Regulation of miR319 and its target gene (MYB3) during vernalization in two wheat cultivars

Many plants adapted to cold climates flower only after an extended period of cold, namely vernalization. In the lifetime of a winter cereals, flowering due to vernalization is not only an essential part of the reproductive process but also a critical developmental stage that can be protect the plant against environmental stresses. This process in cereals such as winter wheat is mainly regulated by the VERNALIZATION genes, VRN1 and VRN2. Although many studies on vernalization in wheat have been reported, the molecular mechanism of vernalization is still largely unknown. Recent studies were shown that a class of small non-coding RNAs, microRNAs (miRNAs), plays a key role in flowering by integrating into the known flowering pathways. In the present study, we investigated the expression of miR319 and its target gene (MYB transcription factor) under the vernalization treatments in spring and winter wheat cultivars. Our results demonstrate that cold treatment induced the miR319 expression in both cultivars, but miR319 level is down-regulated in Norstar and up-regulated in the spring wheat cultivar Baz. Likewise, the expression levels of MYB3 gene was decreased in both cultivars exposed to vernalization. There was reverse relationship between expression of miR319 and its target gene MYB3. These results highlight the complex interactions between genotypes, miRNA and expression of target gene under different vernalization treatment.