leaf surfaces, and investigate whether these are under genetic control. The study provides mechanistic insight into the dynamic regulation of stomatal function by demonstrating a decoupling between anatomical capacity and physiological performance under heat stress, alongside plastic shifts in stomatal traits across sowing times. The identification of 125 candidate QTLs, including numerous stable and co-localised QTL across seasons, supports their incorporation into breeding programs aimed at enhancing resilience and yield stability. This work aligns with the Research Topic by elucidating mechanistic underpinnings of stomatal conductance regulation, bridging stomatal biology with applied crop improvement strategies. This work is critical to improving understanding of plant water relations and carbon uptake under future climate scenarios to ensure food security in a changing climate.

plant biology↗

bioRxiv2024

FieldDino: High-throughput physio-morphological phenotyping of stomatal characteristics for plant breeding research

Stomatal anatomy and physiology define CO2 availability for photosynthesis and regulate plant water use. Despite being key drivers of yield and dynamic responsiveness to abiotic stresses, conventional measurement techniques of stomatal traits are laborious and slow, limiting adoption in plant breeding. Advances in instrumentation and data analyses present an opportunity to screen stomatal traits at scales relevant to plant breeding. We present a high-throughput field-based phenotyping approach, FieldDino, for screening of stomatal physiology and anatomy. The method allows coupled measurements to be collected in <15 s and consists of: (1) stomatal conductance measurements using a handheld porometer; (2) in situ collection of epidermal images with a digital microscope, 3D-printed leaf clip and Python-based app; and (3) automated deep learning analysis of stomatal features. The YOLOv8-M model trained on images collected in the field achieved strong performance metrics with an mAP@0.5 of 97.1% for stomatal detection. Validation in large field trials of 200 wheat genotypes with two irrigation treatments captured wide diversity in stomatal traits. FieldDino enables stomatal data collection and analysis at unprecedented scales in the field. This will advance research on stomatal biology and accelerate the incorporation of stomatal traits into plant breeding programs for resilience to abiotic stress. HighlightChaplin et al., have developed FieldDino which enables rapid, high-throughput phenotyping of stomatal traits, advancing plant breeding research by integrating streamlined in-field measurements with automated deep learning analysis.

physiology↗

bioRxiv2021

Vulnerability to cavitation is linked to home climate precipitation across eight eucalypt species

Vulnerability to cavitation in leaves is the result of highly adaptive anatomical and physiological traits that can be linked to water availability in a species climate of origin. Despite similar gross leaf morphology, eucalypt species are often confined to specific climate envelopes across the variable rainfall environments of Australia. In this study, we investigate how the progression of cavitation differs among eucalypts and whether this is related to other hydraulic and physical leaf traits. We used the Optical Visualisation technique to capture cavitation progression across the leaves of eight eucalypt species (Angophora crassifolia, Corymbia tessellaris, Eucalyptus atrata, Eucalyptus grandis, Eucalyptus laevopinea, Eucalyptus longifolia, Eucalyptus macrandra, Eucalyptus tereticornis) from a wide range of climates and grown in a common garden setting. Vulnerability to cavitation, represented by the leaf water potential required for 50% cavitation of leaf vessels, varied significantly among species (-3.48 MPa to -8.25 MPa) and correlated linearly with home climate precipitation and leaf SLA (R2 of 0.64 and 0.75, respectively). P12-P88, the range of water potentials between which 12% to 88% of cavitation occurs, was decoupled from P50 but also correlated with leaf SLA (R2 of 0.72). We suggest the magnitude of P12-P88 may be representative of a species drought strategy - a large P12-P88 signifying leaves that exhibit drought tolerance (retention of leaves under drought conditions) and a small P12-P88 signifying drought avoidance (leaf shedding after a threshold of drought is reached). Our results agree with other studies that highlight these cavitation metrics as genetically fixed traits. Turgor loss point, on the other hand, may be more plastic, as evidenced by the low variability of this trait across these eucalypt species grown in a common garden environment. Further study will help to establish the SLA-related anatomical traits that impart cavitation resistance and to extend these conclusions to a greater number of species and home climates.

plant biology↗

bioRxiv2020

Open source 3D phenotyping of chickpea plant architecture across plant development

In this work, we developed a low-cost 3D scanner and used an open source data processing pipeline to phenotype the 3D structure of individual chickpea plants. Being able to accurately assess the 3D architecture of plant canopies can allow us to better estimate plant productivity and improve our understanding of underlying plant processes. This is especially true if we can monitor these traits across plant development. Photogrammetry techniques, such as structure from motion, have been shown to provide accurate 3D reconstructions of monocot crop species such as wheat and rice, yet there has been little success reconstructing crop species with smaller leaves and more complex branching architectures, such as chickpea. The imaging system we developed consists of a user programmable turntable and three cameras that automatically captures 120 images of each plant and offloads these to a computer for processing. The capture process takes 5-10 minutes for each plant and the majority of the reconstruction process on a Windows PC is automated. Plant height and total plant surface area were validated against "ground truth" measurements, producing R2 > 0.99 and a mean absolute percentage error < 10%. We demonstrate the ability to assess several important architectural traits, including canopy volume and projected area, and estimate relative growth rate in commercial chickpea cultivars and lines from local and international breeding collections. Detailed analysis of individual reconstructions also allowed us to investigate partitioning of plant surface area, and by proxy plant biomass.

