65 research outputs found
Transpiration difference under high evaporative demand in chickpea ( Cicer arietinum L.) may be explained by differences in the water transport pathway in the root cylinder
Terminal drought substantially reduces chickpea yield. Reducing water use at vegetative
stage by reducing transpiration under high vapor pressure deficit (VPD), i.e. under dry/
hot conditions, contributes to drought adaptation. We hypothesized that this trait could
relate to differences in a genotype’s dependence on root water transport pathways and
hydraulics.
• Transpiration rate responses in conservative and profligate chickpea genotypes were
evaluated under increasing VPD in the presence/absence of apoplastic and cell-to-cell
transport inhibitors.
• Conservative genotypes ICC 4958 and ICC 8058 restricted transpiration under high
VPD compared to the profligate genotypes ICC 14799 and ICC 867. Profligate genotypes
were more affected by aquaporin inhibition of the cell-to-cell pathway than conservative
genotypes, as measured by the root hydraulic conductance and transpiration
under high VPD. Aquaporin inhibitor treatment also led to a larger reduction in root
hydraulic conductivity in profligate than in conservative genotypes. In contrast, blockage
of the apoplastic pathway in roots decreased transpiration more in conservative
than in profligate genotypes. Interestingly, conservative genotypes had high early vigour,
whereas profligate genotypes had low early vigour.
• In conclusion, profligate genotypes depend more on the cell-to-cell pathway, which
might explain their higher root hydraulic conductivity, whereas water-saving by
restricting transpiration led to higher dependence on the apoplastic pathway. This
opens the possibility to screen for conservative or profligate chickpea phenotypes using
inhibitors, itself opening to the search of the genetic basis of these differences
Lymph vessels:the forgotten second circulation in health and disease
The lymphatic circulation is still a somewhat forgotten part of the circulatory system. Despite this, novel insights in lymph angiogenesis in health and disease, application of immune markers for lymphatic growth and differentiation and also the introduction of new imaging techniques to visualize the lymphatic circulation have improved our understanding of lymphatic function in both health and disease, especially in the last decade. These achievements yield better understanding of the various manifestations of lymph oedemas and malformations, and also the patterns of lymphovascular spread of cancers. Immune markers that recognize lymphatic endothelium antigens, such as podoplanin, LYVE-1 and Prox-1, can be successfully applied in diagnostic pathology and have revealed (at least partial) lymphatic differentiation in many types of vascular lesion
Plant vigour QTLs co-map with an earlier reported QTL hotspot for drought tolerance while water saving QTLs map in other regions of the chickpea genome
Background
Terminal drought stress leads to substantial annual yield losses in chickpea (Cicer arietinum L.). Adaptation to water limitation is a matter of matching water supply to water demand by the crop. Therefore, harnessing the genetics of traits contributing to plant water use, i.e. transpiration rate and canopy development dynamics, is important to design crop ideotypes suited to a varying range of water limited environments. With an aim of identifying genomic regions for plant vigour (growth and canopy size) and canopy conductance traits, 232 recombinant inbred lines derived from a cross between ICC 4958 and ICC 1882, were phenotyped at vegetative stage under well-watered conditions using a high throughput phenotyping platform (LeasyScan).
Results
Twenty one major quantitative trait loci (M-QTLs) were identified for plant vigour and canopy conductance traits using an ultra-high density bin map. Plant vigour traits had 13 M-QTLs on CaLG04, with favourable alleles from high vigour parent ICC 4958. Most of them co-mapped with a previously fine mapped major drought tolerance “QTL-hotspot” region on CaLG04. One M-QTL was found for canopy conductance on CaLG03 with the ultra-high density bin map. Comparative analysis of the QTLs found across different density genetic maps revealed that QTL size reduced considerably and % of phenotypic variation increased as marker density increased.
