Annals of botany最新文献

Background and aims: The Lateral Organ Boundaries Domain (LBD) transcription factors play a significant role in root development and abiotic stress in plants. In a previous study, the LBD family gene ThLBD11 was cloned and characterized from Tamarix hispida, being positioned at the second layer of the salt stress gene regulatory network (GRN) in T. hispida. Suggesting that ThLBD11 may play a role in the salt stress process.

Methods: We investigated the salt tolerance function and regulatory mechanisms of ThLBD11 using multiple sequence alignment, phylogenetic tree analysis, biochemical staining, physiological indicators, yeast one-hybrid (Y1H), Electrophoretic Mobility Shift Assay (EMSA), GUS histochemical analysis, GO enrichment analysis, Chromatin immunoprecipitation assay (ChIP) and RT-qPCR.

Key results: In this study, the ThLBD11 was overexpressed in T. hispida. Under salt stress, the OE lines exhibited elevated antioxidant enzyme activity, reduced cellular damage and regulated ion homeostasis. The Y1H, EMSA and GUS histochemical analysis results showed that ThLBD11 was able to specifically bind to CGGC cis-element. By integrating GO enrichment analysis and promoter CGGC element counts, two downstream target genes (ThAHL27, ThATPD) of ThLBD11 in the GRN were confirmed. The RT-qPCR and ChIP-PCR results indicated that ThLBD11 negatively regulated the expression of ThAHL27 and ThATPD by directly binding to their promoter fragments containing the CGGC motif.

Conclusions: ThLBD11 acts as a positive regulator of salt stress tolerance in T. hispida by inhibiting the expression of ThAHL27 and ThATPD. These findings contribute to the understanding of the regulatory mechanism of salt stress adaptation in T. hispida.

Background and aims: Crop growth models (CGM) are a valuable tool for predicting crop performance in contrasting growing conditions and interpreting crop responses to future scenarios. Inaccuracies in the simulation of leaf area dynamics directly impact estimates of intercepted radiation, biomass production and transpiration demand by the crop, especially during the early stages when the canopy is not yet fully covering the soil. An empirical bell-shaped function of individual leaf area versus leaf position, combined with the response of leaf appearance to thermal time, is used in many CGMs to simulate total leaf area per axis and generate canopy leaf area index. This study proposes that an individual leaf area approach, based on predicting blade length and blade width of successive leaves, can make modelling of leaf area dynamics less empirical, while offering the flexibility to better simulate genotypic, and genotypic × environment interaction effects in sorghum (Sorghum bicolor (L.) Moench), maize (Zea mays L.), and pearl millet (Pennisteum americanum L.).

Methods: A generic model of leaf area by leaf position was developed using data on individual blade length and width compiled from numerous experiments over the period 1990-2022 that involved a broad range of genotypes of sorghum, maize, and pearl millet.

Key results: This study developed and tested a generic individual leaf size model for maize, sorghum and pearl millet, based on relationships quantifying length and width of successive leaves. Generic parameters of an expolinear-logistic model obtained across species and related to total leaf number (TLN) as appropriate, facilitated satisfactory predictive performance for blade length, width, and leaf area profiles. Genotypic-specific parameters improved model predictions in this study.

Conclusions: Improvements in parameterisation of canopy development in CGM can enhance predictions of Genotype × Environment × Management (G×E×M) interactions to support identifying breeding targets for enhanced yield and strategies for sustainable crop management.

Background and aims: Dry dehiscent fruits have independently evolved multiple times during angiosperm diversification. A striking example is the convergent evolution of Brassicaceae siliques and Papaveraceae pods, both formed by two fused carpels forming valves that meet at a replum or replum-like structure. In both cases, valve separation occurs through a dehiscence zone at the valve margins in contact with the replum. In Arabidopsis, fruit development is regulated by transcription factors: FRUITFULL (FUL) ensures proper valve cell division, REPLUMLESS (RPL) specifies replum identity and SHATTERPROOF (SHP1/2) genes pattern the dehiscence zone. SHP1/2 also regulate INDEHISCENT (IND) for lignified layer formation and ALCATRAZ (ALC) and SPATULA (SPT) for the non-lignified layer. The network is downregulated by APETALA2 (AP2), which influences replum formation and valve margin growth.

