Genetic improvement of phosphate-limited photosynthesis for high yield in rice.

Low phosphate (Pi) availability decreases photosynthesis, with phosphate limitation of photosynthesis occurring particularly during grain filling of cereal crops; however, effective genetic solutions remain to be established. We previously discovered that rice phosphate transporter OsPHO1;2 controls seed (sink) development through Pi reallocation during grain filling. Here, we find that OsPHO1;2 regulates Pi homeostasis and thus photosynthesis in leaves (source). Loss-of-function of OsPHO1;2 decreased Pi levels in leaves, leading to decreased photosynthetic electron transport activity, CO2 assimilation rate, and early occurrence of phosphate-limited photosynthesis. Interestingly, ectopic expression of OsPHO1;2 greatly increased Pi availability, and thereby, increased photosynthetic rate in leaves during grain filling, contributing to increased yield. This was supported by the effect of foliar Pi application. Moreover, analysis of core rice germplasm resources revealed that higher OsPHO1;2 expression was associated with enhanced photosynthesis and yield potential compared to those with lower expression. These findings reveal that phosphate-limitation of photosynthesis can be relieved via a genetic approach, and the OsPHO1;2 gene can be employed to reinforce crop breeding strategies for achieving higher photosynthetic efficiency.

Overlooked branch turnover creates a widespread bias in forest carbon accounting.

Most measurements and models of forest carbon cycling neglect the carbon flux associated with the turnover of branch biomass, a physiological process quantified for other organs (fine roots, leaves, and stems). Synthesizing data from boreal, temperate, and tropical forests (184,815 trees), we found that including branch turnover increased empirical estimates of aboveground wood production by 16% (equivalent to 1.9 Pg Cy-1 globally), of similar magnitude to the observed global forest carbon sinks. In addition, reallocating carbon to branch turnover in model simulations reduced stem wood biomass, a long-lasting carbon storage, by 7 to 17%. This prevailing neglect of branch turnover suggests widespread biases in carbon flux estimates across global datasets and model simulations. Branch litterfall, sometimes used as a proxy for branch turnover, ignores carbon lost from attached dead branches, underestimating branch C turnover by 38% in a pine forest. Modifications to field measurement protocols and existing models are needed to allow a more realistic partitioning of wood production and forest carbon storage.

Harmonizing the cyano-group and Na to enhance selective photocatalytic O2 activation on carbon nitride for refractory pollutant degradation.

Manipulating exciton dissociation and charge-carrier transfer processes to selectively generate free radicals of more robust photocatalytic oxidation capacity for mineralizing refractory pollutants remains challenging. Herein, we propose a strategy by simultaneously introducing the cyano-group and Na into graphitic carbon nitride (CN) to obtain CN-Cy-Na, which makes the charge-carrier transfer pathways the dominant process and consequently achieves the selective generation of free radicals. Briefly, the cyano-group intensifies the local charge density of CN, offering a potential well to attract the hole of exciton, which accelerates the exciton dissociation. Meanwhile, the separated electron transfers efficiently under the robust built-in electric field induced by the cyano-group and Na, and eventually accumulates in the heptazine ring of CN for the following O2 reduction due to the reinforced electron sink effect caused by Na. As a result, CN-Cy-Na exhibits 4.42 mmol L-1 h-1 productivity with 97.6% selectivity for free radicals and achieves 82.1% total organic carbon removal efficiency in the tetracycline photodegradation within 6 h. Additionally, CN-Cy-Na also shows outstanding photodegradation efficiency of refractory pollutants, including antibiotics, pesticide plastic additives, and dyes. This work presents an innovative approach to manipulating the exciton effect and enhancing charge-carrier mobility within two-dimensional photocatalysts, opening an avenue for precise control of free radical generation.

S1 basic leucine zipper transcription factors shape plant architecture by controlling C/N partitioning to apical and lateral organs.

