Overall coordinator’s report



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Barley Genetics Newsletter (2009) 39:24-76



REPORTS OF THE COORDINATORS
Overall coordinator’s report
Udda Lundqvist

Nordic Genetic Resource Center

P.O. Box 41, SE 230 53 Alnarp, Sweden
e-mail: udda@nordgen.org

Since the latest overall coordinator’s report in Barley Genetics Newsletter Volume 38 not many changes of the coordinators took place. As Mark Sutherland, Australia who should take care of the coordination of the disease and pest resistant genes is so engaged with administration work at his university, we had to find a successor. Professor Frank Ordon from Germany is willing to take over. I wish him welcome to our group.


Several research groups world-wide are working with Single Nucleotide Polymorphism (SNP) genotyping and are using induced mutants from different Gene Banks. Good results have already been published in many publications as different reports are dealing with. About 950 different near isogenic lines (NIL) that are established by J.D. Franckowiak, now working in Australia, are an extraordinary source for this genotyping. During the summer of 2009 about half of these lines have been increased and propagated in Sweden in order to incorporate them in the Nordic Genetic Resource Center (Nordgen), Alnarp, Sweden. The other part will be increased during the summer of 2010 in Sweden. It has been decided to establish an International Centre for Barley Genetics Stocks at Nordgen, Sweden.
Some of us had the opportunity to participate the 14th Australian Barley Technical Symposium at the Sunshine Coast of Queensland, Australia, during september 2009. Several sessions dealed with economics production, quality, biotechnology and future research and production in variable environments of malt and feed barley. Also important presentations were on pest and disease resistant problems and the control of biotic and abiotic stresses. It was very interesting to learn that Australia is fighting with complete other breeding problems to release cultivars than what we have to do in Europe. Especially drought is a large problem in the early season of barley cultivation.


