Potato ( Solanum tuberosum L.) is a modified stem and important food crop rich in starch, proteins, antioxidants, and vitamins. Potato is consumed globally; however, being a temperate region crop, it is negatively affected by temperature rise. Histone methylation dynamically regulates plant growth and development in response to environmental stresses. It is a reversible process mediated by distinct histone methyltransferases and histone demethylases, resulting in the modification of chromatin structure to activate or repress transcription. The JmjC domain-containing histone demethylase proteins are involved in histone demethylation, sustaining homeostasis of histone methylation levels. However, the potato JMJ gene family histone demethylases remain uncharacterized and their expression dynamics under heat stress are unknown. In this study, genome-wide analysis led to the identification of a total of 26 StJMJ proteins in potato, which were classified based on their conserved motifs, domains, and gene structure. Phylogenetic analysis categorized StJMJ gene family into five classes, named as KDM5/JARID1, KDM4/JHDM3, KDM3/JHDM2, JMJD6, and JmjC-only. In silico sub-cellular localization studies showed that StJMJ family members were uniformly distributed among various sub-cellular compartments. Promoter analysis revealed the presence of cis -regulatory elements involved in light, development, hormones, and stress responses. Furthermore, gene expression profiling of StJMJs in leaf and stolon tissues of heat-sensitive (HS) and heat-tolerant (HT) genotypes under elevated temperature was performed. The expression of StJMJ3 , StJMJ6 , StJMJ8 , StJMJ10 , StJMJ12 , StJMJ15 , StJMJ16 , StJMJ17 , StJMJ18 , StJMJ19 , and StJMJ21 were heat inducible in the leaf tissue of both genotypes, while showed antagonistic expression (upregulated in HS, downregulated in HT) in stolon tissue. Additionally, StJMJ11 was found to be significantly upregulated in the leaf and stolon of both genotypes. Collectively, this study hints towards the role of StJMJ genes as important epigenetic regulators modulating heat tolerance in potato.

•The present study focused on blanching methods influence upon starch fractions of potatoes processing varieties.•Kufri frysona had the highest starch content of 69.27 g ̸ 100 g, resistant starch (61.91 g/100 g) and RDS content (4.96 g/100 g) were also higher. In addition, the raw kufri frysona samples had an SDS content of 2.4 g/100 g, which increased by microwave blanching to 27.7 g/100 g.•The starch fractions analysis has proved to be sensitive to changes in treatment conditions with varietal difference, likely to affect glycemic response.

Salinity stress is a major constraint to sustainable crop production due to its adverse impact on crop growth, physiology, and productivity. As potato is the fourth most important staple food crop, enhancing its productivity is necessary to ensure food security for the ever-increasing population. Identification and cultivation of salt-tolerant potato genotypes are imperative mitigating strategies to cope with stress conditions. For this purpose, fifty-three varieties of potato were screened under control and salt stress conditions for growth and yield-related traits during 2020. Salt stress caused a mean reduction of 14.49%, 8.88%, and 38.75% in plant height, stem numbers, and tuber yield, respectively in comparison to control. Based on percent yield reduction, the genotypes were classified as salt-tolerant (seven genotypes), moderately tolerant (thirty-seven genotypes), and salt-sensitive genotypes (nine genotypes). Seven salt-tolerant and nine salt-sensitive genotypes were further evaluated to study their responses to salinity on targeted physiological, biochemical, and ionic traits during 2021. Salt stress significantly reduced the relative water content (RWC), membrane stability index (MSI), photosynthesis rate (Pn), transpiration rate (E), stomatal conductance, and K+/Na+ ratio in all the sixteen genotypes; however, this reduction was more pronounced in salt-sensitive genotypes compared to salt-tolerant ones. The better performance of salt-tolerant genotypes under salt stress was due to the strong antioxidant defense system as evidenced by greater activity of super oxide dismutase (SOD), peroxidase (POX), catalase (CAT), and ascorbate peroxidase (APX) and better osmotic adjustment (accumulation of proline). The stepwise regression approach identified plant height, stem numbers, relative water content, proline content, H2O2, POX, tuber K+/Na+, and membrane stability index as predominant traits for tuber yield, suggesting their significant role in alleviating salt stress. The identified salt-tolerant genotypes could be used in hybridization programs for the development of new high-yielding and salt-tolerant breeding lines. Further, these genotypes can be used to understand the genetic and molecular mechanism of salt tolerance in potato.

