Novel and conserved miRNAs involved in plant development and nitrogen metabolism in durum wheat

MicroRNAs (miRNAs) are small non-coding RNA molecules which down-regulate gene expression by mRNA degradation or translational repression. miRNAs play critical roles in diverse biological processes such as plant development and plant adaptive responses to nutrient deprivation. Nitrogen is the most important nutrient for the growth of plants since it is essential for protein and nucleic acids synthesis, and for other cellular constituents. A limitation of nitrogen in durum wheat plants generally results in a reduction of the yield and of protein quality, with negative effects on the attitude of pasta making. In order to elucidate the role of miRNAs in durum wheat development and nitrogen metabolism, twelve small RNA libraries were generated from different tissues and developmental stages of Ciccio and Svevo cultivars growing under different nitrogen supply conditions. Following high throughput sequencing, conserved and novel miRNAs and their target genes were identified. Several miRNAs were expressed at different levels based on their abundance in Illumina libraries. Selected conserved and novel miRNAs and their corresponding target genes were subjected to quantitative PCR, and for some of them significant differences in expression profiles were confirmed. Some miRNAs were predicted to regulate genes involved in plant development, in important biochemical processes such as photosynthesis, and in nitrogen metabolism. Financial support: Project PON01_01145 "Sviluppo tecnologico e innovazione per la sostenibilità e competitività della cerealicoltura meridionale - ISCOCEM"; Project PRIN 2010-2011 "Identificazione e caratterizzazione di geni utili ad incrementare la produttività e sostenibilità del frumento duro".