Imprinting in plants

Abstract

This review discusses the modern issues in epigenetic regulation in plants related to the imprinting at the levels of genome, locus, and gene. The data described follow the historical order: from the beginning of research into non-crossability of plant forms with different ploidies to the recent communications about allelic imprinting at r1 locus of maize and the control of synthesis of storage proteins with a high forage value. The classical experiments of Kermicle and Lin on the cytogenetic confirmation of the role of parental genome ratio in the endosperm in a successful development of viable caryopses are described in detail. Uniqueness of the experimental technique used by these authors is emphasized. The variants for overcoming the effect of imprinted signal in apomicts and plants with a tetrasporic embryo sac are considered. A considerable attention is paid to the imprinting in the species with polyploid series and to the hypothesis of endosperm balance number. The issues of potential practical application of imprinting in breeding practice are discussed. The results obtained in this direction demonstrate the ways to increase the forage value of maize zeins.