Peleg, Z. ; Shabtay, A. ; Abbo, S. .
Allelic Diversity Between And Within Three Wild Annual Cicer Species.
Genetic Resources and Crop Evolution 2015,
62, 177-188.
Publisher's VersionAbstractMost wild Cicer species have narrow eco-geographic amplitude. Likewise, domesticated chickpea suffers from severe adaptive limitations due to its unique evolutionary history. The wild progenitor may offer only limited adaptive allelic variation for improving the chickpea crop. Therefore, there is a need to explore allelic diversity between and within annual Cicer sp. that span diverse natural habitats. Here we characterized the allelic diversity between and within wild populations of C. pinnatifidum, C. judaicum and C. cuneatum spanning most of their documented native range in Turkey, Israel and Ethiopia. Eco-geographical analysis resulted in clear separation between the collection sites of C. cuneatum in east Africa and the other two east Mediterranean species. Analysis of molecular variance shows that only 18 % of the allelic variation accounts for differences between the three species, while 34 % was contributed from difference between populations. Interestingly, most (48 %) of the allelic variation was detected among accessions within populations. PCoA analysis confirmed the independent taxonomic and indeed the genetic integrity of the two east Mediterranean sister species C. pinnatifidum and C. judaicum. Conservation of large rich populations seems a more effective strategy than the preservation of small thin populations of annual Cicer sp. Given the relatively narrow geographic range of most annual Cicer sp., accessing germplasm lines from ecologically distinct habitats emerges as the most promising strategy for the identification of useful adaptive allelic variation. © 2014, Springer Science+Business Media Dordrecht.
Amram, A. ; Fadida-Myers, A. ; Golan, G. ; Nashef, K. ; Ben-David, R. ; Peleg, Z. .
Effect Of Ga-Sensitivity On Wheat Early Vigor And Yield Components Under Deep Sowing. Front Plant Sci 2015,
6, 487.
AbstractEstablishment of seedlings is a key factor in achievement of uniform field stands and, consequently, stable yields. Under Mediterranean conditions, soil moisture in the upper layer is limited and seedlings may be exposed to frequent dehydration events. The presence of the Reduced height (Rht)-B1b and Rht-D1b semi-dominant dwarfing alleles results in insensitivity to gibberellin (GAI) and, hence, poor emergence from deep sowing. Introduction of alternative dwarfing genes and, thereby, preservation of the gibberellin response (GAR) and coleoptile length, contributes to better emergence from deep sowing. Initially 47 wheat cultivars carrying different Rht alleles were screened for their ability to emerge from deep sowing, and then 17 of them were selected for detailed physiological characterization in the field. The modern wheat lines containing GAI alleles showed significantly lower percentages of emergence from deep sowing than the GAR lines, i.e., 52 and 74%, respectively. Differences in early developmental stages were associated with grain yield, as indicated by a reduction of 37.3% in the modern GAI cultivars. Our results demonstrate the potential of alternative dwarfing genes for improving seedling establishment and grain yields in Mediterranean-like environments.
van Oss, R. ; Abbo, S. ; Eshed, R. ; Sherman, A. ; Coyne, C. J. ; Vandemark, G. J. ; Zhang, H. - B. ; Peleg, Z. .
Genetic Relationship In Cicer Sp. Expose Evidence For Geneflow Between The Cultigen And Its Wild Progenitor. PLoS One 2015,
10, e0139789.
AbstractThere is a debate concerning mono- or poly-phyletic origins of the Near Eastern crops. In parallel, some authors claim that domestication was not possible within the natural range of the wild progenitors due to wild alleles flow into the nascent crops. Here we address both, the mono- or poly-phyletic origins and the domestications within or without the natural range of the progenitor, debates in order to understand the relationship between domesticated chickpea (Cicer arietinum L.) and its wild progenitor (C. reticulatum Ladizinsky) with special emphasis on its domestication centre in southeastern Turkey. A set of 103 chickpea cultivars and landraces from the major growing regions alongside wild accessions (C. reticulatum, C. echinospermum P.H Davis and C. bijugum K.H. Rech) sampled across the natural distribution range in eastern Turkey were genotyped with 194 SNPs markers. The genetic affinities between and within the studied taxa were assessed. The analysis suggests a mono-phyletic origin of the cultigen, with several wild accession as likely members of the wild stock of the cultigen. Clear separation between the wild and domesticated germplasm was apparent, with negligible level of admixture. A single C. reticulatum accession shows morphological and allelic signatures of admixture, a likely result of introgression. No evidence of geneflow from the wild into domesticated germplasm was found. The traditional farming systems of southeaster Turkey are characterized by occurrence of sympatric wild progenitor-domesticated forms of chickpea (and likewise cereals and other grain legumes). Therefore, both the authentic crop landraces and the wild populations native to the area are a unique genetic resource. Our results grant support to the notion of domestication within the natural distribution range of the wild progenitor, suggesting that the Neolithic domesticators were fully capable of selecting the desired phenotypes even when facing rare wild-domesticated introgression events.
