Mildew-resistant barley mutants induced by X-rays

Summary In 1951, a line of the Austrian barley variety Vollkorn (a brewing barley widely grown in Lower Austria) was exposed to X-rays with a view to selecting mildew resistant mutants.Mildew infection was restricted to X₂-ear progenies. In the X₃-generation one mutant (indicated No. 3502/53) was found to be resistant to the mildew races A₁, B, C, D, F and some other mutants showed a moderate resistance to the races A and B.Field trials proved that there was a correlation between the susceptibility to mildew and lodging. Mutant lines with high yields (127% of mother line) combined a good mildew resistance with a good resistance to lodging.The type of resistance induced and its interitance in various mutants is under investigation.Details of irradiation, infection and selection are given by Hänsel (6).Dr., Lecturer in Plant Breeding at the University of Agriculture, Vienna, Geneticist and Cereal Breeder at the Probstdorfer Saatzucht Station, N.Ö., Austria.Director of the Experimental X-ray Station Vienna 9, Alserstrasse 4.     

Long-peduncled dwarf: A new mutant type induced in barley

Summary A new mutant, long-peduncled dwarf, was induced by EMS in C 164 barley. The mutant was characterised by a markedly shorter stature but longer peduncle than the normal plant. The dwarfing of the mutant was due to very short internodes other than the peduncle. The mutant was fully fertile and not associated with any chromosome aberration. The mutant trait was inherited as a single recessive gene designated as lpd. The trait being new may find a significant place in genetic research and also in plant breeding.     

The inheritance of a basal branching type in guar

Summary Eight different genotypes of the F₁ hybrids between Oriental × Asiatic lily (Lilium) hybrids (2n = 2x = 24) were treated with nitrous oxide (N₂O) gas under pressure for 24 and 48 hours. At the time of treatment, all plants possessed early meiotic stages in the anthers of the oldest flower buds. The mature flowers from treated plants were monitored for fertility through pollen germination in vitro as well as by using them in crosses with diploid Asiatic hybrids (2n = 2x = 24) both as male and female parents. In five out of the eight genotypes of OA hybrids there was evidence for the production of 2n pollen which germinated in vitro from either one or both treatments. The 2n pollen from three genotypes was successfully used in crosses. In two cases, the treated plants were successfully used as female parents which indicated the formation of 2n (or 2x) egg cells. From an analysis of 41 sexual polyploid progenies obtained from N₂O treated plants it was shown that they were all euploids consisting of 34 triploids (2n = 3x = 36) and seven tetraploids (2n = 4x = 48). A detailed cytological analysis of 12 progeny plants through genomic in situ hybridization (GISH) proved that N₂O had induced first division restitution gametes in most cases and in two cases they produced gametes through indeterminate meiotic restitution. There was evidence for intergenomic recombination in three cases.     

The cost of participatory barley breeding

Farmer participation in agricultural research is increasingly seen as a powerful methodology to increase the relevance of technologies developed to benefit farmers' communities. In plant breeding, farmer participation is considered as a way to increase the probability of adoption of new varieties. However, the higher expected cost of participatory plant breeding (PPB) is seen as one of the main obstacles to its wider adoption.This paper addresses the issue of the different costs to an Institution of running a PPB program or a non-participatory program and uses the barley-breeding program at the International Center for Agricultural Research in the Dry Areas (ICARDA) as a case study.Observations and data collection were carried out during one full cropping season on the cost of the three main components of the breeding program, i.e. the management of the field trials (land and seedbed preparation, planting, fertilizer application, weed control, harvesting, and seed threshing, cleaning, treating and packaging), the travel to farmers' fields or to the research sites, and the human resources (scientists, technical staff, local workers and farmers) involved in breeding activities.We compared two options for the centralized–non-participatory breeding program, differing in the number of sites (8 and 16) used for the on-farm trials, with 160 options for the decentralized-participatory breeding program, differing in the combination of number of sites (from 4 to 16) and number of trials per site (from 1 to 10).The results show that in both decentralized-participatory and centralized–non-participatory plant breeding the cost of managing the field trials is the highest followed by the cost of human resources and that of travel: the contribution of each component to the total cost varies with the various options and the various combinations of the number of sites and of farmers.The comparison of the aggregated costs indicates that in the case of the ICARDA' barley-breeding program there are no relevant differences between the participatory and the non-participatory plant breeding programs. This is largely associated with the fact that the decentralized-participatory breeding program reaches the same level of development of the breeding material 3 years earlier than the centralized–non-participatory breeding program. Depending on the type of centralized-breeding program and on the combination of number of sites and number of farmers per site in the participatory program, the aggregated costs of the participatory program are lower than those of the centralized-breeding program by between 5 and 28%. At the same level of cost of the centralized program, the model of participatory program used in this study generates more information due to the use of more trials at each site. This improves selection efficiency and provides an analytical tool to optimize the number of sites and of farmers per site.     

