6 research outputs found
Epigenetic chromatin modifiers in barley: I. Cloning, mapping and expression analysis of the plant specific HD2 family of histone deacetylases from barley, during seed development and after hormonal treatment
No full textEpigenetic phenomena have been associated with modifications of chromatin structure. These are achieved, in part, by histone post-translational modifications including acetylations and deacetylations, the later being catalyzed by histone deacetylaces (HDACs). Eukaryotic HDACs are grouped into three major families, RPD3/HDA1, SIR2 and the plant-specific HD2. HDAC genes have been analyzed from model plants such as arabidopsis,rice and maize and have been shown to be involved in various cellular processes including seed development, vegetative and reproductive growth and responses to abiotic and biotic stress, but reports on HDACs from other crops are limited. In this work two full-length cDNAs (HvHDAC2-1 and HvHDAC2-2) encoding two members of the plant-specific HD2 family, respectively, were isolated and characterized from barley (Hordeum vulgare), an agronomically important cereal crop.HvHDAC2-1 andHvHDAC2-2 were mapped on barley chromosomes 1H and 3H, respectively, which could prove useful in developing markers for marker-assisted selection in breeding programs. Expression analysis of the barley HD2 genes demonstrated that they are expressed in all tissues and seed developmental stages examined.Significant differences were observed among tissues and seed stages, andbetween cultivars with varying seed size, suggesting an association of thesegenes with seed development. Furthermore, the HD2 genes from barley werefound to respond to treatments with plant stress-related hormones such asjasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA) implying anassociation of these genes with plant resistance to biotic and abiotic stress.The expression pattern of HD2 genes suggests a possible role for these genesin the epigenetic regulation of seed development and stress response
Epigenetic chromatin modifiers in barley: IV. The study of barley Polycomb group (PcG) genes during seed development and in response to external ABA
No full textAbstract Background Epigenetic phenomena have been associated with the regulation of active and silent chromatin states achieved by modifications of chromatin structure through DNA methylation, and histone post-translational modifications. The latter is accomplished, in part, through the action of PcG (Polycomb group) protein complexes which methylate nucleosomal histone tails at specific sites, ultimately leading to chromatin compaction and gene silencing. Different PcG complex variants operating during different developmental stages have been described in plants. In particular, the so-called FIE/MEA/FIS2 complex governs the expression of genes important in embryo and endosperm development in Arabidopsis. In our effort to understand the epigenetic mechanisms regulating seed development in barley (Hordeum vulgare), an agronomically important monocot plant cultivated for its endosperm, we set out to characterize the genes encoding barley PcG proteins. Results Four barley PcG gene homologues, named HvFIE, HvE(Z), HvSu(z)12a, and HvSu(z)12b were identified and structurally and phylogenetically characterized. The corresponding genes HvFIE, HvE(Z), HvSu(z)12a, and HvSu(z)12b were mapped onto barley chromosomes 7H, 4H, 2H and 5H, respectively. Expression analysis of the PcG genes revealed significant differences in gene expression among tissues and seed developmental stages and between barley cultivars with varying seed size. Furthermore, HvFIE and HvE(Z) gene expression was responsive to the abiotic stress-related hormone abscisic acid (ABA) known to be involved in seed maturation, dormancy and germination. Conclusion This study reports the first characterization of the PcG homologues, HvFIE, HvE(Z), HvSu(z)12a and HvSu(z)12b in barley. All genes co-localized with known chromosomal regions responsible for malting quality related traits, suggesting that they might be used for developing molecular markers to be applied in marker assisted selection. The PcG differential expression pattern in different tissues and seed developmental stages as well as in two barley cultivars with different seed size is suggestive of a role for these genes in barley seed development. HvFIE and HvE(Z) were also found to be induced by the plant hormone ABA implying an association with ABA-mediated processes during seed development, germination and stress response.</p
Phenotypic changes in different spinach varieties grown and selected under organic conditions
No full textOrganic and low-input agriculture needs flexible varieties that can buffer environmental stress and adapt to the needs of farmers. We implemented an experiment to investigate the evolutionary capacities of a sample of spinach (Spinacia oleracea L.) population varieties for a number of phenotypic traits. Three farmers cultivated, selected and multiplied one or several populations over two years on their farms. The third year, the versions of the varieties cultivated and selected by the different farmers were compared to the original seed lots they had been given. After two cycles of cultivation and on-farm mass selection, all the observed varieties showed significant phenotypic changes (differences between the original version and the version cultivated by farmers) for morphological and phenological traits. When the divergence among versions within varieties was studied, the results show that the varieties conserved their identity, except for one variety, which evolved in such a way that it may now be considered two different varieties. The heterogeneity of the population varieties was assessed in comparison with a commercial F1 hybrid used as control, and we found no specific differences in phenotypic diversity between the hybrid and population varieties. The phenotypic changes shown by the population varieties in response to on-farm cultivation and selection could be useful for the development of specific adaptation. These results call into question the current European seed legislation and the requirements of phenotypic stability for conservation varietie
Cereal landraces for sustainable agriculture. A review
