Prospects for breeding of high-protein soybean cultivars: modelling of mechanisms of protein increase in the seeds (report 1)

Most of the known high-protein soybean cultivars form the reduced seed yields. Occasionally high-protein cultivars form a higher seed yield. To improve the efficiency of breeding is necessary to understand the mechanisms of increasing the relative proportion of protein in the seeds, and use in breeding those mechanisms that do not adversely affect the formation of productivity. Researches carried out at VNIIMK in 2013-2015, Krasnodar (Krasnodar region). Soybean cultivars and lines with increased protein content were studied. Mid-protein (38-40%) cultivars were used as standards. The calculated coefficients: coefficient K1 (amount of protein and oil) and the coefficient K2 (ratio protein /oil) were used to identify types of mutual variation of protein and oil contents in seeds. Cluster analysis of the relationship between yield and protein content in the seeds within the experimental group of high-protein soybean samples allowed revealing its heterogeneity. By normalizing the experimental samples the soybean forms combining unusual yield and protein content in seeds were identified. The features of these samples allowed to formulate theoretically different mechanisms of protein accumulation in seeds, including non-reducing the seed productivity. There are proposed four models to increase the protein content in the seeds based on dynamic changes K1 and K2 coefficients proposed: due to the influence by environmental conditions only (ecological model - EM), due to additional biosynthesis of protein reserved fractions (cumulative-protein model - CPM), due to the partial degradation of oil biosynthesis (lipid-degradation model - LDM), due to a partial degradation of the carbohydrate biosynthesis (carbohydrate-degradation model - CDM). In the analysis of protein and oil contents in seeds of breeding samples proposed models will identify assumed mechanisms of increasing the relative proportion of protein.