245 research outputs found
Comparative performance of the stable isotope signatures of carbon, nitrogen and oxygen in assessing early vigour and grain yield in durum wheat
The present paper studied the performance of the stable isotope signatures of carbon (δ13C), nitrogen (δ15N) and oxygen (δ18O) in plants when used to assess early vigour and grain yield (GY) in durum wheat growing under mild and moderate Mediterranean stress conditions. A collection of 114 recombinant inbred lines was grown under rainfed (RF) and supplementary irrigation (IR) conditions. Broad sense heritabilities (H2) for GY and harvest index (HI) were higher under RF conditions than under IR. Broad sense heritabilities for δ13C were always above 0·60, regardless of the plant part studied, with similar values for IR and RF trials. Some of the largest genetic correlations with GY were those shown by the δ13C content of the flag leaf blade and mature grains. Under both water treatments, mature grains showed the highest negative correlations between δ13C and GY across genotypes. Flag leaf δ13C was negatively correlated with GY only under RF conditions. The δ13C in seedlings was negatively correlated, under IR conditions only, with GY but also with early vigour. The sources of variation in early vigour were studied by stepwise analysis using the stable isotope signatures measured in seedlings. The δ13C was able to explain almost 0·20 of this variation under RF, but up to 0·30 under IR. In addition, nitrogen concentration in seedlings accounted for another 0·05 of variation, increasing the amount explained to 0·35. The sources of variation in GY were also studied through stable isotope signatures and biomass of different plant parts: δ13C was always the first parameter to appear in the models for both water conditions, explaining c. 0·20 of the variation. The second parameter (δ15N or N concentration of grain, or biomass at maturity) depended on the water conditions and the plant tissue being analysed. Oxygen isotope composition (δ18O) was only able to explain a small amount of the variation in GY. In this regard, despite the known and previously described value of δ13C as a tool in breeding, δ15N is confirmed as an additional tool in the present study. Oxygen isotope composition does not seem to offer any potential, at least under the conditions of the present study
TRITIMED; a multidisciplinary project to improve drought adaptation in durum wheat
none6noneHABASH D.; ARAUS J.L.; LATIRI K.; KADER A.A.; TUBEROSA R.; NACHIT M.HABASH D.; ARAUS J.L.; LATIRI K.; KADER A.A.; TUBEROSA R.; NACHIT M
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Carbon stable isotope analysis of cereal remains as a way to reconstruct water availability: preliminary results
Reconstructing past water availability, both as rainfall and irrigation, is important to answer questions about the way society reacts to climate and its changes and the role of irrigation in the development of social complexity. Carbon stable isotope analysis of archaeobotanical remains is a potentially valuable method for reconstructing water availability. To further define the relationship between water availability and plant carbon isotope composition and to set up baseline values for the Southern Levant, grains of experimentally grown barley and sorghum were studied. The cereal crops were grown at three stations under five different irrigation regimes in Jordan. Results indicate that a positive but weak relationship exists between irrigation regime and total water input of barley grains, but no relationship was found for sorghum. The relationship for barley is site-specific and inter-annual variation was present at Deir ‘Alla, but not at Ramtha and Khirbet as-Samra
Transcriptome pathways unique to dehydration tolerant relatives of modern wheat
Among abiotic stressors, drought is a major factor responsible for dramatic yield loss in agriculture. In order to reveal differences in global expression profiles of drought tolerant and sensitive wild emmer wheat genotypes, a previously deployed shock-like dehydration process was utilized to compare transcriptomes at two time points in root and leaf tissues using the Affymetrix GeneChip(R) Wheat Genome Array hybridization. The comparison of transcriptomes reveal several unique genes or expression patterns such as differential usage of IP(3)-dependent signal transduction pathways, ethylene- and abscisic acid (ABA)-dependent signaling, and preferential or faster induction of ABA-dependent transcription factors by the tolerant genotype that distinguish contrasting genotypes indicative of distinctive stress response pathways. The data also show that wild emmer wheat is capable of engaging known drought stress responsive mechanisms. The global comparison of transcriptomes in the absence of and after dehydration underlined the gene networks especially in root tissues that may have been lost in the selection processes generating modern bread wheats
How useful is Active Learning for Image-based Plant Phenotyping?
Deep learning models have been successfully deployed for a diverse array of
image-based plant phenotyping applications including disease detection and
classification. However, successful deployment of supervised deep learning
models requires large amount of labeled data, which is a significant challenge
in plant science (and most biological) domains due to the inherent complexity.