Plants tightly control growth of their lateral organs, which led to the concept of apical dominance. However, outgrowth of the dormant lateral primordia is sensitive to the plant's nutritional status, resulting in an immense plasticity in plant architecture. While the impact of hormonal regulation on apical dominance is well characterized, the prime importance of sugar signaling to unleash lateral organ formation has just recently emerged. Here, we aimed to identify transcriptional regulators, which control the trade-off between growth of apical versus lateral organs. Making use of locally inducible gain-of-function as well as single and higher-order loss-of-function approaches of the sugar-responsive S1-basic-leucine-zipper (S1-bZIP) transcription factors, we disclosed their largely redundant function in establishing apical growth dominance. Consistently, comprehensive phenotypical and analytical studies of S1-bZIP mutants show a clear shift of sugar and organic nitrogen (N) allocation from apical to lateral organs, coinciding with strong lateral organ outgrowth. Tissue-specific transcriptomics reveal specific clade III SWEET sugar transporters, crucial for long-distance sugar transport to apical sinks and the glutaminase GLUTAMINE AMIDO-TRANSFERASE 1_2.1, involved in N homeostasis, as direct S1-bZIP targets, linking the architectural and metabolic mutant phenotypes to downstream gene regulation. Based on these results, we propose that S1-bZIPs control carbohydrate (C) partitioning from source leaves to apical organs and tune systemic N supply to restrict lateral organ formation by C/N depletion. Knowledge of the underlying mechanisms controlling plant C/N partitioning is of pivotal importance for breeding strategies to generate plants with desired architectural and nutritional characteristics.

Improved atmospheric constraints on Southern Ocean CO2 exchange.

We present improved estimates of air-sea CO2 exchange over three latitude bands of the Southern Ocean using atmospheric CO2 measurements from global airborne campaigns and an atmospheric 4-box inverse model based on a mass-indexed isentropic coordinate (Mθe). These flux estimates show two features not clearly resolved in previous estimates based on inverting surface CO2 measurements: a weak winter-time outgassing in the polar region and a sharp phase transition of the seasonal flux cycles between polar/subpolar and subtropical regions. The estimates suggest much stronger summer-time uptake in the polar/subpolar regions than estimates derived through neural-network interpolation of pCO2 data obtained with profiling floats but somewhat weaker uptake than a recent study by Long et al. [Science 374, 1275-1280 (2021)], who used the same airborne data and multiple atmospheric transport models (ATMs) to constrain surface fluxes. Our study also uses moist static energy (MSE) budgets from reanalyses to show that most ATMs tend to have excessive diabatic mixing (transport across moist isentrope, θe, or Mθe surfaces) at high southern latitudes in the austral summer, which leads to biases in estimates of air-sea CO2 exchange. Furthermore, we show that the MSE-based constraint is consistent with an independent constraint on atmospheric mixing based on combining airborne and surface CO2 observations.

Pollinator-assisted plant phenotyping, selection, and breeding for crop resilience to abiotic stresses.

Food security is threatened by climate change, with heat and drought being the main stresses affecting crop physiology and ecosystem services, such as plant-pollinator interactions. We hypothesize that tracking and ranking pollinators' preferences for flowers under environmental pressure could be used as a marker of plant quality for agricultural breeding to increase crop stress tolerance. Despite increasing relevance of flowers as the most stress sensitive organs, phenotyping platforms aim at identifying traits of resilience by assessing the plant physiological status through remote sensing-assisted vegetative indexes, but find strong bottlenecks in quantifying flower traits and in accurate genotype-to-phenotype prediction. However, as the transport of photoassimilates from leaves (sources) to flowers (sinks) is reduced in low-resilient plants, flowers are better indicators than leaves of plant well-being. Indeed, the chemical composition and amount of pollen and nectar that flowers produce, which ultimately serve as food resources for pollinators, change in response to environmental cues. Therefore, pollinators' preferences could be used as a measure of functional source-to-sink relationships for breeding decisions. To achieve this challenging goal, we propose to develop a pollinator-assisted phenotyping and selection platform for automated quantification of Genotype × Environment × Pollinator interactions through an insect geo-positioning system. Pollinator-assisted selection can be validated by metabolic, transcriptomic, and ionomic traits, and mapping of candidate genes, linking floral and leaf traits, pollinator preferences, plant resilience, and crop productivity. This radical new approach can change the current paradigm of plant phenotyping and find new paths for crop redomestication and breeding assisted by ecological decisions.

