Mechanistic Concept of Physiological, Biochemical, and Molecular Responses of the Potato Crop to Heat and Drought Stress

Integration of multi-omics data and deep phenotyping provides insights into responses to single and combined abiotic stress in potato

Potato (Solanum tuberosum) is highly water and space efficient but susceptible to abiotic stresses such as heat, drought, and flooding, which are severely exacerbated by climate change. Our understanding of crop acclimation to abiotic stress, however, remains limited. Here, we present a comprehensive molecular and physiological high-throughput profiling of potato (Solanum tuberosum, cv. Désirée) under heat, drought, and waterlogging applied as single stresses or in combinations designed to mimic realistic future scenarios. Stress responses were monitored via daily phenotyping and multi-omics analyses of leaf samples comprising proteomics, targeted transcriptomics, metabolomics, and hormonomics at several timepoints during and after stress treatments. Additionally, critical metabolites of tuber samples were analyzed at the end of the stress period. We performed integrative multi-omics data analysis using a bioinformatic pipeline that we established based on machine learning and knowledge networks. Waterlogging produced the most immediate and dramatic effects on potato plants, interestingly activating ABA responses similar to drought stress. In addition, we observed distinct stress signatures at multiple molecular levels in response to heat or drought and to a combination of both. In response to all treatments, we found a downregulation of photosynthesis at different molecular levels, an accumulation of minor amino acids, and diverse stress-induced hormones. Our integrative multi-omics analysis provides global insights into plant stress responses, facilitating improved breeding strategies toward climate-adapted potato varieties.

Calmodulin and calcium signaling in potato tuberization: The role of membrane transporters in stress adaptation

Potato tuberization is a complex developmental process influenced by environmental factors, such as light and temperature, as well as genetic and biochemical factors. Tuber formation is responsive to day length, with shorter days inducing tuberization more effectively than longer days. Potato tuber yield is regulated by signaling networks involving hormones, transcriptional regulators, and sugars. Calcium plays a pivotal role in this process. Elevated cytoplasmic calcium is detected by calcium sensors, including calmodulins (CaMs), calmodulin-like proteins (CMLs), Ca2+-dependent protein kinases (CDPKs), and calcineurin-B-like proteins (CBLs), promoting tuberization and growth. This review provides mechanistic insights into calcium signaling in potato tuberization, emphasizing its role in stress adaptation. This review further explores the role of calcium/calmodulin in stress response mechanisms and the membrane transporters that facilitate adaptation to environmental challenges like drought, cold, flooding, and heat stress, which are significant threats to potato production globally. Additionally, calcium signaling helps develop tolerance to both abiotic stresses and pathogens, ultimately enhancing plant immune responses to protect potato tubers.

Cultivars and Their Developmental Phases Interact with Temperature Fluctuations to Modulate Growth, Productivity and Seed Tuber Physiology of Potatoes (Solanum tuberosum L.)

In view of raising concerns of climate change, the impact of temperature on potato (Solanum tuberosum L.) growth and productivity was investigated by planting at different times to expose plants to natural variations in air and soil temperatures. Over two seasons with differing temperature patterns, emergence, stem and tuber numbers, tuber size distribution, yield, processing quality, and seed tuber behavior were analyzed. Postharvest, tubers from each planting were stored and replanted to assess temperature carryover effects. Generally, delayed plantings increased the average number of stems per plant (37%) but did not alter the tuber numbers per plant. Early (18 April) and mid-season (9 May) plantings produced higher yields, while late planting (30 May) reduced total yield (42%), US No. 1 yield (48%), and tuber numbers (34%). Moreover, the storage period influenced subsequent stems per plant more than the prior-year temperature conditions. Optimal productivity was achieved by planting during cooler establishment temperatures, followed by warmer tuberization and relatively cooler bulking temperatures. Diurnal temperature variations and growing degree days had minimal effects on stems per plant, whereas storage duration (chronological age) and temperature significantly impacted physiological aging. These findings help growers optimize planting times to enhance tuber storability and yield to improve end use.