The progress of inbreeding in a pedigree-bred population of barley

in the pedigree of a group of several intervarietal crosses in barley, individual plant progenies from F₄ F₅ and F₆ generations were studied along with three of their parents for comparing the within-family variances (² w) in them using it as a measure of progress towards homozygosity. For plant height the value of w ² in F₆ was not significantly higher than the one in parents whereas for spike length there was observed a significant excess of within-family variability in F₆ over the parents. This excess was attributed to a differential survival of heterozygous progenies under selection despite some selection pressure against the heterozygosity in marked chromosome segments. The adaptive role of heterozygote advantage in the populations of such predominantly self-fertilized species has been briefly discussed.     

Genetic analysis of resistance in barley to barley yellow dwarf virus

The inheritance of resistance to barley yellow dwarf virus (BYDV) was studied in the selected 24 spring and winter barley cultivars that showed a high or intermediate resistance level in 1994‐97 field infection tests. The polymerase chain reaction diagnostic markers YLM and Ylp were used to identify the resistance gene Yd2. The presence of the Yd2 gene was detected with both markers in all the resistant spring barley cultivars and lines from the CIMMYT/ICARDA BYDV nurseries. The results of field tests and genetic analyses in winter barley corresponded with marker analyses only when the Ylp marker was used. Genes non‐allelic with Yd2 were detected by genetic analyses and the Ylp marker in moderately resistant spring barley cultivars ‘Malvaz’, ‘Atribut’ and ‘Madras’, and in the winter barley cultivars ‘Perry’ and ‘Sigra’. Significant levels of resistance to BYDV were obtained by combining the resistance gene Yd2 with genes detected in moderately resistant cultivars. The utilization of analysed resistance sources in barley breeding is discussed.     

Mapping and candidate gene identification of loci induced by phytohormones in barley (Hordeum vulgare L.)

Phytohormones, a group of structurally unrelated small molecules are plant-signalling compounds that trigger induced resistance against certain pathogens and herbivores. The hormones jasmonic acid (JA), ABA, salicilic acid (SA) and ethylene (ET) are known to play major roles in regulating plant defence responses. In order to determine the changes in growth and in the chlorophyll content induced by the exogenous application of these elicitors, a set of DH lines of the Oregon-Wolfe Barley mapping population, previously screened to locate aphid resistant genes, was investigated. The aim of the current research was to map the induced defence genes and to reveal the relationship with aphid resistance. There were highly significant differences between controls and hormone treated plants in the aerial fresh and dry weights (AFW, ADW), the foliar area (FA) and the root dry weight (RDW). More than 15 JA and ET-induced lines exceeded the chlorophyll (Ch) values of their controls. Most of the plant traits were associated with the same genetic windows on chromosomes 3H, 5H and 7H in the controls and hormone treated plants. QTL(s) identified on chromosome 3H and 5H explained most of the variation of AFW, ADW, FA and RDW of controls and treated plants. QTL(s) located on chromosome 5H were associated with the variation of chlorophyll contents on JA-treated plants. The Ch in ET and ABA-treated plants was associated with two different regions on chromosome 7H. One of the latter genetic windows also explained the variation of RDW of ET- and ABA-treated plants. A sequence homology search was performed to derive the putative function of the genes linked to the QTLs. Several QTLs were identified located close to aphid resistance genes previously mapped. This is the first report of genes associated with hormone response in barley that could be involved with insect resistance. Those recombinant lines carrying the appropriate alleles could be useful for breeding barley to enlarge the genetic base of defence against stress.     

