The phytochrome-interacting factor (PIF) proteins are part of a subfamily of basic helix–loop–helix (bHLH) transcription factors that integrate with phytochromes (PHYs) and are known to play important roles in adaptive changes in plant architecture. However, the characterization and function of PIFs in potatoes are currently poorly understood. In this study, we identified seven PIF members in potatoes and named them StPIF01-1, StPIF01-2, StPIF03, StPIF06-1, StPIF06-2, StPIF07, and StPIF09 based on their location in potato chromosomes. The chromosomal location, gene structures, physicochemical characteristics, phylogenetic tree, and tissue-specific expression of StPIFs were also analyzed. RT-qPCR analysis revealed that the StPIF3 gene was highly induced by shade and may play a crucial regulatory role in potato responses to shade stress. Also, multiple cis-regulatory elements involved in light response were detected in the promoter of the StPIF genes. Subcellular localization analysis indicated that the StPIF3-encoding protein is mainly localized in the nucleus. Transgenic overexpression of StPIF3 in potatoes increased stem length, chlorophyll accumulation, and enhanced shade-avoidance symptoms, whereas the StPIF3-interfering lines had a lower plant height and more chlorophyll accumulation. These findings enhance our comprehension of StPIF gene roles, potentially advancing potato yield and quality research. This study provides detailed information about StPIFs and identifies the function of StPIF3, which is involved in shade-avoidance syndrome.

Plants require adequate water for growth, development, and reproduction. Peptides play a key role in plant growth and development and act in a similar manner to plant hormones. However, only a few peptides have been identified to play a role in abiotic stress tolerance in potato. In this study, we identified fourteen members of the epidermal patterning factor (EPF) family in potato, which were designated as StEPF1-14 according to their chromosomal locations. We also conducted a comprehensive analysis of their chromosomal distribution, gene structures, physicochemical properties, phylogenetic relationships, and tissue-specific expression patterns. RT-qPCR analysis revealed that the StEPF4 gene is significantly induced by drought stress, suggesting its potential role as a negative regulator in the plant’s response to drought. Furthermore, multiple cis-regulatory elements associated with drought-responsive regulation were identified within the promoter region of the StEPF genes. Here, we isolated an EPF secreted Cys-rich small peptide StEPF4 from ‘Atlantic’ and explored its mechanism in plant response to drought stress. We found that StEPF4 was greatly induced by dehydration treatment in potato. To investigate its potential biological functions, StEPF4 was knocked down in potato. The StEPF4 knocked down lines (KdStEPF4) significantly decreased stomatal density, resulting in a decrease in the transpiration rate. KdStEPF4 lines maintained a higher photosynthetic rate and lowered the water loss rate of leaves compared with the control, resulting in increased drought resistance. Taken together, this study provides detailed information about StEPFs, and our findings also show that StEPF4 plays an essential role in regulating drought resistance by reducing stomatal density in potato.

Drought stress severely impairs crop growth and agricultural productivity. Stomata, specialized structures in the leaf epidermis, play a critical role in gas exchange and transpiration. Therefore, reducing stomatal density to minimize water loss is an effective strategy for enhancing crop drought tolerance. The SDD1 gene was characterized as a negative regulator of stomatal density, and its function has been well characterized in model plants. However, its role in potato remains largely unknown. In this study, we identified a potato SDD1-like gene, StSDD1, which is predominantly expressed in young leaves and induced by drought stress and various hormones. Subcellular localization revealed that the StSDD1 fusion protein localizes to the plasma membrane and cytoplasm. Overexpression of StSDD1 decreased stomatal density and improved water use efficiency, leading to enhanced drought tolerance, whereas knockdown transgenic lines exhibited the opposite phenotype. Additionally, altering StSDD1 expression affected the expression of key stomatal development genes and several physiological and photosynthetic drought-related parameters. Taken together, our results suggest that StSDD1 enhances drought tolerance, potentially by reducing stomatal density. These findings indicate a role for StSDD1 in this process and provide a valuable genetic resource for molecular breeding of drought-resistant crops.

MicroRNAs (miRNAs) are non-coding, single-stranded RNA molecules that regulate gene expression post-transcriptionally. Potato, an essential crop for food and fodder, experiences reduced quality and yield under shading. Although miRNAs have known roles in various plants, their regulatory mechanisms in potato shade avoidance remain unexplored. To investigate this, we constructed nine small RNA libraries from potato samples at 0, 5, and 10 days post-shade treatment. High-throughput sequencing identified 525 miRNAs (307 known and 218 novel) from 99 families, and 166 differentially expressed miRNAs (DEMs) were detected. qRT-PCR verified 10 DEMs, confirming sequencing reliability. Using TargetFinder, we predicted 4320 target genes of DEMs, which were enriched in plant–pathogen interaction and hormone signal transduction pathways, among others. These findings indicate that miRNAs may play key regulatory roles in potato shade avoidance by targeting specific genes, providing valuable insights for future functional studies and potential yield enhancement.