Yasir Majeed

Soil salinization critically impacts potato cultivation by restricting growth, yield, and tuber quality. The MAPK pathway, evolutionarily conserved in plants, modulates hormonal balance, development, and abiotic stress responses. This study investigates the functional role of StMAPK19, a TDY-type mitogen-activated protein kinase gene, in potato salt tolerance. Phylogenetic analysis classified StMAPK19 into a TDY-motif subgroup, and subcellular localization revealed its presence in the plasma membrane, cytoplasm, and nucleus. Under NaCl stress (50, 100, and 150 mM), StMAPK19 expression was significantly upregulated in roots, stems, and leaves. Phenotypic analyses demonstrated that StMAPK19-overexpressing (OE) plants exhibited enhanced salt tolerance, marked by improved plant height, tuber yield, and biomass (fresh/dry weights), whereas RNA interference (RNAi) knockdown lines showed reduced growth. OE plants displayed elevated antioxidant enzyme activities, such as catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), higher proline accumulation, and reduced oxidative stress markers, including hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), while RNAi lines exhibited compromised antioxidant capacity and exacerbated oxidative damage. Expression profiling revealed upregulation of stress-responsive genes (StCAT, StSOD, StPOD, StP5CS) in OE plants and downregulation in RNAi lines. Gas exchange measurements further indicated that OE plants maintained higher photosynthetic rates, transpiration, and stomatal conductance under salt stress compared to non-transgenic (NT) controls, whereas RNAi plants experienced significant declines. These findings demonstrate that StMAPK19 enhances salt tolerance by modulating ROS scavenging, osmoregulatory substance biosynthesis, photosynthetic efficiency, and stress-related gene expression. This study provides critical insights into the molecular mechanisms of salt tolerance in potatoes, offering potential targets for breeding resilient varieties to mitigate salinity-induced agricultural losses.

The functional role of MAPKK genes in potato (Solanum tuberosum L.) under high-temperature stress remains unexplored, despite their critical importance in stress signaling and yield protection. We characterized StMAPKK1, a novel group D MAPKK localized to plasma membrane/cytoplasm. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed cultivar-specific upregulation in potato (‘Atlantic’ and ‘Desiree’) leaves under heat stress (25 °C, 30 °C, and 35 °C). Transgenic lines overexpressing (OE) StMAPKK1 exhibited elevated antioxidant enzyme activity, including ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), mitigating oxidative damage. Increased proline and chlorophyll accumulation and reduced oxidative stress markers, hydrogen peroxide (H₂O₂) and malondialdehyde (MDA), indicate improved cellular redox homeostasis. The upregulation of key antioxidant and heat stress-responsive genes (StAPX, StCAT1/2, StPOD12/47, StFeSOD2/3, StMnSOD, StCuZnSOD1/2, StHSFA3 and StHSP20/70/90) strengthened the enzymatic defense system, enhanced thermotolerance, and improved photosynthetic efficiency, with significant improvements in net photosynthetic rate (Pn), transpiration rate (E), and stomatal conductance (Gs) under heat stress (35 °C) in StMAPKK1-OE plants. Superior growth and biomass (plant height, plant and its root fresh and dry weights, and tuber yield) accumulation, confirming the positive role of StMAPKK1 in thermotolerance. Conversely, RNA interference (RNAi)-mediated suppression of StMAPKK1 led to a reduction in enzymatic activity, proline content, and chlorophyll levels, exacerbating oxidative stress. Downregulation of antioxidant-related genes impaired ROS scavenging capacity and declines in photosynthetic efficiency, growth, and biomass, accompanied by elevated H₂O₂ and MDA accumulation, highlighting the essential role of StMAPKK1 in heat stress adaptation. These findings highlight StMAPKK1’s potential as a key genetic target for breeding heat-tolerant potato varieties, offering a foundation for improving crop resilience in warming climates.

Heat stress severely impacts the growth and development of potato plants. However, the molecular mechanisms underlying thermotolerance, particularly the role of WRKY transcription factors (TFs), remain poorly understood. Here, we identified StWRKY65 as a heat-responsive gene in potato, demonstrating significant transcriptional upregulation under 30°C and 35°C heat stress conditions. Phylogenetic analysis classified StWRKY65 into the WRKY Group II family, revealing high evolutionary conservation with its tomato ortholog SlWRKY65. Subcellular localization confirmed its nuclear targeting. Additionally, we generated transgenic potato lines with overexpression (OE) or RNA interference (RNAi)-mediated suppression of the target gene. Under heat stress, OE lines exhibited enhanced thermotolerance, manifested through improvements in plant height, fresh/dry weights of plants and roots, tuber yield, photosynthetic efficiency, transpiration rate, and stomatal conductance. Concurrently, compared to non-transgenic (NT) controls, StWRKY65 overexpression significantly elevated the activities of antioxidant enzymes (ascorbate peroxidase [APX], catalase [CAT], peroxidase [POD], superoxide dismutase [SOD]), proline accumulation, and total chlorophyll content, while reducing malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels. Conversely, RNAi lines displayed heightened heat sensitivity, impaired growth parameters, diminished antioxidant capacity, and elevated oxidative stress markers. Furthermore, StWRKY65 overexpression transcriptionally activated key antioxidant enzyme-related genes (StAPX, StCAT1/2, StPOD12/47, StFeSOD2/3, StMnSOD, StCuZnSOD1/2), whereas its knockdown produced opposing effects. This study demonstrates the pivotal role of StWRKY65 in enhancing potato thermotolerance by simultaneously boosting antioxidant defenses and maintaining photosynthetic efficiency under heat stress. As climate change intensifies thermal extremes, these findings position StWRKY65 as a valuable genetic target for developing heat-resistant potato varieties, offering a timely strategy to protect this vital crop and global food security.

