Development of EMS-induced mutation population for amylose and resistant starch variation in bread wheat (Triticum aestivum) and identification of candidate genes responsible for amylose variation

Mishra, Ankita; Singh, Anuradha; Sharma, Monica; Kumar, Pankaj; Roy, Joy

doi:10.1186/s12870-016-0896-z

Cited by 61 publications

(34 citation statements)

References 60 publications

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“…Previous studies have shown the effects of null SBE and SS genes on starch composition in durum and hexaploid wheat backgrounds [6,19,20,22,23,32,35]. No full null ssiia mutants, however, have been developed in a single hexaploid wheat genotype.…”

Section: Discussionmentioning

confidence: 99%

“…Starch branching enzymes (SBEs) and debranching enzymes (DBEs) work together to create the α-(1,6) branching patterns that are characteristic of amylopectin [8,16]. Mutations in SBE genes in cereals, including durum (genome AABB) and bread wheat (genome AABBDD), have shown an increase in amylose [6,19,20]. Starch synthase enzymes (SS) are responsible for the short chains of glucose polymers between branched clusters, thus are important for the organization of the higher structure of starch granules [8,16,21].…”

Section: Introductionmentioning

confidence: 99%

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Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Schoen

Joshi

Tiwari

et al. 2020

Preprint

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Abstract Background Lack of nutritionally appropriate foods is one of the leading causes of obesity in the US and worldwide. Wheat (Triticum aestivum) provides 20% of the calories consumed daily across the globe. The nutrients in the wheat kernel come primarily from the starch composed of amylose and amylopectin. Resistant starch content, which is known to have significant human health benefits, can be increased by modifying starch synthesis pathways. Starch synthase enzyme SSIIa, also known as starch granule proteins isoform-1 (SGP-1), is integral to the biosynthesis of the branched and readily digestible glucose polymer amylopectin. In this study, a triple knockout mutant genotype (ssiia ∆ ABD) at the SSIIa locus was developed in elite hard red winter wheat variety ‘Jagger’. Results Knock-out mutations in SSIIa in the three genomes of wheat variety ‘Jagger’ were identified using TILLING. Subsequently, these loss-of function mutations on A, B, and D genomes were genetically combined to generate a triple knockout mutant genotype ssiia ∆ ABD. The ssiia ∆ ABD had an amylose content of 35.70% compared to 31.15% in Jagger, leading to ~ 118% increase in resistant starch in the ssiia ∆ ABD genotype of Jagger wheat. The single individual genome mutations also had various effects on starch composition. Conclusions This marks the first time a full null ssiia knockout has been achieved in a single elite cultivar background and shows the potential for developing nutritionally superior foods in a non-GM approach. Since all the mutants have been developed in an elite wheat cultivar, their adoption in production and supply will be easy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Schoen

Joshi

Tiwari

et al. 2020

Preprint

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“…Previous studies have shown the effects of null SBE and SS genes on starch composition in durum and hexaploid wheat backgrounds [7,28,29,31,32,35,42,43]. Yamamori et al (2000) developed a full null ssiia individual by crossing three different wheat varieties that contained null ssiia in each subgenome [31].…”

