Manifestation of agronomically valuable traits in the progeny of a sorghum mutant carrying the genetic construct for RNA silencing of the γ-kafirin gene.

Improving the nutritional value of grain sorghum, a drought- and heat-tolerant grain crop, is an important task in the context of global warming. One of the reasons for the low nutritional value of sorghum grain is the resistance of its storage proteins (kafirins) to proteolytic digestion, which is due, among other things, to the structural organization of protein bodies, in which γ-kafirin, the most resistant to proteases, is located on the periphery, encapsulating more easily digested α-kafirins. The introduction of genetic constructs capable of inducing RNA silencing of the γ-kafirin (gKAF1) gene opens up prospects for solving this problem. Using Agrobacterium-mediated genetic transformation of immature embryos of the grain sorghum cv. Avans we have obtained a mutant with improved digestibility of endosperm proteins (up to 92 %) carrying a genetic construct for RNA silencing of the gKAF1 gene. The goal of this work was to study the stability of inheritance of the introduced genetic construct in T2-T4 generations, to identify the number of its copies, as well as to trace the manifestation of agronomically valuable traits in the offspring of the mutant. The mutant lines were grown in experimental plots in three randomized blocks. The studied lines were characterized by improved digestibility of kafirins, a modified type of endosperm, completely or partially devoid of the vitreous layer, an increased percentage of lysine (by 75 %), reduced plant height, peduncle length, 1000-grains weight, and grain yield from the panicle. In T2, a line with monogenic control of GA resistance was selected. qPCR analysis showed that in different T3 and T4 plants, the genetic construct was present in 2-4 copies. In T3, a line with a high digestibility of endosperm proteins (81 %) and a minimal decrease in agronomically valuable traits (by 5-7 %) was selected.

[Immunochemical Detection of Azospirilla in Soil with Genus-Specific Antibodies].

Immunoelectrophoresis and immunodiffusion analysis with antibodies to whole intact cells of the type strain of nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 revealed at least three conservative surface immunogenic proteins of azospirilla. Cross-reactions with these proteins made it possible to use the above antibodies for detection of azospirilla as a genus-specific probe conjugated with horseradish peroxidase as an enzymatic label. Direct immune-enzyme analysis of soil suspensions (typical chernozem, Saratov oblast) confirmed applicability of the conjugates based on genus-specific antibodies to the surface proteins of azospirilla for direct detection of this bacterial genus in environmental samples. These results provide a basis for broad application of this method for analysis of Azospirillum occurrence in soil.

Investigation of enzymatic degradation of pectin polysaccharides under limiting conditions.

The dynamics of changes in spectra of oligosaccharide fragments formed during enzymatic degradation of plant pectins at low enzyme/substrate ratio was studied. It is shown that degradation of deesterified pectin molecules is a discrete and determined process manifested in establishment of a stable polysaccharide spectrum. It is noted that introduction of chemical modifications into the polysaccharide substrate structure preserves the discreteness of the polymer molecule fragmentation but changes the spectrum of formed oligosaccharide fragments. It is supposed that degradation is defined by the spatial (three-dimensional) organization of the polysaccharide molecule.