List of Barley Coordinators

Chromoosome 1H (5): Gunter Backes, The University of Copenhagen, Faculty of Life Science, Department of Agricultural Sciences, Thorvaldsensvej 40, DK-1871 Fredriksberg C, Denmark. FAX: +45 3528 3468; e-mail: <guba@life.ku.dk>
Chromosome 2H (2): Jerry. D. Franckowiak, Hermitage Research Station, Agri-science Queensland, Department of Employment, Economic Development and Innovation, Warwick, Queensland 4370, Australia, FAX: +61 7 4660 3600; e-mail: <jerome.franckowiak@deedi.qld.gpv.au>
Chromosome 3H (3): Luke Ramsey, Genetics Programme, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom. FAX: +44 1382 562426. E-mail: <Luke.Ramsey@scri.sari.ac.uk>
Chromosome 4H (4): Arnis Druka, Genetics Programme, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom. FAX: +44 1382 562426. e-mail: <adruka@scri.sari.ac.uk>
Chromosome 5H (7): George Fedak, Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, ECORC, Ottawa, ON, Canada K1A 0C6, FAX: +1 613 759 6559; e-mail: <fedakga@agr.gc.ca>
Chromosome 6H (6): Victoria Carollo Blake, Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717, USA.e-mail: <vblake@montana.edu>
Chromosome 7H (1): Lynn Dahleen, USDA-ARS, State University Station, P.O. Box 5677, Fargo, ND 58105, USA. FAX: + 1 701 239 1369; e-mail: <DAHLEENL@fargo.ars.usda.gov>
Integration of molecular and morphological marker maps: David Marshall, Genetics Programme, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, United Kingdom. FAX: 44 1382 562426. e-mail: <David.Marshall@scri.ac.uk>
Barley Genetics Stock Center: Harold Bockelman, USDA-ARS, National Small Grains Germplasm Research Facility, 1691 S. 2700 W., Aberdeen, ID 83210, USA. FAX: +1 208 397 4165; e-mail: <nsgchb@ars-grin.gov>
Trisomic and aneuploid stocks: Harold Bockelman, USDA-ARS, National Small Grains Germplasm Research Facility, 1691 S. 2700 W., Aberdeen, ID 83210, USA. FAX: +1 208 397 4165; e-mail: <nsgchb@ars-grin.gov >
Translocations and balanced tertiary trisomics: Andreas Houben, Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, DE-06466 Gatersleben, Germany. FAX: +49 39482 5137; e-mail: <houben@ipk-gatersleben.de>
List of Barley Coordinators (continued)
Desynaptic genes: Andreas Houben, Institute of Plant Genetics and Crop Plant Research, Corrensstrasse 3, DE-06466 Gatersleben, Germany. FAX: +49 39482 5137; e-mail: <houben@ipk-gatersleben.de>
Autotetraploids: Wolfgang Friedt, Institute of Crop Science and Plant Breeding, Justus-Liebig-University, Heinrich-Buff-Ring 26-32, DE-35392 Giessen, Germany. FAX: +49 641 9937429; e-mail: <wolfgang.friedt@agrar.uni-giessen.de>
Disease and pest resistance genes: Frank Ordon, Julius Kühn Institute (JKI), Institute for Resistance Research and Stress Tolerance, Erwin-Baur-Strasse 27, DE-06484 Quedlinburg, Germany. e-mail: <frank.ordon@jki.bund.de>
Eceriferum genes: Udda Lundqvist, Nordic Genetic Resource Center, P.O. Box 41, SE-230 53 Alnarp, Sweden. FAX:.+46 40 536650; e-mail: < udda@nordgen.org>
Chloroplast genes: Mats Hansson, Carlsberg Research Center, Gamle Carlsberg vej 10, DK-2500 Valby, Copenhagen Denmark. e-mail: <mats@crc.dk>
Genetic male sterile genes: Mario C. Therrien, Agriculture and Agri-Food Canada, P.O. Box 1000A, R.R. #3, Brandon, MB, Canada R7A 5Y3, FAX: +1 204 728 3858; e-mail: <MTherrien@agr.gc.ca>
Ear morphology genes: Udda Lundqvist, Nordic Genetic Resource Center, P.O. Box 41, SE-230 53 Alnarp, Sweden. FAX: +46 40 536650; e-mail: < udda@nordgen.org>

or

Antonio Michele Stanca: Istituto Sperimentale per la Cerealicoltura, Sezione di Fiorenzuola d’Arda, Via Protaso 302, IT-29017 Fiorenzuola d’Arda (PC), Italy. FAX +39 0523 983750, e-mail: <michele@stanca.it>40 536650


Semi-dwarf genes: Jerry D. Franckowiak, Hermitage Research Station, Agri-science Queensland, Department of Employment, Economic Development and Innovation, Warwick, Queensland 4370, Australia, FAX: +61 7 4660 3600; e-mail: < jerome.franckowiak@deedi.qld.gpv.au >
Early maturity genes: Udda Lundqvist, Nordic Genetic Resource Center, P.O. Box 41,

SE-230 53 Alnarp, Sweden. FAX: +46 40 536650; e-mail: <udda@nordgen.org>


Barley-wheat genetic stocks: A.K.M.R. Islam, Department of Plant Science, Waite Agricultural Research Institute, The University of Adelaide, Glen Osmond, S.A. 5064, Australia. FAX: +61 8 8303 7109; e-mail: <rislam@waite.adelaide.edu.au>

Coordinator’s Report: Barley Chromosome 1H (5)
Gunter Backes
The University of Copenhagen
Faculty of Life Sciences


