Search

In many regions of the world, the cultivation of landraces is still common, in particular in centres of crop diversity. Significant effort has been put into ex situ conservation of landraces but limited data exist on the changes in genetic diversity that occur over time in farmers’ fields. We assessed temporal changes in barley landrace diversity in Jordan using seed samples collected in 1981 and 2012 from the same locations. We did not observe significant changes in the amount of genetic diversity, but samples collected in 2012 were more homogenous and less locally distinct. In two sites, we observed replacement of the old material. We observed a change in phenotype, and phenotypes were found to be more homogeneous among sites in 2012. Climate changed significantly over the study period, becoming hotter and dryer, but we did not identify any correlation between the changes in climate and genetic and phenotypic variations. While the amount of genetic diversity in terms of allelic richness and number of multi-locus genotypes has been maintained, local distinctiveness among landrace barley populations in Jordan was reduced. [ABSTRACT FROM AUTHOR]

Fungal diseases are a major constraint for wheat production. Effective disease resistance is essential for ensuring a high production quality and yield. One of the most severe fungal diseases of wheat is Septoria tritici blotch ( STB), which influences wheat production across the world. In this study, genomewide association mapping was used to identify new chromosomal regions on the wheat genome conferring effective resistance towards STB. A winter wheat population of 164 North European varieties and breeding lines was genotyped with 15K single nucleotide polymorphism ( SNP) wheat array. The varieties were evaluated for STB in field trials at three locations in Denmark and across 3 years. The association analysis revealed four quantitative trait loci, on chromosomes 1B, 2A, 5D and 7A, highly associated with STB resistance. By comparing varieties containing several quantitative trait loci ( QTL) with varieties containing none of the found QTL, a significant difference was found in the mean disease score. This indicates that an effective resistance can be obtained by pyramiding several QTL. [ABSTRACT FROM AUTHOR]

Barley ( Hordeum vulgare) is cultivated on 49.1 million hectares worldwide with 50.2% of the area located in Europe. Powdery mildew, caused by Blumeria graminis f. sp. hordei ( Bgh), occurs wherever barley is grown. Cultivar resistance plays an important role in global barley production, especially in parts of Europe where high concentrations of both spring and winter types are grown. The aim of this report was to postulate specific resistance genes in barleys from nine European countries registered in the Czech Republic from 2011 to 2015. Thirty-five spring cultivars and 27 winter barleys were tested with 56 diverse Bgh isolates. Twenty-five known resistance genes were postulated, and unknown genes were detected in Sandra, Saturn and Zeppelin. Unidentified specific resistance genes were also present in winter hybrids Hobbit and Wootan. Spring cultivars Arthur and Francin consisted of three and two genotypes, respectively. Resistance gene mlo was present in 26 spring cultivars, and the proportion of cultivars with this gene increased from 62.9% in 2006-2010 to 75.7% in 2011-2015. The gene Mlp1 was identified for the first time in German winter cultivar Saturn. Five spring cultivars registered in Slovakia were included in the tests. All the cultivars that were tested contained one or more specific resistance genes to powdery mildew. Adaptability of the pathogen and possibilities for breeding winter barleys are discussed. [ABSTRACT FROM AUTHOR]

Genomic prediction has emerged as a powerful genomic tool to assist breeding of complex traits. In this study, we employed a population of 647 triticale doubled haploid lines derived from four families to assess the potential of this approach for triticale breeding. All lines were phenotyped for grain yield, thousand-kernel weight, biomass yield, plant height, frost tolerance and Fusarium head blight resistance. The obtained prediction accuracies were moderate to high and consisted to varying degrees of within- and among-family variance, in line with the different degrees of phenotypic differences between family means. The prediction accuracy within individual families also varied with the genetic complexity of the traits and was generally highest based on effect estimation with lines from the respective family, whereas the prediction accuracy decreased with decreasing relatedness among the families. Taken together, our results illustrate the potential of genomic prediction to increase selection gain in triticale breeding, but the composition of the training set is of utmost importance, and consequently, the implementation of this approach in applied breeding programmes is not straightforward. [ABSTRACT FROM AUTHOR]

