Xun Tang

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.

The ubiquitin-proteasome system (UPS) is one of the major pathways for targeted protein degradation in eukaryotes. As essential components of the UPS, deubiquitinating enzymes (DUBs) play critical roles in reversibly regulating ubiquitin-mediated protein degradation. The UCH family of deubiquitinating enzymes is involved in maintaining protein homeostasis and modulating abiotic stress responses. In this study, we examined the expression pattern of StUCH1 by RT-qPCR, quantifying its transcript levels in different tissues and under PEG6000-induced osmotic stress. We evaluated the drought resistance of StUCH1 transgenic plants by measuring the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as malondialdehyde (MDA) content under PEG-simulated drought conditions. The subcellular localization of StUCH1 was determined using a GFP-StUCH1 fusion protein. We performed yeast two-hybrid (Y2H) screening to identify StUCH1-interacting proteins, and further validated these interactions using firefly luciferase complementation (LUC) assays. Our results showed that StUCH1 expression was highest in flowers and lowest in stems, and was significantly upregulated under PEG6000-induced osmotic stress. Under drought stress, the activities of SOD, CAT, and POD in pRI201-StUCH1 overexpression lines were significantly higher than those in wild-type (WT) and RNAi-StUCH1 knockdown lines, whereas MDA content showed the opposite trend. StUCH1 was localized to the nucleus, where it exerts its biological function. StARFA1B, StPRK, and StFBA were identified as StUCH1-interacting partners via Y2H screening, and their interactions were confirmed by LUC assays. In conclusion, StUCH1 positively regulates drought stress responses in potato by enhancing antioxidant enzyme activities, thereby conferring improved drought tolerance.

Plants adapt to changing environments by evolving distinctive mechanisms like post‐translational modification (PTM) of proteins such as ubiquitination and SUMOylation. PTMs can impact protein interactions, stability, and cellular or sub‐cellular localization, thereby introducing added complexity by altering proteins. In plants, the SUMOylation pathway plays a significant role in responding to environmental stimuli such as heat, cold, drought, and salt stresses. Ubiquitination and SUMOylation have a similar process of activating, conjugating, and attaching modifiers to the target protein. However, unlike SUMO, the ubiquitin pathway boasts a wide array of enzymes for specificity. The SUMO system has a limited number of ligases even in fully sequenced plant genomes. Current studies have emphasized the SUMO proteases, especially the ubiquitin‐like protease (ULPs), which play roles in detaching SUMO from its substrate. Research on SUMO proteases indicates that the enzymatic removal of SUMO from its substrate by these active proteases is a vital aspect of the SUMO system. This review paper delves into the roles of ULPs in stress responses, highlighting the crucial balance between promoting growth and managing stress by fine‐tuning SUMO attachment and removal.

Protein ubiquitination is an important regulatory mechanism for biological growth and development against environmental influences, and can affect several biological processes, including the growth, development, and stress responses of plants. However, the function of potato-related ubiquitin-conjugating enzymes in abiotic stress tolerance is poorly understood. In this study, a StUBC13 with a UBC conserved structural domain was identified in potato and its function was investigated under osmotic stress and salt stress conditions. The observation of plant phenotypes under stress conditions revealed that overexpressed plants grew better than wild-type plants. In line with the above results, the determination of stress-related physiological indices revealed that the overexpression transgenic plants had better stress tolerance and stronger adaptation to environmental stress, and the transgenic plants were found to tolerate better drought and salt stress by decreasing their malondialdehyde (MDA) content and increasing their superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) contents under stress conditions. Based on these results, StUBC13 has an important regulatory role in the response of plants to abiotic stresses (osmotic stress and salt stress), and overexpression of this gene can improve the tolerance of potatoes to osmotic and salt stresses.

The ubiquitin-proteasome system (UPS) is a key protein degradation pathway in eukaryotes, in which E3 ubiquitin ligases mediate protein ubiquitination, directly or indirectly targeting substrate proteins to regulate various biological processes, including plant growth, hormone signaling, immune responses, and adaptation to abiotic stress. In this study, we identified plant U-box protein 51 in Solanum tuberosum (StPUB51) as an E3 ubiquitin ligase through transcriptomic analysis, and used it as a candidate gene for gene-function analysis. Quantitative real-time PCR (qRT-PCR) was used to examine StPUB51 expression across different tissues, and its expression patterns under simulated drought stress induced by polyethylene glycol (PEG 6000) were assessed. Transgenic plants overexpressing StPUB51 and plants with down-regulated StPUB51 expression were generated to evaluate drought tolerance. The activities of key antioxidant enzymes-superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) as well as malondialdehyde (MDA) content in transgenic plants’ leaves were measured under drought conditions. Protein–protein interactions involving StPUB51 were explored via yeast two-hybrid (Y2H) screening, with interaction verification by bimolecular fluorescence complementation (BiFC). StPUB51 was predominantly expressed in stems, with lower expression observed in tubers, and its expression was significantly upregulated in response to 20% PEG-6000 simulated drought. Subcellular localization assays revealed nuclear localization of the StPUB51 protein. Under drought stress, StPUB51-overexpressing plants exhibited enhanced SOD, POD, and CAT activities and reduced MDA levels, in contrast to plants with suppressed StPUB51 expression. Y2H and BiFC analyses identified two interacting proteins, StSKP2A and StGATA1, which may be functionally linked to StPUB51. Collectively, these findings suggest that StPUB51 plays a positive regulatory role in drought tolerance, enhancing resilience in potato growth and stress adaptation.

