scholarly journals Delineation of post-phloem assimilate transport pathway into developing caryopsis of Brachypodium distachyon

2019 ◽  
Author(s):  
Charles Ugochukwu Solomon ◽  
Sinead Drea
Keyword(s):  
Vascular Bundle ◽  
Brachypodium Distachyon ◽  
Transfer Cells ◽  
Assimilate Transport ◽  
List Type ◽  
Transport Pathway ◽  
Crop Species ◽  
Vascular Connection ◽  
Rice Endosperm ◽  
Developing Grains

AbstractAssimilates stored in mature cereal grains are mobilized from source tissues and transported towards developing grains through the vascular bundle. Due to the lack of direct vascular connection between maternal grain vascular bundle and filial tissues, post-phloem transportation of assimilates into grain endosperm relies on transfer cells that lie between the grain vascular bundle and the endosperm. Here, we propose Caryopsis Endosperm Assimilate Acquisition Route (CEAAR) models that describes the exact path of assimilate import into caryopsis endosperms. Using fluorescent tracer dyes we also delineated the route of assimilate delivery into Brachypodium distachyon endosperm and classified it as ventral circuitous (vc-CEAAR), an assimilate import model also found in rice. Furthermore, we report a detailed anatomical study of post-phloem assimilate transport pathway in developing grains of Brachypodium distachyon. Our results highlight major anatomical similarities and differences between the grain post-phloem transfer cells of Brachypodium and those of crop species such as rice, wheat, and barley relevant to post-phloem assimilate transport.HighlightsBased on existing work, we propose Caryopsis Endosperm Assimilate Acquisition Route (CEAAR) models, that describes the exact path of assimilate import into caryopsis endosperms.The structure of the post-phloem transfer cells of Brachypodium distachyon mirrors temperate and tropical cereals.Assimilate delivery into Brachypodium distachyon endosperm is identical to assimilate import into rice endosperm.

scholarly journals LED light gradient as a screening tool for light quality responses in model plant species

2020 ◽  
Author(s):  
P. Lejeune ◽  
A. Fratamico ◽  
F. Bouché ◽  
S. Huerga Fernández ◽  
P. Tocquin ◽  
...  
Keyword(s):  
Brachypodium Distachyon ◽  
Production Costs ◽  
Fluorescent Light ◽  
Plant Responses ◽  
Light Spectrum ◽  
Crop Species ◽  
Phenotypic Data ◽  
Euphorbia Peplus ◽  
Light Gradient ◽  
Species Specific

AbstractCurrent developments in light-emitting diodes (LEDs) technologies have opened new perspectives for sustainable and highly efficient indoor cultivation. The introduction of LEDs not only allows a reduction in the production costs on a quantitative level, it also offers opportunities to manipulate and optimise qualitative traits. Indeed, while plants respond strongest to red and blue lights for photosynthesis, the whole light spectrum has an effect on plant shape, development, and chemical composition. In order to evaluate LEDs as an alternative to traditional lighting sources, the species-specific plant responses to distinct wavelengths need to be evaluated under controlled conditions. Here, we tested the possibility to use light composition gradients in combination with semi-automated phenotyping to rapidly explore the phenotypic responses of different species to variations in the light spectrum provided by LED sources. Plants of seven different species (Arabidopsis thaliana, Ocimum basilicum, Solanum lycopersicum, Brachypodium distachyon, Oryza sativa, Euphorbia peplus, Setaria viridis) were grown under standard white fluorescent light for 30 days, then transferred to a Red:Blue gradient for another 30 days and finally returned to white light. In all species, differences in terms of dimension, shape, and color were rapidly observed across the gradient and the overall response was widely species-dependent. The experiment yielded large amounts of imaging-based phenotypic data and we suggest simple data analysis methods to aggregate the results and facilitate comparisons between species. Similar experimental setups will help achieve rapid environmental optimization, screen new crop species and genotypes, or develop new gene discovery strategies.

scholarly journals Growth and grain yield of eight maize hybrids is aligned with water transport, stomatal conductance, and photosynthesis in a semi-arid irrigated system

2021 ◽  
Author(s):  
Sean M Gleason ◽  
Lauren Nalezny ◽  
Cameron Hunter ◽  
Robert Bensen ◽  
Satya Chintamanani ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Grain Yield ◽  
Water Transport ◽  
Co2 Assimilation ◽  
Specific Conductance ◽  
Soil Conditions ◽  
Transport Pathway ◽  
Crop Species ◽  
Leaf Level ◽  
Improved Performance

