| Summary: | In potato, high levels of nitrogen (N) can lead to excessive vegetative growth at the expense of tuber development, resulting in lower yield and poor-quality tubers. We found that <i>Solanum tuberosum CLE4</i> (<i>StCLE4</i>) is expressed most strongly in the roots grown in N-rich media, and it positively regulates potato root growth under N-deficient conditions. We noted that StCLE4 functions as a negative regulator of normal shoot apex development similar to CLV3 in Arabidopsis. Transcriptomic analysis revealed that overexpression of <i>StCLE4</i> resulted in the repression of the <i>StIT1</i> gene, a regulator of potato tuber initiation. <i>StCLE4</i>-overexpressing stolons were converted into branches, that were similar to a mild phenotype of the <i>it1</i> (<i>identity of tuber 1</i>) mutant. We also found that NIN-like proteins, key regulators of nitrate signaling bind to the regulatory sequence of <i>StIT1</i> in a yeast one-hybrid assay. Taken together, our findings suggest that StCLE4 regulates shoot, root, and stolon growth in potato.
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