Effect of suppressing the synthesis of different kafirin sub-classes on grain endosperm texture, protein body structure and protein nutritional quality in improved sorghum lines

Silva, Laura S. da; Jung, Rudolf; Zhao, Zuo-yo; Glassman, Kimberly; Taylor, Janet; Taylor, John R.N.

doi:10.1016/j.jcs.2011.04.009

Cited by 60 publications

(58 citation statements)

References 23 publications

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“…To gain insight into all-trans β-carotene accumulation throughout seed development, we determined the accumulation of PSY1 protein (the enzyme that controls the rate-limiting step of carotenoid biosynthesis) by LC-MS/MS at six stages of seed development (10,17,24,30,38, and 45 DAP) in event ABS203-4. We found that PSY1 accumulated to the highest levels at the milkstage (around 17 DAP) and declined sharply to an undetected level at maturity (around 45 DAP) (Fig.…”

Section: Significancementioning

confidence: 99%

“…The improvement of micronutrients in food crops has attracted considerable attention, and significant advances have been made in a range of major crops (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Nutritional improvement in sorghum was undertaken a decade ago (23,24); however, progress has lagged behind the progress in other crops. One reason was the recalcitrance of sorghum to genetic modification via transformation.…”

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confidence: 99%

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Elevated vitamin E content improves all- trans β-carotene accumulation and stability in biofortified sorghum

Che

Zhao

Glassman

et al. 2016

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

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Micronutrient deficiencies are common in locales where people must rely upon sorghum as their staple diet. Sorghum grain is seriously deficient in provitamin A (β-carotene) and in the bioavailability of iron and zinc. Biofortification is a process to improve crops for one or more micronutrient deficiencies. We have developed sorghum with increased β-carotene accumulation that will alleviate vitamin A deficiency among people who rely on sorghum as their dietary staple. However, subsequent β-carotene instability during storage negatively affects the full utilization of this essential micronutrient. We determined that oxidation is the main factor causing β-carotene degradation under ambient conditions. We further demonstrated that coexpression of homogentisate geranylgeranyl transferase (HGGT), stacked with carotenoid biosynthesis genes, can mitigate β-carotene oxidative degradation, resulting in increased β-carotene accumulation and stability. A kinetic study of β-carotene degradation showed that the half-life of β-carotene is extended from less than 4 wk to 10 wk on average with HGGT coexpression.β-carotene accumulation | β-carotene stability | vitamin E | HGGT | biofortified sorghum T he importance of vitamin A for human health has been widely addressed (1-6). A 2009 Global Report (7) summarized vitamin A as being "vital for survival and sight; to boost the immune system, vitamin A is a critical micronutrient for survival and physical health of children exposed to disease." In Africa, malnutrition is a serious challenge, but micronutrient deficiency also plays a dominant role in the overall food security of that continent. Based on this global report, the five countries having the highest proportions of preschool age children with vitamin A deficiency were all located in Africa: 95.6% in Sao Tome and Principe, 84.4% in Kenya, 75.8% in Ghana, 74.8% in Sierra Leone, and 68.8% in Mozambique. Sorghum (Sorghum bicolor L.) is one of the most important staple foods for an estimated 500 million people, primarily those living in arid and semiarid areas. In Africa, it is the second most important cereal; about 300 million people rely on it as their daily staple food. Although sorghum is gluten-free and could be an attractive replacement for wheat-allergy sufferers, it is considered a nutrient-poor crop (8, 9) with very low amounts of β-carotene (10). The improvement of micronutrients in food crops has attracted considerable attention, and significant advances have been made in a range of major crops (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Nutritional improvement in sorghum was undertaken a decade ago (23, 24); however, progress has lagged behind the progress in other crops. One reason was the recalcitrance of sorghum to genetic modification via transformation. Recent improvements in sorghum transformation have largely overcome this barrier and offer an alternative approach to genetic improvements in sorghum (25).One of our objectives is to develop sorghum lines with enhanced and stabilized provitamin A (β-car...

