Genetic modification of sorghum for improved nutritional value: state of the problem and current approaches

Abstract

Background: Low digestibility of seed storage proteins (kafirins) and low nutritional grain value are one of the most important directions of genetic improvement of sorghum. In this review, we summarize experiments on improving protein digestibility, and increasing nutritional value of sorghum grain using genetic engineering approaches, primarily, by the introduction of genetic constructs that cause the silencing of γ-and/or α-kafirins. Key points of improvement of Agrobacterium-mediated genetic transformation, which was used for introduction of these genetic constructs in sorghum genome, are discussed. Transgenic sorghum harboring the genetic constructs inducing silencing of kafirins are characterized by reduction of kafirin oligomers, an increase of in vitro digestibility of proteins of flour, an increase in the proportion of essential amino acids, lysine, in particular, a changes in the ultrastructure of endosperm protein bodies (in case of α-kafirin silencing), which acquire an irregular shape with invaginations, and modification of endosperm texture, which become floury devoid of the vitreous layer. In some cases transgenic events with vitreous endosperm and high digestibility of kafirins were observed, which, in this connection, may be of interest for practical sorghum breeding. There are evidences that in vitro protein digestibility in transgenic plants with genetic construct for γ-kafirin silencing grown in the field plot was substantially lower than in the plants grown in the pots in greenhouse conditions. These facts indicate that suppression of the synthesis of kafirins occurring at epigenetic level as a result of the expression of the genetic constructs for silencing, is influenced by environment. In this connection, the use of methods of genome editing, in particular, editing the nucleotide sequences of the α-or γ-kafirin genes, opens wider prospects for improving the digestibility of kafirins and increasing the nutritional value of sorghum grain. Current approaches for biofortification of sorghum grain with amino acids and micronutrients are discussed.Citation: Elkonin L, Italyanskaya J, Panin V. Genetic modification of sorghum for improved nutritional value: state of the problem and current approaches.Citation: Elkonin L, Italyanskaya J, Panin V. Genetic modification of sorghum for improved nutritional value: state of the problem and current approaches.

African Sorghum-Based Fermented Foods: Past, Current and Future Prospects

“…Fermented foods, including sorghum-based fermented products, are of prominent significance to the economy, health and nutrition of Africa. The nutritional value and profile of sorghum needs to be improved using techniques like the development of novel sorghum lines in order to improve the digestibility of sorghum proteins and genetic modification for improved nutritional value [180,181]. While these propositions could be successful, it would be important for high sorghum eating populations to complement their diet with foods rich in an appropriate nutrient balance, such as vegetables, fruits, animal products and nutrient-dense plant sources such as legumes [182,183].…”

Current Status and Potential of Biofortification to Enhance Crop Nutritional Quality: An Overview

“…They possess the immense potential to develop biofortified varieties within less time and cost [77,78]. Recent advancements in biotechnological approaches have enabled the development of a large number of commercial crop varieties through genetic engineering with increased essential micronutrients, minerals, fatty acids, and amino acids [45], such as Fe-dense rice [79], wheat [80], and sorghum (Sorghum bicolor) [81], which have helped improve the human health status through enhanced nutrition [17] (Table 2). In the case of some micronutrients like Fe and Zn, their absorption is vulnerable due to anti-nutritional factors like phytic acid.…”

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