Biology subjects

Peleg, Z.

Publications and source records attributed to Peleg, Z..

15 recordsLinked to original sources

bioRxiv2024

Leveraging genomics and temporal high-throughput phenotyping to enhance association mapping and yield prediction in sesame

Sesame (Sesamum indicum) is an important oilseed crop with rising demand due to its high oil quality. To meet these future demands, there is an urgent need to develop and integrate new breeding strategies. While genomic resources have advanced genetic research in sesame, implementation of high-throughput phenotyping and genetic analysis of longitudinal traits remains limited. Here, we combined high-throughput phenotyping and random regression models to investigate the dynamics of plant height, leaf area index, and five spectral vegetation indices throughout the sesame growing seasons in a diversity panel. Modeling the temporal phenotypic and additive genetic trajectories revealed distinct patterns corresponding to the sesame growth cycle. We also conducted longitudinal genomic prediction and association mapping of plant height using various models and cross-validation schemes. Moderate prediction accuracy was obtained when predicting new genotypes at each time point, and moderate to high values were obtained when forecasting future phenotypes. Association mapping revealed three genomic regions in linkage groups 6, 8, and 11 conferring trait variation over time and growth rate. Furthermore, we leveraged correlations between the temporal trait and seed-yield and applied multi-trait genomic prediction. We obtained an improvement over single-trait analysis, especially when phenotypes from earlier time points were used, highlighting the potential of using a high-throughput phenotyping platform as a selection tool. Our results shed light on the genetic control of longitudinal traits in sesame and underscore the potential of high-throughput phenotyping to detect a wide range of traits and genotypes that can inform sesame breeding efforts to enhance yield.

plant biology↗

bioRxiv2023

Optimization of chickpea irrigation in a semi-arid climate based on morpho-physiological parameters

While the world population is steadily growing, the demand for plant-based protein in general, and chickpea in particular, is rising. Heatwaves and terminal drought are the main environmental constraints on chickpea production worldwide. Thus, developing better irrigation management for the chickpea agro-system can promote higher and more sustainable yields. Supplemental irrigation at the right timing and dose can increase yield dramatically. Here, we studied the response of a modern Kabuli chickpea cultivar to supplemental irrigation during the critical pod-filling period over three growing seasons (2019-2021) in northern Negev, Israel, under semi-arid conditions. Six irrigation treatments were applied based on irrigation factors of 0, 0.5, 0.7, 1.0, 1.2, and 1.4 of crop evapotranspiration (ET0) as measured by an on-site meteorological station. Morpho-physiological parameters and above-ground biomass accumulation were monitored throughout the cropping seasons, and the final grain yield was determined at maturation. Irrigation onset was determined based on plants leaf water potential ({Psi}LWP > 15 bar) in the field. Our results indicate that optimal water status (as reflected by pressure chamber values) was 12-14 bar during the irrigation period. Irrigation according to evapotranspiration (ET0) with an irrigation factor of 1.2 resulted in the highest grain yields over the three years. To ensure optimal water supply during the reproductive phase compatible with the crop water requirements, maintaining a 25 mm node length above the last fully developed pod and a 90 mm distance between the last fully developed pod to the stem apex is recommended. In conclusion, irrigation onset when the crop is already at mild drought stress, followed by sufficient irrigation while following the indicated morphology and water potential values, may help farmers optimize irrigation and maximize chickpea crop production. HighlightsO_LIChickpea irrigation is optimized based on meteorological data (ETc) and morphological traits. C_LIO_LIMorphological- not only physiological- traits can capture the dynamics of crop water status. C_LIO_LIIrrigation onset should be at mild drought stress (>15 bar) during the reproductive stage. C_LIO_LIExtending the reproductive phase is essential for grain yield improvement under semi-arid conditions. C_LIO_LIIF=1.2 provides the most productive irrigation regime for chickpea in Mediterranean conditions. C_LI

plant biology↗

bioRxiv2022

Multi-environment analysis enhances genomic prediction accuracy of agronomic traits in sesame