Department of Agricultural Sciences

Thorvaldsensvej 40
DK-1871 Frederiksberg C, Denmark

e-mail: guba@life.ku.dk
A member of the cellulose synthase-like gene family, HvCslF9 was localized to chromosome 1H, bin 7 (Burton et al., 2008). The family includes seven genes in barley and there is evidence that the gene is involved in the synthesis of β-glucan.
In a doubled haploid population (100 lines) from a cross between the two-row spring barley line BCD47 and the variety ‘Baronesse’, on chromosome 1H, bin 3/4, a QTL affecting both heading date (LOD 2.1 – 2.9), photoperiod response (LOD 1.7), physiological maturity (LOD 1.8) and grain filling period (LOD 1.4) was localized (Castro et al., 2008). The phenotyping was based on eight field experiments covering three years. Besides, two major QTLs for heading date and physiological maturity explained most of the phenotypic variation.
A QTL for heading date, when sown in autumn in four field experiments, and for short photoperiod, measured in two green house experiments, was localized to 1H, bin 11 (Cuesta-Marcos et al., 2008a). The localisation was carried out in 120 doubled haploid lines from a cross between the French two-row cultivars ‘Beka’ and ‘Mogador’. Ppd-H2 might be a candidate gene for this QTL.
Fifteen small interconnected doubled haploid populations (7 to 20 lines each, adding up to 281 lines in total), were cultivated under the same conditions as the population described in the precedent paragraph. In the field experiments, the heading date was measured, while in the greenhouse experiment, Cuesta-Marcos et al. (2008b) determined the number of leaves. Again, on chromosome 1H, bin 11, a QTL, likely representing Ppd-H2, affected both traits.
Verhoeven et al., 2008 were interested in the habitat-specific selection on heading-date related QTLs. For this purpose, they tested 140 F2:3 families from a cross between two wild barley lines (Hordeum vulgare ssp. spontaneum) originating from two different environments. They tested the lines in different controlled and natural environments and localized relatively large overlapping areas affecting seed weight (measured in field experiments) and relative growth rate (measured in a green house experiment) on chromosome 1H.
In an association study using a population consisting of 83 barley landraces, 44 old genotypes and 65 modern genotypes from within the Mediterranean basin, Pswarayi et al., 2008 detected associations for grain yield in bin 2 and bin 8 of chromosome 1H. The experiment was carried out in Spain (one year) and Syria (two years) on two locations with high and low yield potential, respectively. Both mentioned associations were detected in the low-yield environment in Syria.
A QTL for coleoptiles elongation under uncovered darkness (LOD 3.9) was found by Takahashi et al. (Takahashi et al., 2008) on chromosome 1H, bin 14. The authors phenotyped 150 doubled haploid lines from the Harrington/TR306 population in pot experiments.
Ulrich et al. (Ullrich et al., 2008) analyzed 150 doubled haploid lines from ‘Steptoe’/’Morex’ for pre-harvest sprouting. They found a QTL for germination percentage on chromosome 1H, bin 14, with an LR of 12. The ears from plants grown in one field and one green house environment were treated for five days in a mist chamber.
In two doubled haploid populations, one including 92 lines from the cross TX0425/‘Franklin’ and one including 177 lines from the cross ‘Yerong’/‘Franklin’, Li et al. (2008) searched for QTLs related to waterlogging tolerance. In TX0425/‘Franklin’, they detected a QTL for chlorosis after two weeks of waterlogging on chromosome 1H bin 6/7 (LOD 2.8). In the population derived from ‘Yerong’/‘Franklin’ they detected another QTL effecting leaf yellowing after 2 weeks of waterlogging in bin 8/9 (LOD 2.8).
