Molecular structure of soybean E-genes and their functional mutations

Abstract

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.