Sesame is an ancient oilseed crop containing many valuable nutritional components. Recently, the demand for sesame seeds and their products has increased worldwide, making it necessary to enhance the development of high-yielding cultivars. One approach to enhance genetic gain in breeding programs is genomic selection. However, studies on genomic selection and genomic prediction in sesame are limited. In this study, we performed genomic prediction for agronomic traits using the phenotypes and genotypes of a sesame diversity panel grown under Mediterranean climatic conditions over two growing seasons. We aimed to assess the accuracy of prediction for nine important agronomic traits in sesame using single- and multi-environment analyses. In single-environment analysis, genomic best linear unbiased prediction, BayesB, BayesC, and reproducing kernel Hilbert spaces models showed no substantial differences. The average prediction accuracy of the nine traits across these models ranged from 0.39-0.79 for both growing seasons. In the multi-environment analysis, the marker-by-environment interaction model, which decomposed the marker effects into components shared across environments and environment-specific deviations, improved the prediction accuracies for all traits by 15%-58% compared to the single-environment model, particularly when borrowing information from other environments was made possible. Our results showed that single-environment analysis produced moderate-to-high genomic prediction accuracy for agronomic traits in sesame. The multi-environment analysis further enhanced this accuracy by exploiting marker-by-environment interaction. We concluded that genomic prediction using multi-environmental trial data could improve efforts for breeding cultivars adapted to the semi-arid Mediterranean climate.

genetics↗

bioRxiv2021

Wild Wheat Introgression Promotes Temporal Water fluxes Dynamics under Terminal Drought Stress through Plant-Atmospheric Interrelations

Drought intensity as experienced by plants depends upon soil moisture status and atmospheric variables such as temperature, radiation, and air vapour pressure deficit (VPD). Although the role of shoot architecture with these edaphic and atmospheric factors is well-characterized, the extent to which shoot and root dynamic interactions as a continuum are controlled by genotypic variation is less known. Here, we targeted these interactions using a wild emmer introgression line (IL20) with a distinct drought-induced shift in the shoot-to-root ratio and its drought-sensitive recurrent parent Svevo. Using a gravimetric platform, we show that IL20 maintained higher root water influx and gas exchange under drought stress, which supported a greater growth. Interestingly, the advantage of IL20 in root water influx and transpiration was expressed earlier during the daily diurnal cycle under lower VPD and therefore supported higher transpiration efficiency. Application of structural equation model indicates that under drought, VPD and radiation are antagonistic to transpiration rate, whereas the root water influx operates as feedback for the higher atmospheric responsiveness of leaves. Collectively, our results suggest that a drought-induced shift in root-to-shoot ratio can improve plant water uptake potential in a short preferable time window determined by both water and atmospheric parameters.

plant biology↗

bioRxiv2021

Spectral estimation of in-vivo wheat chlorophyll a/b ratio under contrasting water availabilities

To meet the ever-growing global population necessities, it is needed to identify climate change-relevant plant traits to integrate into breeding programs. Developing new tools for fast and accurate estimation of chlorophyll parameters, chlorophyll a (Chl-a), chlorophyll b (Chl-b) content, and their ratio (Chl-a/b), can promote breeding programs of wheat with enhanced climate adaptively. Spectral reflectance of leaves is affected by changes in pigments concentration and can be used to estimate chlorophyll parameters. The current study identified and validated the top spectral indices known and developed new vegetation indices (VIs) for Chl-a and Chl-b content estimation and used them to non-destructively estimate Chl-a/b values and compare them to hyperspectral estimations. Three wild emmer introgression lines, with contrasting drought stress responsiveness dynamics, were selected. Well and limited irrigation irrigation regimes were applied. The wheat leaves were spectrally measured with a handheld spectrometer to acquire their reflectance at the 330 to 790 nm range. Regression models based on calculated VIs as well as all hyperspectral curves were calibrated and validated against chlorophyll extracted values. The developed VIs resulted in high accuracy of Chl-a and Chl-b estimation allowing indirect non-destructive estimation of Chl-a/b with root mean square error (RMSE) values that could fit 6 to 10 times in the range of the measured values. They also performed similarly to the hyperspectral models. Altogether, we present here a new tool for a non-destructive estimation of Chl-a/b which can serve as a basis for future breeding efforts of climate-resilience wheat as well as other crops.

physiology↗

bioRxiv2021

Genome-wide association uncovers the genetic architecture of tradeoff between flowering date and yield components in sesame