There is increasing interest in understanding how trait networks can be manipulated to improve the performance of crop species. Working towards this goal, we have identified key traits linking the acquisition of water, the transport of water to the sites of evaporation and photosynthesis, stomatal conductance, and growth across eight maize hybrid lines grown under well-watered and water-limiting conditions in Northern Colorado. Under well-watered conditions, well-performing hybrids exhibited high leaf-specific conductance, low operating water potentials, high rates of midday stomatal conductance, high rates of net CO2 assimilation, greater leaf osmotic adjustment, and higher end-of-season growth and grain yield. This trait network was similar under water-limited conditions with the notable exception that linkages between water transport, midday stomatal conductance, and growth were even stronger than under fully-watered conditions. The results of this experiment suggest that similar trait networks might confer improved performance under contrasting climate and soil conditions, and that efforts to improve the performance of crop species could possibly benefit by considering the water transport pathway within leaves, as well as within the whole-xylem, in addition to root-level and leaf-level traits.

scholarly journals Asparagine accumulation in chicory storage roots is controlled by translocation and feedback regulation of asparagine biosynthesis in leaves

2020 ◽  
Author(s):  
Emanoella Soares ◽  
Leonard Shumbe ◽  
Nicholas Dauchot ◽  
Christine Notté ◽  
Claire Prouin ◽  
...  
Keyword(s):  
Public Health ◽  
High Temperature ◽  
Feedback Loop ◽  
Reducing Sugars ◽  
Feedback Regulation ◽  
Negative Feedback Loop ◽  
List Type ◽  
Storage Roots ◽  
Crop Species ◽  
Selection Of

SummaryThe presence of acrylamide (AA), a potentially carcinogenic and neurotoxic compound, in food has become a major concern for public health. AA in plant-derived food mainly arises from the reaction of the amino acid asparagine (Asn) and reducing sugars during processing of foodstuffs at high temperature.Using a selection of genotypes from the chicory germplasm we performed Asn measurements in storage roots and leaves to identify genotypes contrasting for Asn accumulation. We combined molecular analysis and grafting experiments to show that leaf to root translocation controls asparagine biosynthesis and accumulation in chicory storage roots.We could demonstrate that Asn accumulation in storage roots depends on Asn biosynthesis and transport from the leaf, and that a negative feedback loop by Asn on CiASN1 expression impacts Asn biosynthesis in leaves.Our results provide a new model for asparagine biosynthesis in root crop species and highlight the importance of characterizing and manipulating asparagine transport to reduce AA content in processed plant-based foodstuffs.

scholarly journals Arabidopsis leaf hydraulic conductance is regulated by xylem-sap pH, controlled, in turn, by a P-type H+-ATPase of vascular bundle sheath cells

2017 ◽  
Author(s):  
Yael Grunwald ◽  
Noa Wigoda ◽  
Nir Sade ◽  
Adi Yaaran ◽  
Tanmayee Torne ◽  
...  
Keyword(s):  
Proton Pump ◽  
Vascular Bundle ◽  
Xylem Sap ◽  
Hydraulic Conductance ◽  
Bundle Sheath ◽  
List Type ◽  
Mesophyll Cells ◽  
Leaf Hydraulic Conductance ◽  
Bundle Sheath Cells ◽  
Sheath Cells

AbstractThe leaf vascular bundle sheath cells (BSCs) that tightly envelop the leaf veins, are a selective and dynamic barrier to xylem-sap water and solutes radially entering the mesophyll cells. Under normal conditions, xylem-sap pH of <6 is presumably important for driving and regulating the transmembranal solute transport. Having discovered recently a differentially high expression of a BSCs proton pump, AHA2, we now test the hypothesis that it regulates this pH and leaf radial water fluxes.We monitored the xylem-sap pH in the veins of detached leaves of WT Arabidopsis, AHA mutants, and aha2 mutants complemented with AHA2 gene solely in BSCs. We tested an AHA inhibitor and stimulator, and different pH buffers. We monitored their impact on the xylem-sap pH and the whole leaf hydraulic conductance (Kleaf), and the effect of pH on the water osmotic permeability (Pf) of isolated BSCs protoplasts.Our results demonstrated that AHA2 is necessary for xylem-sap acidification, and in turn, for elevating Kleaf. Conversely, knocking out AHA2 alkalinized the xylem-sap. Also, elevating xylem sap pH to 7.5 reduced Kleaf and elevating external pH to 7.5 decreased the BSCs Pf.All these demonstrate a causative link between AHA2 activity in BSCs and leaf radial water conductance.One-sentence summaryBundle-sheath cells can control the leaf hydraulic conductance by proton-pump-regulated xylem sap pH

scholarly journals Changes in ambient temperature are the prevailing cue in determining Brachypodium distachyon diurnal gene regulation

2019 ◽  
Author(s):  
Kirk J-M. MacKinnon ◽  
Benjamin J. Cole ◽  
Chang Yu ◽  
Joshua H. Coomey ◽  
Nolan T. Hartwick ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Regulation ◽  
Circadian Clock ◽  
Clock Genes ◽  
Brachypodium Distachyon ◽  
Regulation Of Gene Expression ◽  
Enrichment Analysis ◽  
Grass Species ◽  
List Type ◽  
Sequence Motifs