Auxin regulates source-sink carbohydrate partitioning and reproductive organ development in rice.

Carbohydrate partitioning between the source and sink tissues plays an important role in regulating plant growth and development. However, the molecular mechanisms regulating this process remain poorly understood. In this study, we show that elevated auxin levels in the rice dao mutant cause increased accumulation of sucrose in the photosynthetic leaves but reduced sucrose content in the reproductive organs (particularly in the lodicules, anthers, and ovaries), leading to closed spikelets, indehiscent anthers, and parthenocarpic seeds. RNA sequencing analysis revealed that the expression of AUXIN RESPONSE FACTOR 18 (OsARF18) and OsARF2 is significantly up- and down-regulated, respectively, in the lodicule of dao mutant. Overexpression of OsARF18 or knocking out of OsARF2 phenocopies the dao mutant. We demonstrate that OsARF2 regulates the expression of OsSUT1 through direct binding to the sugar-responsive elements (SuREs) in the OsSUT1 promoter and that OsARF18 represses the expression of OsARF2 and OsSUT1 via direct binding to the auxin-responsive element (AuxRE) or SuRE in their promoters, respectively. Furthermore, overexpression of OsSUT1 in the dao and Osarf2 mutant backgrounds could largely rescue the spikelets' opening and seed-setting defects. Collectively, our results reveal an auxin signaling cascade regulating source-sink carbohydrate partitioning and reproductive organ development in rice.

Reduced global fire activity due to human demography slows global warming by enhanced land carbon uptake.

Fire is an important climate-driven disturbance in terrestrial ecosystems, also modulated by human ignitions or fire suppression. Changes in fire emissions can feed back on the global carbon cycle, but whether the trajectories of changing fire activity will exacerbate or attenuate climate change is poorly understood. Here, we quantify fire dynamics under historical and future climate and human demography using a coupled global climate­fire­carbon cycle model that emulates 34 individual Earth system models (ESMs). Results are compared with counterfactual worlds, one with a constant preindustrial fire regime and another without fire. Although uncertainty in projected fire effects is large and depends on ESM, socioeconomic trajectory, and emissions scenario, we find that changes in human demography tend to suppress global fire activity, keeping more carbon within terrestrial ecosystems and attenuating warming. Globally, changes in fire have acted to warm climate throughout most of the 20th century. However, recent and predicted future reductions in fire activity may reverse this, enhancing land carbon uptake and corresponding to offsetting ∼5 to 10 y of global CO2 emissions at today's levels. This potentially reduces warming by up to 0.11 °C by 2100. We show that climate­carbon cycle feedbacks, as caused by changing fire regimes, are most effective at slowing global warming under lower emission scenarios. Our study highlights that ignitions and active and passive fire suppression can be as important in driving future fire regimes as changes in climate, although with some risk of more extreme fires regionally and with implications for other ecosystem functions in fire-dependent ecosystems.

Efficient sugar utilization and transition from oxidative to substrate-level phosphorylation in high starch storage roots of African cassava genotypes.

Cassava's storage roots represent one of the most important sources of nutritional carbohydrates worldwide. Particularly, smallholder farmers in sub-Saharan Africa depend on this crop plant, where resilient and yield-improved varieties are of vital importance to support steadily increasing populations. Aided by a growing understanding of the plant's metabolism and physiology, targeted improvement concepts already led to visible gains in recent years. To expand our knowledge and to contribute to these successes, we investigated storage roots of eight cassava genotypes with differential dry matter content from three successive field trials for their proteomic and metabolic profiles. At large, the metabolic focus in storage roots transitioned from cellular growth processes toward carbohydrate and nitrogen storage with increasing dry matter content. This is reflected in higher abundance of proteins related to nucleotide synthesis, protein turnover, and vacuolar energization in low starch genotypes, while proteins involved in sugar conversion and glycolysis were more prevalent in high dry matter genotypes. This shift in metabolic orientation was underlined by a clear transition from oxidative- to substrate-level phosphorylation in high dry matter genotypes. Our analyses highlight metabolic patterns that are consistently and quantitatively associated with high dry matter accumulation in cassava storage roots, providing fundamental understanding of cassava's metabolism as well as a data resource for targeted genetic improvement.