Genome wide identification of Dof transcription factors in Carmine radish reveals RsDof33 role in cadmium stress and anthocyanin biosynthesis

Carmine radish (Raphanus sativus L.) is cultivated in Fuling, Chongqing, for its red color. Dof-TFs are critical in regulating plant growth, development, stress responses, and signal transduction.This work comprehensively examined the structure, evolution, and expression of the carmine radish Dof gene and its behavior under cadmium (Cd) stress. The radish genome has 59 RsDofs, which are divided into nine clusters (A: 8, B1: 10, B2: 10, C1: 3, C2.1: 5, C2.2: 4, C3: 11, D1: 4, and D2: 4). Phylogenetic tree analysis revealed significant Dof gene family resemblance between Arabidopsis thaliana and Brassica napus. Perhaps segment duplication resulted in RsDof gene family expansion. Cd stress-induced RsDof expression patterns were studied using an RNA-seq atlas and qRT-PCR. The majority of RsDofs were tissue-specific and Cd-sensitive. The involvement of RsDof genes in Cd stress response and anthocyanin synthesis was verified using qRT-PCR. RsDof33 is involved in Cd stress response and anthocyanin synthesis. A. thaliana overexpressed the recombinant fusion protein RsDof33-GFP, which was localized to the nucleus, resulting in fewer rosette leaves, delayed flowering, and higher anthocyanin concentration. RsDof33-expressing plants had significantly higher transcript levels of the auxin biosynthetic genes YUCCA (AtYUC2), auxin efflux carrier (AtPIN4), and AtKNAT2, which are involved in leaf shape development, as well as AtPAL, AtCHS, AtCHI, AtDFR, AtLDOX, and AtUF3GT. These findings indicate that RsDofs are critical to plant development and stress responses.

Physiological Responses and Metabolic Characteristics of Proso Millet Under Drought Stress During Germination Period

To clarify the impact of drought stress during germination on proso millet's physiological responses and metabolic features, this study used physiological and targeted-like metabolomics methods. With Longmi No. 7 (drought-tolerant, L1) and Longmi No. 15 (drought-sensitive, L2) as materials, we studied the enzyme activities, osmotic adjustment substances, and differential metabolites of proso millet. Results showed that under drought stress, L1's enzyme activities and osmotic adjustment substance contents were significantly higher than L2's, especially at 48-h treatment. 1085 known metabolites were identified from 24 samples, under normal germination, L1's main differential metabolites (amino acids, flavonoids, phytohormone, lipids, sugars, etc.) were enriched in amino acid, lipid, sugar, and energy metabolism pathways. L2's (amino acids, sugars, flavonoids, etc.) were in sugar, lipid metabolism, secondary metabolite biosynthesis, and amino acid metabolism pathways. At 24-h treatment, the metabolic pathways of L1 were mainly concentrated in carbohydrate and nucleotide metabolism, while those of L2 were mainly in carbohydrate and lipid metabolism. At 48 h, the metabolic pathways of L1 were mainly in carbohydrate, energy and lipid metabolism, and those of L2 were mainly in carbohydrate, lipid metabolism, biosynthesis of other secondary metabolites and amino acid metabolism. Under stress, L1's main differential metabolites were organic acids, sugars, flavonoids, amino acids, etc.; L2's were phytohormones, organic acids, sugars, flavonoids, amino acids. This study provides a new direction for the development of proso millet sprouts. Meanwhile, it offers new ideas and theoretical bases for the development of functional foods and the regulation of nutritional components of proso millet.

Cobalt-induced oxidative stress and defense responses of Adhatoda vasica proliferated shoots

BACKGROUND

Levels of heavy metal pollution are increasing due to industrial activities and urban expansion. While cobalt (Co) can be toxic to plants at high levels and isn't considered essential, it plays a beneficial role in many enzymes and is critical for various biological functions. We conducted experiments to determine how Adhatoda vasica proliferated shoots react to exposure to various Co concentrations (50-1000 µM). We employed physiological and biochemical markers to elucidate the response mechanisms of this medicinal plant. The experiment was conducted in two replicates per treatment. The statistical analysis was based on data from four biological replicates per treatment.