Potato is a temperate crop consumed globally as a staple food. High temperature negatively impacts the tuberization process, eventually affecting crop yield. DNA methylation plays an important role in various developmental and physiological processes in plants. It is a conserved epigenetic mark determined by the dynamic concurrent action of cytosine-5 DNA methyltransferases (C5-MTases) and demethylases (DeMets). However, C5-MTases and DeMets remain unidentified in potato, and their expression patterns are unknown under high temperatures. Here, we performed genome-wide analysis and identified 10 C5-MTases and 8 DeMets in potatoes. Analysis of their conserved motifs, gene structures, and phylogenetic analysis grouped C5-MTases into four subfamilies (StMET, StCMT3, StDRM, and StDNMT2) and DeMets into three subfamilies (StROS, StDML, and StDME). Promoter analysis showed the presence of multiple cis-regulatory elements involved in plant development, hormone, and stress response. Furthermore, expression dynamics of C5-MTases and DeMets were determined in the different tissues (leaf, flower, and stolon) of heat-sensitive (HS) and heat-tolerant (HT) genotypes under high temperature. qPCR results revealed that high temperature resulted in pronounced upregulation of CMT and DRM genes in the HT genotype. Likewise, demethylases showed strong upregulation in HT genotype as compared to HS genotype. Several positive (StSP6A and StBEL5) and negative (StSP5G, StSUT4, and StRAP1) regulators are involved in the potato tuberization. Expression analysis of these genes revealed that high temperature induces the expression of positive regulators in the leaf and stolon samples of HT genotype, possibly through active DNA demethylation and RNA-directed DNA methylation (RdDM) pathway components. Our findings lay a framework for understanding how epigenetic pathways synergistically or antagonistically regulate the tuberization process under high-temperature stress in potatoes. Uncovering such mechanisms will contribute to potato breeding for developing thermotolerant potato varieties.

Sub-tropicalisation of potato has increased the threat of dry rot during postharvest potato storage at elevated temperatures (10–12 °C). Potatoes meant for processing are generally stored at 10–12 °C, where not only sugars accumulate during prolonged storage, also Fusarium species affects the tuber quality and leads to more losses. Therefore, the present study aimed to reduce the physiological and pathological losses by retaining the processing quality of potatoes through coating with three concentrations of chitosan (0.1%, 0.25% and 0.5%). Tubers were stored at 12 ± 1 °C with 90–95% relative humidity up to 170 days and analysed periodically. Sugar accumulation reduced with chitosan coating of tubers. Chip colour was retained in all coated as well as uncoated tubers. Coating at 0.25% chitosan showed improved chip colour compared to others. Concentration of flavouring compounds increased with increasing chitosan concentration. Chitosan coating reduced the rate of respiration and weight loss. Maximum decrease in rate of respiration with coating was 22% in cultivar Kufri Jyoti and 25% in cultivar Kufri Frysona. Weight loss decrease was 26% in Kufri Jyoti and 15% in Kufri Frysona compared to uncoated tubers. Chitosan coating reduced the Fusarium incidence significantly in dose-dependent manner. Chitosan at 0.25% concentration was able to completely inhibit Fusarium growth. Coating of whole potatoes with chitosan increased the storage life of tubers by reducing the pathological and physiological losses. Coating of tubers with chitosan prior to cold storage will help potato processors to reduce postharvest losses.