In an greenhouse experiment with well-watered and drought-stress treatments Guo et al. (2008) measured different chlorophyll-related traits on 194 recombinant inbred lines originating from a cross between ‘Arta’ and the wild barley (Hordeum vulgare ssp. spontaneum) line 41-1. On chromosome 1H, a QTL for initial photosynthesis was discovered in bin 11 (LOD 2.8).
Another experiment dealing with drought related trait was carried out as a field experiment with four Mediterranean locations in two years on 158 recombinant inbred lines from the cross ‘Tadmor’/‘ER/Apm’ (von Korff et al., 2008a). Several traits related to drought stress, plant morphology and development were observed. On chromosome 1H, five QTLs were observed: in bin 7 and 8 two QTLs affecting heading date (F-values 12.1 and 20.8, respectively), in bin 9 a QTL affecting spike length (F-value 15.7), in bin 12 a QTL affecting both growth vigour and days to maturity (F-values 19.5 and 31.4, respectively) and in bin 14 a QTL affecting the grain filling period (F-value 20.8).
In an advanced back-cross population (301 BC2DH lines) originating from a cross between ‘Scarlett’ and the wild barley (H. vulgare ssp. spontaneum) line ISR42-8, von Korff et al. (2008b) analyzed malting quality traits on kernels harvested from four locations through two years. Six QTLs were detected on chromosome 1H: in bin 3 a QTL for protein content, (F-value 11), in bin 3/4 a QTL for α-amylase activity (F-value 11), in bin 4 a QTL for malt extract (F-value 16.3), in bin 6-8 a QTL for friability and protein content (F-values 153 and 59, respectively), in bin 6-9 a QTL for viscosity, in bin 7 another QTL for malt extract (F-value 45), in bin 10 a QTL for friability and viscosity (F-value 23 and 15, respectively) and in bin 13 another QTL for protein content. For the last-mentioned QTL the wild barley contributed the advantageous allele.
Two major QTLs for resistance against spot blotch, caused by Cochliobolus sativus, were localized by Kuldeep et al. (2008) on chromosome 1H of barley. One was localized in bin 6/7 (LOD 9.0) and one was localized in bin 6/7 (LOD 18.9). A further QTL was localized on chromosome 7H. The analysis was carried out in field experiments (one location, 3 years) on a population of 200 recombinant inbred lines (F5 - F7) from a cross between the resistant line IBON 18 and the susceptible line RD 2508.
The QTL locus Rphq21 conferring resistance against leaf rust, caused by Puccinia hordei, was located on chromosome 1H, bin 5/6 by Marcel et al. (2008). The resistance was effective against one out of 4 isolates in the seedling stage of barley. It was localized with an LOD of 3.9 in a population of 103 recombinant inbred lines (F9) from the cross L94/‘Vada’.
Jafary et al. (2008) studied non-host resistance in barley against heterologous rust fungi. For this purpose, they infected two different populations of barley with Puccinia triticina, P. persistens, P. hordei-murini and P. hordei-secalini. On chromosome 1H, two QTLs conferring resistance against P. hordei-murini were localized. In the population consisting of 113 recombinant inbred lines (F9) from the cross ‘SusPtrit’/‘Cepada Capa’ a QTL in bin 2-4 was detected and in the other population, consisting of 92 doubled haploid lines from the Oregon-Wolfe Barley population, a QTL in bin 6-8 was found.

