Plant, Cell & Environment最新文献

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.

Photoperiod/thermo-sensitive genic male sterility (P/TGMS) is critical for rice two-line hybrid system. Previous studies showed that slow development of pollen is a general mechanism for sterility-to-fertility conversion of TGMS in Arabidopsis. However, whether this mechanism still exists in rice is unknown. Here, we identified a novel rice TGMS line, ostms16, which exhibits abnormal pollen exine under high temperature and fertility restoration under low temperature. In mutant, a single base mutation of OsTMS16, a fatty acyl-CoA reductase (FAR), reduced its enzyme activity, leading to defective pollen wall. Under high temperature, the mOsTMS16^M549I couldn't provide sufficient protection for the microspores. Under low temperature, the enzyme activity of mOsTMS16^M549I is closer to that of OsTMS16, so that the imperfect exine could still protect microspore development. These results indicated whether the residual enzyme activity in mutant could meet the requirement in different temperature is a determinant factor for fertility conversion of P/TGMS lines. Additionally, we previously found that res2, the mutant of a polygalacturonase for tetrad pectin wall degradation, restored multiple TGMS lines in Arabidopsis. In this study, we proved that the osres2 in rice restored the fertility of ostms16, indicating the slow development is also suitable for the fertility restoration in rice.

Salt stress constrains the development and growth of plants. To tolerate it, mechanisms of endocytosis and vacuolar compartmentalization of Na⁺ are induced. In this work, the genes that encode a putative activator of vesicular trafficking called MON1/CCZ1 from Solanum chilense, SchMON1 and SchCCZ1, were co-expressed in roots of Arabidopsis thaliana to determine whether the increase in prevacuolar vesicular trafficking also increases the Na⁺ compartmentalization capacity and tolerance. Initially, we demonstrated that both SchMON1 and SchCCZ1 genes rescued the dwarf phenotype of both A. thaliana mon1-1 and ccz1a/b mutants associated with the loss of function, and both proteins colocalized with their functional targets, RabF and RabG, in endosomes. Transgenic A. thaliana plants co-expressing these genes improved salt stress tolerance compared to wild type plants, with SchMON1 contributing the most. At the sub-cellular level, co-expression of SchMON1/SchCCZ1 reduced ROS levels and increased endocytic activity, and number of acidic structures associated with autophagosomes. Notably, greater Na⁺ accumulation in vacuoles of cortex and endodermis was evidenced in the SchMON1 genotype. Molecular analysis of gene expression in each genotype supported these results. Altogether, our analysis shows that root activation of prevacuolar vesicular trafficking mediated by MON1/CCZ1 emerges as a promising physiological molecular mechanism to increase tolerance to salt stress in crops of economic interest.

As the single link between leaves and the rest of the plant, petioles must develop conductive tissues according to the water influx and sugar outflow of the leaf lamina. A scaling relationship between leaf area and anatomical traits of xylem and phloem is expected to improve the efficiency of these tissues. However, the different constraints compromising the functionality of both tissues (e.g., risk of cavitation) must not be disregarded. Additionally, deciduous and evergreen plants may have different strategies to produce and package their petiole conduits to cope with environmental restrictions. We explored in 33 oak species the relationships between petiole anatomical traits, leaf area, stomatal conductance, and photosynthesis rate. Results showed allometric scaling between anatomical structure of xylem and phloem with leaf area. We also found correlations between photosynthesis rate, stomatal conductance, and anatomical traits in the petiole. The main novelty is how oaks present a different strategy depending on the leaf habit. Deciduous species tend to increase their diameters to achieve greater leaf-specific conductivity. By contrast, evergreen oaks develop larger xylem conductive areas for a given leaf area than deciduous ones. This trade-off between safety-efficiency in petioles has never been attributed to the leaf habit of the species.

Soybean (Glycine max) is the single most important global source of vegetable protein. Yield improvements per unit land area are needed to avoid further expansion onto natural systems. Mesophyll conductance (g_m) quantifies the ease with which CO₂ can diffuse from the sub-stomatal cavity to Rubisco. Increasing g_m is attractive since it increases photosynthesis without increasing water use. Most measurements of g_m have been made during steady-state light saturated photosynthesis. In field crop canopies, light fluctuations are frequent and the speed with which g_m can increase following shade to sun transitions affects crop carbon gain. Is there variability in g_m within soybean germplasm? If so, indirect selection may have indirectly increased g_m during domestication and subsequent breeding for sustainability and yield. A modern elite cultivar (LD11) was compared with four ancestor accessions of Glycine soja from the assumed area of domestication by concurrent measurements of gas exchange and carbon isotope discrimination (∆¹³C). g_m was a significant limitation to soybean photosynthesis both at steady state and through light induction but was twice the value of the ancestors in LD11. This corresponded to a substantial increase in leaf photosynthetic CO₂ uptake and water use efficiency.