Methods: Using previously published and new in situ RNA hybridization expression data, we evaluated how this network applies to basal eudicots.

Key results: In Bocconia frutescens, homologue expression suggests conserved roles for FUL and AP2 in fruit wall proliferation, acting antagonistically to ALC and RPL homologues localized to the dehiscence zone. A role for STK homologues in dehiscence zone formation cannot be excluded, while a role of AG-like genes, the closest homologues of SHP during fruit development, is unlikely.

Conclusions: Our findings indicate significant rewiring of the fruit developmental network between basal and core eudicots, underscoring the need for functional studies in non-eudicot species to validate this framework.

Background and aims: Throughout leaf development, cell expansion is dynamic and driven by the balance between local cell wall mechanical properties and the intracellular turgor pressure that overcomes the stiffness of the cell wall leading to plastic deformation. The epidermal pavement cells in most leaves begin development as small, polygonally shaped cells, but in mature leaves epidermal pavement cells are often shaped as highly lobed puzzle pieces. However, the developmental and biomechanical trajectories between these two end points have not before been fully characterized.

Methods: We characterized how epidermal pavement cell size and shape, cell wall thickness and hydraulic traits change during leaf expansion in the tropical understorey fern Microsorum grossum (Polypodiaceae).

Key results: As fronds expanded by approximately two orders of magnitude in size, epidermal pavement cells became increasingly lobed as cell walls thickened. Furthermore, the timing of these developmental changes varied across the lamina, starting first near the frond base and midrib, followed by more apical and lateral regions. During expansion, fronds also underwent substantial physiological changes: as cells expanded and cell walls thickened, intracellular turgor pressure and the bulk cell wall modulus of elasticity both increased while the water potential at turgor loss and the minimum epidermal conductance to water vapour both decreased.

Conclusions: These results highlight the dynamic coordination between anatomical and physiological traits throughout leaf development, provide valuable data for biophysical modelling of leaf development, and highlight the vulnerability of developing leaves to drought conditions.

Background and aims: Successional theory predicts directional shifts in plant community composition following disturbance. However, the long-term effects of chronic, recurring disturbances on plant ecological strategies at the community level in human-altered landscapes, and how they differ between the assemblages of native and alien species, remain poorly understood.

Methods: Using Grime's competitor, stress-tolerator, ruderal (CSR) framework, we examine temporal and spatial changes in plant strategies at the community level in the Three Gorges Reservoir Area, China. Based on repeated plant community surveys in 2012 and 2018 at the same localities, we assess the differences in the assemblages of native and alien strategies in response to chronic disturbances by extreme hydrological fluctuations and intense human activities over time and along a shoreline-to-upland disturbance gradient.

Key results: Our results reveal a temporal shift in native assemblages, with a decline in R-score and an increase in C- and S-scores, while alien assemblages maintained a strong R-strategy. Spatial patterns show that native assemblages adopted a mid-elevation peak in C-strategy, with S- and R-strategies dominating at higher and lower elevations, respectively. In contrast, there is no spatial variation in the CSR strategies of alien plant assemblages.

Conclusions: Our findings demonstrate that chronic disturbances (e.g. water fluctuations and human activities) drive a spatiotemporal decoupling of the CSR strategies between native and alien plant assemblages. This divergence requires targeted management by prioritizing suppression of ruderal alien species and promoting competitive and stress-tolerant native species to guide succession dynamics.

Background and aims: Intraspecific trait variations in response to nutrient availability are expected to depend on (1) the category of traits considered, and (2) species ecology, with species requiring high nutrient levels expected to be more plastic. However, there are few comparisons of trait responses considering simultaneously (a) above-ground traits approximating ecological strategies, (b) root traits involved in nutrient acquisition, and (c) traits integrating the whole plant, and including multiple species.

Methods: We studied 17 annual species coming from two contrasted environments in the same rangeland of southern France. Plants were grown in a common garden under two fertilization treatments.