The Yd2 gene and enhanced resistance to barley yellow dwarf virus (BYDV) in winter barley

A breeding programme was developed to obtain barley yellow dwarf virus (BYDV)-resistant winter genotypes using the Yd2 gene. The aim was to incorporate the Yd2 allele into the new high-yielding genotypes to release cultivars that allow barley cultivation in areas where BYDV is endemic. The resistant lines were developed using pedigree selection. An ICARDA resistant line (83RCBB130) carrying the Yd2 gene was crossed with three susceptible, high-yielding winter varieties and their F₁ lines were either selfed or backcrossed to the matching susceptible parent. The best lines selected from subsequent selfing generations were evaluated in replicated trials in the presence or absence of BYDV, starting from F₆ and BC₁F₅ to F₈ and BC₁F₇ generations. Four genotypes with superior agronomic traits and BYDV resistance were selected.     

Inheritance of earliness in barley

The data collected by Johnson and Paul (1958) from five crosses for the study of the inheritance of earliness in barley have been re-analysed by following biometrical techniques as developed by Mather (1949).Earliness in barley was found to be controlled by polymeric genes. Two to five effective factors were estimated to be operating, affecting earliness in the various crosses.Presence of overdominance was observed in three of the five crosses, while in the remaining two crosses no dominance was noted.Transgressive segregation was observed in the two crosses, Frontier x Bonneville and Montcalm x Atsel. The cross, Montcalm x Atsel, may be a source for breeding a new strain which might be expected to mature earlier than the early parent, Atsel.University of Alberta Postdoctorate Research Fellow     

The frequency of natural cross-fertilisation in sequential sowings of winter barley

Summary Estimations of random mating frequency were computed for a series of sequential autumn sowings of populations of winter barley. The estimations were by means of the maximum likelihood scoring method and three varieties, each carrying a recessive genetic marker, provided three independent estimations for each population. High levels of out-crossing were found in sowings made early in September, and a trend towards absence of out-crossing in populations sown in late November was evident. Although fluctuations in this trend could be accounted for by fluctuations in meteorological factors, a more profound underlying effect was evident in that the three marker varieties behaved similarly, though to different degrees. It is postulated that the principle effect of sowing date, as it affects out-crossing, is upon the development of the flowering apex, and that environmental conditions at flowering time merely modify flowering behaviour.     

The genetic basis of scald resistance in western Canadian barley cultivars

Summary The genetic basis of resistance to scald (Rhynchosporium secalis) within barley breeding populations is poorly understood. The design of effective genetically based resistance strategies is predicated on knowledge of the identity of the resistance genes carried by potential parents. The resistance exhibited by a broad selection of western Canadian barley lines was investigated by evaluating their reactions to five R. secalis isolates. Results were compared to the resistance exhibited by previously characterized lines. This comparison, combined with pedigree analysis indicated that there are two different resistance genes present inwwestern Canadian cultivars. These genes were shown to be independent through analysis of a segregating population derived from a cross between Falcon and CDC Silky. This evidence, along with observed linkage of the gene in CDC Silky with an allele specific amplicon developed for a Rhynchosporium secalis resistance locus on chromosome 3, provides evidence that the gene in Falcon is the Rh2 gene derived from Atlas, and the gene (s) in CDC Silky is located within the Rh/Rh3/Rh4 cluster and is similar to the Rh gene in Hudson.     

Meta-analysis of QTL associated with tolerance to abiotic stresses in barley

A meta-analysis of quantitative trait loci (QTL) associated with tolerance to abiotic stresses in barley was carried out using results from 35 different experiments. ??MetaQTL?? software was used to project QTL positions on a reference map. Three hundred and thirty-seven QTL for traits associated with tolerance to abiotic stresses were included in this analysis which identified 79 metaQTL (MQTL) including 26 for drought, 11 for low temperature, 22 for salinity, 17 for water-logging, and 3 for mineral toxicity and deficiency. The distribution of MQTL was similar to that of the initial QTL. Many of these MQTL were located on chromosomes 2H (mainly for water-logging and drought) and 5H (mainly for salinity and low temperature). It inferred that chromosomes 2H and 5H were important for researches on barley abiotic tolerance, and the genes associated with abiotic stresses were concentrated relatively. As expected from trait correlations, 22.8?% of these MQTL displayed overlapping CIs. These overlapping regions were mainly on chromosomes 1H, 2H and 4H. The results indicated that the tolerance to diverse abiotic stresses were associated with each other in barley. Additionally, 67 candidate genes responsive to abiotic stresses were co-located with the abiotic-stress MQTL. Of them, a total of 55 had different conserved motifs. It inferred that the tolerance to abiotic stresses was contributed by multi-genes with diverse functions, though there might be some important genes associated with the tolerance to abiotic stresses in barley. Additionally, of these candidate genes, scsnp02622, scsnp01644 and scsnp19641 could be better for further studies of abiotic stresses tolerance.     