In CMS (cytoplasmic male sterility)-based hybrid rye ( Secale cereale L.) breeding, effective pollen-fertility restoration is an essential prerequisite for achieving maximum grain yield on the one hand and for minimizing ergot ( Claviceps purpurea) infestation on the other. Restorer genes for the CMS-inducing 'Pampa' cytoplasm derived from landraces collected in Iran and Argentina are used by breeders for achieving this goal. Here, restorer genes from four germplasm sources ('Altevogt 14160', ' IRAN III', 'Trenelense' and 'Pico Gentario') were analysed by producing three-way cross hybrids between an elite CMS single cross and pollinators with and without a given restorer gene. Materials were evaluated on large drilled plots for restorer index ( RI), grain yield, plant height and other traits in six environments. In experiment 1, a restorer gene from 'Altevogt 14160' was used. Seven pairs of marker-selected carrier and non-carrier backcross lines served as pollinators. In experiment 2, the pollinators were 17 backcross line pairs from the other three germplasm sources. These lines were grouped as high ( RI > 67%) and low restorers ( RI < 30%), respectively, using testcrosses with a highly diagnostic CMS tester. Hybrids carrying an exotic restorer gene suffered from a significant grain yield reduction by 4.4% and 9.4% and were 9.3 and 4.8 cm taller in experiments 1 and 2, respectively. Thousand-kernel weight was reduced, whereas quality traits were only slightly affected. For all traits, significant genetic variance existed among the testcrosses to the presence vs. absence of a given exotic restorer gene. This offers a chance for the breeder to reduce or ultimately overcome the presently observed performance reductions brought about by exotic restorer genes. [ABSTRACT FROM AUTHOR]

The cytoplasmic male sterility ( CMS) system msm1 in barley is known to be thermosensitive, sometimes resulting in spontaneous fertility restoration in the absence of the corresponding restorer gene Rfm1. Here, we investigated genotypic differences concerning temperature sensitivity and the plant developmental stage at which elevated temperature induces spontaneous fertility restoration in three CMS mother lines. While one line stayed completely male sterile, a significantly higher fertility was observed in two lines after treatment from growth stage DC 41 until maturation. Microscopic analysis revealed that sterile anthers contained neither intact pollen, nor remains of aborted pollen grains, whereas pollen was visible in anthers of potentially fertile plants. We conclude that the barley CMS system affects anther and pollen development prior to meiosis. Elevated temperature during heading and flowering can lead to a spontaneous fertility restoration by reactivating pollen growth. Nevertheless, genotypic variation exists enabling the selection for stable CMS mother lines and the development of F1 hybrids with high hybridity. As spontaneous fertility restoration due to environmental effects is difficult to phenotype, further investigations will focus on the development of molecular markers for marker-assisted selection. [ABSTRACT FROM AUTHOR]

Germplasms consisting of 64 wild barley accessions ( Hordeum vulgare ssp. spontaneum) were examined for polymorphisms in α-amylase using both isoelectric focusing ( IEF) and thermostability assays. Wide variation was found for the high pI α-amylase with 20 IEF band patterns identified. Enzyme activity and thermostability assays showed large differences among α-amylase isoenzymes. Two wild accessions Tel-Shoket CPI 77146-32 and Afiq CPI 77128-41 showed superior enzyme activity and thermostability compared with commercial varieties such as 'Baudin', 'Flagship' or 'Navigator'. The functionality of the Tel-Shoket allele was validated in backcross lines with 'Flagship' as the recurrent parent. The Tel-Shoket allele at the amy1 locus increased α-amylase thermostability at 75°C by 8.4% and α-amylase activity in kilned malt by 18.7%. The introgression of the wild allele also led to significant improvements in fermentability, hot water extract and viscosity. Gene sequencing showed that there are three single nucleotide polymorphisms in the Tel-Shoket amy1 sequence, which can be used as diagnostic markers for the selection of this allele in breeding programmes. [ABSTRACT FROM AUTHOR]