Golan, G. ; Oksenberg, A. ; Peleg, Z. .
Genetic Evidence For Differential Selection Of Grain And Embryo Weight During Wheat Evolution Under Domestication. J Exp Bot 2015,
66, 5703-11.
AbstractWheat is one of the Neolithic founder crops domesticated ~10 500 years ago. Following the domestication episode, its evolution under domestication has resulted in various genetic modifications. Grain weight, embryo weight, and the interaction between those factors were examined among domesticated durum wheat and its direct progenitor, wild emmer wheat. Experimental data show that grain weight has increased over the course of wheat evolution without any parallel change in embryo weight, resulting in a significantly reduced (30%) embryo weight/grain weight ratio in domesticated wheat. The genetic factors associated with these modifications were further investigated using a population of recombinant inbred substitution lines that segregated for chromosome 2A. A cluster of loci affecting grain weight and shape was identified on the long arm of chromosome 2AL. Interestingly, a novel locus controlling embryo weight was mapped on chromosome 2AS, on which the wild emmer allele promotes heavier embryos and greater seedling vigour. To the best of our knowledge, this is the first report of a QTL for embryo weight in wheat. The results suggest a differential selection of grain and embryo weight during the evolution of domesticated wheat. It is argued that conscious selection by early farmers favouring larger grains and smaller embryos appears to have resulted in a significant change in endosperm weight/embryo weight ratio in the domesticated wheat. Exposing the genetic factors associated with endosperm and embryo size improves our understanding of the evolutionary dynamics of wheat under domestication and is likely to be useful for future wheat-breeding efforts.
Shaar-Moshe, L. ; Hübner, S. ; Peleg, Z. .
Identification Of Conserved Drought-Adaptive Genes Using A Cross-Species Meta-Analysis Approach. BMC Plant Biol 2015,
15, 111.
AbstractBACKGROUND: Drought is the major environmental stress threatening crop-plant productivity worldwide. Identification of new genes and metabolic pathways involved in plant adaptation to progressive drought stress at the reproductive stage is of great interest for agricultural research.
RESULTS: We developed a novel Cross-Species meta-Analysis of progressive Drought stress at the reproductive stage (CSA:Drought) to identify key drought adaptive genes and mechanisms and to test their evolutionary conservation. Empirically defined filtering criteria were used to facilitate a robust integration of 17 deposited microarray experiments (148 arrays) of Arabidopsis, rice, wheat and barley. By prioritizing consistency over intensity, our approach was able to identify 225 differentially expressed genes shared across studies and taxa. Gene ontology enrichment and pathway analyses classified the shared genes into functional categories involved predominantly in metabolic processes (e.g. amino acid and carbohydrate metabolism), regulatory function (e.g. protein degradation and transcription) and response to stimulus. We further investigated drought related cis-acting elements in the shared gene promoters, and the evolutionary conservation of shared genes. The universal nature of the identified drought-adaptive genes was further validated in a fifth species, Brachypodium distachyon that was not included in the meta-analysis. qPCR analysis of 27, randomly selected, shared orthologs showed similar expression pattern as was found by the CSA:Drought.In accordance, morpho-physiological characterization of progressive drought stress, in B. distachyon, highlighted the key role of osmotic adjustment as evolutionary conserved drought-adaptive mechanism.
CONCLUSIONS: Our CSA:Drought strategy highlights major drought-adaptive genes and metabolic pathways that were only partially, if at all, reported in the original studies included in the meta-analysis. These genes include a group of unclassified genes that could be involved in novel drought adaptation mechanisms. The identified shared genes can provide a useful resource for subsequent research to better understand the mechanisms involved in drought adaptation across-species and can serve as a potential set of molecular biomarkers for progressive drought experiments.