References:
Burton, R.A., S.A. Jobling, A.J. Harvey, N.J. Shirley, D.E. Mather, A. Bacic and G.B. Fincher, 2008. The genetics and transcriptional profiles of the cellulose synthase-like HvCslF gene family in barley. Plant Physiol. 146: 1821-1833.
Castro, A.J., P.M. Hayes, L. Viega and I. Vales, 2008. Transgressive segregation for phenological traits in barley explained by two major QTL alleles with additivity. Plant Breed. 127: 561-568.
Cuesta-Marcos, A., E. Igartua, F.J. Ciudad, P. Codesal, J.R. Russell, J.L. Molina-Cano, M. Moralejo, P. Szücs, M.P. Gracia, J.M. Lasa and A.M. Casas, 2008a. Heading date QTL in a spring x winter barley cross evaluated in Mediterranean environments. Mol. Breed. 21: 455-471.
Cuesta-Marcos, A., A.M. Casas, S. Yahiaoui, M.P. Gracia, J.M. Lasa and E. Igartua, 2008b. Joint analysis for heading date QTL in small interconnected barley populations. Mol. Breed. 21: 383-399.
Guo, P.G., M. Baum, R.K. Varshney, A. Graner, S. Grando and S. Ceccarelli, 2008. QTLs for chlorophyll and chlorophyll fluorescence parameters in barley under post-flowering drought. Euphytica 163: 203-214.
Jafary, H., G. Albertazzi, T.C. Marcel and R.E. Niks, 2008. High diversity of genes for nonhost resistance of barley to heterologous rust fungi. Genetics 178: 2327-2339.
Kuldeep, T., R. Nandan, U. Kumar, L.C. Prasad, R. Chand and A.K. Joshi, 2008. Inheritance and identification of molecular markers associated with spot blotch (Cochliobolus sativus L.) resistance through microsatellites analysis in barley. Genet. Mol. Biol. 31: 734-742.
Li, H.B., R. Vaillancourt, N. Mendham and M.X. Zhou, 2008. Comparative mapping of quantitative trait loci associated with waterlogging tolerance in barley (Hordeum vulgare L.). BMC Genom. 9: 401.
Marcel, T.C., B. Gorguet, M.T. Ta, Z. Kohutova, A. Vels and R.E. Niks, 2008. Isolate specificity of quantitative trait loci for partial resistance of barley to Puccinia hordei confirmed in mapping populations and near-isogenic lines. New Phytologist 177: 743-755.
Pswarayi, A., F.A. van Eeuwijk, S. Ceccarelli, S. Grando, J. Comadran, J.R. Russell, N. Pecchioni, A. Tondelli, T. Akar, A. Al-Yassin, A. Benbelkacem, H. Ouabbou, W.T.B. Thomas and I. Romagosa, 2008. Changes in allele frequencies in landraces, old and modern barley cultivars of marker loci close to QTL for grain yield under high and low input conditions. Euphytica 163: 435-447.
Takahashi, H., M. Noda, K. Sakurai, A. Watanabe, H. Akagi, K. Sato and K. Takeda, 2008. QTLs in barley controlling seedling elongation of deep-sown seeds. Euphytica 164: 761-768.
Ullrich, S.E., J.A. Clancy, I.A. del Blanco, H.J. Lee, V.A. Jitkov, F. Han, A. Kleinhofs and K. Matsui, 2008. Genetic analysis of preharvest sprouting in a six-row barley cross. Mol. Breed. 21: 249-259.
Verhoeven, K.J.F., H. Poorter, E. Nevo and A. Biere, 2008. Habitat-specific natural selection at a flowering-time QTL is a main driver of local adaptation in two wild barley populations. Mol. Ecol. 17: 3416-3424.
von Korff, M., S. Grando, A. Del Greco, D. This, M. Baum and S. Ceccarelli, 2008a. Quantitative trait loci associated with adaptation to Mediterranean dryland conditions in barley. Theor. Appl. Genet. 117: 653-669.
von Korff, M., H.J. Wang, J. Léon and K. Pillen, 2008b. AB-QTL analysis in spring barley: III. Identification of exotic alleles for the improvement of malting quality in spring barley (H. vulgare ssp. spontaneum). Mol. Breed. 21: 81-93.