Root-to-shoot signaling positively mediates source-sink relation in late growth stages in diploid and tetraploid wheat.

Non-hydraulic root source signaling (nHRS) is a unique positive response to soil drying in the regulation of plant growth and development. However, it is unclear how the nHRS mediates the tradeoff between source and sink at the late growth stages and its adaptive mechanisms in primitive wheat. To address this issue, a root-splitting design was made by inserting solid partition in the middle of the pot culture to induce the occurrence of nHRS using four wheat cultivars (MO1 and MO4, diploid; DM22 and DM31, tetraploid) as materials. Three water treatments were designed as 1) both halves watered (CK), 2) holistic root system watered then droughted (FS), 3) one-half of the root system watered and half droughted (PS). FS and PS were designed to compare the role of the full root system and split root system to induce nHRS. Leaves samples were collected during booting and anthesis to compare the role of nHRS at both growth stages. The data indicated that under PS treatment, ABA concentration was significantly higher than FS and CK, demonstrating the induction of nHRS in split root design and nHRS decreased cytokinin (ZR) levels, particularly in the PS treatment. Soluble sugar and proline accumulation were higher in the anthesis stage as compared to the booting stage. POD activity was higher at anthesis, while CAT was higher at the booting stage. Increased ABA (nHRS) correlated with source-sink relationships and metabolic rate (i.e., leaf) connecting other stress signals. Biomass density showed superior resource acquisition and utilization capabilities in both FS and PS treatment as compared to CK in all plants. Our findings indicate that nHRS-induced alterations in phytohormones and their effect on source-sink relations were allied with the growth stages in primitive wheat.

Tissue- and time-dependent metabolite profiles during early grain development under normal and high night-time temperature conditions.

BACKGROUND: Wheat grain development in the first few days after pollination determines the number of endosperm cells that influence grain yield potential and is susceptible to various environmental conditions, including high night temperatures (HNTs). Flag leaves and seed-associated bracts (glumes, awn, palea, and lemma) provide nutrients to the developing seed. However, the specific metabolic roles of these tissues are uncertain, especially their dynamics at different developmental stages and the time in a day. Tissue- and time-dependent metabolite profiling may hint at the metabolic roles of tissues and the mechanisms of how HNTs affect daytime metabolic status in early grain development. RESULTS: The metabolite profiles of flag leaf, bract, seed (embryo and endosperm), and entire spike were analyzed at 12:00 (day) and 23:00 (night) on 2, 4, and 6 days after fertilization under control and HNT conditions. The metabolite levels in flag leaves and bracts showed day/night oscillations, while their behaviors were distinct between the tissues. Some metabolites, such as sucrose, cellobiose, and succinic acid, showed contrasting oscillations in the two photosynthetic tissues. In contrast, seed metabolite levels differed due to the days after fertilization rather than the time in a day. The seed metabolite profile altered earlier in the HNT than in the control condition, likely associated with accelerated grain development caused by HNT. HNT also disrupted the day/night oscillation of sugar accumulation in flag leaves and bracts. CONCLUSIONS: These results highlight distinct metabolic roles of flag leaves and bracts during wheat early seed development. The seed metabolite levels are related to the developmental stages. The early metabolic events in the seeds and the disruption of the day/night metabolic cycle in photosynthetic tissues may partly explain the adverse effects of HNT on grain yield.

Unraveling the genetic potential of nitrous oxide reduction in wastewater treatment: insights from metagenome-assembled genomes.