Unrevealing the genetic makeup of crop morpho-agronomic traits is essential for improving yield quality and sustainability. Sesame (Sesamum indicum L.), one of the oldest oil-crops in the world, which despite its economical and agricultural importance, is an orphan crop-plant that undergone limited modern selection, thus, preserving wide genetic diversity. Here we harnessed this natural variation in a newly developed sesame panel (SCHUJI) to perform genome-wide association studies for morpho-agronomic traits under the Mediterranean climate conditions. Field-based phenotyping of the SCHUJI panel across two seasons exposed wide phenotypic variation for all traits. Using 20,294 single-nucleotide polymorphism markers, we detected 50 genomic signals associated with these traits. Major genomic region on LG2 was associated with flowering date and yield-related traits, exemplified the key role of the flowering date on productivity. Our results shed light on the genetic architecture of flowering date and its interaction with yield components in sesame and may serve as a basis for future sesame breeding programs in the Mediterranean basin.

plant biology↗

bioRxiv2020

Deciphering the genetic basis of wheat seminal root anatomy uncovers ancestral axial conductance alleles

Root axial conductance which describes the ability of water to pass throw the xylem, contributes to the rate of water uptake from the soil throughout the whole plant lifecycle. In a rainfed wheat agro-system, grain-filling is typically occurring during declining water availability (i.e. terminal drought). Therefore, preserving soil water moisture during grain filling could serve as a key adaptive trait. We hypothesized that lower wheat root axial conductance can promote higher yields under terminal drought. A segregating population derived from a cross between durum wheat and its direct progenitor wild emmer wheat was used to underpin the genetic basis of seminal root architectural and functional traits. We detected 75 QTL associated with seminal roots morphological, anatomical, and physiological traits, with several hotspots harboring co-localized QTL. We further validated the axial conductance and central metaxylem QTL using wild introgression lines. Field-based characterization of genotypes with contrasting axial conductance suggested the contribution of low axial conductance as a mechanism for water conservation during grain filling and consequent increase in grain size and yield. Our findings underscore the potential of introducing wild alleles to reshape the wheat root system architecture for greater adaptability under changing climate.

plant biology↗

bioRxiv2020

Genetic improvement of wheat early vigor promote weed-competitiveness under Mediterranean climate

Chemical weed-control is the most effective practice for wheat, however, rapid evolution of herbicide-resistant weeds threat food-security and calls for integration of non-chemical practices. We hypothesis that integration of GAR dwarfing-genes into elite wheat cultivars can promote early vigor and weed-competitiveness under Mediterranean climate. We develop near-isogenic lines of bread wheat cultivars with GAR dwarfing genes and evaluate them for early vigor and weed-competitiveness under various environmental and management conditions to identify promising NIL for weed-competitiveness and grain yield. While all three NILs, OC1 (Rht8,12), ZC4 (Rht12,13), and BNMF12 (Rht12), responded to gibberellic acid, they exhibited differences in early vigor. Greenhouse and field evaluation highlighted OC1 as a promising line, with significant advantage in early vigor over its parental. To facilitate accurate and continuous early vigor data collection, we applied non-destructive image-based phenotyping approaches which offers non-expensive and end-user friendly solution for selection. NIL OC1 was tested under different weed density level, infestation waves, and temperatures and highlight the complex genotypic x environmental x management interactions. Our findings demonstrate the potential of genetic modification of dwarfing genes as promising approach to improve weed-competitiveness, and serve as basis for future breeding efforts to support sustainable wheat production under semi-arid Mediterranean climate.

plant biology↗

bioRxiv2020

Wild emmer introgressions alter root-to-shoot growth dynamics under water stress

Water deficit is a major limiting factor for wheat (Triticum sp.) development and productivity. One approach to increase water stress adaptation in wheat is incorporating novel alleles from the drought-adapted wheat progenitor, wild emmer (T. turgidum ssp. dicoccoides). We explored this idea in the context of vegetative growth by examining the phenotypic consequence of a series of wild emmer (acc. Zavitan) introgressions into elite durum wheat (cv. Svevo) under water-limited conditions. Using image-based phenotyping we cataloged divergent (from Svevo) growth responses to water stress ranging from high plasticity to high stability among the introgression lines. We identified an introgression line (IL20) that exhibits a highly plastic response to water stress by shifting its root-to-shoot biomass ratio for detailed characterization. By combining genotypic information with root transcriptome analysis, we propose several candidate genes (including a root-specific kinase) that can confer the shoot-to-root carbon resource allocation in IL20 under water stress. Discovery of high plasticity trait in IL20 in response to water stress highlights the potential of wild introgressions for enhancing stress adaptation via mechanisms that may be absent or rare in elite breeding material.

plant biology↗

bioRxiv2019

Variation in phosphorus and sulfur content shapes the genetic architecture and phenotypic associations within wheat grain ionome