SUMMARYPlants are continuously exposed to diurnal fluctuations in light and temperature, and spontaneous changes in their physical or biotic environment. The circadian clock coordinates regulation of gene expression with a 24-hour period, enabling the anticipation of these events.We used RNA sequencing to characterize the Brachypodium distachyon transcriptome under light and temperature cycles, as well as under constant conditions.Approximately 3% of the transcriptome was regulated by the circadian clock, a smaller proportion reported in most other species. For most transcripts that were rhythmic under all conditions, including many known clock genes, the period of gene expression lengthened from 24 to 27 h in the absence of external cues. To functionally characterize the cyclic transcriptome in B. distachyon, we used Gene Ontology enrichment analysis, and found several terms significantly associated with peak expression at particular times of the day. Furthermore we identified sequence motifs enriched in the promoters of similarly-phased genes, some potentially associated with transcription factors.When considering the overlap in rhythmic gene expression and specific pathway behavior, thermocycles was the prevailing cue that controlled diurnal gene regulation. Taken together, our characterization of the rhythmic B. distachyon transcriptome represents a foundational resource with implications in other grass species.

scholarly journals Programmed Cell Death in Developing Brachypodium distachyon Grain

2021 ◽  
Vol 22 (16) ◽  
pp. 9086
Author(s):  
Safia Saada ◽  
Charles Ugochukwu Solomon ◽  
Sinéad Drea
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Grain Shape ◽  
Brachypodium Distachyon ◽  
Endosperm Development ◽  
Developmental Sequence ◽  
Model Species ◽  
Processing Enzymes ◽  
Molecular Aspects ◽  
Developing Grains

The normal developmental sequence in a grass grain entails the death of several maternal and filial tissues in a genetically regulated process termed programmed cell death (PCD). The progression and molecular aspects of PCD in developing grains have been reported for domesticated species such as barley, rice, maize and wheat. Here, we report a detailed investigation of PCD in the developing grain of the wild model species Brachypodium distachyon. We detected PCD in developing Brachypodium grains using molecular and histological approaches. We also identified in Brachypodium the orthologs of protease genes known to contribute to grain PCD and surveyed their expression. We found that, similar to cereals, PCD in the Brachypodium nucellus occurs in a centrifugal pattern following anthesis. However, compared to cereals, the rate of post-mortem clearance in the Brachypodium nucellus is slower. However, compared to wheat and barley, mesocarp PCD in Brachypodium proceeds more rapidly in lateral cells. Remarkably, Brachypodium mesocarp PCD is not coordinated with endosperm development. Phylogenetic analysis suggests that barley and wheat possess more vacuolar processing enzymes that drive nucellar PCD compared to Brachypodium and rice. Our expression analysis highlighted putative grain-specific PCD proteases in Brachypodium. Combined with existing knowledge on grain PCD, our study suggests that the rate of nucellar PCD moderates grain size and that the pattern of mesocarp PCD influences grain shape.

scholarly journals Programmed Cell Death in the Developing Brachypodium distachyon Grain

2019 ◽  
Author(s):  
Safia Saada ◽  
Charles Ugochukwu Solomon ◽  
Sinéad Drea
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Grain Shape ◽  
Brachypodium Distachyon ◽  
Endosperm Development ◽  
List Type ◽  
Developmental Sequence ◽  
Model Species ◽  
Processing Enzymes ◽  
Molecular Aspects

SummaryThe normal developmental sequence in a grass grain entails the death of several maternal and filial tissues in a genetically regulated process termed programmed cell death (PCD). The progression and molecular aspects of PCD in developing grain have been reported for domesticated species like barley, rice, maize and wheat. Here, we report a detailed investigation of PCD in the developing grain of a wild model species, Brachypodium distachyon.We detected PCD in developing Brachypodium grains using molecular and histological approaches. We also identified and surveyed the expression of Brachypodium orthologs of protease genes known to contribute to grain PCD.We found that Brachypodium nucellus degenerates by PCD in a centrifugal pattern following anthesis, although at a slower rate compared to cultivated cereals. Mesocarp PCD was not coordinated with endosperm development. Brachypodium lacks an expansion of vacuolar processing enzymes known for their roles in nucellar PCD.Combined with existing knowledge on grain PCD, our study suggests the importance of rapid nucellar PCD for grain size and that the pattern of mesocarp PCD affects grain shape.