The creation and maintenance of two spring barley varieties

Summary An old hybrid population of the interspecific cross Hordeum laevigatum x Goudgerst was chosen as initial material on a selection basis in 1947. We succeeded in raising the mildew-resistant fodder barley varieties Minerva and Vada which are also suitable for the production of pearled barley.It is remarkable that without backcrossing from this interspecific crossing, varieties have been obtained with such a high production capacity. Crosses of Hordeum laevigatum with other barley varieties, excelling Goudgerst in production, may lead to even better results.     

Identification of barley strains with improved amino acid balance

Summary Four barley strains viz. 1098–2, 1098–7, 1098–9 and 733–6, obtainedfrom the progeny of the crosses, Jyoti x Hyproly and Vijay x Hiproly which showed an increase in the grain protein content and an improvement in amino acid balance, were identified.     

The inheritance of winter hardiness in Pisum. III. Stem branching in autumn growth

Summary In the process of developing a winter hardy culinary pea for Michigan (Markarian et al., 1968), it has been determined that the habit of plant growth necessary to accomplish over wintering is a rosette of spreading branches with short internodes, lying prostrate on the ground. Inheritance of number of stem-branches in peas sown on September 7, 1964, in East Lansing, Michigan, was studied by comparing inbreds, reciprocal hybrids, and their selfs and backcrosses. Parental inbreds were Jade, an early, upright, predominantly single stemmed culinary type and a F₅ selection of a hybrid between Early Perfection and Austrian Winter which had the prostrate growth habit described above. A range of segregation from 1 to 8 branches observed in F₂ and F₃ populations indicates two major gene pairs acting in an additive manner.Present address: University of Minnesota, St. Paul, Minnesota, and Curtice-Burns, Inc., Rochester, New York, respectively.     

Characterization of greenbug resistance in barley

The greenbug [Schizaphis graminum (Rondani)] is an extremely damaging pest of barley (Hordeum vulgare L.), particularly in the southern Great Plains of the USA. Winter barley targeted for production in this region should incorporate resistance to greenbug in the form of the resistance gene Rsg1a (in ‘Post 90′) or Rsg2b (in PI 426756). This study was conducted to fully characterize the resistance profile of these two genes against important greenbug biotypes, and to determine which of the two resistance genes is most effective in protecting barley from the greenbug. Eight barley and four wheat cultivars and germplasms were challenged with six greenbug biotypes and damage ratings were recorded for each combination. In five of the six tests, ‘Post 90’ was significantly more resistant than PI 426756 to greenbug feeding damage. Based on the results presented here, we conclude that the resistance gene, Rsg1a, in ‘Post 90’ is the better choice for use in breeding programmes and will provide better protection than Rsg2b against the greenbug.     

Inheritance of gramine content in barley

The inheritance of gramine indole alkaloid was studied in F1 and F2 generations derived from crosses between wild ( Hordeum vulgare subsp. spontaneum) and cultivated ( H. vulgare subsp. vulgare) barley at adult stage in the field. The means of gramine content were very low in F1s and F2s in April and May. The ratio of progeny containing gramine to those without gramine (near zero or undetectable) fit a mono-genic or di-genic model in F2 generation. However, the content of gramine might be controlled by minor genes in the gramine-containing plants. The direction of dominance was toward lower gramine content. The averages of dominance ( h/d) in F1 and F2 ranged from partial to complete. Broad-sense heritabilities were high (0.70 to 0.77). The usefulness of hybrids for breeding aphid resistance and possibility increasing palatability of grazing pasture for sheep and cattle is discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Chromosomal regions associated with barley yellow dwarf virus resistance in oat

Immature embryos of the spring barley variety GoldenPromise, were bombarded with three different particledelivery systems and both transient and stabletransformation examined. In addition, a range oftechniques for the preparation of the DNA coated goldparticles was examined. Fertile transgenic barleyplants were obtained using three particle preparationtechniques which differed in the amount of gold andDNA used for each bombardment. However, only one ofthe particle delivery systems, the PDS 1000/He device,appeared to be effective in yielding transformedbarley plants.