This study explores the genetic landscape of nitrous oxide (N2O) reduction in wastewater treatment plants (WWTPs) by profiling 1,083 high-quality metagenome-assembled genomes (HQ MAGs) from 23 Danish full-scale WWTPs. The focus is on the distribution and diversity of nitrous oxide reductase (nosZ) genes and their association with other nitrogen metabolism pathways. A custom pipeline for clade-specific nosZ gene identification with higher sensitivity revealed 503 nosZ sequences in 489 of these HQ MAGs, outperforming existing Kyoto Encyclopedia of Genes and Genomes (KEGG) module-based methods. Notably, 48.7% of the total 1,083 HQ MAGs harbored nosZ genes, with clade II being predominant, accounting for 93.7% of these genes. Taxonomic profiling highlighted the prevalence of nosZ-containing taxa within Bacteroidota and Pseudomonadota. Chloroflexota exhibited unexpected affiliations with both the sec and tat secretory pathways, and all were found to contain the accessory nosB gene, underscoring the importance of investigating the secretory pathway. The majority of non-denitrifying N2O reducers were found within Bacteroidota and Chloroflexota. Additionally, HQ MAGs with genes for dissimilatory nitrate reduction to ammonium and assimilatory nitrate reduction frequently co-occurred with the nosZ gene. Traditional primers targeting nosZ often focus on short-length amplicons. Therefore, we introduced custom-designed primer sets targeting near-full-length nosZ sequences. These new primers demonstrate efficacy in capturing diverse and well-characterized sequences, providing a valuable tool with higher resolution for future research. In conclusion, this comprehensive analysis enhances our understanding of N2O-reducing organisms in WWTPs, highlighting their potential as N2O sinks with the potential for optimizing wastewater treatment processes and mitigating greenhouse gas emissions. IMPORTANCE: This study provides critical insights into the genetic diversity of nitrous oxide reductase (nosZ) genes and the microorganisms harboring them in wastewater treatment plants (WWTPs) by exploring 1,083 high-quality metagenome-assembled genomes (MAGs) from 23 Danish full-scale WWTPs. Despite the pivotal role of nosZ-containing organisms, their diversity remains largely unexplored in WWTPs. Our custom pipeline for detecting nosZ provides near-full-length genes with detailed information on secretory pathways and accessory nos genes. Using these genes as templates, we developed taxonomically diverse clade-specific primers that generate nosZ amplicons for phylogenetic annotation and gene-to-MAG linkage. This approach improves detection and expands the discovery of novel sequences, highlighting the prevalence of non-denitrifying N2O reducers and their potential as N2O sinks. These findings have the potential to optimize nitrogen removal processes and mitigate greenhouse gas emissions from WWTPs by fully harnessing the capabilities of the microbial communities.

AtALMT5 mediates vacuolar fumarate import and regulates the malate/fumarate balance in Arabidopsis.

Malate and fumarate constitute a significant fraction of the carbon fixed by photosynthesis, and they are at the crossroad of central metabolic pathways. In Arabidopsis thaliana, they are transiently stored in the vacuole to keep cytosolic homeostasis. The malate and fumarate transport systems of the vacuolar membrane are key players in the control of cell metabolism. Notably, the molecular identity of these transport systems remains mostly unresolved. We used a combination of imaging, electrophysiology and molecular physiology to identify an important molecular actor of dicarboxylic acid transport across the tonoplast. Here, we report the function of the A. thaliana Aluminium-Activated Malate Transporter 5 (AtALMT5). We characterised its ionic transport properties, expression pattern, localisation and function in vivo. We show that AtALMT5 is expressed in photosynthetically active tissues and localised in the tonoplast. Patch-clamp and in planta analyses demonstrated that AtALMT5 is an ion channel-mediating fumarate loading of the vacuole. We found in almt5 plants a reduced accumulation of fumarate in the leaves, in parallel with increased malate concentrations. These results identified AtALMT5 as an ion channel-mediating fumarate transport in the vacuoles of mesophyll cells and regulating the malate/fumarate balance in Arabidopsis.

Preferential Carbon Allocation Into Vegetative Ramets and Belowground Organs During the Seed-Filling Stage Limits Seed Set in Leymus chinensis.

Clonal perennial grasses are the dominant species in almost all natural grasslands, however their seed production is typically low. The reasons why seed set is so low remains unclear. We studied a rhizomatous grass (Leymus chinensis) using 13C tracing the different photosynthetic organs to investigate carbon fixation and allocation during the seed-filling stage. We found that the vegetative ramet leaves are the largest (81%) source for total plant fixed carbon, whereas almost all carbon is allocated to vegetative reproduction. The spike is the largest (54%) carbon source for the seeds. However, the spike produced carbon only allocated 37% to the seeds, with the majority allocated to vegetative reproduction. This preferential carbon allocation to vegetative reproduction limits sexual reproduction. Nitrogen application significantly increased assimilated carbon. However, nearly all increased carbon accumulated in the vegetative reproduction rather than in the seeds. Only the carbon produced by the spike increased its allocation to the seeds by 13%. Taken together, we conclude that the predominance of vegetative reproduction, combined with self-incompatibility, results in low ovule fertilization and very weak seed sink strength for carbon competition, suggests that the weak seed sink strength is the key reason causing low seed set in L. chinensis.