The introgression lines (ILs) of the wild tomato species Solanum pennellii have been widely used to identify genes related to yield, texture, disease resistance and stress tolerance. In addition to flavour, fruit firmness is an important evaluation index and essential trait indicating tomato fruit quality. Quantitative trait loci (QTL) for fruit firmness have been identified through hand squeezing and pericarp puncturing. However, these techniques hardly reveal the force value of the whole fruit suffering from rupture or deformation. In this study, S. pennellii ILs were used to identify QTLs related to fruit firmness through flat-plate compression. Nine QTLs for enhancing and sixteen QTLs for decreasing fruit firmness were successfully identified. Compared with that of 'M82', the amount of QTLs that enhance fruit firmness increased by 8.76% to 21.00%, and the amount of QTLs that reduce fruit firmness decreased by −8.27% to −30.80%. The QTL Crf12a and Crf-R-7b is the strongest and weakest QTL, respectively, while they are very stable in all independent biological trials. Six QTLs should be further confirmed through open-field trials. [ABSTRACT FROM AUTHOR]

The stem solidness trait in wheat has been the most effective mechanism for management of the wheat stem sawfly ( WSS) for six decades. However, recent results have shown that in certain genotypes, the degree of stem solidness is not a useful indicator of WSS resistance. A morphological characterization of solidness expression indicated that in the genotype 'Conan', very solid pith undergoes rapid retraction during stem maturation, resulting in significantly less solidness at maturity. In other solid-stemmed genotypes, including the standard WSS-resistant cultivar 'Choteau', dense pith in the stem remains nearly unchanged throughout plant development. In cage trials, 'Conan' plants were less preferred for oviposition by the WSS when paired with 'Choteau' plants. Field bioassays using near-isogenic lines differing for alleles at Qss.msub-3 BL showed that the Conan allele provides higher levels of early stem solidness and rapid pith retraction during stem maturation. These results suggest that the traditional approach for increasing WSS resistance by selecting for increasing stem solidness needs to be modified to consider temporal variations in pith expression associated with alleles at Qss.msub-3 BL. [ABSTRACT FROM AUTHOR]

Grain yield and its component trait thousand kernel weight are important traits in triticale breeding programmes. Here, we used a large mapping population of 647 doubled haploid lines derived from four families to dissect the genetic architecture underlying grain yield and thousand kernel weight by multiple-line cross QTL mapping. We identified 3 QTL for grain yield and 13 for thousand kernel weight which cross-validated explained 5.2% and 48.2% of the genotypic variance, respectively. Both traits showed a positive phenotypic correlation, and we found two QTL overlapping between them. Full two-dimensional epistasis scans revealed epistatic QTL for both traits, suggesting that epistatic interactions contribute to their genetic architecture. Based on QTL identified in our results, we conclude that the potential for marker-assisted selection is limited for grain yield but more promising for thousand kernel weight. [ABSTRACT FROM AUTHOR]

This study aimed at developing, characterizing and evaluating two maize phenotypic-selected introgression libraries for a collection of dominant plant height ( PHT)-increasing alleles by introgressing donor chromosome segments ( DCS) from Germplasm Enhancement of Maize ( GEM) accessions into elite inbred lines: PHB47 and PHZ51. Different backcross generations ( BC1- BC4) were developed and the tallest 23 phenotype-selected introgression families ( PIFs) from each introgression library ( PHB47 or PHZ51) were selected for single nucleotide polymorphism genotyping to localize DCS underlying PHT. The result shows that most PIFs carrying DCS were significantly ( α = 0.01) taller than the respective recurrent parent. In addition, they contained larger donor genome proportions than expected in the absence of selection or random mating across all BC generations. The DCS were distributed over the whole genome, indicating a complex genetic nature underlying PHT. We conclude that our PIFs are enriched for favourable PHT-increasing alleles. These two libraries offer opportunities for future PHT gene isolation and allele characterization and for breeding purposes, such as novel cultivars for biofuel production. [ABSTRACT FROM AUTHOR]