Coordinator’s report: Chromosome 2H (2)


J.D. Franckowiak
Hermitage Research Station

Agri-science Queensland

Department of Employment, Economic Development and Innovation

Warwick, Queensland 4370, Australia
e-mail: jerome.franckowiak@deedi.qld.gov.au

Three genes [Ppd-H1 (synonym Eam1 on 2HS), HvCO1 (synonym Vrn-H3 on 7HS), and HvFT1 (positional associated with esp7S on 7HS)] known to play essential roles in the regulation of flowering time under long days in barley were analyzed for nucleotide diversity in a collection of 220 spring barley accessions by Stracke et al. (2009). The coding region of Ppd-H1 was highly diverse, while both HvCO1 and HvFT1 showed a rather limited level of diversity. The Ppd-H1 alleles (the late flowering haplotype was more common than the five early haplotypes combined) were strongly associated with flowering time across four environments, showing a difference of five to ten days between the most extreme haplotypes. The association between flowering time and the variation at HvFT1 and HvCO1 was strongly dependent on the haplotype present at Ppd-H1.


Karsai et al. (2008) examined the interaction of vernalization (Vrn) and photoperiod sensitivity (Ppd) genes in progenies variable winter and spring growth habits under various thermo- and photoperiods. Alleles at the Ppd-H1 (Eam1 on 2HS) locus were found to interact with alleles for spring growth habit at the Vrn-H1 (Sgh2 on 5HL) locus. Certain allele combinations at these two loci interacted with alleles at the Ppd-H2 (1HL) locus under various thermo- and photoperiods to produce short-day photoperiod responses, when the dominant allele at the Ppd-H1 locus was absent.
Custa-Marcos et al. (2009) studied the genetic control of flowering time under Northern Spanish (Mediterranean) conditions using a new population derived from the spring x winter cross Beka x Mogador. A set of 120 doubled haploid lines was evaluated in the field, and under controlled temperature and photoperiod conditions. Genotyping included markers for vernalization candidate genes: HvBM5 (Vrn-H1 on 5HL), HvZCCT (Vrn-H2 on 4HL), and HvT SNP22 (Ppd-H1 on 2HS). Four major QTL, and the interactions between them, accounted for most of the variation in both field (71 to 92%) and greenhouse trials (55 to 86%). These were coincident with the location of the major genes for response to vernalization and a gene for short photoperiod response (Ppd-H2 on 1HL). A major QTL, near the centromere of chromosome 2H (Eam6 or eps2S), was the most important under autumn sowing conditions. Although it was detected under all conditions, its action seemed dependent on environmental cues. The presence of the winter Mogador allele at the two loci combined with the effect of Ppd-H2 was found to cause short-day vernalization.
Mittal et al. (2008) reported response to Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov) infestations was associated with a minor QTL on 2H near marker GBM1523, which explained 6% of the variation. The RWA feeding damage results were based on testing of 191 F2–derived F3 families from the cross Morex x STARS-9301B where Morex is a susceptible six-rowed malting barley and STARS-9301B is a selection from RWA-resistant Afghanistan introduction PI 366450.
Roslinsky et al. (2007) reported markers for low phytate genes. Seed homozygous for low phytic acid 1-1 (lpa1-1) or low phytic acid 2-1 (lpa2-1) has a 50 and 70% decrease in seed phytate, respectively. These mutations were previously mapped to chromosomes 2HL and 7HL respectively. They converted RFLP marker ABC153 located in the same region of 2H as lpa1-1 to a sequence-characterized-amplified-region (SCAR) marker. Segregation analysis of the CDC McGwire × Lp422 doubled haploid population confirmed linkage between the SCAR marker and the lpa1-1 locus with 15% recombination.
Palmer et al. (2009) describe archaeobotanical samples of barley found at Qasr Ibrim as having a two-rowed phenotype that is unique to the region of archaeological sites upriver of the first cataract of the Nile. The pictured spike set little or no seed in the lateral spikelets and shows lateral bracts (spikelets) that are typical of intermediates between two- and six-rowed spikes. This phenotype was reported to occur throughout all strata at Qasr Ibrim, which range in age from 3000 to a few hundred years. Palmer et al. (2009) extracted ancient DNA from barley samples from the entire range of occupancy of the site and studied the Vrs1 locus on 2HL that is responsible for row number. They found a genotype that is consistent with the six-rowed condition. These results indicate a six-rowed ancestry for the Qasr Ibrim barley, but a loss of lateral fertility, possibly caused by alleles at the Int-c locus. The consistency of this genotype/phenotype discord over time supports a scenario of adoption of this barley type by successive cultures.