Heat stress severely restricts potato tuber growth and development, yet the roles of WRKY transcription factors (TFs) in mediating heat responses remain poorly understood. Using quantitative reverse transcription PCR (qRT-PCR), we identified StWRKY75 in potato cultivars ‘Atlantic’ and ‘Desiree’ as a heat-inducible gene, showing significant upregulation under 30°C and 35°C treatments. Phylogenetic analysis classified StWRKY75 into the WRKY Group II family, with close evolutionary homology to tomato SlWRKY75, and subcellular localization confirmed its nuclear targeting. To characterize its function, we generated transgenic lines overexpressing StWRKY75 (OE) or knockdown by RNA interference (RNAi). Under heat stress conditions, OE plants demonstrated superior thermotolerance compared to non-transgenic (NT) controls, manifested by improved growth parameters (plant height, tuber weight per plant, fresh weight, dry weight, root fresh weight, and root dry weight), enhanced activities of antioxidant enzymes (ascorbate peroxidase [APX], catalase [CAT], peroxidase [POD], and superoxide dismutase [SOD]), increased proline accumulation, elevated photosynthetic efficiency, and reduced malondialdehyde (MDA) content. Conversely, RNAi lines exhibited compromised thermotolerance with reversed growth parameters and biochemical characteristics. qRT-PCR analysis revealed that StWRKY75 positively regulated key heat-stress responsive genes, including those encoding antioxidant enzymes (StAPX, StCAT, StSOD, StPOD), proline biosynthesis Pyrroline-5-carboxylate synthase (StP5CS), and heat shock proteins (StHSP20, StHSP70, StHSP90). These findings demonstrate that StWRKY75 acts as a positive regulator of potato thermotolerance by enhancing growth, antioxidant capacity, proline metabolism, photosynthesis, and heat-responsive gene expression, providing a valuable target for improving crop heat resilience in breeding programs.

GATA factors are evolutionarily conserved transcription regulators that are implicated in the regulation of physiological changes under abiotic stress. Unfortunately, there are few studies investigating the potential role of GATA genes in potato plants responding to salt and osmotic stresses. The physicochemical properties, chromosomal distribution, gene duplication, evolutionary relationships and classification, conserved motifs, gene structure, interspecific collinearity relationship, and cis-regulatory elements were analyzed. Potato plants were treated with NaCl and PEG to induce salinity and osmotic stress responses. qRT-PCR was carried out to characterize the expression pattern of StGATA family genes in potato plants subjected to salinity and osmotic stress. StGATA12 loss-of-function and gain-of-function plants were established. Morphological phenotypes and growth were indicated. Photosynthetic gas exchange was suggested by the net photosynthetic rate, transpiration rate, and stomatal conductance. Physiological indicators and the corresponding genes were indicated by enzyme activity and mRNA expression of genes encoding CAT, SOD, POD, and P5CS, and contents of H₂O₂, MDA, and proline. The expression patterns of StGATA family genes were altered in response to salinity and osmotic stress. StGATA12 protein is located in the nucleus. StGATA12 is involved in the regulation of potato plant growth in response to salinity and osmotic stress. Overexpression of StGATA12 promoted photosynthesis, transpiration, and stomatal conductance under salinity and osmotic stress. StGATA12 overexpression induced biochemical responses of potato plants to salinity and osmotic stress by regulating the levels of H₂O₂, MDA, and proline and the activity of CAT, SOD, and POD. StGATA12 overexpression induced the up-regulation of StCAT, StSOD, StPOD, and StP5CS against salinity and osmotic stress. StGATA12 could reinforce the ability of potato plants to resist salinity and osmosis-induced damages, which may provide an effective strategy to engineer potato plants for better adaptability to adverse salinity and osmotic conditions.

Autophagy is a highly conserved method of recycling cytoplasm components in eukaryotes. It plays an important role in plant growth and development, as well as in response to biotic and abiotic stresses. Although autophagy‐related genes (ATGs) have been identified in several crop species, their particular role in potato (Solanum tuberosum L.) remains unclear. Several transcription factors and signaling genes in the transgenic lines of the model plant Arabidopsis thaliana, such as AtTSPO, AtBES1, AtPIP2;7, AtCOST1 as well as AtATI1/2, ATG8f, GFP‐ATG8F‐HA, AtDSK2, AtNBR1, AtHKT1 play crucial functions under drought and salt stresses, respectively. In this study, a total of 29 putative StATGs from 15 different ATG subfamilies in the potato genome were identified. Their physicochemical properties, evolutionary connections, chromosomal distribution, gene duplication, protein–protein interaction network, conserved motifs, gene structure, interspecific collinearity relationship, and cis‐regulatory elements were analyzed. The results of qRT‐PCR detection of StATG expression showed that 29 StATGs were differentially expressed in potato's leaves, flowers, petiole, stem, stolon, tuber, and root. StATGs were dynamically modulated by salt and drought stresses and up‐regulated under salt and drought conditions. Our results showed that the StATG8a localized in the cytoplasm and the nucleus. Potato cultivar “Atlantic” overexpressing or downregulating StATG8a were constructed. Based on physiological, biochemical, and photosynthesis parameters, potato lines overexpressing StATG8a exhibited 9 times higher drought and salt tolerance compared to non‐transgenic plants. In contrast, the potato plants with knockdown expression showed a downtrend in drought and salt tolerance compared to non‐transgenic potato lines. These results could provide new insights into the function of StATG8a in salt and drought response and its possible mechanisms.