RESULTS

Interestingly, the lowest Co concentration (50 µM) increased proliferated shoot growth by 41.45%. In contrast, higher Co concentrations (100-1000 µM) had detrimental effects on proliferated shoot development, water content, and photosynthetic pigment concentrations. As Co concentration increased, proliferated shoots produced excessive concentrations of reactive oxygen species (ROS). This ROS overproduction is believed to be the primary cause of oxidative damage, as evidenced by the elevated concentrations (18.46%-72.84%) of malondialdehyde (MDA) detected. In response to Co stress, non-enzymatic antioxidants were activated in a concentration-dependent manner. Co administration significantly increased the concentrations of different stress-protective compounds in shoots, including total antioxidants (133.18%), ascorbic acids (217.94%), free and bound phenolics (97.70% and 69.72%, respectively), proline (218.59%), free amino acids (206.96%), soluble proteins (65.97%), and soluble carbohydrates (18.52%). FTIR analysis further corroborated changes in the chemical composition of proliferated shoots. The analysis revealed variations in the peaks associated with major macromolecules, including phenolic compounds, lipids, proteins, carbohydrates, cellulose, hemicellulose, and sugars.

CONCLUSIONS

Our study offers the first comprehensive investigation into mechanisms by which Co stress triggers oxidative damage and alters functional groups in the medicinal plant, Adhatoda vasica.

An updated mechanistic overview of nitric oxide in drought tolerance of plants

Drought stress, an inevitable global issue due to climate change, hinders plant growth and yield. Nitric oxide (NO), a tiny gaseous signaling compound is now gaining massive attention from the plant science community due to its unparalleled array of mechanisms for ameliorating various abiotic stresses, including drought. Supplementation of NO has shown its astounding effect in improving drought tolerance by prominently influencing its tendency to modulate stomatal movement and reduce oxidative stress; it can enormously affect the various other physio-biochemical processes such as root structure, photosynthesis, osmolyte cumulation, and seed establishment of plants due to its amalgamation with a wide range of molecules during drought conditions. The production and inhibition of root development majorly depend on NO concentration and/or experimental conditions. As a lipophilic free gasotransmitter, NO readily reacts with free metals and oxygen species and has been shown to enhance or reduce the redox homeostasis of plants, depending on whether acting in a chronic or acute mode. NO can easily alter the enzymes, protein activities, and genomic transcriptional and post-translational modifications that assist functional retrieval from water stress. Although progress is ongoing, much work remains to be done to describe the proper target site and mechanistic approach of this vibrant molecule in plant drought tolerance. This detailed review navigates through the comprehensive and clear picture of the mechanistic potential of NO in drought stress following molecular approaches and suggests effective physiological and biochemical strategies to overcome the negative impacts of drought. We explore its potential to increase crop production, thereby ensuring global food security in drought-prone areas. In an era marked by unrelenting climatic conditions, the implications of NO show a promising approach to sustainable farming, providing a beacon of hope for future crop productivity.

Systemic acquired resistance inducing chemicals mitigate black scurf disease in potato by activating defense-related enzymes

