Rht-B1 is one of the most important genes responsible for the height of bread winter wheat (Triticum aestivum L.). Studies of dwarfing genes are crucial for both improving genetic potential of the bread wheat cultivar and developing new effective breeding strategies in conditions of insufficient moisture. In this study, tall isogenic lines containing wild type Rht-B1a allele (Odes'ka 267 and Odes'ka 51) and short ones containing Rht-B1b (Odes'ka 267 b ) and Rht-B1e (Odes'ka 51 e ) alleles was analysed. The aim of the experiment was to evaluate direct and pleiotropic effects of these alleles on main agronomic traits of winter wheat in the south steppe region of Ukraine. Methods used are allele-specific PCR, polyacrylamide gel electrophoresis (PAGE), structural analysis of main agronomic traits and statistical data processing. Effects of Rht-B1b and Rht-B1e alleles on important agronomic characteristics of winter wheat were evaluated and were found differences in their influence on such traits: plant height, thousand kernel weight, total protein content, absolute protein content of thousand kernels. Rht-B1e reduces plant height more dramatically than Rht-B1b: decrease in plant height was 40.0% and 17.6%, respectively. The negative effects of Rht-B1e are decline in number of fertile spikelets, number and weight of kernels in the main ear, thousand kernel weight, whereas in plants with Rht-B1b these traits were increased, compared to the Rht-B1a allele plants. Main spike density was decreased by both alleles, but for Rht-B1e the drop was bigger. Rht-B1e more essentially increased productive tillering than Rht-B1b. In drought conditions plants with Rht-B1e allele showed less productivity than those containing Rht-B1b compared to respective recurrent wild type allele lines.

In this review, we discuss features of the molecular structure of known E-loci (early maturity) and their involvement in signaling to plant flowering, depending on the sensitivity of soybean genotypes to the photoperiod. These loci contribute to the adaptation of plants to a wide range of natural conditions due to mutations in genes and QTL that control flowering time. At the molecular level, E-genes are significantly different in structural features, origin and function. The lenghth of the identified genes range from one exon to 525 bp encoding the transcription factor (E1), up to 14 exons and about 20 kb for the GmGIa gene (E2). Among the functional mutations that in most cases lead to partial or complete loss of function, there are single-nucleotide substitutions or deletions, insertions of transposon-like sequences that can lead to amino acid substitutions in the protein, shift of the reading frame, appearance of the premature stop-codon. E-gene products are receptors of signals coming from the environment and they participate in signaling pathways that control the photoperiod. The overall impact and interactions between E-genes have not been fully studied yet, the molecular structure was investigated only for E1-E4, for which a genetic network of interactions was proposed, while at the same time five loci (E6-E9 and E11) were only mapped on soybean chromosomes, and the existence of a separate E5 locus has not yet been established. In eight of the 11 E-loci, the dominant allele causes late flowering. Also there is a pleiotropic effect of E-gene alleles on yield, plant height, stress resistance, and response to low temperatures. Knowledge of the allelic state of only some of the 11 genes is not sufficient. A comprehensive understanding of the functioning of the photoperiodic genetic response network is needed. E-genes are genetic determinants that can be used during selection and creation of new varieties with programmed rates of development.