Potato (Solanum tuberosum L.) is a major global food crop, and oxidative stress can significantly impact its growth. Previous studies have shown that its resistance to oxidative stress is mainly related to transcription factors, post-translational modifications, and antioxidant enzymes in vivo, but the specific molecular mechanisms remain unclear. In this study, we analyzed the transcriptome data from potato leaves treated with H₂O₂ and Methyl viologen (MV), and a control group, for 12 h. We enriched 8334 (CK vs. H₂O₂) and 4445 (CK vs. MV) differentially expressed genes (DEGs), respectively, and randomly selected 15 DEGs to verify the sequencing data by qRT-PCR. Gene ontology (GO) enrichment analysis showed that the DEGs were mainly concentrated in cellular components and related to molecular function, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that most of the DEGs were related to metabolic pathways, plant hormone signal transduction, MAPK-signaling pathway, and plant–pathogen interactions. In addition, several candidate transcription factors, mainly including MYB, WRKY, and genes associated with Ca²⁺-mediated signal transduction, were also found to be differentially expressed. Among them, the plant hormone genes Soltu.DM.03G022780 and Soltu.DM.06G019360, the CNGC gene Soltu.DM.06G006320, the MYB transcription factors Soltu.DM.06G004450 and Soltu.DM.09G002130, and the WRKY transcription factor Soltu.DM.06G020440 were noticeably highly expressed, which indicates that these are likely to be the key genes in the regulation of oxidative stress tolerance. Overall, these findings lay the foundation for further studies on the molecular mechanisms of potato leaves in response to oxidative stress.

Plants often experience abiotic stress, which severely affects their growth. With the advent of global warming, drought stress has become a pivotal factor affecting crop yield and quality. Increasing numbers of studies have focused on elucidating the molecular mechanisms underlying plant responses to drought stress. As molecular switches, transcription factors (TFs) are key participants in drought‐resistance regulatory networks in crops. TFs regulate the transcription of downstream genes and are regulated by various upstream regulatory factors. Therefore, understanding the mechanisms of action of TFs in regulating drought stress can help enhance the adaptive capacity of crops under drought conditions. In this review, we summarize the structural characteristics of several common TFs, their multiple drought‐response pathways, and recently employed research strategies. We describe the application of new technologies such as analysis of stress granule dynamics and function, multi‐omics data, gene editing, and molecular crosstalk between TFs in drought resistance. This review aims to familiarize readers with the regulatory network of TFs in drought resistance and to provide a reference for examining the molecular mechanisms of drought resistance in plants and improving agronomic traits.

Soil salinity has become an increasingly serious problem worldwide, greatly limiting crop development and yield, and posing a major challenge to plant breeding. Basic leucine zipper (bZIP) transcription factors are the most widely distributed and conserved transcription factors and are the main regulators controlling various plant response processes against external stimuli. The bZIP protein contains two domains: a highly conserved, DNA-binding alkaline region, and a diverse leucine zipper, which is one of the largest transcription factor families in plants. Plant bZIP is involved in many biological processes, such as flower development, seed maturation, dormancy, and senescence, and plays an important role in abiotic stresses such as salt damage, drought, cold damage, osmotic stress, mechanical damage, and ABA signal response. In addition, bZIP is involved in the regulation of plant response to biological stresses such as insect pests and pathogen infection through salicylic acid, jasmonic acid, and ABA signal transduction pathways. This review summarizes and discusses the structural characteristics and functional characterization of the bZIP transcription factor group, the bZIP transcription factor complex and its molecular regulation mechanisms related to salt stress resistance, and the regulation of transcription factors in plant salt stress resistance. This review provides a theoretical basis and research ideas for further exploration of the salt stress-related functions of bZIP transcription factors. It also provides a theoretical basis for crop genetic improvement and green production in agriculture.

Ubiquitin-conjugating enzymes (E2s/UBC) are components of the ubiquitin proteasome system (UPS), and the ubiquitin-conjugating enzyme variant (UEV) is one of E2s (ubiquitin-conjugating enzymes, UBC) subfamily. The UEVs and UBC13 play an auxiliary role in mediating Lys63-linked polyUb chain assembly, which is correlated with target protein non-proteolytic functions, such as DNA repair or response to stress. However, the collaborative mechanism of StUBC13 (homologue of AtUBC13) and StUEVs (the UEVs in potato) involved in potato are not fully understood understood. Here, we identified two StUBC13 and seven StUEVs from potato genome. We analyzed protein motif and conserved domain, gene structure, phylogenetic features, cis-acting elements of StUBC13 and StUEVs. Subsequently, we screened StUBC13 partners protein and verified interaction between StUBC13 and StUEVs using yeast two-hybrid, split luciferase complementation (SLC) and bimolecular fluorescence complementation (BiFC) approach. The expression profile and qRT-PCR analysis suggested that StUBC13 and StUEVs gene exhibited a tissue-specific expression and were induced by different stress. Overall, this investigative study provides a comprehensive reference and view for further functional research on StUBC13 and StUEV1s in potato.