The potato, being an underground vegetable crop, faces consistent threats from soil- and tuber-borne fungal and bacterial pathogens. Black scurf and stem canker disease caused by the fungal pathogen Rhizoctonia solani Kuhn is a critical global concern in the potato cultivation system. In this study, we evaluated the disease mitigation potential of five systemic acquired resistance-inducing chemicals viz., salicylic acid, jasmonic acid, β-aminobutyric acid, γ-aminobutyric acid and hydrogen peroxide (H2O2). Two common methods, tuber dipping and foliar spray, were utilized in this experiment to evaluate pathogen inhibition on inoculated tubers. The results revealed that all the systemic acquired resistance inducing chemicals were effective in disease suppression in a concentration-dependent manner compared to an inoculated control. Significant differences (P < 0.005) were evident among the various treatment combinations, with salicylic acid being the most effective in alleviating black scurf disease. Maximum reduction in disease incidence compared to the control was observed with salicylic acid (57.89% and 73.68%), followed by jasmonic acid (52.63% and 65.78%) and H2O2 (49.99% and 60.52%) under the tuber dipping treatment combinations. Whereas, in the foliar application, the maximum reduction in disease incidence compared to the control was observed with salicylic acid (44.73 and 63.15%), followed by jasmonic acid (42.10 and 60.52%) and H2O2 (39.46 and 52.63%). The tuber dipping treatments were significantly more efficacious (P < 0.005) compared to foliar spray for all treatment combinations. The biochemical analysis of defense-related enzymes and metabolites demonstrated the induced resistance activation under these treatments. The activity of peroxidase, polyphenol oxidase, and phenyl ammonia-lyase was significantly higher in treated tubers as compared to inoculated and uninoculated control. The total phenol content was also elevated in treated tubers as compared to the respective control. Altogether, these resistance-inducing chemicals can be successfully included in integrated disease management programs.

Identification of heat stress-related genomic regions by genome-wide association study in Solanum tuberosum

The climate crisis impairs yield and quality of crucial crops like potatoes. We investigated the effects of heat stress on five morpho-physiological parameters in a diverse panel of 178 potato cultivars under glasshouse conditions. Overall, heat stress increased shoot elongation and green fresh weight, but reduced tuber yield, starch content and harvest index. Genomic information was obtained from 258 tetraploid and three diploid cultivars by a genotyping-by-sequencing approach using methylation-sensitive restriction enzymes. This resulted in an enrichment of sequences in gene-rich regions. Population structure analyses using genetic distances and hierarchical clustering revealed strong kinship but weak overall population structure cultivars. A genome-wide association study (GWAS) was conducted with a subset of 20 K stringently filtered SNPs to identify quantitative trait loci (QTL) linked to heat tolerance. We identified 67 QTL and established haploblock boundaries to narrow down the number of candidate genes. Additionally, GO-enrichment analyses provided insights into gene functions. Heritability and genomic prediction were conducted to assess the usability of the collected data for selecting breeding material. The detected QTL might be exploited in marker-assisted selection to develop heat-resilient potato cultivars.

Integrated stress responses in okra plants (cv. ''Meya']: unravelling the mechanisms underlying drought and nematode co-occurrence

BACKGROUND

Climate change threatens sub-Saharan Africa's agricultural production, causing abiotic and biotic stressors. The study of plant responses to joint stressors is crucial for understanding molecular processes and identifying resilient crops for global food security. This study aimed to explore the shared and tailored responses of okra plants (cv. ''Meya'), at the biochemical and molecular levels, subjected to combined stresses of drought and Meloidogyne incognita infection.

DESIGN

The study involved 240 okra plants in a completely randomized design, with six treatments replicated 20 times. Okra plants were adequately irrigated at the end of every 10-days water deficit that lasted for 66 days (D). Also, the plants were infected with M. incognita for 66 days and irrigated at 2-days intervals (R). The stresses were done independently, in sequential combination (D before R and R before D) and concurrently (R and D). All biochemical and antioxidant enzyme assays were carried out following standard procedures.