The paraveinal mesophyll: a specialized path for intermediary transfer of assimilates in legume leaves

2000 ◽  
Vol 27 (9) ◽  
pp. 757 ◽  
Author(s):  
Alexis J. Lansing ◽  
Vincent R. Franceschi
Keyword(s):  
Vascular System ◽  
Phloem Loading ◽  
Assimilate Transport ◽  
Vascular Bundles ◽  
Transport Pathway ◽  
Mesophyll Cells ◽  
Diffusion Limitations ◽  
Unit Leaf ◽  
Paraveinal Mesophyll ◽  
Leaf Surface Area

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 The distance between sites of synthesis of assimilates and the site of phloem loading can be large, and specialized leaf cell layers such as the paraveinal mesophyll (PVM) might act to enhance the efficiency of transport. A number of techniques were used to analyse PVM of legume leaves with respect to a hypothesized function in transfer of assimilates between tissues. Of 39 legume species examined, PVM was found in 22. Leaves of all PVM-containing species had multiple palisade parenchyma layers, while non-PVM species generally had only one distinct palisade layer. Morphometric analysis identified a significant correlation between PVM presence and greater numbers of palisade cells per unit leaf surface area. Comparison of photosynthetic rates of four PVM and four non-PVM species showed the PVM species had higher rates on a leaf area basis than all but one of the non-PVM species. Microautoradiography of 14CO2 pulse–chase studies in soybean demonstrated PVM is an intermediary tissue in transfer of assimilates to vascular bundles. In addition, PVM cells but not mesophyll cells, were enriched in a sucrose binding protein previously found to be associated with sucrose-transporting tissues. The structural, positional and transport data support the hypothesis that the PVM acts as a transport pathway between the vascular system and photoassimilatory cells of the leaf, and has probably evolved to overcome diffusion limitations imposed by multiple palisade layers.

scholarly journals Diversity, dynamics and effects of LTR retrotransposons in the model grass Brachypodium distachyon

2019 ◽  
Author(s):  
C Stritt ◽  
M Wyler ◽  
EL Gimmi ◽  
M Pippel ◽  
AC Roulin
Keyword(s):  
Brachypodium Distachyon ◽  
Gc Content ◽  
List Type ◽  
High Plasticity ◽  
Long Terminal Repeat Retrotransposon ◽  
Transpositional Activity ◽  
Genome Wide ◽  
Model Grass ◽  
Diversity Dynamics ◽  
Evolutionary Lineages

SummaryTransposable elements (TEs) are the main reason for the high plasticity of plant genomes, where they occur as communities of diverse evolutionary lineages. Because research has typically focused on single abundant families or summarized TEs at a coarse taxonomic level, our knowledge about how these lineages differ in their effects on genome evolution is still rudimentary.Here we investigate the community composition and dynamics of 32 long terminal repeat retrotransposon (LTR-RT) families in the 272 Mb genome of the Mediterranean grass Brachypodium distachyon.We find that much of the recent transpositional activity in the B. distachyon genome is due to centromeric Gypsy families and Copia elements belonging to the Angela lineage. With a half-life as low as 66 ky, the latter are the most dynamic part of the genome and an important source of within-species polymorphisms. Second, GC-rich Gypsy elements of the Retand lineage are the most abundant TEs in the genome. Their presence explains more than 20 percent of the genome-wide variation in GC content and is associated to higher methylation levels.Our study shows how individual TE lineages change the genetic and epigenetic constitution of the host beyond simple changes in genome size.

scholarly journals Increased SBPase activity improves photosynthesis and grain yield in wheat grown in greenhouse conditions

2017 ◽  
Vol 372 (1730) ◽  
pp. 20160384 ◽  
Author(s):  
Steven M. Driever ◽  
Andrew J. Simkin ◽  
Saqer Alotaibi ◽  
Stuart J. Fisk ◽  
Pippa J. Madgwick ◽  
...  
Keyword(s):  
Seed Yield ◽  
Brachypodium Distachyon ◽  
Yield Potential ◽  
Total Biomass ◽  
Leaf Photosynthesis ◽  
Primary Target ◽  
Crop Species ◽  
Cycle Enzyme ◽  
Protein Levels ◽  
Transgenic Lines

To meet the growing demand for food, substantial improvements in yields are needed. This is particularly the case for wheat, where global yield has stagnated in recent years. Increasing photosynthesis has been identified as a primary target to achieve yield improvements. To increase leaf photosynthesis in wheat, the level of the Calvin–Benson cycle enzyme sedoheptulose-1,7-biphosphatase (SBPase) has been increased through transformation and expression of a Brachypodium distachyon SBPase gene construct. Transgenic lines with increased SBPase protein levels and activity were grown under greenhouse conditions and showed enhanced leaf photosynthesis and increased total biomass and dry seed yield. This showed the potential of improving yield potential by increasing leaf photosynthesis in a crop species such as wheat. The results are discussed with regard to future strategies for further improvement of photosynthesis in wheat. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

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