Long term nitrogen deficiency alters expression of miRNAs and alters nitrogen metabolism and root architecture in Indian dwarf wheat (Triticum sphaerococcum Perc.) genotypes

The important roles of plant microRNAs (miRNAs) in adaptation to nitrogen (N) deficiency in different crop species especially cereals (rice, wheat, maize) have been under discussion since last decade with little focus on potential wild relatives and landraces. Indian dwarf wheat (Triticum sphaerococcum Percival) is an important landrace native to the Indian subcontinent. Several unique features, especially high protein content and resistance to drought and yellow rust, make it a very potent landrace for breeding. Our aim in this study is to identify the contrasting Indian dwarf wheat genotypes based on nitrogen use efficiency (NUE) and nitrogen deficiency tolerance (NDT) traits and the associated miRNAs differentially expressed under N deficiency in selected genotypes. Eleven Indian dwarf wheat genotypes and a high NUE bread wheat genotype (for comparison) were evaluated for NUE under control and N deficit field conditions. Based on NUE, selected genotypes were further evaluated under hydroponics and miRNome was compared by miRNAseq under control and N deficit conditions. Among the identified, differentially expressed miRNAs in control and N starved seedlings, the target gene functions were associated with N metabolism, root development, secondary metabolism and cell-cycle associated pathways. The key findings on miRNA expression, changes in root architecture, root auxin abundance and changes in N metabolism reveal new information on the N deficiency response of Indian dwarf wheat and targets for genetic improvement of NUE.