RESULTS

Significant reductions in leaf relative water content were recorded in all stressed plants, especially in leaves of plants under individual drought stress (D) (41.6%) and plants stressed with root-knot nematode infection before drought stress (RBD) (41.4%). Malondialdehyde contents in leaf tissues from plants in D, nematode-only stress (RKN), drought stress before root-knot nematode infection (DBR), RBD, and concurrent drought-nematode stress (RAD) significantly increased by 320.2%, 152.9%, 186.5%, 283.7%, and 109.6%, respectively. Plants in D exhibited the highest superoxide dismutase activities in leaf (147.1% increase) and root (105.8% increase) tissues. Catalase (CAT) activities were significantly increased only in leaves of plants in D (90.8%) and RBD (88.9%), while only roots of plants in D exhibited a substantially higher CAT activity (139.3% increase) in comparison to controlled plants. Okra plants over-expressed NCED3 and under-expressed Me3 genes in leaf tissues. The NCED3 gene was overexpressed in roots from all treatments, while CYP707A3 was under-expressed only in roots of plants in RBD and RKN. CYP707A3 and NCED3 were grouped as closely related genes, while members of the Me3 genes were clustered into a separate group.

CONCLUSION

The biochemical and molecular responses observed in okra plants (cv. ''Meya') subjected to combined stresses of drought and Meloidogyne incognita infection provide valuable insights into enhancing crop resilience under multifaceted stress conditions, particularly relevant for agricultural practices in sub-Saharan Africa facing increasing climatic challenges.

Contribution of the regulatory miR156-SPL9 module to the drought stress response in pigmented potato (Solanum tuberosum L.)

Potato (Solanum tuberosum L.) is nowadays an important component of diversified cropping systems due to its adaptability, yielding capacity, and nutrition contribution. Breeding programs aiming at raising potato's nutritional value have mainly focused on the accumulation in potato tubers of health-promoting phytochemicals such as anthocyanins. In different plant species, increased amounts of anthocyanins in vegetative tissues have been associated with enhanced tolerance to abiotic and biotic stresses that challenge agrifood systems in the current context of global climate change. In the present study, we aimed at gaining insight into the effect of anthocyanin accumulation on the potato plants response to drought stress using three different potato genotypes with differential canopy and tuber pigmentation: the purple fleshed commercial variety Bleuet; the red fleshed breeding clone DAR170; and the non-pigmented commercial variety Monalisa. The varieties Bleuet and DAR170 exhibiting higher anthocyanin content in vegetative tissues than the Monalisa variety showed a remarkable inhibition of stem growth development under drought stress treatment suggestive of an anthocyanin-mediated physiological shift from growth to resilience as a mechanism of stress tolerance. The results of the expression analysis of stu-miR156a and its target StSPL9 gene in the potato plants with different anthocyanin content, as well as their change in response to drought stress support the participation of the conserved miR156-SPL9 regulatory module in coordinating potato plants development and plant responses to drought stress, involving precise fine-tuning of anthocyanin biosynthesis.

Identification of autophagy-related genes ATG18 subfamily genes in potato (Solanum tuberosum L.) and the role of StATG18a gene in heat stress

Autophagy is a highly conserved process in eukaryotes that is used to recycle the cellular components from the cytoplasm. It plays a crucial function in responding to both biotic and abiotic stress, as well as in the growth and development of plants. Autophagy-related genes (ATG) and their functions have been identified in numerous crop species. However, their specific tasks in potatoes (Solanum tuberosum L.), are still not well understood. This work is the first to identify and characterize the potato StATG18 subfamily gene at the whole-genome level, resulting in a total of 6 potential StATG18 subfamily genes. We analyzed the phylogenetic relationships, chromosome distribution and gene replication, conserved motifs and gene structure, interspecific collinearity relationship, and cis-regulatory elements of the ATG18 subfamily members using bioinformatics approaches. Furthermore, the quantitative real-time polymerase chain reaction (qRT-PCR) analysis suggested that StATG18 subfamily genes exhibit differential expression in various tissues and organs of potato plants. When exposed to heat stress, their expression pattern was observed in the root, stem, and leaf. Based on a higher expression profile, the StATG18a gene was further analyzed under heat stress in potatoes. The subcellular localization analysis of StATG18a revealed its presence in both the cytoplasm and nucleus. In addition, StATG18a altered the growth indicators, physiological characteristics, and photosynthesis of potato plants under heat stresses. In conclusion, this work offers a thorough assessment of StATG18 subfamily genes and provides essential recommendations for additional functional investigation of autophagy-associated genes in potato plants. Moreover, these results also contribute to our understanding of the potential mechanism and functional validation of the StATG18a gene's persistent tolerance to heat stress in potato plants.