Dissection of the genetic basis of ionome is crucial for the understanding of the physiological and biochemical processes underlying mineral accumulation in seeds, as well as for efficient crop breeding. Most of the elements essential for plants are metals stored in seeds as chelate complexes with phytic acid or sulfur-containing compounds. We assume that the involvement of phosphorus and sulfur in metal chelation is the reason for strong phenotypic associations within ionome. Thus, we adjusted element concentrations for the effect of variation in phosphorus and sulfur seed content. The genetic architecture of wheat grain ionome was characterize by QTL analysis using a cross between durum and wild emmer wheat. Adjustment for variation in P and S drastically changed phenotypic associations within ionome and considerably improved QTL detection power and accuracy, resulting in identification of 105 QTLs and 437 QTL effects for 11 elements. A search for candidate genes revealed some strong functional associations of genes involved in transport and metabolism of ions and elements. Thus, we have shown that accounting for variation in P and S is crucial for understanding of the physiological and genetic regulation of mineral composition of wheat grain ionome and can be implemented for other plants.

genetics↗

bioRxiv2019

Genomic architecture of phenotypic plasticity of complex traits in tetraploid wheat in response to water stress

Phenotypic plasticity is one of the main mechanisms of adaptation to abiotic stresses via changes in critical developmental stages. Altering flowering phenology is a key evolutionary strategy of plant adaptation to abiotic stresses in order to achieve maximum possible reproduction. The current study is the first to apply the linear regression residuals as a drought plasticity scores, while taking into account the differences in flowering phenology and trait variation under non-stress conditions. We characterized the genomic architecture of 17 complex traits and their drought plasticity using a mapping population derived from a cross between durum wheat (Triticum durum) and wild emmer wheat (T. dicoccoides). We identified 79 QTLs, of which 33 were plastic in response to water stress and exhibited epistatic interactions and/or pleiotropy between the initial and plasticity traits. Vrn-B3 (TaTF1) residing within an interval of a major drought-escape QTL was proposed as a candidate gene. The favorable alleles for most of the plasticity QTLs were contributed by wild emmer, demonstrating the high potential of wild relatives for wheat improvement. Our study presents a new approach for quantification of plant adaptation to various stresses and provides new insights into the genetic basis of wheat complex traits under water-deficit stress.\n\nHighlightThe study presents a new approach for quantification of plant adaptation to various stresses and provides new insights into the genetic basis of wheat complex traits under water-deficit stress.

genetics↗

bioRxiv2019

GNI-A1 mediates trade-off between grain number and grain weight in tetraploid wheat

Grain yield is a highly polygenic trait determined by the number of grains per unit area, as well as by grain weight. In wheat, grain number and grain weight are usually negatively correlated. Yet, the genetic basis underlying trade-off between the two is mostly unknown. Here, we fine-mapped a grain weight QTL using wild emmer introgressions in a durum wheat background, and showed that grain weight is associated with the GNI-A1 gene, a regulator of floret fertility. In-depth characterization of grain number and grain weight indicated that suppression of distal florets by the wild emmer GNI-A1 allele increase weight of proximal grains in basal and central spikelets due to alteration in assimilate distribution. Re-sequencing of GNI-A1 in tetraploid wheat demonstrated the rich allelic repertoire of the wild emmer gene pool, including a rare allele which was present in two gene copies and contained a non-synonymous mutation in the C-terminus of the protein. Using an F2 population generated from a cross between wild emmer accessions Zavitan, which carries the rare allele, and TTD140, we demonstrated that this unique polymorphism is associated with grain weight, independent of grain number. Moreover, we showed, for the first time, that GNI-A1 proteins are transcriptional activators and that selection in domesticated wheat targeted compromised activity of the protein. Our finding expand the knowledge of the genetic basis underlying trade-off between key yield components and may contribute to breeding efforts for enhanced grain yield.

plant biology↗

bioRxiv2018

Unleashing floret fertility by a mutated homeobox gene improved grain yield during wheat evolution under domestication