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Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

Elevated vitamin E content improves all- trans β-carotene accumulation and stability in biofortified sorghum

Che

Zhao

Glassman

et al. 2016

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

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“…Additional washing and centrifugation steps were required with the latter to obtain PP by wet milling with similar protein contents (25-30%). The TG and HD samples had all floury endosperm texture, whereas C had some peripheral corneous endosperm and Macia had intermediate endosperm texture (7). The floury endosperm texture of TG and HD probably facilitated the wet milling process, allowing easier separation of the protein bodies from the starch granules because of the weaker starchprotein and protein-protein matrix compared to grain of medium to hard endosperm texture (12).…”

Section: Resultsmentioning

confidence: 99%

Transgenic Sorghum with Altered Kafirin Synthesis: Kafirin Solubility, Polymerization, and Protein Digestion

Silva

Taylor

2011

J. Agric. Food Chem.

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Transgenic sorghum (TG) lines with altered kafirin synthesis, particularly suppression of gamma-kafirin synthesis, and improved protein quality have been developed. The proportion of kafirin extracted with 60% tert-butanol alone was greatly increased in the TG lines. However, the total amount of kafirin remained unchanged.Further, in the TG lines, the kafirin was much less polymerized by disulfide bonding.There was also evidence of compensatory synthesis of other kafirin proteins. Cooked protein digestibility was increased in the TG form, even after removal of interfering starch.The TG protein bodies were intermediate in appearance between the normal type and the invaginated high digestibility mutants. Hence, the increased protein digestibility of these TG lines is probably related to their lower levels of disulfide-bonded kafirin polymerization, allowing better access of proteases. This work appears to confirm that disulfide bond formation in kafirin is responsible for the reduced protein digestibility of cooked sorghum.

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“…25 Transgenic sorghum lines with down regulation of synthesis of various combinations of kafirin classes have resulted in protein bodies with varying degrees of deformity. [26][27][28][29] It also appears likely that the different prolamin classes may play specific roles in the formation and functionality of kafirin and zein structures. Schober et al 30 found that zein, which was predominantly α-zein, with approximately 10% co-extracted β-and γ-zein was the best for aggregation in warm water to produce a gluten-like material, whereas film formation was less sensitive to the presence of β-and γ-zein.…”

Section: Introductionmentioning

confidence: 99%

Role of γ-Kafirin in the Formation and Organization of Kafirin Microstructures

Anyango

Taylor

2013

J. Agric. Food Chem.

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The possible importance of the cysteine-rich γ-prolamin in kafirin and zein functionality has been neglected. Gamma-kafirin"s role in organized microstructures was investigated in microparticles. Residual kafirin (total kafirin minus -kafirin) "microparticles" were nondiscrete (amorphous mass of material), as viewed by electron microscopy and atomic force microscopy. Adding 15% -kafirin to residual kafirin resulted in formation of a mixture of non-discrete material and nanosize discrete spherical structures. Adding 30% -kafirin to the residual kafirin resulted in discrete spherical nanosize particles. FTIR indicated that γ-kafirin had a mixture of random coil and β-sheet conformation, in contrast to total kafirin which is mainly α-helical. Gamma-kafirin also had a very high glass transition temperature (T g ) (270 o C). The conformation and high T g of γ-kafirin probably confer structural stability to kafirin microstructures. Due to its ability to form disulfide cross-links, gamma-kafirin appears to be essential to form and stabilize organized microstructures.

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Effect of suppressing the synthesis of different kafirin sub-classes on grain endosperm texture, protein body structure and protein nutritional quality in improved sorghum lines

Cited by 60 publications

References 23 publications

Elevated vitamin E content improves all- trans β-carotene accumulation and stability in biofortified sorghum

Elevated vitamin E content improves all- trans β-carotene accumulation and stability in biofortified sorghum

Transgenic Sorghum with Altered Kafirin Synthesis: Kafirin Solubility, Polymerization, and Protein Digestion

Role of γ-Kafirin in the Formation and Organization of Kafirin Microstructures

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