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Haplotyping, linkage mapping and expression analysis of barley genes regulated by terminal drought stress influencing seed quality.

Worch S, Rajesh K, Harshavardhan VT, Pietsch C, Korzun V, Kuntze L, Börner A, Wobus U, Röder MS, Sreenivasulu N - BMC Plant Biol. (2011)

Bottom Line: The linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress.The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars.Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.

View Article: PubMed Central - HTML - PubMed

Affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr.3, 06466 Gatersleben, Germany.

ABSTRACT

Background: The increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate. Thus, high priority research aims at the identification of relevant allelic variation present both in the crop itself as well as in its progenitors. This study is based on the characterization of genetic variation in barley, with a view to enhancing its response to terminal drought stress.

Results: The expression patterns of drought regulated genes were monitored during plant ontogeny, mapped and the location of these genes was incorporated into a comprehensive barley SNP linkage map. Haplotypes within a set of 17 starch biosynthesis/degradation genes were defined, and a particularly high level of haplotype variation was uncovered in the genes encoding sucrose synthase (types I and II) and starch synthase. The ability of a panel of 50 barley accessions to maintain grain starch content under terminal drought conditions was explored.

Conclusion: The linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress. The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars. Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.

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Expression profiles of mapped barley genes up-regulated by drought stress. Upper panel: hormone and signalling genes, lower panel: transcription factor families. For abbreviations, see Figure 2 legend. Expression data from individual replications are given in Additional file 3.
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Figure 3: Expression profiles of mapped barley genes up-regulated by drought stress. Upper panel: hormone and signalling genes, lower panel: transcription factor families. For abbreviations, see Figure 2 legend. Expression data from individual replications are given in Additional file 3.

Mentions: An ABA signalling gene (protein phosphatase 2C, marker GBS3123), a bZIP ABA-responsive element binding protein (GBS3212) were consistently up-regulated by drought throughout development in barley (Figure 3). In A. thaliana, protein phosphatase 2C regulates a Snf1-related kinase [25], and mediates signal transduction to an ABF2 transcription factor [26]. Thus in barley, it seems likely that an ABA signalling pathway orchestrates the adaptive response to drought, not just at the seedling stage but also in the flag leaf, awn, lemma and palea (Figure 3). In addition several Ras family G-proteins (GBS3161, GBS3162, GBS3163, GBS3245) thought to be involved in ABA signalling are found to be induced in 21 day seedlings and flag leaf (Figure 3). Several ABA-induced late embryogenesis abundant proteins (GBS3120, GBS3121, GBS3248) were induced to drought in seedlings (Figure 3), and these have been shown previously to be involved in desiccation tolerance [27]. A number of ABA signalling related genes were included in the genetic map (Additional file 3). Other transcription factors were induced by drought in a non-organ specific manner; these included AP2/ERF II (GBS3206), VII (GBS3208), VIII (GBS3207), bHLH (GBS3210), bZIP (GBS3212, GBS3211), MYB (GBS3142, GBS3145, GBS3219), NAC (GBS3146, GBS3147) and several other unclassified factors (Figure 3). The specific function(s) of most of these regulators remains unclear, but their up-regulation by drought stress indicates that they probably do play a role in the plant's response to water deficit.


Haplotyping, linkage mapping and expression analysis of barley genes regulated by terminal drought stress influencing seed quality.

Worch S, Rajesh K, Harshavardhan VT, Pietsch C, Korzun V, Kuntze L, Börner A, Wobus U, Röder MS, Sreenivasulu N - BMC Plant Biol. (2011)

Expression profiles of mapped barley genes up-regulated by drought stress. Upper panel: hormone and signalling genes, lower panel: transcription factor families. For abbreviations, see Figure 2 legend. Expression data from individual replications are given in Additional file 3.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3025944&req=5

Figure 3: Expression profiles of mapped barley genes up-regulated by drought stress. Upper panel: hormone and signalling genes, lower panel: transcription factor families. For abbreviations, see Figure 2 legend. Expression data from individual replications are given in Additional file 3.
Mentions: An ABA signalling gene (protein phosphatase 2C, marker GBS3123), a bZIP ABA-responsive element binding protein (GBS3212) were consistently up-regulated by drought throughout development in barley (Figure 3). In A. thaliana, protein phosphatase 2C regulates a Snf1-related kinase [25], and mediates signal transduction to an ABF2 transcription factor [26]. Thus in barley, it seems likely that an ABA signalling pathway orchestrates the adaptive response to drought, not just at the seedling stage but also in the flag leaf, awn, lemma and palea (Figure 3). In addition several Ras family G-proteins (GBS3161, GBS3162, GBS3163, GBS3245) thought to be involved in ABA signalling are found to be induced in 21 day seedlings and flag leaf (Figure 3). Several ABA-induced late embryogenesis abundant proteins (GBS3120, GBS3121, GBS3248) were induced to drought in seedlings (Figure 3), and these have been shown previously to be involved in desiccation tolerance [27]. A number of ABA signalling related genes were included in the genetic map (Additional file 3). Other transcription factors were induced by drought in a non-organ specific manner; these included AP2/ERF II (GBS3206), VII (GBS3208), VIII (GBS3207), bHLH (GBS3210), bZIP (GBS3212, GBS3211), MYB (GBS3142, GBS3145, GBS3219), NAC (GBS3146, GBS3147) and several other unclassified factors (Figure 3). The specific function(s) of most of these regulators remains unclear, but their up-regulation by drought stress indicates that they probably do play a role in the plant's response to water deficit.

Bottom Line: The linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress.The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars.Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.

View Article: PubMed Central - HTML - PubMed

Affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr.3, 06466 Gatersleben, Germany.

ABSTRACT

Background: The increasingly narrow genetic background characteristic of modern crop germplasm presents a challenge for the breeding of cultivars that require adaptation to the anticipated change in climate. Thus, high priority research aims at the identification of relevant allelic variation present both in the crop itself as well as in its progenitors. This study is based on the characterization of genetic variation in barley, with a view to enhancing its response to terminal drought stress.

Results: The expression patterns of drought regulated genes were monitored during plant ontogeny, mapped and the location of these genes was incorporated into a comprehensive barley SNP linkage map. Haplotypes within a set of 17 starch biosynthesis/degradation genes were defined, and a particularly high level of haplotype variation was uncovered in the genes encoding sucrose synthase (types I and II) and starch synthase. The ability of a panel of 50 barley accessions to maintain grain starch content under terminal drought conditions was explored.

Conclusion: The linkage/expression map is an informative resource in the context of characterizing the response of barley to drought stress. The high level of haplotype variation among starch biosynthesis/degradation genes in the progenitors of cultivated barley shows that domestication and breeding have greatly eroded their allelic diversity in current elite cultivars. Prospective association analysis based on core drought-regulated genes may simplify the process of identifying favourable alleles, and help to understand the genetic basis of the response to terminal drought.

Show MeSH
Related in: MedlinePlus