Section: Discussionmentioning

confidence: 99%

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Schoen

Joshi

Tiwari

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: Lack of nutritionally appropriate foods is one of the leading causes of obesity in the US and worldwide. Wheat (Triticum aestivum) provides 20% of the calories consumed daily across the globe. The nutrients in the wheat grain come primarily from the starch composed of amylose and amylopectin. Resistant starch content, which is known to have significant human health benefits, can be increased by modifying starch synthesis pathways. Starch synthase enzyme SSIIa, also known as starch granule protein isoform-1 (SGP-1), is integral to the biosynthesis of the branched and readily digestible glucose polymer amylopectin. The goal of this work was to develop a triple null mutant genotype for SSIIa locus in the elite hard red winter wheat variety ‘Jagger’ and evaluate the effect of the knock-out mutations on resistant starch content in grains with respect to wild type. Results: Knock-out mutations in SSIIa in the three genomes of wheat variety ‘Jagger’ were identified using TILLING. Subsequently, these loss-of function mutations on A, B, and D genomes were combined by crossing to generate a triple knockout mutant genotype Jag-ssiia-∆ABD. The Jag-ssiia-∆ABD had an amylose content of 35.70% compared to 31.15% in Jagger, leading to ~118% increase in resistant starch in the Jag-ssiia-∆ABD genotype of Jagger wheat. The single individual genome mutations also had various effects on starch composition. Conclusions: Our full null Jag-ssiia-∆ABD mutant showed a significant increase in RS without the shriveled grain phenotype seen in other ssiia knockouts in elite wheat cultivars. Moreover, this study shows the potential for developing nutritionally improved foods in a non-GM approach. Since all the mutants have been developed in an elite wheat cultivar, their adoption in production and supply will be feasible in future.

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“…In the present study, a modest population size (3,634 M 1 ) was assessed to obtain mutations in most genes of the wheat genome. In previous reports, varying population sizes (from 1,536 to 6,066) were used for identifying mutations in hexaploid wheat genome [ 41 – 44 ]. Population sizes can be increased to increase the chances of retrieving multiple deleterious alleles in all genes.…”

Section: Discussionmentioning

confidence: 99%

Identification of induced mutations in hexaploid wheat genome using exome capture assay

et al. 2018

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Wheat is a staple food crop of many countries. Improving resilience to biotic and abiotic stresses remain key breeding targets. Among these, rust diseases are the most detrimental in terms of depressing wheat production. In the present study, chemical mutagenesis was used to induce mutations in the wheat variety NN-Gandum-1. This cultivar is moderately resistant to leaf and yellow rust. The aim of mutagenesis was to improve resistance to the disease as well as to study function of genes conferring resistance to the disease. In the present investigation, a 0.8% EMS dose was found optimum for supporting 45–55% germination of NN-Gandum-1. A total of 3,634 M2 fertile plants were produced from each of the M1 plant. Out of these, 33 (0.91%) and 20 plants (0.55%) showed absolute resistance to leaf and yellow rust, respectively. While 126 (3.46%) and 127 plants (3.49%) exhibited high susceptibility to the leaf and yellow rust, respectively. In the M4 generation, a total of 11 M4 lines (nine absolute resistant and two highly susceptible) and one wild type were selected for NGS-based exome capture assay. A total of 104,779 SNPs were identified that were randomly distributed throughout the wheat sub genomes (A, B and D). Induced mutations in intronic sequences predominated. The highest total number of SNPs detected in this assay were mapped to chr.2B (14,273 SNPs), which contains the highest number of targeted base pairs in the assay. The average mutation density across all regions interrogated was estimated to be one mutation per 20.91 Mb. The highest mutation frequency was found in chr.2D (1/11.7 kb) and the lowest in chr.7D (1/353.4 kb). Out of the detected mutations, 101 SNPs were filtered using analysis criteria aimed to enrich for mutations that may affect gene function. Out of these, one putative SNP detected in Lr21 were selected for further analysis. The SNP identified in chimeric allele (Lr21) of a resistant mutant (N1-252) was located in a NBS domain of chr.1BS at 3.4 Mb position. Through computational analysis, it was demonstrated that this identified SNP causes a substitution of glutamic acid with alanine, resulting in a predicted altered protein structure. This mutation, therefore, is a candidate for contributing to the resistance phenotype in the mutant line. Based on this work, we conclude that the wheat mutant resource developed is useful as a source of novel genetic variation for forward-genetic screens and also as a useful tool for gaining insights into the important biological circuits of different traits of complex genomes like wheat.

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Development of EMS-induced mutation population for amylose and resistant starch variation in bread wheat (Triticum aestivum) and identification of candidate genes responsible for amylose variation

Cited by 61 publications

References 60 publications

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

Identification of induced mutations in hexaploid wheat genome using exome capture assay

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