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.

Pseudomonas syringae pv. actinidiae biovar 3 (Psa3) has decimated kiwifruit orchards growing susceptible kiwifruit Actinidia chinensis varieties. Effector loss has occurred recently in Psa3 isolates from resistant kiwifruit germplasm, resulting in strains capable of partially overcoming resistance present in kiwiberry vines (Actinidia arguta, Actinidia polygama, and Actinidia melanandra). Diploid male A. melanandra recognises several effectors, sharing recognition of at least one avirulence effector (HopAW1a) with previously studied tetraploid kiwiberry vines. Sequencing and assembly of the A. melanandra genome enabled the characterisation of the transcriptomic response of this non-host to wild-type and genetic mutants of Psa3. A. melanandra appears to mount a classic effector-triggered immunity (ETI) response to wildtype Psa3 V-13, as expected. Surprisingly, the type III secretion (T3SS) system-lacking Psa3 V-13 ∆hrcC strain did not appear to trigger pattern-triggered immunity (PTI) despite lacking the ability to deliver immunity-suppressing effectors. Contrasting the A. melanandra responses to an effectorless Psa3 V-13 ∆33E strain and to Psa3 V-13 ∆hrcC suggested that PTI triggered by Psa3 V-13 was based on the recognition of the T3SS itself. The characterisation of both ETI and PTI branches of innate immunity responses within A. melanandra further enables breeding for durable resistance in future kiwifruit cultivars.

Lycoris aurea, celebrated for its visually striking flowers and significant medicinal value due to the presence of alkaloids such as lycorine and galanthamine, has intricate yet poorly understood regulatory mechanisms. This study provides a detailed examination of the transcriptomic, metabolomic and ecological dynamics of L. aurea, aiming to elucidate the underlying molecular mechanisms of alkaloid biosynthesis. Our comparative analysis across different ecological settings highlighted key genes involved in alkaloid biosynthesis, such as genes encoding aldehyde dehydrogenase and norbelladine 4'-O-methyltransferase, which were distinctively increased in the high alkaloids-producing group. We identified a total of 6871 differentially expressed genes and 915 metabolites involved in pathways like terpenoid backbone biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis. Protein interaction network analysis revealed significant upregulation of photosynthesis, photosystem and photosynthetic membrane pathways in the alkaloids-producing region. Furthermore, our research delineated the interactions among soil microbial communities, genes and plant and soil biochemical properties, noting that bacterial populations correlate with soil properties that favour the activation of metabolic pathways essential for alkaloid production. Collectively, this study advances our understanding of the genetic and metabolic alkaloid biosynthesis pathways in L. aurea, shedding light on the complex interactions that govern alkaloid production.

Actin depolymerizing factors (ADFs), like other actin-binding proteins (ABPs), are modified by phosphorylation to regulate the dynamics of the actin filaments, thereby functioning in various processes throughout the plant lifecycle. In this study, we found that the Arabidopsis thaliana cytoplasmic kinase AGC1.7 interacts with ADF7 in vitro and in vivo. AGC1.7 phosphorylates ADF7 at its Ser-6, Ser-103 and Ser-104 residues in vitro, while replacing these residues with alanine promotes ADF7-mediated actin depolymerization in vitro. Expression of the phosphorylation-mimetic mutant protein ADF7^S6/103/104D driven by the pollen-specific LAT52 promoter fully rescues the defects in germination rate, silique length and seeds per silique in both adf7-2 and agc1.5 agc1.7 (agcdm) mutants. Our data establish a model whereby AGC1.7-mediated ADF7 phosphorylation plays an important role in pollen germination and pollen tube growth.

Plants produce an immense diversity of defensive specialized metabolites. However, despite extensive functional characterization, the relative importance of different defensive compounds is rarely examined in natural settings. Here, we compare the efficacy of three Nicotiana benthamiana defensive compounds, nicotine, acylsugars and a serine protease inhibitor, by growing plants with combinations of knockout mutations in a natural setting, quantifying invertebrate interactions and comparing relative plant performance. Among the three tested compounds, acylsugars had the greatest defensive capacity, affecting aphids, leafhoppers, spiders and flies. Nicotine mutants displayed increased leafhopper feeding and aphid colonization. Plants lacking both nicotine and acylsugars were more susceptible to flea beetles and thrips. By contrast, knockout of the serine protease inhibitor did not affect insect herbivory in the field. Complementary experiments under controlled laboratory conditions with caterpillars, grasshoppers and aphids confirmed results obtained in a natural setting. We conclude that the three metabolite groups collectively provide broad-spectrum protection to N. benthamiana. However, there is a gradient in their effects on the interacting invertebrates present in the field. Furthermore, we demonstrate that, even if individual metabolites do not have a measurable defensive benefit on their own, they can have an additive effect when combined with other defensive compounds.