Specifically, data annotation is costly, laborious, time consuming and needs
domain expertise for phenotyping tasks, especially for diseases. To overcome
this challenge, active learning algorithms have been proposed that reduce the
amount of labeling needed by deep learning models to achieve good predictive
performance. Active learning methods adaptively select samples to annotate
using an acquisition function to achieve maximum (classification) performance
under a fixed labeling budget. We report the performance of four different
active learning methods, (1) Deep Bayesian Active Learning (DBAL), (2) Entropy,
(3) Least Confidence, and (4) Coreset, with conventional random sampling-based
annotation for two different image-based classification datasets. The first
image dataset consists of soybean [Glycine max L. (Merr.)] leaves belonging to
eight different soybean stresses and a healthy class, and the second consists
of nine different weed species from the field. For a fixed labeling budget, we
observed that the classification performance of deep learning models with
active learning-based acquisition strategies is better than random
sampling-based acquisition for both datasets. The integration of active
learning strategies for data annotation can help mitigate labelling challenges
in the plant sciences applications particularly where deep domain knowledge is
required
Diversity of a cytokinin dehydrogenase gene in wild and cultivated barley
The cytokinin dehydrogenase gene HvCKX2.1 is the regulatory target for the most abundant heterochromatic small RNAs in drought-stressed barley caryopses. We investigated the diversity of HvCKX2.1 in 228 barley landraces and 216 wild accessions and identified 14 haplotypes, five of these with ten or more members, coding for four different protein variants. The third largest haplotype was abundant in wild accessions (51 members), but absent from the landrace collection. Protein structure predictions indicated that the amino acid substitution specific to haplotype 3 could result in a change in the functional properties of the HvCKX2.1 protein. Haplotypes 1–3 have overlapping geographical distributions in the wild population, but the average rainfall amounts at the collection sites for haplotype 3 plants are significantly higher during November to February compared to the equivalent data for plants of haplotypes 1 and 2. We argue that the likelihood that haplotype 3 plants were excluded from landraces by sampling bias that occurred when the first wild barley plants were taken into cultivation is low, and that it is reasonable to suggest that plants with haplotype 3 are absent from the crop because these plants were less suited to the artificial conditions associated with cultivation. Although the cytokinin signalling pathway influences many aspects of plant development, the identified role of HvCKX2.1 in the drought response raises the possibility that the particular aspect of cultivation that mitigated against haplotype 3 relates in some way to water utilization. Our results therefore highlight the possibility that water utilization properties should be looked on as a possible component of the suite of physiological adaptations accompanying the domestication and subsequent evolution of cultivated barley
Altered developmental programs and oriented cell divisions lead to bulky bones during salamander limb regeneration
There are major differences in duration and scale at which limb development and regeneration proceed, raising the question to what extent regeneration is a recapitulation of development. We address this by analyzing skeletal elements using a combination of micro-CT imaging, molecular profiling and clonal cell tracing. We find that, in contrast to development, regenerative skeletal growth is accomplished based entirely on cartilage expansion prior to ossification, not limiting the transversal cartilage expansion and resulting in bulkier skeletal parts. The oriented extension of salamander cartilage and bone appear similar to the development of basicranial synchondroses in mammals, as we found no evidence for cartilage stem cell niches or growth plate-like structures during neither development nor regeneration. Both regenerative and developmental ossification in salamanders start from the cortical bone and proceeds inwards, showing the diversity of schemes for the synchrony of cortical and endochondral ossification among vertebrates
Stable carbon Isotope evidence for neolithic and bronze age crop water management in the eastern mediterranean and southwest asia
In a large study on early crop water management, stable carbon isotope discrimination was determined for 275 charred grain samples from nine archaeological sites, dating primarily to the Neolithic and Bronze Age, from the Eastern Mediterranean and Western Asia. This has revealed that wheat (Triticum spp.) was regularly grown in wetter conditions than barley (Hordeum sp.), indicating systematic preferential treatment of wheat that may reflect a cultural preference for wheat over barley. Isotopic analysis of pulse crops (Lens culinaris, Pisum sativum and Vicia ervilia) indicates cultivation in highly varied water conditions at some sites, possibly as a result of opportunistic watering practices. The results have also provided evidence for local land-use and changing agricultural practices
Bioenergy and Agriculture:Promises and Challenges.Bioenergy and Agricultural Research for Development.Policy Brief No 7 of 12
Converting agriculture to produce energy as well as food has
become an important and well-funded global research goal
as petroleum reserves fall and fuel prices rise. But the use of crop
biomass—both grain and other plant parts—as a raw material for
bioenergy production may compete with food and feed supplies and
remove valuable plant residues that help sustain soil productivity
and structure and avoid erosion. Agricultural research can mitigate
these trade-offs by enhancing the biomass traits of dual-purpose
food crops, developing new biomass crops for marginal lands where
there is less competition with food crops, and developing sustainable
livestock management systems that are less dependent on biomass
residuals for feeds. Agronomists will need to define the minimum
thresholds of crop residues for sustainable production in particular
farming systems, especially in low-yield rainfed systems (that
produce less than 5–6 metric tons of grain and straw per hectare),
and to establish the level of additional residues that may be removed
for other purposes, including biofuel production. Enhanced root
growth offers another avenue for maintaining soil organic matter.
Agricultural research can also help improve the energy efficiency of
biomass crops, enhancing their value as renewable energy sources
with low net carbon emissions
Rapid phenotyping of crop root systems in undisturbed field soils using X-ray computed tomography
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