No full textModern agriculture and conventional breeding and the liberal use of high inputs has resulted in the loss of genetic diversity and the stagnation of yields in cereals in less favourable areas. Increasingly landraces are being replaced by modern cultivars which are less resilient to pests, diseases and abiotic stresses and thereby losing a valuable source of germplasm for meeting the future needs of sustainable agriculture in the context of climate change. Where landraces persist there is concern that their potential is not fully realised. Much effort has gone into collecting, organising, studying and analysing landraces recently and we review the current status and potential for their improved deployment and exploitation, and incorporation of their positive qualities into new cultivars or populations for more sustainable agricultural production. In particular their potential as sources of novel disease and abiotic stress resistance genes or combination of genes if deployed appropriately, of phytonutrients accompanied with optimal micronutrient concentrations which can help alleviate aging-related and chronic diseases, and of nutrient use efficiency traits. We discuss the place of landraces in the origin of modern cereal crops and breeding of elite cereal cultivars, the importance of on-farm and ex situ diversity conservation; how modern genotyping approaches can help both conservation and exploitation; the importance of different phenotyping approaches; and whether legal issues associated with landrace marketing and utilisation need addressing. In this review of the current status and prospects for landraces of cereals in the context of sustainable agriculture, the major points are the following: (1) Landraces have very rich and complex ancestry representing variation in response to many diverse stresses and are vast resources for the development of future crops deriving many sustainable traits from their heritage. (2) There are many germplasm collections of landraces of the major cereals worldwide exhibiting much variation in valuable morphological, agronomic and biochemical traits. The germplasm has been characterised to variable degrees and in many different ways including molecular markers which can assist selection. (3) Much of this germplasm is being maintained both in long-term storage and on farm where it continues to evolve, both of which have their merits and problems. There is much concern about loss of variation, identification, description and accessibility of accessions despite international strategies for addressing these issues. (4) Developments in genotyping technologies are making the variation available in landraces ever more accessible. However, high quality, extensive and detailed, relevant and appropriate phenotyping needs to be associated with the genotyping to enable it to be exploited successfully. We also need to understand the complexity of the genetics of these desirable traits in order to develop new germplasm. (5) Nutrient use efficiency is a very important criterion for sustainability. Landrace material offers a potential source for crop improvement although these traits are highly interactive with their environment, particularly developmental stage, soil conditions and other organisms affecting roots and their environment. (6) Landraces are also a potential source of traits for improved nutrition of cereal crops, particularly antioxidants, phenolics in general, carotenoids and tocol in particular
Investigations into the Characteristics of Historic Barley Varieties with Reference to Fungal Diseases and Physiology
No full textThe aim of this study was to characterise modern and historic barley varieties for agronomic and growth characteristics and to assess their resistance to Fusarium and mildew diseases.
Barley is a major agricultural crop cultivated throughout the world providing an important source of energy and protein for humans and animals. To achieve its potential, however, it must be carefully managed to avoid diseases particularly those caused by fungi which can cause serious economic losses and affect food safety and quality.
Contemporary barley varieties have been selected for yield and disease resistance. However, long term resistance to disease is increasingly difficult to achieve as microorganisms mutate and maintain their virulence. Investigating the potential of historic barley varieties as a genetic resource for future developments is one approach to obtaining novel attributes which may have been overlooked when breeding focused on yield rather than character of barley and on disease resistance.
To examine the characteristics and disease resistance of historic barley varieties a series of investigations was conducted. Initially a screening was initiated by growing thirteen historic barley varieties and two modern barley varieties in a field trial in 2009. Growth features, yield and symptoms of mildew and Fusarium Head Blight (FHB) were scored and compared. This field experiment was repeated in 2010 with six of these varieties at the John Innes Centre by deliberately exposing the plants to F. culmorum Fu 42. A further experiment was conducted at the same time by growing seven varieties in glasshouse conditions at the University of Sunderland under inoculated and uninoculated conditions.
From both growing seasons clear differences were found for the level of F. culmorum infection between the different barley cultivars with infection levels in heads ranging from 16% for Chevalier and 86.4% for Tipple barley varieties respectively. Nitrogen increased the level of FHB in all varieties possibly because
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of increased plant leaf number, tillers and humidity within the environment around the plant.
Mycotoxin analysis showed that F. culmorum infection resulted in mycotoxin contamination of all varieties. However, levels of mycotoxin were significantly lower in Chevalier barley compared to other barley varieties including the two modern varieties, Tipple and Westminster. Observations using scanning electron microscopy indicated a different pattern of fungal growth in Chevalier barley with limited fungal development on both external and internal surfaces compared to other susceptible varieties.
In general resistance against FHB disease depends on variable responses including plant physiology and morphology, antifungal compounds or resistance genes. Different flowering dates or flowering periods could be also considered reasons for different infection levels. However, in this study the duration of anthesis was not assessed and could be an important factor. Further experiments to identify the flowering times of different varieties could be considered for further research.
The lower levels of disease associated with lower levels of mycotoxins and a reduced fungal development in Chevalier barley indicated that this variety has a strong resistance against FHB disease. This may be because of its late flowering and its tall height minimising colonisation from the soil. However, Chevalier barley was found to be very susceptible to powdery mildew disease, particularly in glasshouse studies.
The potential of Chevalier barley to produce good malt was indicated when compared to modern varieties suggesting that Chevalier may be a valuable breeding stock for future developments