plant biology↗

bioRxiv2020

Identification of QTLs for dynamic and steady state photosynthetic traits in a barley mapping population

Enhancing the photosynthetic induction response to fluctuating light has been suggested as a key target for improvement in crop breeding programs, with the potential to substantially increase whole canopy carbon assimilation and contribute to crop yield potential. Rubisco activation may be the main physiological process that will allow us to achieve such a goal. In this study, we phenotypically assessed the rubisco activation rate in a doubled haploid (DH) barley mapping population [131 lines from a Yerong/Franklin (Y/F) cross] after a switch from moderate to saturating light. Rates of rubisco activation were found to be highly variable across the mapping population, with a median activation rate of 0.1 min-1 in the slowest genotype and 0.74 min-1 in the fastest genotype. A QTL for rubisco activation rate was identified on chromosome 7H. This is the first report on the identification of a QTL for rubisco activation rate in planta and the discovery opens the door to marker assisted breeding to improve whole canopy photosynthesis of barley. Further strength is given to this finding as this QTL colocalised with QTLs identified for steady state photosynthesis and stomatal conductance. Several other distinct QTLs were identified for these steady state traits, with a common overlapping QTL on chromosome 2H, and distinct QTLs for photosynthesis and stomatal conductance identified on chromosomes 4H and 5H respectively. Future work should aim to validate these QTLs under field conditions so that they can be used to aid plant breeding efforts. HighlightSignificant variation exists in the photosynthetic induction response after a switch from moderate to saturating light across a barley doubled haploid population. A QTL for rubisco activation rate was identified on chromosome 7H, as well as overlapping QTLs for steady state photosynthesis and stomatal conductance.

plant biology↗

bioRxiv2018

PARbars: cheap, easy to build ceptometers for continuous measurement of light interception in plant canopies

Short AbstractDetailed instructions on how to build, calibrate and collect research quality data from PARbar ceptometers are presented.\n\nLong AbstractCeptometry is a technique used to measure the transmittance of photosynthetically active radiation through a plant canopy using multiple light sensors connected in parallel on a long bar. Ceptometry is often used to infer properties of canopy structure and light interception, notably leaf area index (LAI) and effective plant area index (PAIeff). Due to the high cost of commercially available ceptometers, the number of measurements that can be taken is often limited in space and time. This limits the usefulness of ceptometry for studying genetic variability in light interception, and precludes thorough analysis of, and correction for, biases that can skew measurements depending on the time of day. We developed continuously logging ceptometers (called PARbars) that can be produced for USD $75 each and yield high quality data comparable to commercially available alternatives. Here we provide detailed instruction on how to build and calibrate PARbars, how to deploy them in the field and how to estimate PAI from collected transmittance data. We provide representative results from wheat canopies and discuss further considerations that should be made when using PARbars.

plant biology↗

bioRxiv2018

Rate of photosynthetic acclimation to fluctuating light varies widely among genotypes of wheat

HighlightSignificant variation exists in the acclimation time of photosynthesis following dark-to-light transitions across wheat genotypes, under field and controlled conditions. Slow acclimation reduced daily carbon assimilation by up to 16%.\n\nAbstractCrop photosynthesis and yield are limited by slow photosynthetic induction in sunflecks. We quantified variation in induction kinetics across diverse genotypes of wheat for the first time. In a preliminary study using penultimate leaves of 58 genotypes grown in the field, we measured induction kinetics for maximum assimilation rate (Amax) after a shift from full darkness to saturating light (1700 mol m-2 s-1) with 1-4 replicates per genotype. We then grew 10 of these genotypes with contrasting responses in a controlled environment and quantified induction kinetics of carboxylation capacity (Vcmax) from dynamic A vs ci curves after a shift from low to high light (50 to 1500 mol m-2 s-1), with 5 replicates per genotype. Within-genotype median time for 95% induction (t95) varied from 8.4 to 23.7 min across genotypes for Amax in field-grown penultimate leaves, and from 6.7 to 10.4 min for Vcmaxin chamber-grown flag leaves. Our simulations suggested that non-instantaneous acclimation reduces daily net carbon gain by up to 16%, and that breeding to speed up Vcmax induction in the slowest genotype to match that in the fastest genotype could increase daily net carbon gain by more than 4%, particularly for leaves that experience predominantly short-duration sunflecks.

physiology↗