Biology subjects

Calderini, D. F.

Publications and source records attributed to Calderini, D. F..

6 recordsLinked to original sources

bioRxiv2026

Seed size and source reduction during seed filling effect on quality traits of winter and spring rapeseed

CONTEXTRapeseed is a globally significant oil crop, exhibiting highly plastic responses among seed yield components (seed number and weight). However, there remains a notable gap in knowing the distribution of quality traits among seed size categories and understanding how seed size and source-sink (S-S) ratio influence comprehensive seed quality traits. OBJECTIVEThis study investigated the effects of seed size and S-S ratio reduction on the quality traits of winter and spring rapeseed genotypes. METHODSThe experiments were carried out at field conditions in Valdivia, Chile, where seed yield, yield components, oil, protein, and element concentrations (P, K, S, Ca, Mg, B, Cu, Fe, Mn, Zn, and Na) were evaluated across five seed size categories; very small (< 1.4 mm), small (1.4-1.7 mm), medium (1.7-2.0 mm), large (2.0-2.36 mm), and very large (> 2.36 mm). Treatments included a control and a reduced S-S ratio (75% shading), which significantly increased seed weight (P < 0.05). RESULTSBoth genotype and seed size affected (P< 0.050) the quality traits. Larger seeds exhibited higher Mg and B concentrations, as well as lower K, Ca, Fe and Na. Shading affected seed size distribution, favouring a higher proportion of large seeds. Under the shading treatment, the small seed category reached 5% lower oil concentration, while protein seed concentration increases 6% in both genotypes. Principal component analysis highlighted the complex interaction between yield, yield components, and quality traits, since there was no clear separation between different seed size categories and S-S ratio treatments. CONCLUSIONThese results provide insights into the plasticity of rapeseed quality traits, highlighting their collective impact on nutrient profiles. SIGNIFICANCEThis information is helpful for optimising cultivation practices and informing breeding programmes aimed at improving seed quality, particularly in high-yielding environments susceptible to environmental stresses. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/707178v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@19d16eforg.highwire.dtl.DTLVardef@4cc16forg.highwire.dtl.DTLVardef@12f741borg.highwire.dtl.DTLVardef@6fa37a_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2026

Multi-Level Characterization Reveals Divergent Heat Response Strategies Across Wheat Genotypes of Different Ploidy

Understanding heat stress (HS) responses in wheat is important for breeding varieties adapted to increasing temperature. HS during grain filling reduces wheat yield, but transcriptional and alternative-splicing responses among wheat genotypes of different ploidy remain poorly characterized. We conducted two field experiments with diploid Triticum monococcum, tetraploid T. turgidum subsp. durum, and hexaploid T. aestivum. In Exp. 2, one genotype per species was exposed to severe HS for four consecutive days beginning 10 days after anthesis, and grains were sampled for RNA sequencing 3 h after treatment onset. Mean grain yield declined by 59.4%, 19.0%, and 37.9% in the diploid, tetraploid, and hexaploid genotypes, respectively, accompanied by reductions in thousand-grain weight. After homoeolog grouping, the tetraploid genotype had the smallest fraction of heat-responsive groups and the hexaploid the largest. HS also altered alternative splicing, with broader functional enrichment in the hexaploid genotype. In this genotype, all three homoeologs of an NF-YB gene showed heat-induced skipping of exon E6, and the splice products of the D-genome locus were confirmed by RT-PCR and Sanger sequencing. These results show that the three examined genotypes differed in phenotypic, transcriptional, and splicing responses to HS and identify NF-YB splicing as a candidate component of the hexaploid grain response. Main conclusionEarly grain-filling heating reduced yield and altered transcription and splicing in the three examined wheat genotypes, including increased NF-YB exon E6 skipping in the hexaploid wheat genotype.

plant biology↗

bioRxiv2025

TaExpA6, VRT-A2 and TaGW2 genes differentially affect grain weight, grain number and yield of wheat through their physiological determinants

Physiological basis of the trade-off between grain number (GN) and thousand grain weight (TGW) is key to improve wheat yield. To that end, three wheat line groups were assessed at conventional (300-350 pl m-2) and low (44 pl m-2) plant rates in the field: TaExpA6 (ectopic expression), TaGW2 (TaGW2 triple mutant), and TaP1xGW2A (VRT-A2 ectopic expression and TaGW2-A knock-out), together with their wild-types (WT). Except TaP1xGW2A, the manipulated lines increased TGW over their WTs. However, only the transgenic TaExpA6 line reached higher grain yield (GY) than its WT, whereas increased TGW recorded by the triple knockout of TaGW2 was fully compensated by reduced spike number (SpN) and grain number per spike (GNS). Contrasting effects of TaExpA6 and TaGW2 lines were found on the ovary weight and floret dynamics, associated with the trade-off between GW and GN. Interestingly, the overexpression of TaExpA6 gene acts in grain tissues at post-anthesis avoiding the overlap with GN determination, while TaGW2 disruption constrains tillering, likely as a pleiotropic effect, and shifts intra-spike resource allocation promoting early ovary growth at the expense of distal floret development and GNS. Low plant rate increased resource allocation to the spike, mitigating the GW-GNS trade-off and increasing both traits simultaneously.

plant biology↗

bioRxiv2025

Source-sink reduction and improvement in rapeseed (Brassica napus L.) during the exponential grain filling phase and responses of grain yield, its components and grain quality traits