Genetic diversity of 33 Qinghai-Tibetan wild barley accessions and 56 landraces collected primarily from other parts of China was evaluated with 52 SSR markers by Gong et al. (2009). At the 52 SSR loci, 206 alleles were detected of which 111 were common alleles. Polymorphism information content (PIC) values ranged from 0 to 0.81 with an average of 0.54 for Qinghai-Tibetan wild barley and 0 to 0.79 with an average of 0.49 for landraces. Twenty-four unique alleles were observed in Qinghai-Tibetan wild barley, and the frequency of unique alleles in Qinghai-Tibetan wild barley was about 2.1 times higher than that in the landraces. Only chromosome 2H had more unique alleles in the landraces.
Chen et al. (2009b) studied mechanisms for low temperature tolerance in reproductive tissues (LTR tolerance) in barley using Amagi Nijo x WI2585 and Haruna Nijo x Galleon populations. Flowering time and spike morphology traits were associated with the LTR tolerance loci. In spring-type progeny of both crosses, winter alleles at the vernalization response locus on 5HL (Vrn-H1) were linked in coupling with LTR tolerance and earlier flowering. In contrast, tolerance on 2HL was coupled with late flowering alleles at a locus named Flt-2L. Both chromosome regions influenced chasmogamy/cleistogamy (open/closed florets), although tolerance was associated with cleistogamy at the 2HL locus and chasmogamy at the 5HL locus. LTR tolerance controlled by both loci was accompanied by shorter spikes, fewer florets per spike on 5HL (possibly Eam5) and shorter rachis internodes on 2HL (possibly Zeo2). The Eps-2S or Eam6 locus on 2HS segregated in both crosses and influenced spike length and flowering time but not LTR tolerance. Thus, none of the traits was consistently correlated with LTR tolerance.
Chen et al. (2009a) identified a major gene-rich region on the end of the long arm of Triticeae group 2 chromosomes that exhibits high recombination frequencies, making it an attractive region for positional cloning. Traits known to be controlled by this region include chasmogamy/cleistogamy, frost tolerance at flowering, grain yield, head architecture, and resistance to Fusarium head blight and rusts. To assist these cloning efforts, detailed genetic maps of barley chromosome 2H, including 61 polymerase chain reaction markers, were constructed. Collinearity with rice occurred in eight distinct blocks, including five blocks in the terminal gene-rich region. Sequencing across 91 gene fragments totaling 107 kb from four barley genotypes revealed the highest single nucleotide substitution and insertion-deletion polymorphism levels in the terminal regions of the chromosome arms.
Guo et al. (2008) analyzed the quantitative trait loci (QTL) controlling chlorophyll content and chlorophyll fluorescence in RILs developed from the cross between ‘Arta’ and Hordeum spontaneum 41-1. Five traits, chlorophyll content, and four chlorophyll fluorescence parameters, namely initial fluorescence (Fo), maximum fluorescence (Fm), variable fluorescence (Fv), and maximum quantum efficiency of PSII (Fv/Fm) which are related to the activity of the photosynthetic apparatus, were measured under well-watered and drought stress conditions at post-flowering stage. QTL analysis identified a total of nine and five genomic regions, under well watered and drought stress conditions, respectively. No common QTL was detected except one for chlorophyll content. The desirable QTL under drought were from Arta. A QTL for Fv/Fm, which is related to the drought tolerance of photosynthesis, was identified on 2H at 116 cM. In addition, another QTL for Fv/Fm was also located on 2H at 135.7 cM. Guo et al. (2008) suggest that two major loci on 2H are involved in the development of functional chloroplast at post-flowering stage for drought tolerance of photosynthesis in barley under drought stress
To understand genetic patterns of the morphological and physiological traits in flag leaf of barley, a DH population derived from Yerong (six-rowed) x Franklin (two-rowed) was used by Xue et al. (2008) to determine QTL controlling length, width, length/width, and chlorophyll content of flag leaves. A total of 9 QTL showing significantly additive effect were detected in 8 intervals on 5 chromosomes. The variation of individual QTL ranged from 1.9 to 20.2%. For chlorophyll content expressed as SPAD value, 4 QTL were identified on chromosomes 2H, 3H and 6H; for leaf length and width, 2 QTL located on chromosomes 5H and 7H, and 2 QTL located on chromosome 5H were detected; and for length/width, 1 QTL was detected on chromosome 7H. The two QTL for chlorophyll content detected on 2H were at different positions than those reported by Guo et al. (2008).
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