Floret fertility is a key trait to determine the number of grains per inflorescence in cereals. During wheat (Triticum sp.) evolution, floret fertility has been increased and current bread wheat (T. aestivum L.) produces three to five grains per spikelet; however, little is known about the genetic basis controlling floret fertility. Here we identify the quantitative trait locus Grain Number Increase 1 (GNI1), encoding a homeodomain leucine zipper class I (HD-Zip I) transcription factor. GNI1 evolved in the Triticeae through gene duplication and functionalization. GNI1 was predominantly expressed in the most apical floret primordia and parts of the rachilla, suggesting that GNI1 inhibits rachilla growth and development. GNI1 expression decreased during wheat evolution, and as a consequence, more fertile florets and grains per spikelet are being produced. Genetic analysis revealed that the reduced-function allele of GNI1-A contributes to increase the number of fertile florets per spikelet. The knockdown of GNI1 in transgenic hexaploid wheat improved fertile floret and grain number. Furthermore, wheat plants carrying the impaired allele increased grain yield under field conditions. Our findings illuminate that gene duplication and functionalization generated evolutionary novelty for floret fertility (i.e. reducing floral numbers) while the mutations towards increased grain production were under selection during wheat evolution under domestication.\n\nSignificance StatementGrain number is a fundamental trait for cereal grain yield; but its underlying genetic basis is mainly unknown in wheat. Here we show for the first time a direct link between increased floret fertility, higher grain number per spike and higher plot-yields of wheat in the field. We have identified GNI1 gene encoding an HD-Zip I transcription factor responsible for increased floret fertility. The wild type allele imposes an inhibitory role specifically during rachilla development, indicating that expression of this protein actively shuts-down grain yield potential; whereas, the reduced-function allele enables more florets and grains to be produced. GNI1 evolved through gene duplication in Triticeae and its mutations were under parallel human selection during wheat and barley evolution under domestication.

plant biology↗

bioRxiv2018

Genome based QTL and meta-QTL analyses of thousand-kernel weight in tetraploid wheat

The domestication and subsequent genetic improvement of wheat led to the development of large-seeded cultivated wheat species relative to their smaller-seeded wild progenitors. While increased grain weight (GW) continues to be an important goal of many wheat breeding programs, few genes underlying this trait have been identified despite an abundance of studies reporting quantitative trait loci (QTLs) for GW. Here we perform a QTL analysis for GW using a population of recombinant inbred lines (RILs) derived from the cross between wild emmer wheat accession Zavitan and durum wheat variety Svevo. Identified QTLs in this population were anchored to the recent Zavitan reference genome, along with previously published QTLs for GW in tetraploid wheat. This genome-based, meta-QTL analysis enabled the identification of a locus on chromosome 6A whose introgression from wild wheat positively affects GW. The locus was validated using an introgression line carrying the 6A GW QTL region from Zavitan in a Svevo background, resulting in >8% increase in GW compared to Svevo. Using the reference sequence for the 6A QTL region, we identified a wheat ortholog to OsGRF4, a rice gene previously associated with GW. The coding sequence of this gene (TtGRF4-A) contains four SNPs between Zavitan and Svevo, one of which reveals the Zavitan allele to be rare in a core collection of wild emmer and completely absent from the domesticated emmer genepool. Similarly, another wild emmer accession (G18-16) was found to carry a rare allele of TtGRF4-A that also positively affects GW and is characterized by a unique SNP absent from the entire core collection. These results exemplify the rich genetic diversity of wild wheat, posit TtGRF4-A as a candidate gene underlying the 6A GW QTL, and suggest that the natural Zavitan and G18-16 alleles of TtGRF4-A have potential to increase wheat yields in breeding programs.

plant biology↗

bioRxiv2018

Phenotypic plasticity facilitates alterations in life-history strategies under combinations of environmental stresses

Plants developed various reversible and non-reversible acclimation mechanisms to cope with the multifaceted nature of abiotic stress combinations. We hypothesized that in order to endure these stress combinations, plants elicit distinctive acclimation strategies through specific trade-offs between reproduction and defense. To investigate Brachypodium distachyon acclimation strategies to combinations of salinity, drought and heat, we applied a system biology approach, integrating physiological, metabolic and transcriptional analyses. We analyzed the trade-offs among functional and performance traits, and their effects on plant fitness. A combination of drought and heat resulted in escape strategy, while under a combination of salinity and heat, plants exhibited avoidance strategy. On the other hand, under combinations of salinity and drought, with or without heat stress, plant fitness (i.e. germination rate of subsequent generation) was severely impaired. These results indicate that under combined stresses, plants life-history strategies were shaped by the limits of phenotypic and metabolic plasticity and the trade-offs between traits, thereby giving raise to distinct acclimations. Our findings provide a mechanistic understanding of plant acclimations to combinations of abiotic stresses and shed light on the different life-history strategies that can contribute to grass fitness and possibly to their dispersion under changing environments.

plant biology↗