Development of high amylose wheat through TILLING

Slade, Ann J.; McGuire, Cate; Loeffler, Dayna; Mullenberg, Jessica; Skinner, Wayne S.; Fazio, Gia; Holm, Aaron; Brandt, Kali M; Steine, Michael N.; Goodstal, John F; Knauf, Vic

doi:10.1186/1471-2229-12-69

Cited by 196 publications

(166 citation statements)

References 68 publications

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“…The high accumulation of amylose in crystalline lamellae disorders the packing of lamellar structure and destroys the granule layered organization (Blazek and Gilbert, 2011). The very high amylose in wheat and barley starches alters starch morphology from disk-shaped to sickle-shaped granules with a significant loss of birefringence (Regina et al, 2006(Regina et al, , 2010Carciofi et al, 2012;Slade et al, 2012).…”

Section: The Gradual Reduction Of Three Sbes Is Responsible For Granumentioning

confidence: 99%

Gradually Decreasing Starch Branching Enzyme Expression Is Responsible for the Formation of Heterogeneous Starch Granules

Wang

Lin

et al. 2017

Plant Physiol.

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Rice (Oryza sativa) endosperm is mainly occupied by homogeneous polygonal starch from inside to outside. However, morphologically different (heterogeneous) starches have been identified in some rice mutants. How these heterogeneous starches form remains unknown. A high-amylose rice line (TRS) generated through the antisense inhibition of starch branching synthase I (SBEI) and SBEIIb contains four heterogeneous starches: polygonal, aggregate, elongated, and hollow starch; these starches are regionally distributed in the endosperm from inside to outside. Here, we investigated the relationship between SBE dosage and the morphological architecture of heterogeneous starches in TRS endosperm from the view of the molecular structure of starch. The results indicated that their molecular structures underwent regular changes, including gradually increasing true amylose content but decreasing amylopectin content and gradually increasing the ratio of amylopectin long chain but decreasing the ratio of amylopectin short chain. Granule-bound starch synthase I (GBSSI) amounts in the four heterogeneous starches were not significantly different from each other, but SBEI, SBEIIa, and SBEIIb showed a gradually decreasing trend. Further immunostaining analysis revealed that the gradually decreasing SBEs acting on the formation of the four heterogeneous granules were mainly due to the spatial distribution of the three SBEs in the endosperm. It was suggested that the decreased amylopectin in starch might remove steric hindrance and provide extra space for abundant amylose accumulation when the GBSSI amount was not elevated. Furthermore, extra amylose coupled with altered amylopectin structure possibly led to morphological changes in heterogeneous granules.

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Section: The Gradual Reduction Of Three Sbes Is Responsible For Granumentioning

confidence: 99%

Gradually Decreasing Starch Branching Enzyme Expression Is Responsible for the Formation of Heterogeneous Starch Granules

Wang

Lin

et al. 2017

Plant Physiol.

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“…RNAi suppression of all three SBE isoform activities in barley such that most of the measurable activity is lost, resulting in a severe high amylose starch phenotype [308]. In both wheat and barley, the suppression of SBEII isoforms through TILLING and RNAi technologies has resulted in high amylose endosperm starches [309][310][311].…”

Section: Branch Linkage Formation By Starch Branching Enzymesmentioning

confidence: 99%

Starch Biosynthesis in the Developing Endosperms of Grasses and Cereals

Tetlow

Emes

2017

Agronomy

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Abstract:The starch-rich endosperms of the Poaceae, which includes wild grasses and their domesticated descendents the cereals, have provided humankind and their livestock with the bulk of their daily calories since the dawn of civilization up to the present day. There are currently unprecedented pressures on global food supplies, largely resulting from population growth, loss of agricultural land that is linked to increased urbanization, and climate change. Since cereal yields essentially underpin world food and feed supply, it is critical that we understand the biological factors contributing to crop yields. In particular, it is important to understand the biochemical pathway that is involved in starch biosynthesis, since this pathway is the major yield determinant in the seeds of six out of the top seven crops grown worldwide. This review outlines the critical stages of growth and development of the endosperm tissue in the Poaceae, including discussion of carbon provision to the growing sink tissue. The main body of the review presents a current view of our understanding of storage starch biosynthesis, which occurs inside the amyloplasts of developing endosperms.