The barley ( Hordeum vulgare L.) mutant erectoides-k.32 ( ert-k.32) was isolated in 1947 from an X-ray-mutant population of cultivar 'Bonus'. The mutant was released as a cultivar in 1958 with the name 'Pallas' - one of the first cereal crop cultivars developed from induced mutants. 'Pallas' is a semi-dwarf barley cultivar known for its culm stability and resistance to lodging. In total, eight allelic ert-k mutants are known that show different phenotypic strength concerning culm length and spike architecture. They represent alternatives to the widely used, but pleiotropic 'Green Revolution' alleles of the Sdw1 ( semidwarf1/denso) and Uzu1 ( semi-brachytic1) genes in breeding of robust elite barley cultivars. In the present study, we locate Ert-k to a 15.7- cM region in the centromeric region of chromosome 6H. Although the interval is estimated to contain approximately 700 genes, the work provides a solid foundation for the identification of the underlying mutations causing the ert-k lodging-resistant phenotype. In addition, the linked markers could be used to follow the ert-k mutant genotype in marker-assisted selection of new lodging-resistant barley cultivars. [ABSTRACT FROM AUTHOR]

The Russian wheat aphid ( RWA), Diuraphis noxia ( Kurdjumov), is an important pest of small-grain cereals, particularly wheat, worldwide. The most efficient strategy against the RWA is to identify sources of resistance and to introduce them into susceptible wheat genotypes. This study was conducted to determine the mode of inheritance of the RWA resistance found in ICARDA accession IG 100695, to identify wheat microsatellite markers closely linked to the gene and to map the chromosomal location of the gene. Simple sequence repeat (SSR) marker scores were identified in a mapping population of 190 F2 individuals and compared, while phenotypic screening for resistance was performed in F2 : 3 families derived from a cross between ' Basribey' (susceptible) and IG 100695 (resistant). Phenotypic segregation of leaf chlorosis and rolling displayed the effect of a single dominant gene, temporarily denoted Dn100695, in IG 100695. Dn100695 was mapped on the short arm of chromosome 7D with four linked SSR markers, Xgwm44, Xcfd14, Xcfd46 and Xbarc126. Dn100695 and linked SSR markers may be useful for improving resistance for RWA in wheat breeding. [ABSTRACT FROM AUTHOR]

The prediction accuracy in genomic selection is affected by complex interactions of molecular, genetic and phenotypic factors. Despite the extensive use of biparental populations for empirical- and simulationbased studies, the highly variable prediction accuracies produced by cross-validation have not been further investigated. Understanding factors correlated with the variability in prediction accuracy could provide new insights for estimation set (ES) design. In this study, we employed simulations and show that parameters derived from marker data are not associated with prediction accuracy within biparental populations and, therefore, cannot serve as tool for optimum ES design. In contrast, the phenotypic variance in the ES is a major factor correlated with prediction accuracy. In particular, for estimation sets of small size, a large phenotypic variance probably ensures that more quantitative trait loci are segregating in the ES which consequently allows a better marker effect estimation. While the ES phenotypic variance is not known beforehand, we discuss approaches how prediction accuracy could nevertheless be maximized for small estimation sets, towards a more efficient implementation of genomic selection within biparental families in plant breeding. [ABSTRACT FROM AUTHOR]

Introgression populations are developed to make genetic resources for breeding purposes available. In the case that the number of donor segments exceeds the number of lines, genome-wide prediction ( GWP) methods are suggested as promising for the analysis of such populations. Our objectives were to characterize a rye introgression population with the Rye5K SNP assay and to apply a GWP model with a modification of the restricted maximum likelihood procedure that yields heteroscedastic variances to detect significant donor effects. The introgression lines ( ILs) carried on average 4.6 donor segments with a mean length of 27 cM and represented 94% of the donor genome. Two donor effects were detected that significantly increased thousand-kernel weight. We found four donor effects for protein, total pentosan and starch content that can improve baking quality. Three donor effects for protein content were observed for improving feeding purposes and one donor effect for starch content to improve ethanol production. The effects were localized to small genomic regions. Consequently, these ILs can improve rye breeding by directly employing them in breeding programmes for variety development. [ABSTRACT FROM AUTHOR]