RhLHY-RhTPPF-Tre6P Inhibits Flowering in Rosa hybrida Under Insufficient Light by Regulating Sugar Distribution.

Light is crucial for flower bud development in plants, serving as both signal and energy source. However, the mechanisms by which daylength and light intensity regulate flowering in modern roses remain unclear. In Rosa hybrida 'Carola', insufficient light delays flowering and reduces the sugar content in terminal buds. RNA sequencing identified the Trehalose-6-phosphate phosphatase F (RhTPPF) gene as a key responder to insufficient light, modulating Tre6P metabolism. Overexpression of RhTPPF in rose calli enhanced sugar accumulation and suppressed the synthesis of RhCO/FT. In tobacco, overexpression of RhTPPF delayed the transition from vegetative growth to flowering, while silencing RhTPPF in roses accelerated flowering. Silencing RhTPPF in roses elevated trehalose-6-phosphate (Tre6P) levels and decreased trehalose. Transcriptome data showed that the expression level of RhTPPF was highly correlated with the circadian rhythm gene LATE ELONGATED HYPOCOTYL (RhLHY). Yeast one-hybrid assays, dual luciferase assays and EMSA revealed that RhLHY directly binds to the RhTPPF promoters. Overexpression of RhLHY suppressed flowering, while silencing RhLHY promoted flowering. Furthermore, altering the expression of RhLHY influenced Tre6P synthesis and the expression of sucrose-related transport genes. These findings suggest a RhLHY-RhTPPF-Tre6P regulatory module that maintains sugar balance and inhibits flower formation under reduced light conditions by modulating sugar distribution.

A Coupled Model of Hydraulic Eco-Physiology and Cambial Growth - Accounting for Biophysical Limitations and Phenology Improves Stem Diameter Prediction at High Temporal Resolution.

Traditional photosynthesis-driven growth models have considerable uncertainties in predicting tree growth under changing climates, partially because sink activities are directly affected by the environment but not adequately addressed in growth modelling. Therefore, we developed a semi-mechanistic model coupling stomatal optimality, temperature control of enzymatic activities and phenology of cambial growth. Parameterized using Bayesian inference and measured data on Picea abies and Pinus sylvestris in peatland and mineral soils in Finland, the coupled model simulates transpiration and assimilation rates and stem radial dimension (SRD) simultaneously at 30 min resolution. The results suggest that both the sink and phenological formulations with environmental effects are indispensable for capturing SRD dynamics across hourly to seasonal scales. Simulated using the model, growth was more sensitive than assimilation to temperature and soil water, suggesting carbon gain is not driving growth at the current temporal scale. Also, leaf-specific production was occasionally positively correlated with growth duration but not with growth onset timing or annual cambial area increment. Thus, as it is hardly explained by carbon gain, phenology itself should be included in sink-driven growth models of the trees in the boreal zone and possibly other environments where sink activities and photosynthesis are both restrained by harsh conditions.

Unravelling the neglected role of ultraviolet radiation on stomata: A meta-analysis with implications for modelling ecosystem-climate interactions.

