No abstract

This paper reports on the first advanced backcross-QTL (quantitative trait locus) project which utilizes spring barley as a model. A BC(2)F(2) population was derived from the initial cross Apex ( Hordeum vulgare ssp. vulgare, hereafter abbreviated with Hv) x ISR101-23 ( H. v. ssp. spontaneum, hereafter abbreviated with Hsp). Altogether 136 BC(2)F(2) individuals were genotyped with 45 SSR (simple sequence repeat) markers. Subsequently, field data for 136 BC(2)F(2) families were collected for 13 quantitative traits measured in a maximum of six environments. QTLs were detected by means of a two-factorial ANOVA with a significance level of P < 0.01 for a marker main effect and a marker x environment (M x E) interaction, respectively. Among 585 marker x trait combinations tested, 86 putative QTLs were identified. At 64 putative QTLs, the marker main effect and at 27 putative QTLs, the M x E interaction were significant. In five cases, both effects were significant. Among the putative QTLs, 29 (34%) favorable effects were identified from the exotic parent. At these marker loci the homozygous Hsp genotype was associated with an improvement of the trait compared to the homozygous Hv genotype. In one case, the Hsp allele was associated with a yield increase of 7.7% averaged across the six environments tested. A yield QTL in the same chromosomal region was already reported in earlier barley QTL studies.

Salinity is one of the major limitations to wheat production worldwide. This study was designed to evaluate the level of genetic variation among 150 internationally derived wheat genotypes for salinity tolerance at germination, seedling and adult plant stages, with the aim of identifying new genetic resources with desirable adaptation characteristics for breeding programmes and further genetic studies. In all the growth stages, genotype and salt treatment effects were observed. Salt stress caused 33 %, 51 % and 82 % reductions in germination vigor, seedling shoot dry matter and seed grain yield, respectively. The rate of root and shoot water loss due to salt stress exhibited significant negative correlation with shoot K + , but not with shoot Na + and shoot K + /Na + ratio. The genotypes showed a wide spectrum of response to salt stress across the growth stages; however, four genotypes, Altay2000, 14IWWYTIR-19 and UZ-11CWA-8 (tolerant) and Bobur (sensitive), exhibited consistent responses to salinity across the three growth stages. The tolerant genotypes possessed better ability to maintain stable osmotic potential, low Na + accumulation, higher shoot K + concentrations, higher rates of PSII activity, maximal photochemical efficiency and lower nonphotochemical quenching (NPQ), resulting in the significantly higher dry matter production observed under salt stress. The identified genotypes could be used as parents in breeding for new varieties with improved salt tolerance as well as in further genetic studies to uncover the genetic mechanisms governing salt stress response in wheat.

The objective of the present study was to identify favourable exotic Quantitative Trait Locus (QTL) alleles for the improvement of agronomic traits in the BC 2 DH population S42 derived from a cross between the spring barley cultivar Scarlett and the wild barley accession ISR42-8 (Hordeum vulgare ssp. spontaneum). QTLs were detected as a marker main effect and/or a marker · environment interaction effect (M · E) in a three-factorial ANOVA. Using field data of up to eight environments and genotype data of 98 SSR loci, we detected 86 QTLs for nine agronomic traits. At 60 QTLs the marker main effect, at five QTLs the M · E interaction effect, and at 21 QTLs both the effects were significant. The majority of the M · E interaction effects were due to changes in magnitude and are, therefore, still valuable for marker assisted selection across environments. The exotic alleles improved performance in 31 (36.0%) of 86 QTLs detected for agronomic traits. The exotic alleles had favourable effects on all analysed quantitative traits. These favourable exotic alleles were detected, in particular on the short arm of chromosome 2H and the long arm of chromosome 4H. The exotic allele on 4HL, for example, improved yield by 7.1%. Furthermore, the presence of the exotic allele on 2HS increased the yield component traits ears per m 2 and thousand grain weight by 16.4% and 3.2%, respectively. The present study, hence, demonstrated that wild barley does harbour valuable alleles, which can enrich the genetic basis of cultivated barley and improve quantitative agronomic traits.

No abstract

In the present paper, we report on the selection of two sets of candidate introgression lines (pre-ILs) in spring barley. Two BC2DH populations, S42 and T42, were generated by introgressing an accession of Hordeum vulgare ssp. spontaneum (ISR42-8, from Israel) into two different spring barley cultivars, Scarlett (S) and Thuringia (T). From these BC2DH populations two sets with 49 (S42) and 43 (T42) pre-ILs were selected, and their genomic architecture as revealed by SSR marker analysis was characterised. The selected pre-ILs cover at least 98.1% (S42) and 93.0% (T42) of the exotic genome in overlapping introgressions and contain on average 2 (S42) and 1.5 (T42) additional non-target introgressions. In order to illustrate a potential application and validation of these pre-ILs, the phenotypic effect of the exotic introgression at the locus of the major photoperiod response gene Ppd-H1 was analysed. Pre-ILs carrying the introgression at the Ppd-H1 locus flowered significantly earlier than the elite parents, and the introgression maintained its effect across the two genetic backgrounds and across four tested environments. The selected pre-ILs represent a first promising step towards the assessment and utilization of genetic variation present in exotic barley. They may promote the breeding progress, serve for the verification of QTL effects and provide a valuable resource for the unravelling of gene function, e.g. by expression profiling or map-based cloning.

The increasing salinization of agricultural lands is a threat to global wheat production. Understanding of the mechanistic basis of salt tolerance (ST) is essential for developing breeding and selection strategies that would allow for increased wheat production under saline conditions to meet the increasing global demand. We used a set that consists of 150 internationally derived winter and facultative wheat cultivars genotyped with a 90K SNP chip and phenotyped for STacross three growth stages and for ionic (leaf K + and Na + contents) traits to dissect the genetic architecture regulating ST in wheat. Genome-wide association mapping revealed 187 Single Nucleotide Polymorphism (SNPs) (R 2 = 3.00-30.67%), representing 37 quantitative trait loci (QTL), significantly associated with the ST traits. Of these, four QTL on 1BS, 2AL, 2BS and 3AL were associated with ST across the three growth stages and with the ionic traits. Novel QTL were also detected on 1BS and 1DL. Candidate genes linked to these polymorphisms were uncovered, and expression analyses were performed and validated on them under saline and non-saline conditions using transcriptomics and qRT-PCR data. Expressed sequence comparisons in contrasting ST wheat genotypes identified several non-synonymous/missense mutation sites that are contributory to the ST trait variations, indicating the biological relevance of these polymorphisms that can be exploited in breeding for ST in wheat.

No abstract