MicroRNA and target gene dynamics in potato under nitrogen deficiency

Plant growth and stress tolerance depend critically on nitrogen (N), an essential macronutrient that regulates key molecular and physiological processes. High potato yields and quality require optimized N fertilization, while improving nitrogen use efficiency minimizes fertilizer use. Developing N-use efficient potato varieties necessitates advanced breeding programs focused on identifying genes that enhance NUE. The regulatory roles of potato microRNAs (miRNAs) and their target genes in N metabolism under nitrogen deficiency (ND) remain poorly understood, despite research on their responses to various stresses. This study will investigate the functions of miRNAs in enabling plants to adapt to N). A total of 303 conserved miRNAs were identified, including 91 novel and 212 known miRNAs. Gene ontology classification yielded 53 functional annotations across 20 molecular functions, 13 cellular components, and 20 biological processes. Anticipated target genes are linked with transcription factors including NAC, ARFs, NF-YA, AP2, antioxidant enzymes, nitrate transporters, and root development processes. Our research demonstrated the crucial roles of miR169, miR172, miR399, miR408, and miR167 as key regulators of ND response in potato. Expression analysis revealed up-regulation of miR408, miR399, and miR172 in the tolerant genotypes Avin and D394, while miR169 and miR167 were down-regulated. These differentially expressed miRNAs, exhibiting high or low levels in the roots of Avin and D394, contribute to enhanced root growth, increased antioxidant enzyme activity, and improved nitrate transport. Furthermore, this study suggests strategies for manipulating these miRNAs and their target genes to develop N-use efficient potato varieties through transgenic or breeding programs.