Conclusion
Earlier reported drought tolerance hotspot is a vigour locus. The fact that canopy conductance traits, i.e. the other important determinant of plant water use, mapped on CaLG03 provides an opportunity to manipulate these loci to tailor recombinants having low/high transpiration rate and plant vigour, fitted to specific drought stress scenarios in chickpea
Breeding Drought-Tolerant Pearl Millet using conventional and genomic approaches: Achievements and prospects
Pearl millet [Pennisetum glaucum (L.) R. Br.] is a C4 crop cultivated for its grain and stover in crop-livestock-based rain-fed farming systems of tropics and subtropics in the Indian subcontinent and sub-Saharan Africa. The intensity of drought is predicted to further exacerbate because of looming climate change, necessitating greater focus on pearl millet breeding for drought tolerance. The nature of drought in different target populations of pearl millet-growing environments (TPEs) is highly variable in its timing, intensity, and duration. Pearl millet response to drought in various growth stages has been studied comprehensively. Dissection of drought tolerance physiology and phenology has helped in understanding the yield formation process under drought conditions. The overall understanding of TPEs and differential sensitivity of various growth stages to water stress helped to identify target traits for manipulation through breeding for drought tolerance. Recent advancement in high-throughput phenotyping platforms has made it more realistic to screen large populations/germplasm for drought-adaptive traits. The role of adapted germplasm has been emphasized for drought breeding, as the measured performance under drought stress is largely an outcome of adaptation to stress environments. Hybridization of adapted landraces with selected elite genetic material has been stated to amalgamate adaptation and productivity. Substantial progress has been made in the development of genomic resources that have been used to explore genetic diversity, linkage mapping (QTLs), marker-trait association (MTA), and genomic selection (GS) in pearl millet. High-throughput genotyping (HTPG) platforms are now available at a low cost, offering enormous opportunities to apply markers assisted selection (MAS) in conventional breeding programs targeting drought tolerance. Next-generation sequencing (NGS) technology, micro-environmental modeling, and pearl millet whole genome re-sequence information covering circa 1,000 wild and cultivated accessions have helped to greater understand germplasm, genomes, candidate genes, and markers. Their application in molecular breeding would lead to the development of high-yielding and drought-tolerant pearl millet cultivars. This review examines how the strategic use of genetic resources, modern genomics, molecular biology, and shuttle breeding can further enhance the development and delivery of drought-tolerant cultivars
SpaTemHTP: A Data Analysis Pipeline for Efficient Processing and Utilization of Temporal High-Throughput Phenotyping Data
The rapid development of phenotyping technologies over the last years gave the
opportunity to study plant development over time. The treatment of the massive
amount of data collected by high-throughput phenotyping (HTP) platforms is however
an important challenge for the plant science community. An important issue is to
accurately estimate, over time, the genotypic component of plant phenotype. In outdoor
and field-based HTP platforms, phenotype measurements can be substantially affected
by data-generation inaccuracies or failures, leading to erroneous or missing data. To
solve that problem, we developed an analytical pipeline composed of three modules:
detection of outliers, imputation of missing values, and mixed-model genotype adjusted
means computation with spatial adjustment. The pipeline was tested on three different
traits (3D leaf area, projected leaf area, and plant height), in two crops (chickpea,
sorghum), measured during two seasons. Using real-data analyses and simulations,
we showed that the sequential application of the three pipeline steps was particularly
useful to estimate smooth genotype growth curves from raw data containing a large
amount of noise, a situation that is potentially frequent in data generated on outdoor
HTP platforms. The procedure we propose can handle up to 50% of missing values. It
is also robust to data contamination rates between 20 and 30% of the data. The pipeline
was further extended to model the genotype time series data. A change-point analysis
allowed the determination of growth phases and the optimal timing where genotypic
differences were the largest. The estimated genotypic values were used to cluster the
genotypes during the optimal growth phase. Through a two-way analysis of variance
(ANOVA), clusters were found to be consistently defined throughout the growth duration.