Key results: We evidenced no effect of origin on trait values, suggesting little or no differentiation according to the environment of origin. Among the 14 traits measured, whole-plant traits, in particular plant nitrogen content, plant dry mass and root mass fraction, showed strong plastic responses to fertilization, whereas the response was weak or even absent for above- and below-ground organ-level traits related to ecological strategies, suggesting that they play a secondary role in plant responses to nutrient availability. Finally, species' ecological preferences (i.e. their nutrient requirements), predicted the plasticity in plant nitrogen content per mass, whereas species position along the acquisition-conservation trade-off (approximated by leaf traits) predicted plasticity in plant dry mass. This cautions against the systematic use of leaf traits as a proxy of species ecology and functioning.

Conclusions: Our results challenge the assumption that leaf traits universally reflect plant responses to nutrient availability. They advocate a better characterization of traits directly involved in nutrient acquisition and underscore the importance of considering how trait-trait and trait-environment relationships may depend on the group of species considered. These findings offer an avenue for more accurate predictions of plant responses to nutrient gradients in natural and managed ecosystems.

Background and aims: Botanical literature is filled with studies which tried to demonstrate that leaves of many gymnosperms have an endodermis with Casparian bands or a sheath of sclerified cells around leaf veins. Direct photographic evidence of an endodermis with Casparian bands (strips) is lacking for the leaves of many gymnosperms. Our goal was to confirm with direct evidence an endodermis with Casparian bands or a vein sheath in leaves of representative gymnosperms via histochemical staining and epifluorescence microscopy, while extending previous work by examining understudied petioles and leaf bases.

Methods: We sectioned leaves fresh with razor blades and viewed them unstained or stained, usually with berberine hemisulfate, counterstained with gentian violet, and phloroglucinol HCl. Bright-field, epifluorescence and/or laser confocal microscopies on a Zeiss LSM700 were used for viewing and imaging.

Key results: Most members of Pinaceae of Pinophyta (13 species of genera Cedrus, Pseudotsuga, Larix, Picea and Pinus) had endodermis with distinct Casparian bands in needles. We identified endodermis in the distal petiolar regions of nine of these same species. Sclerified vein sheaths or partial vein sheaths were observed in 10 species of 41 studied among Cycadophyta (Cycas), Ginkgophyta (Ginkgo) and the Pinophyta Podocarpaceae (Dacrycarpus, Dacrydium), Cupressaceae (Metasequoia), Taxaceae (Amentotaxus) and Pinaceae (Keteleeria, Abies, Tsuga).

Conclusions: Endodermis with Casparian bands is only characteristic of most species of Pinaceae; vein sheaths are found in three genera of Pinaceae and six genera of the other families of gymnosperms, but most gymnospermous leaves lack endodermis and vein sheath, particularly in petiolar and leaf base regions. The presence of endodermis with Casparian bands could have contributed to the adaptation of the Pinaceae to extreme environments; members of genera such as Picea and Pinus are the typical treeline species in many mountain ranges across the world.

Background: Brown algae developed multicellularity independently of plants and animals. Once formed, the embryo rapidly establishes growth hotspots that lay the foundation for the development of the adult stage. The mechanisms that control the establishment of these growth hotspots are unknown.

Scope: Using diagrams and 3-D schematics, this review unpacks the different growth strategies of these organisms, focusing on localized 3-D growth in a particular cell or tissue. The sequence of cell divisions leading to the formation of 3-D tissues is compared among algae of the orders Sphacelariales, Dictyotales, Laminariales and Fucales, thereby providing an overview of the range of growth strategies selected in this phylum. I specifically focus on the orientation of cell divisions, which generally alternates in most brown algae, being perpendicular to the previous plane of cell division. These cell division characteristics, specific to brown algae, implement the building plans of 3-D bodies.

Conclusions: This review highlights the diversity of 3-D growth strategies within the brown algae, illustrating several cases and providing a framework for a broader comparison with other multicellular organisms, which developed 3-D tissues elsewhere within the eukaryote tree. It also addresses the potential underlying cellular mechanisms that control cell division plane orientation, and questions the level of cell autonomy with respect to neighbouring cells and the external environment.