Rapeseed (Brassica napus L.) final grain weight and in turn grain yield, results from the interaction between assimilate supply (source) and sink capacity; however, the extent to which source limitation constrains yield formation during grain filling remains under debate. Understanding how the manipulation of the source-sink ratio (S-S ratio) affects yield and grain traits is critical for elucidating the physiological mechanisms behind yield stability in high-yield environments. This study aimed to evaluate how variations in the S-S ratio during the grain-filling phase influence grain weight and yield, biomass allocation, grain-filling dynamics, and grain quality traits in rapeseed. A field experiment was conducted during two seasons in Valdivia, Chile. One high-yield potential and adapted hybrid (Click CL) was evaluated under three radiation regimes in a randomized complete block design: control, -50% incident radiation (shading), and +50 % incident radiation (reflected radiation pannels, PET). S-S ratio treatments were applied from the beginning of grain filling (BBCH 71) to physiological maturity (BBCH 89) aimed at modify the S-S ratio during the actual grain filling period. The reduced S-S ratio increased thousand-grain weight (TGW), particularly in basal siliques, resulting in yield compensation and demonstrating a strong structural and physiological buffering capacity. Conversely, increasing the S-S ratio enhanced grain number and grain yield, while TGW remained stable. Grain quality traits responded asymmetrically: under reduced S-S, oil concentration slightly declined whereas protein concentration increased. The increased S-S ratio, had no effect on grain oil and protein concentrations, remaining similar to the control. Sieving analyses revealed a shift toward larger grain size classes under reduced S- S, whereas the distribution under increased S-S resembled the control. Overall, these findings indicate that rapeseed maintains yield stability through compensatory adjustments in grain weight and size distribution under contrasting assimilate availabilities. Under high-radiation temperate conditions, rapeseed productivity during grain filling is predominantly governed by sink capacity, highlighting its physiological plasticity and resilience to variations in source-sink balance HighlightsO_LIIn high-yield conditions without structural changes, grain filling depends on sink capacity. C_LIO_LIA 50% reduction in radiation increases grain weight and maintains grain yield. C_LIO_LIA 50% increase in radiation raises grain number and yield via more grains per plant. C_LIO_LISource reduction shifts grains to larger sizes; source increase maintains stability. C_LIO_LIOil in grain is stable with increased radiation, declines when it is reduced. C_LI

physiology↗

bioRxiv2024

Resilience of rapeseed to heat stress during grain filling in a high yielding environment

Global climate change is driving the temperature increase, which negatively impacts on crop production. Most heat stress studies in rapeseed have been conducted under controlled conditions, limiting their results to true field crops. This study aimed to assess the sensitivity of rapeseed to temperature increase during two phases of the grain filling period in southern Chile, a high-yield potential environment. To our knowledge, this is the first field study evaluating the effects of heat stress at different phases of grain filling in rapeseed. Three field experiments were conducted with two adapted spring rapeseed hybrids, Lumen and Solar CL, under three temperature treatments: a control at ambient temperature, a 5{degrees}C increase from the beginning of flowering to 15 days after flowering (DAF), and the same increase from 15 to 30 DAF. Crop and climate variables, including air temperature and solar radiation were recorded along the experiments. Slight effects on grain yield due to heat stress were found, however, the hybrids exhibited different sensitivities, with Lumen being less affected than Solar CL. Grian yield of the last hybrid showed positive association with photothermal quotient and negatively with temperature, while Lumen did not show relationship. The most significant impact on grain yield occurred during the first half of grain filling (0-15 DAF), resulting in a reduction of 26.8% of grain number in Solar CL, compared to a 6.0% reduction in Lumen across experiments. Grain weight remained little affected by thermal stress, indicating its conservative behaviour and tolerance in southern Chile conditions. Grain oil concentration was scarcely sensitive, while grain protein concentration increased under heat stress. The low impact on the crop outcomes of our studies may be attributed to the lower background temperature of southern Chile, suggesting that this environment may confer greater rapeseed heat tolerance during grain filling than in other agroecosystems.

physiology↗

bioRxiv2024

The trade-off between grain weight and grain number in wheat is explained by the overlapping of the key phases determining these major yield components

Enhancing grain yield is a primary goal in the cultivation of major staple crops, including wheat. Recent research has focused on identifying the physiological and molecular factors that influence grain weight, a critical determinant of crop yield. However, a bottleneck has arisen due to the trade-off between grain weight and grain number, whose underlying causes remain elusive. In a novel approach, a wheat expansin gene, TaExpA6, known for its expression in root tissues, was engineered to express in the grains of the spring wheat cultivar Fielder. This modification led to increases in both grain weight and yield without adversely affecting grain number. Conversely, a triple mutant line targeting the gene TaGW2, a known negative regulator of grain weight, resulted in increased grain weight but decreased grain number, potentially offsetting yield gains. This study aimed to evaluate four wheat genotypes: (i) a transgenic line expressing TaExpA6, (ii) its wild-type counterpart (Fielder), (iii) a TaGW2 triple mutant line, and (iv) its wild-type. Conducted in southern Chile, the study employed a Complete Randomized Block Design with four replications, under well-managed field conditions including fertilization, irrigation, and pest control. The primary metrics assessed were grain yield, grain number, and average grain weight per spike, along with detailed measurements of grain weight and dimensions across the spike, and ovary weight at pollination (Waddingtons scale 10). The expression levels of TaExpA6 and TaGW2 were also monitored post-anthesis. Results indicated that both the TaExpA6 line and the triple mutant line achieved significantly higher average grain weights compared to their respective wild types. Notably, the TaExpA6 line did not exhibit a reduction in grain number, thereby enhancing grain yield per spike. In contrast, the triple mutant line showed a reduced grain number per spike, with no significant change in overall yield. Analysis of ovary size, grain weight dynamics, and gene expression patterns suggests that the trade-off between grain weight and number could be attributed to the overlapping of the critical periods for the determination of these traits.

plant biology↗