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Dodig D.,Maize Research Institute Zemun Polje | Zoric M.,University of Novi Sad | Kobiljski B.,Institute of Field and Vegetative Crops | Surlan-Momirovic G.,University of Belgrade | Quarrie S.A.,Northumbria University
Crop and Pasture Science | Year: 2010

This study was conducted to assess drought tolerance and regional-based patterns of diversity of bread wheat accessions and to identify new sources of diversity that could accelerate the development of improved wheat varieties better suited to meeting the challenges posed by changing climate in Southern and Eastern Europe. For this, genetic diversity assessed by simple sequence repeats (SSR) markers was compared with diversity evaluated using 19 phenotypic traits averaged over irrigated and drought-stress field conditions. Thirty-six SSR were used to profile 96 wheat genotypes from the collection of genetic resources at the Institute of Field and Vegetable Crops, Novi Sad, Serbia. A total of 46 loci and 366 alleles were detected, with a range of 3-21 alleles per locus. The polymorphic information content was estimated to be 0.61. The genetic distance for all possible 4560 pairs of genotypes ranged from 0.06 to 0.91 with an average of 0.65. Genotypes were grouped according to their drought tolerance (high, medium, low) and region of origin. Analysis of molecular variance showed that over 96% of the total variation could be explained by the variance within the drought tolerance and geographical groups. As a whole, genetic diversity among the high drought tolerance genotypes was considerably higher than that among low drought tolerance genotypes. Comparative analysis of SSR diversity among six regional groups revealed that the genotypes from North America exhibited more genetic diversity than those from other regions. Two dendrograms were constructed based on phenotypic and molecular analyses using the Unweighted Pair Group Method with Arithmetic Mean method and were found to be topologically different. Genotypes characterised as highly drought tolerant were distributed among all SSR-based cluster groups. This implied that the genetic basis of drought tolerance in these genotypes was different, thereby enabling wheat breeders to combine these diverse sources of genetic variability to improve drought tolerance in their breeding programs. © 2010 CSIRO.

Zoric M.,Institute of Field and Vegetative Crops | Dodig D.,Maize Research Institute Zemun Polje | Dodig D.,Northumbria University | Kobiljski B.,Institute of Field and Vegetative Crops | And 2 more authors.
Genetica | Year: 2012

A set of 96 winter wheat accessions sampled from a variety of geographic origins, including cultivars and breeding lines, were characterized with 46 genome-wide SSR loci for genetic diversity and population structure. The genetic diversity within these accessions was examined using a genetic distance-based and a model-based clustering method. The model-based analysis identified an underlying population structure comprising of four distinct sub-populations which corresponded well with distance-based groupings. Information on the population structure is taken into account in an association mapping study of grain yield from a 3-years field trial incorporating fully irrigated, rainfed and drought stress treatments. A total of 21 marker-grain yield associations (P < 0.01) were identified with nine SSR markers. Most associations were detected only in one to three environments (treatment/year combination), with an average R2 value around 13 %. However, marker gwm484 (on chromosome 2D) was associated with yield in six environments, including irrigated, rainfed and drought stress treatments, suggesting it could be used to improve grain yield across a range of environments. Variation in grain yield at this locus was associated with earliness, early vigour, kernels per spikelet and harvest index. Microsatellite locus psp3200 (on chromosome 6D) was associated with yield in dry and hot environments, which was related to earliness, early vigour, productive tillering and total biomass per plant. Partial least squares regression, with nine environmental factors, showed that precipitation from tillering to maturity was the main environmental factor causing marker × environment associations for grain yield. © 2012 Springer Science+Business Media B.V.

Dodig D.,Maize Research Institute Zemun Polje | Dodig D.,Northumbria University | Zoric M.,Institute of Field and Vegetative Crops | Kobiljski B.,Institute of Field and Vegetative Crops | And 4 more authors.
International Journal of Molecular Sciences | Year: 2012

Genetic analyses and association mapping were performed on a winter wheat core collection of 96 accessions sampled from a variety of geographic origins. Twenty-four agronomic traits were evaluated over 3 years under fully irrigated, rainfed and drought treatments. Grain yield was the most sensitive trait to water deficit and was highly correlated with above-ground biomass per plant and number of kernels per m2. The germplasm was structured into four subpopulations. The association of 46 SSR loci distributed throughout the wheat genome with yield and agronomic traits was analyzed using a general linear model, where subpopulation information was used to control false-positive or spurious marker-trait associations (MTAs). A total of 26, 21 and 29 significant (P < 0.001) MTAs were identified in irrigated, rainfed and drought treatments, respectively. The marker effects ranged from 14.0 to 50.8%. Combined across all treatments, 34 significant (P < 0.001) MTAs were identified with nine markers, and R2 ranged from 14.5 to 50.2%. Marker psp3200 (6DS) and particularly gwm484 (2DS) were associated with many significant MTAs in each treatment and explained the greatest proportion of phenotypic variation. Although we were not able to recognize any marker related to grain yield under drought stress, a number of MTAs associated with developmental and agronomic traits highly correlated with grain yield under drought were identified. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

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