Stomata play a pivotal role in regulating gas exchange between plants and the atmosphere controlling water and carbon cycles. Accordingly, we investigated the impact of ultraviolet-B radiation, a neglected environmental factor varying with ongoing global change, on stomatal morphology and function by a Comprehensive Meta-Analysis. The overall UV effect at the leaf level is to decrease stomatal conductance, stomatal aperture and stomatal size, although stomatal density was increased. The significant decline in stomatal conductance is marked (6% in trees and >10% in grasses and herbs) in short-term experiments, with more modest decreases noted in long-term UV studies. Short-term experiments in growth chambers are not representative of long-term field UV effects on stomatal conductance. Important consequences of altered stomatal function are hypothesized. In the short term, UV-mediated stomatal closure may reduce carbon uptake but also water loss through transpiration, thereby alleviating deleterious effects of drought. However, in the long term, complex changes in stomatal aperture, size, and density may reduce the carbon sequestration capacity of plants and increase vegetation and land surface temperatures, potentially exacerbating negative effects of drought and/or heatwaves. Therefore, the expected future strength of carbon sink capacity in high-UV regions is likely overestimated.

Improving Process-Based Modelling to Simulate the Effects of Low-Temperature Stress During Pre-Anthesis on the Quality Characteristics of Wheat Grains.

Low temperatures in late spring pose a potential threat to the maintenance of grain yield and quality. Despite the importance of protein and starch in wheat quality, they are often overlooked in models addressing climate change effects. In this study, we conducted multiyear environment-controlled phytotron experiments and observed adverse effects resulting from low-temperature stress (LTS) on plant carbon and nitrogen dynamics, grain protein and starch formation, and sink capacity. We quantified the relationships between low temperature during the jointing and booting stages and plant nitrogen uptake, grain nitrogen accumulation, grain starch accumulation, grain setting, and potential grain weight using source-sink relationship-based methods. The LTS factor was introduced to account for the cultivar-specific to LTS at different growth stages. Compared with the original model, the improved model produced fewer errors when simulating aboveground nitrogen accumulation, grain protein concentration, grain starch concentration, grain starch yield, grain number, and grain weight under LTS, with reductions of 60%, 71%, 73%, 58%, 50% and 65%, respectively. The improvements in the model enhance its mechanism and applicability in assessing short-term successive frost effects on wheat grain quality. Furthermore, when using the improved model, special attention should be given to the low-temperature sensitivity parameters.

Same, Yet Different: Towards Understanding Nutrient Use In Hemp- And Drug-Type Cannabis.

Cannabis sativa L., one of humanity's oldest cultivated crops, has a complex domestication history due to its diverse uses for fibre, seed, oil and drugs, and its wide geographic distribution. This review explores how human selection has shaped the biology of hemp and drug-type Cannabis, focusing on acquisition and utilisation of nitrogen and phosphorus, and how resulting changes in source-sink relations shape their contrasting phenology. Hemp has been optimized for rapid, slender growth and nutrient efficiency, whereas drug-type cultivars have been selected for compact growth with large phytocannabinoid producing female inflorescences. Understanding these nutrient use and ontogenetic differences will enhance our general understanding of resource allocation in plants. Knowledge gained in comparison with other model species, such as tomato, rice or Arabidopsis thaliana can help inform crop improvement and sustainability in the Cannabis industry.

Anthocyanins act as a sugar-buffer and an alternative electron sink in response to starch depletion during leaf senescence: a case study on a typical anthocyanic tree species, Acer japonicum.

We hypothesized that anthocyanins act as a sugar-buffer and an alternative electron sink during leaf senescence to prevent sugar-mediated early senescence and photoinhibition. To elucidate the role of anthocyanin, we monitored seasonal changes in photosynthetic traits, sugar, starch and N contents, pigment composition, and gene expression profiles in leaves exposed to substantially different light conditions within a canopy of an adult fullmoon maple (Acer japonicum) tree. Enhancement of starch amylolysis accompanied by cessation of starch synthesis occurred in the same manner independent of light conditions. Leaf sugar contents increased, but reached upper limits in the late stage of leaf senescence, even though leaf anthocyanins further increased after complete depletion of starch. Sun-exposed leaves maintained higher energy consumption via electron flow than shade-grown leaves during leaf N resorption. Thus, anthocyanins accumulated in sun-exposed leaves might have a regulative role as a sugar-buffer, retarding leaf senescence, and an indirect photoprotective role as an alternative sink for electron consumption to compensate declines in other metabolic processes such as starch and protein synthesis. In this context, anthocyanins may be key substrates protecting both outer-canopy leaves (against photoinhibition) and inner-canopy leaves (via shading by outer-canopy leaves) from high light stress during N resorption.