Therefore, we could show, on a wide range of scenarios, that the pipeline facilitated
efficient extraction of useful information from outdoor HTP platform data. High-quality
plant growth time series data is also provided to support breeding decisions. The R
code of the pipeline is available at https://github.com/ICRISAT-GEMS/SpaTemHTP
Environmental characterization and yield gap analysis to tackle genotype-by-environment-by-management interactions and map region-specific agronomic and breeding targets in groundnut
The high degree of Genotype by Environment by Management (GxExM) interactions is a serious challenge for
production and crop improvement efforts. This challenge is especially true for a crop like groundnut that is often
grown as a rainfed crop in diverse environments and management, leading to considerable production fluctuations
among regions and seasons. Developing a means to characterize the drivers of variable yield and to
identify region specific breeding objectives were the main motivations for this research, using groundnut production
in India, as a case study for rainfed crops. Historically, five groundnut production areas have been
considered by Indian crop improvement programs. Our objectives were to assess the relevance of this zonation
system and possibly to re-define production areas with a higher degree of similarities into homogeneous production
units (HPUs). Towards this, we used yield gap analysis and the geo-biophysical characters of the production
region to understand and deal with GxExM interactions. Weather and soil data, crop parameters, and
management information data were collected and groundnut production was simulated at the district scale over
30 consecutive years. Consequently, the geographic distribution of the potential yields and the yield gaps were
first estimated to understand the main production limitations in a given region. Large and variable yield gaps
(with a mean of ~70 %) were observed and results revealed a readily exploitable production gap (~ 8 M tons),
which might be bridged by following recommended agronomic practices. Water deficit limited the yield potential
by an average of 40 %, although with large variability among districts. However, large and variable yield gaps
remained. To resolve the unexplained variation, principal component and cluster analysis of agronomic model
output together with geo-biophysical indicators for each district were carried out. This resulted in seven HPUs,
having well-defined production-limiting constraints. Grouping by HPU greatly reduced variance in actual and
simulated yields, as compared to grouping across all groundnut production zones in India. The HPU based
approach delimited precise geographic regions within which HPU-specific GxM products could be designed by
crop improvement programs to boost productivity
Breeding Drought-Tolerant Pearl Millet Using Conventional and Genomic Approaches: Achievements and Prospects
Pearl millet [Pennisetum glaucum (L.) R. Br.] is a C4 crop cultivated for its grain and
stover in crop-livestock-based rain-fed farming systems of tropics and subtropics in
the Indian subcontinent and sub-Saharan Africa. The intensity of drought is predicted
to further exacerbate because of looming climate change, necessitating greater focus
on pearl millet breeding for drought tolerance. The nature of drought in different target
populations of pearl millet-growing environments (TPEs) is highly variable in its timing,
intensity, and duration. Pearl millet response to drought in various growth stages
has been studied comprehensively. Dissection of drought tolerance physiology and
phenology has helped in understanding the yield formation process under drought
conditions. The overall understanding of TPEs and differential sensitivity of various
growth stages to water stress helped to identify target traits for manipulation through
breeding for drought tolerance. Recent advancement in high-throughput phenotyping
platforms has made it more realistic to screen large populations/germplasm for droughtadaptive
traits. The role of adapted germplasm has been emphasized for drought
breeding, as the measured performance under drought stress is largely an outcome
of adaptation to stress environments. Hybridization of adapted landraces with selected
elite genetic material has been stated to amalgamate adaptation and productivity.
Substantial progress has been made in the development of genomic resources
that have been used to explore genetic diversity, linkage mapping (QTLs), markertrait
association (MTA), and genomic selection (GS) in pearl millet. High-throughput
genotyping (HTPG) platforms are now available at a low cost, offering enormous
opportunities to apply markers assisted selection (MAS) in conventional breeding
programs targeting drought tolerance. Next-generation sequencing (NGS) technology,
micro-environmental modeling, and pearl millet whole genome re-sequence information
covering circa 1,000 wild and cultivated accessions have helped to greater understand germplasm, genomes, candidate genes, and markers. Their application in molecular
breeding would lead to the development of high-yielding and drought-tolerant pearl
millet cultivars. This review examines how the strategic use of genetic resources, modern
genomics, molecular biology, and shuttle breeding can further enhance the development
and delivery of drought-tolerant cultivars
Loss of DPP4 activity is related to a prothrombogenic status of endothelial cells: implications for the coronary microvasculature of myocardial infarction patients
Pro-coagulant and pro-inflammatory intramyocardial (micro)vasculature plays an important role in acute myocardial infarction (AMI). Currently, inhibition of serine protease dipeptidyl peptidase 4 (DPP4) receives a lot of interest as an anti-hyperglycemic therapy in type 2 diabetes patients. However, DPP4 also possesses anti-thrombotic properties and may behave as an immobilized anti-coagulant on endothelial cells. Here, we studied the expression and activity of endothelial DPP4 in human myocardial infarction in relation to a prothrombogenic endothelial phenotype. Using (immuno)histochemistry, DPP4 expression and activity were found on the endothelium of intramyocardial blood vessels in autopsied control hearts (n = 9). Within the infarction area of AMI patients (n = 73), this DPP4 expression and activity were significantly decreased, coinciding with an increase in Tissue Factor expression. In primary human umbilical vein endothelial cells (HUVECs), Western blot analysis and digital imaging fluorescence microscopy revealed that DPP4 expression was strongly decreased after metabolic inhibition, also coinciding with Tissue Factor upregulation. Interestingly, inhibition of DPP4 activity with diprotin A also enhanced the amount of Tissue Factor encountered and induced the adherence of platelets under flow conditions. Ischemia induces loss of coronary microvascular endothelial DPP4 expression and increased Tissue Factor expression in AMI as well as in vitro in HUVECs. Our data suggest that the loss of DPP4 activity affects the anti-thrombogenic nature of the endothelium
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