Small RNA Inheritance in Hybrids and Allopolyploids

Abstract

Small RNAs, including microRNAs (miRNAs), small interfering RNAs (siRNAs), and trans-acting siRNAs (tasiRNAs), control gene expression and epigenetic regulation. Although the physiological and developmental roles of miRNAs and siRNAs have been extensively studied, their roles in morphological diversity among closely related species and in interspecific hybrids and allopolyploids are poorly understood. Here, we discussed recent findings of small RNA regulation with an emphasis on hybrids, interspecific hybrids, and allopolyploids. Divergence between siRNAs and inheritance of these siRNAs through maternal or paternal genome during gametogenesis may exert trans-acting effects on transposable elements and on genes that are important to genomic stability and phenotypic variation. Moreover, expression changes in miRNAs and tasiRNAs between related species or parents may play a role in target gene regulation that is important to growth and development in hybrids and allopolyploids. Inheritance of small RNAs through maternal or paternal genome in interspecific hybrids and allopolyploids are reminiscent of parent-of-origin effects of small RNA regulation on offspring in heterozygous organisms including humans.