The present study was aimed to assess the genetic analysis of tuber yield, processing and nutritional traits in potatoes based on evaluation of 23 genotypes during the winter crop season in sub-tropical plains of India. Characters, viz. reducing sugars followed by chip colour score, phenols, soluble proteins, sucrose, total free amino acids and marketable tuber yield had high genotypic and phenotypic variation, heritability and genetic advance as percent of mean and can be improved by practising selection in potato breeding programme. The results revealed that table potatoes possessed high yield and high phenols content. Whereas, processing potatoes recorded moderate tuber yield, but had high soluble protein and high ascorbic acid, low reducing sugars, low sucrose, low phenols and low total free amino acids. Study suggests that genotypes with moderate to high tuber dry matter, high soluble protein and high ascorbic acid should be selected for improving nutritionally superior table potatoes.

Tubers of forty four indigenous potato varieties were assessed for storage behaviour at room temperature, tuber dry matter content and cooking quality during 2010, 2011 and 2012. The maximum, minimum temperatures and relative humidity during storage period ranged between 26 to 40 °C, 17–28 °C and 18 to 82 %, respectively. The lowest total weight loss was recorded in variety Kufri Pushkar (7.7 %) followed by Kufri Lalima (7.9 %), Kufri Surya (8.3 %), Kufri Red (9.2 %), Kufri Dewa, Kufri Sheetman (9.3 %), Kufri Chandramukhi, Kufri Jyoti (9.5 %), Kufri Sindhuri (9.6 %), Kufri Kuber (9.7 %), Kufri Chipsona-1 (9.8 %), Kufri Kundan (9.9 %) and Kufri Chamatkar (10.0 %). Highest tuber dry matter content (%) was observed in Variety Kufri Kundan (24.2) followed by Kufri Himsona (23.7), Kufri Frysona (23.6), Kufri Kuber (22.7), Kufri Chipsona-2 (22.3). Kufri Khasigaro (22.0), Kufri Sheetman (21.9), Kufri Chipsona-3 (21.7) and lowest in Variety Kufri Khyati and Kufri Pukhraj (16.1 %). Of the total varieties, 14 were adjudged as floury, 15 mealy, 14 waxy and one (Kufri Ashoka) as soggy. The total weight loss had highly significant and positive correlation with sprout weight/Kg tubers (r = 0.76**), physiological weight loss (r = 0.97**). Based on the results potato varieties namely, Kufri Chamatkar, Kufri Chipsona-1, Kufri Chandramukhi, Kufri Dewa, Kufri Jyoti, Kufri Kuber, Kufri Kundan, Kufri Lalima, Kufri Lauvkar, Kufri Pushkar, Kufri Red, Kufri Safed, Kufri Sheetman, Kufri Sindhuri possessed excellent keeping quality with medium to long tuber dormancy, low storage losses, medium to high tuber dry matter and good flavour. The information generated in this study can be utilized in the breeding programme. This can also help the farmer to choose and cultivate the potato varieties as per demand of the consumers.

Potato flavour depends on the level of umami compounds and volatiles. Major umami compounds present in potatoes are 5′-nucleotides (adenosine-5′-monophosphate: AMP and guanosine-5′-monophosphate: GMP) and amino acids (aspartic acid and glutamic acid). The level of these compounds in Indian potato cultivars has not been investigated. Therefore, a method was standardized for the detection of umami 5′-nucleotides from raw and microwave cooked tubers of forty four Indian potato cultivars using high performance liquid chromatography. In raw tubers, concentration of 5′-nucleotides ranged from 1.70 µg g−1 fr. wt. in Kufri Jawahar to 6.68 µg g−1 fr. wt. in Kufri Muthu. In microwave cooked potatoes concentration of 5′ nucleotides ranged from 2.97 µg g−1 fr. wt. in Kufri Jawahar to 9.54 µg g−1 fr. wt. in Kufri Himalini. Under microwave cooking, the concentration of 5′-nucleotides was found to increase manifolds ranging from the highest in Kufri Lalima (272 %) to the lowest in Kufri Kundan (0 %). A positive correlation existed between the level of 5′-nucleotides and organoleptic scores given by the panelists. A positive correlation was observed in the flavour of varieties having dry matter of <18 %. Further investigations on the concentration of umami compounds in Indian potato cultivars may lead to finding out better tasting cultivars for potato product development.