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“…In other cereals, down-regulation of soluble starch synthase (SS) SSIIa and of SBE results in greater RS in barley (12,13) and wheat (14)(15)(16)(17)(18)(19)(20). Because the molecular basis underlying RS production is largely unknown, discovery of new RS genes is vital both for the elucidation of RS biosynthesis and for the breeding of high-RS varieties.…”

mentioning

confidence: 99%

Critical roles of soluble starch synthase SSIIIa and granule-bound starch synthase Waxy in synthesizing resistant starch in rice

Zhou

Wang

Liu

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

169

172

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Changes in human lifestyle and food consumption have resulted in a large increase in the incidence of type-2 diabetes, obesity, and colon disease, especially in Asia. These conditions are a growing threat to human health, but consumption of foods high in resistant starch (RS) can potentially reduce their incidence. Strategies to increase RS in rice are limited by a lack of knowledge of its molecular basis. Through map-based cloning of a RS locus in indica rice, we have identified a defective soluble starch synthase gene (SSIIIa) responsible for RS production and further showed that RS production is dependent on the high expression of the Waxy a (Wx a ) allele, which is prevalent in indica varieties. The resulting RS has modified granule structure; high amylose, lipid, and amylose-lipid complex; and altered physicochemical properties. This discovery provides an opportunity to increase RS content of cooked rice, especially in the indica varieties, which predominates in southern Asia.diabetes | resistant starch biosynthesis | soluble starch synthase | granule-bound starch synthase | amylose-lipid complex I ncreases in the incidence of type-2 diabetes are being observed throughout the world. This increase is thought to be due to changes in both diet and lifestyle (1, 2) and is increasingly apparent in Asia. Consumption of foods high in resistant starch (RS) can help to control type-2 diabetes, because its slow digestion and absorption by the small intestine decreases postprandial glucose and insulin responses (3). Foods high in RS also potentially protect against pathogen infection, diarrhea, inflammatory bowel disease, colon cancer, and chronic renal and hepatic diseases. Consumption of RS can increase satiety and reduce calorie intake to help weight management (3). Thus, improvement of the amounts and properties of RS in foods is an important goal.Rice (Oryza sativa L.) is consumed by more than half the world's population (4), and for many, it is the primary source of nutrients and carbohydrates for energy. Consumption of 18-20 g of RS (5, 6) is recommended per day for health benefits, but hot cooked rice typically contains <3% RS (7). Rice varieties or mutants with improved RS have been identified, such as Goami No. 2, Gongmi No. 3, RS111, and Jiangtangdao 1 (7-10).A high-RS, high-amylose transgenic rice line has been developed by suppressing the expression of starch branching enzymes (SBEs) (11) and a mutation of SBEIIb cosegregated with RS content in rice (8). In other cereals, down-regulation of soluble starch synthase (SS) SSIIa and of SBE results in greater RS in barley (12, 13) and wheat (14)(15)(16)(17)(18)(19)(20). Because the molecular basis underlying RS production is largely unknown, discovery of new RS genes is vital both for the elucidation of RS biosynthesis and for the breeding of high-RS varieties. We therefore screened a mutagenized population of the hybrid-rice restorer line R7954 for mutants with high RS in hot cooked rice. This strategy was designed to identify new RS genes of practical value ...

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Development of high amylose wheat through TILLING

Cited by 196 publications

References 68 publications

Gradually Decreasing Starch Branching Enzyme Expression Is Responsible for the Formation of Heterogeneous Starch Granules

Gradually Decreasing Starch Branching Enzyme Expression Is Responsible for the Formation of Heterogeneous Starch Granules

Starch Biosynthesis in the Developing Endosperms of Grasses and Cereals

Critical roles of soluble starch synthase SSIIIa and granule-bound starch synthase Waxy in synthesizing resistant starch in rice

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