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.
When natural gases are transported, there are usually accompanying mechanical impurities (liquid, sand, and corrosion and erosion products), which affect the reliability of the gas pumping plant (GPP), compressor stations (CS), major pipelines (MP), and users' equipment.To reduce the adverse effects of those components on the working lives of compressors employing centrifugal pumps, one employs single-stage or two-stage gas purifiers. A single-stage unit usually employs a dust trap (DT) designed by the Central Petroleum Design Company and equipped with cyclones 600 mm in diameter designed by the Gas Industry Research Institute.Such plant provides a comparatively high degree of removal for mechanical impurities (100% for ones of 40-50 ~m size), but it is of poor performance in removing liquid, and it also has elevated hydraulic resistance, which increases the energy consumption. Better gas treatment is provided by two-stage cleaning, with a separating filter located after the DT, which improves the performance but at the same time raises the resistance and increases the energy consumption.The DT characteristics may be improved, including the efficiency and resistance from research conducted by the Central Petroleum Design Company (TsKBN) involving the creation of a new DT ahead of the pumps that provides improved performance in treating the gas to remove solid impurities (down to a level of 5 mg/m 3) and also of improved performance in removing liquid (down to 15 mg/m3), with reduced resistance (by 30-35%), and containing less metal (by 10-15%).The research involved developing a new working element and performing comparative tests on various designs for trapping impurities.The basic design parameters of these elements are shown in Figs. 1 and 2 and in Table 1. A distinctive feature of the new element is that it provides two-stage removal of liquid and mechanical impurities and is equipped with a channel for recirculating the gas that provides improved efficiency and throughput [1, 2].The components were tested on TsKBN atmospheric and pilot-plant testers employing conditions as close as possible to those of actual operations as regards speed and initial contents of liquid and mechanical impurities, which involved the addition to the gas flow of dust, water, oil, and a two-phase dust plus oil mixture.Results. The lowest resistance coefficients occurred in the Russian components from TsKBN and VNIIGAZ and from the foreign firms of Paladon and Klanki. The effects of the medium (water and dust) on the resistance were slight throughout the speed range. Increasing the diameter or length in a given model raised the resistance by up to 21%. The material from which the component was made had only a slight effect on the resistance (reduction by up to 3% for corrosion-resistant steels by comparison with carbon ones).It was found that the TsKBN and Paladon components removed over 99% of the water; the performance in removing dust increased with the speed and attained 98% in the speed range used for the TsKBN component, or 94%...
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