Biology subjects

Reynolds, M. P.

Publications and source records attributed to Reynolds, M. P..

7 recordsLinked to original sources

bioRxiv2026

Night temperature determines nearly half of wheat yield variation globally

Daily minimum temperature (Tmin) is increasing faster than maximum temperature (Tmax). However, the impact of Tmin on crop productivity is barely studied. Effects of environmental covariates on yield were examined using 42 years of trials at 255 sites representing spring wheat regions globally. Grain-filling was the most sensitive growth stage: Average Tmin explained 40% of yield variation, and 52% when also considering radiation, while average Tmax explained just 20% of variation. Yield declined linearly between the observed range from 8 to 22{o}C average Tmin. Generally, a 1{o}C increased Tmin reduced yield by [~]0.5 t/ha, with high radiation partially offsetting negative effects. Average increase of 1.2{o}C at test sites over 42 years reduced yield by more than 10%. Shorter grain-filling duration likely reduced yield, as well as increased nocturnal rate of dark respiration. A better understanding of drivers of variation in respiration and adaptation to warmer nights could generate a step change in wheat yield.

plant biology↗

bioRxiv2025

Yield from the shadows: beyond top layer photosynthesis to enhance crop productivity

Photosynthesis research in crops typically focuses on upper canopy layers, which is partly for convenience and partly for the sake of achieving stable datasets under high light conditions. This neglects significant contributions from light - limited portions of the canopy within the lower layers. This study aimed to provide an empirical quantification of the role of these hidden layers of wheat canopies in the context of canopy scale productivity. We demonstrate that light-saturated photosynthetic rates (Asat) in middle and bottom layers at key growth stages can be strong predictors of grain yield. Despite variability in architecture across layers, light interception remained similar and key associations between biomass accumulation and yield with Asat emerged. Yield showed positive associations with photosynthesis in all canopy layers but was stronger at the top layer during grain filling and at the bottom layer during booting. Whole canopy photosynthetic rates were influenced by top layer architecture, N availability in the middle and bottom layers and leaf angles at the bottom of the canopy. Our findings suggest that measurements within hidden layers are required, and that optimizing middle and bottom layer Asat during the vegetative period and top layer Asat during grain filling can boost food security.

ecology↗

bioRxiv2025

The Global Wheat Full Semantic Organ Segmentation (GWFSS) dataset

Computer vision is increasingly used in farmers fields and agricultural experiments to quantify important traits. Imaging setups with a sub-millimetre ground sampling distance enable the detection and tracking of plant features, including size, shape, and colour. Although todays AI-driven foundation models segment almost any object in an image, they still fail for complex plant canopies. To improve model performance, the global wheat dataset consortium assembled a diverse set of images from experiments around the globe. After the head detection dataset (GWHD), the new dataset targets a full semantic segmentation (GWFSS) of wheat organs (leaves, stems and spikes) covering all developmental stages. Images were collected by 11 institutions using a wide range of imaging setups. Two datasets are provided: i) a set of 1096 diverse images in which all organs were labelled at the pixel level, and (ii) a dataset of 52,078 images without annotations available for additional training. The labelled set was used to train segmentation models based on DeepLabV3Plus and Segformer. Our Segformer model performed slightly better than DeepLabV3Plus with a mIOU for leaves and spikes of ca. 90%. However, the precision for stems with 54% was rather lower. The major advantages over published models are: i) the exclusion of weeds from the wheat canopy, ii) the detection of all wheat features including necrotic and senescent tissues and its separation from crop residues. This facilitates further development in classifying healthy vs. unhealthy tissue to address the increasing need for accurate quantification of senescence and diseases in wheat canopies.

plant biology↗

bioRxiv2022

The effects of brief heat during early booting on reproductive, developmental and physiological performance in common wheat (Triticum aestivum L.)

Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop wheat is heat sensitive, but often exposed to high temperatures during cultivation. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34{degrees}C/28{degrees}C, day/night) or extreme (37{degrees}C/27{degrees}C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed as heat stress increased from mild to extreme. Even under mild heat a significant decrease in pollen viability and grain number per spike from primary spike was observed compared with the control (21{degrees}C/15{degrees}C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of Photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll SPAD measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics and leaf senescence under heat. The identified tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.

plant biology↗

bioRxiv2022

Exotic alleles contribute to heat tolerance in wheat under field conditions

Global warming is one of the most significant threats to food security. With temperatures predicted to rise and extreme weather events becoming more common we must safeguard food production by developing crop varieties that are more tolerant to heat stress without compromising yield under favourable conditions. By evaluating 149 spring wheat lines in the field under yield potential and heat stressed conditions, we demonstrate how strategic integration of exotic material significantly increases yield under heat stress compared to elite lines, with no significant yield penalty under favourable conditions. Genome-wide association analysis revealed three marker trait associations, which together increase yield under heat stress by over 50% compared to lines without the advantageous alleles and was associated with approximately 2{degrees}C lower canopy temperature. We identified an Aegilops tauschii introgression underlying the most significant of these associations. By comparing overlapping recombination of this introgressed segment between lines, we identified a 1.49Mbp region of the introgression responsible for this association that increases yield under heat stress by 32.4%. The genes within this region were extracted from diverse Ae. tauschii genomes, revealing a novel Ae. tauschii MAPK gene, a SOC1 orthologue and a pair of type-B two-component response regulators. Incorporating these exotic alleles into breeding programmes could serve as a pre-emptive strategy to produce high yielding wheat cultivars that are resilient to the effects of future climate uncertainty with no yield penalty under favourable conditions.

plant biology↗

bioRxiv2020

Uncovering candidate genes involved in photosynthetic capacity using unexplored genetic variation in Spring Wheat

To feed an ever-increasing population we must leverage advances in genomics and phenotyping to harness the variation in wheat breeding populations for traits like photosynthetic capacity which remains unoptimized. Here we survey a diverse set of wheat germplasm containing elite, introgression and synthetic derivative lines uncovering previously uncharacterised variation. We demonstrate how strategic integration of exotic material alleviates the D genome genetic bottleneck in wheat, increasing SNP rate by 62% largely due to Ae. tauschii synthetic wheat donors. Across the panel, 67% of the Ae. tauschii donor genome is represented as introgressions in elite backgrounds. We show how observed genetic variation together with hyperspectral reflectance data can be used to identify candidate genes for traits relating to photosynthetic capacity using association analysis. This demonstrates the value of genomic methods in uncovering hidden variation in wheat and how that variation can assist breeding efforts and increase our understanding of complex traits.

plant biology↗

bioRxiv2018

Elucidating the genetic basis of biomass accumulation and radiation use efficiency in spring wheat and its role in yield potential

One of the major challenges for plant scientists is increasing wheat (Triticum aestivum) yield potential (YP). A significant bottleneck for increasing YP is achieving increased biomass through optimization of Radiation Use Efficiency (RUE) along the crop cycle. Exotic material such as landraces and synthetic wheat has been incorporated into breeding programs in an attempt to alleviate this, however their contribution to YP is still unclear. To understand the genetic basis of biomass accumulation and RUE we applied genome-wide association study (GWAS) to a panel of 150 elite spring wheat genotypes including many landrace and synthetically derived lines. The panel was evaluated for 31traits over two years under optimal growing conditions and genotyped using the 35K Wheat Breeders array. Marker-trait-association identified 94 SNPs significantly associated with yield, agronomic and phenology related traits along with RUE and biomass at various growth stages that explained 7-17 % of phenotypic variation. Common SNP markers were identified for grain yield, final biomass and RUE on chromosomes 5A and 7A. Additionally we show that landrace and synthetic derivative lines showed higher thousand grain weight (TGW), biomass and RUE but lower grain number (GNO) and harvest index (HI). Our work demonstrates the use of exotic material as a valuable resource to increase YP. It also provides markers for use in marker assisted breeding to systematically increase biomass, RUE and TGW and avoid the TGW/GNO and BM/HI trade-off. Thus, achieving greater genetic gains in elite germplasm while also highlighting genomic regions and candidate genes for further study.

plant biology↗