Generation of doubled haploid plants is a powerful tool in breeding, as homozygous individuals will be obtained directly from hybrids. However, genotype variability in regeneration efficiency of most European wheat ( Triticum aestivum L.) varieties has limited its use in wheat. This study intended to identify quantitative trait loci ( QTLs) for green plantlet regeneration from wheat microspore cultures. A QTL analysis using DAr T markers was conducted based on a bi-parental F3 population, derived from a cross between the varieties Svilena and Jensen, which displayed markedly different capacity for plantlet regeneration. Two QTLs on chromosome 1B and 7B explained 53% of the variation in green plantlet regeneration. Furthermore, a collection of 94 European wheat varieties was genotyped and phenotyped. The microspore response level was low among western and northern European wheat varieties, and the positive QTLs found in the bi-parental population were rare in the variety collection. Identification of the two QTLs enables introduction of high regeneration efficiency into wheat germplasm. Moreover, our results proved that the efficient regeneration observed for one variety could be crossed into modern winter wheat. [ABSTRACT FROM AUTHOR]

The ease with which seeds are detached from panicles is one of the early domestication traits. Genotypes with sticky panicles are hard to thresh, and whenever threshed, the grain tends to remain attached to the glume which reduces market value and processability. This study was conducted to determine the genetic mechanisms underlying the threshability trait in sorghum. Four seed parents and eleven pollinators differing for threshability were intercrossed in Design II mating scheme and the resulting hybrids and the parents were grown in four environments. Threshability was estimated as the ratio of seed yield to panicle weight ( TW) and proportion of seeds without sticky glumes ( TG). Variation was significant among the entries, inbreds and hybrids with GCA for TG and TW varying markedly. Mean TG for inbred and hybrids of low threshable genotypes was not markedly different indicating that threshability trait is under the control of additive genes with dominant or partially dominant effects. Segregation analysis indicates that the TG trait may be under the control of few major genes with approximately one to three loci affecting the trait. [ABSTRACT FROM AUTHOR]

We report on a new adult plant resistance (APR) gene Rph23 conferring resistance to leaf rust in barley. The gene was identified and characterized from a doubled haploid population derived from an intercross between the Australian barley varieties Yerong (Y) and Franklin (F). Genetic analysis of adult plant field leaf rust scores of the Y/F population collected over three successive years indicated involvement of two highly additive genes controlling APR, one of which was named Rph23. The gene was mapped to chromosome 7HS positioned at a genetic distance 36.6 cM. Rph23 is closely linked to marker Ebmac0603, which is flanked by markers bPb-8660 and bPb-9601 with linkage distances of 0.8 and 5.1 cM, respectively. A PCR-based marker was optimized for marker-assisted selection of Rph23, and on the basis of this marker, the gene was postulated as being common in Australian and global barley germplasm. Pedigree and molecular marker analyses indicated that the six-rowed black Russian landrace 'LV-Taganrog' is the likely origin of Rph23. [ABSTRACT FROM AUTHOR]

Heat and drought are the most important wheat production constraints worldwide. The objectives of this research were to evaluate the independent and combined effects of drought and heat in SeriM82/Babax population. Genotypes showed 11, 38 and 52% losses in grain yield ( YLD) in 2010-11 and 18, 25 and 48% in 2011-12 under heat, drought and combined stress, respectively. Seri M82 had higher YLD than Babax under heat and combined stress. Grain per spike and canopy temperature at vegetative stage ( CTv) in irrigated, day to heading and CT at grain-filling stage ( CTg) in drought, CTg and thousand-grain weight ( TGW) in heat and in combined trials were the best predictors of YLD. Results indicated that due to genotype by environment interactions not all stress-adaptive traits could be accumulated in a single genotype. In general, day to heading, CTg and grain weight are suggested as indirect selection criteria for increasing YLD under heat and drought stresses. In particular, CTg could be used as a rapid and effective criterion for screening a high number of genotypes. [ABSTRACT FROM AUTHOR]

Hybrid breeding is a promising approach to increase the yield potential in wheat ( Triticum aestivum L.). The profitability of wheat hybrids highly depends on a cost-efficient system for hybrid seed production for which an adequate outcrossing in the male pool is of utmost importance. Employing a set of 51 elite winter wheat lines, we developed and evaluated phenotyping methods for floral and flowering traits with relevance for improved cross-pollination. We observed significant genotypic variances and high heritabilities for most traits, including important traits like pollen mass and anther extrusion. Our results suggest the utility of the developed phenotyping approaches for applied plant breeding and the potential of the traits to assist in the design of the male ideotype for increased cross-fertilization. [ABSTRACT FROM AUTHOR]