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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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The expression profiles of a selection of starch biosynthesis/degradation genes responsive to drought during development (panel A). For abbreviations, see Figure 2 legend and expression data from individual replications are given in Additional file 3. The location of SNPs and the resulting haplotypes (H) present in both sucrose synthase types I (GBS3129) and II (GBS3258) genes are given in panel B. Black arrows indicate exonic regions and grey bars untranslated regions. Introns are represented by dashed lines. Shown below are the haplotype groups with the respective polymorphisms and the number of lines per group. Triangles indicate accession-specific SNPs. Haplotypes of all the genes detailed in Additional file 5. Correlation of seed starch content under drought to specific haplotypes of sucrose synthase type II is given in Additional file 6.
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Figure 5: The expression profiles of a selection of starch biosynthesis/degradation genes responsive to drought during development (panel A). For abbreviations, see Figure 2 legend and expression data from individual replications are given in Additional file 3. The location of SNPs and the resulting haplotypes (H) present in both sucrose synthase types I (GBS3129) and II (GBS3258) genes are given in panel B. Black arrows indicate exonic regions and grey bars untranslated regions. Introns are represented by dashed lines. Shown below are the haplotype groups with the respective polymorphisms and the number of lines per group. Triangles indicate accession-specific SNPs. Haplotypes of all the genes detailed in Additional file 5. Correlation of seed starch content under drought to specific haplotypes of sucrose synthase type II is given in Additional file 6.

Mentions: In contrast, the down-regulation of the gene family members of key starch biosynthesis genes, sucrose synthase, ADP-glucose pyrophosphorylase are down-regulated by terminal drought stress in the post anthesis period during 20 DAF (Figure 5A). Several genes associated with the activity of the starch branching enzyme became activated by terminal drought stress, which has implications for the synthesis of amylopectin. Certain genes involved in starch degradation (e.g., those encoding sd1-ß-amylase and chloroplast-targeted ß-amylase) were also induced by drought stress, which points to a concerted fine tuning of starch biosynthesis and degradation in impairing seed starch accumulation and seed quality. However, many genes associated with carbohydrate metabolism including the genes encoding sucrose synthase type I (GBS3129), ADP-glucose pyrophosphorylase large subunit (GBS3259) and starch branching enzyme class II (GBS3257) were up-regulated by drought stress in seedlings, the flag leaf, the awn, lemma and palea (Figure 5A). The production of starch in vegetative tissues of Arabidopsis thaliana has been found to be negatively correlated with plant biomass [36]. Likewise, we might expect that starch accumulation in vegetative tissues negatively affects plant growth under drought stress.


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)

The expression profiles of a selection of starch biosynthesis/degradation genes responsive to drought during development (panel A). For abbreviations, see Figure 2 legend and expression data from individual replications are given in Additional file 3. The location of SNPs and the resulting haplotypes (H) present in both sucrose synthase types I (GBS3129) and II (GBS3258) genes are given in panel B. Black arrows indicate exonic regions and grey bars untranslated regions. Introns are represented by dashed lines. Shown below are the haplotype groups with the respective polymorphisms and the number of lines per group. Triangles indicate accession-specific SNPs. Haplotypes of all the genes detailed in Additional file 5. Correlation of seed starch content under drought to specific haplotypes of sucrose synthase type II is given in Additional file 6.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: The expression profiles of a selection of starch biosynthesis/degradation genes responsive to drought during development (panel A). For abbreviations, see Figure 2 legend and expression data from individual replications are given in Additional file 3. The location of SNPs and the resulting haplotypes (H) present in both sucrose synthase types I (GBS3129) and II (GBS3258) genes are given in panel B. Black arrows indicate exonic regions and grey bars untranslated regions. Introns are represented by dashed lines. Shown below are the haplotype groups with the respective polymorphisms and the number of lines per group. Triangles indicate accession-specific SNPs. Haplotypes of all the genes detailed in Additional file 5. Correlation of seed starch content under drought to specific haplotypes of sucrose synthase type II is given in Additional file 6.
Mentions: In contrast, the down-regulation of the gene family members of key starch biosynthesis genes, sucrose synthase, ADP-glucose pyrophosphorylase are down-regulated by terminal drought stress in the post anthesis period during 20 DAF (Figure 5A). Several genes associated with the activity of the starch branching enzyme became activated by terminal drought stress, which has implications for the synthesis of amylopectin. Certain genes involved in starch degradation (e.g., those encoding sd1-ß-amylase and chloroplast-targeted ß-amylase) were also induced by drought stress, which points to a concerted fine tuning of starch biosynthesis and degradation in impairing seed starch accumulation and seed quality. However, many genes associated with carbohydrate metabolism including the genes encoding sucrose synthase type I (GBS3129), ADP-glucose pyrophosphorylase large subunit (GBS3259) and starch branching enzyme class II (GBS3257) were up-regulated by drought stress in seedlings, the flag leaf, the awn, lemma and palea (Figure 5A). The production of starch in vegetative tissues of Arabidopsis thaliana has been found to be negatively correlated with plant biomass [36]. Likewise, we might expect that starch accumulation in vegetative tissues negatively affects plant growth under drought stress.

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