Leaf Membrane Stability under High Temperatures as an Indicator of Heat Tolerance in Potatoes and Genome-Wide Association Studies to Understand the Underlying Genetics

High temperatures during the crop growing season are becoming more frequent and unpredictable, resulting in reduced crop productivity and quality. Heat stress disrupts plant metabolic processes that affect cell membrane composition and integrity. Cell membrane permeability, ion leakage, and heat shock proteins have been evaluated to screen for heat tolerance in plants. In potatoes, it is unclear whether leaf membrane stability under heat stress is correlated with underground tuber productivity and quality. The main goal of this study was to evaluate if leaf membrane relative electrolyte conductivity (REC) under high temperatures could be used to identify heat-tolerant potato genotypes. Electrolyte leakage assays, correlation estimations, and genome-wide association studies were carried out in 215 genotypes. Expression levels of small heat shock protein 18 (sHSP18) were evaluated in the heat-sensitive potato variety Russet Burbank and compared with those of the heat-tolerant variety Vanguard Russet using Western blotting. Significant differences were observed among genotypes for leaf membrane REC under extreme heat (50°C); REC values ranged from 47.0-99.5%. Leaf membrane REC was positively correlated with tuber external and internal defects and negatively correlated with yield. REC was negatively correlated with the content of several tuber minerals, such as nitrogen, magnesium, and manganese. Eleven quantitative trait loci (QTLs) were identified for leaf membrane REC, explaining up to 13.8% of the phenotypic variance. Gene annotation in QTL areas indicated associations with genes controlling membrane solute transport and plant responses to abiotic stresses. Vanguard Russet had lower leaf REC and higher expression of sHSP18 under high-temperature stress. Our findings indicate that leaf membrane REC under high temperatures can be used as an indicator of potato heat tolerance.

Yield reduction caused by elevated temperatures and high nitrogen fertilization is mitigated by SP6A overexpression in potato (Solanum tuberosum L.)

Potatoes (Solanum tuberosum L.) are a fundamental staple for millions of people worldwide. They provide essential amino acids, vitamins, and starch - a vital component of the human diet, providing energy and serving as a source of fiber. Unfortunately, global warming is posing a severe threat to this crop, leading to significant yield losses, and thereby endangering global food security. Industrial agriculture traditionally relies on excessive nitrogen (N) fertilization to boost yields. However, it remains uncertain whether this is effective in combating heat-related yield losses of potato. Therefore, our study aimed to investigate the combinatory effects of heat stress and N fertilization on potato tuber formation. We demonstrate that N levels and heat significantly impact tuber development. The combination of high N and heat delays tuberization, while N deficiency initiates early tuberization, likely through starvation-induced signals, independent of SELF-PRUNING 6A (SP6A), a critical regulator of tuberization. We also found that high N levels in combination with heat reduce tuber yield rather than improve it. However, our study revealed that SP6A overexpression can promote tuberization under these inhibiting conditions. By utilizing the excess of N for accumulating tuber biomass, SP6A overexpressing plants exhibit a shift in biomass distribution towards the tubers. This results in an increased yield compared to wild-type plants. Our results highlight the role of SP6A overexpression as a viable strategy for ensuring stable potato yields in the face of global warming. As such, our findings provide insights into the complex factors impacting potato crop productivity.

Rapid and low-cost screening for single and combined effects of drought and heat stress on the morpho-physiological traits of African eggplant (Solanum aethiopicum) germplasm

Drought and heat are two stresses that often occur together and may pose significant risks to crops in future climates. However, the combined effects of these two stressors have received less attention than single-stressor investigations. This study used a rapid and straightforward phenotyping method to quantify the variation in 128 African eggplant genotype responses to drought, heat, and the combined effects of heat and drought at the seedling stage. The study found that the morphophysiological traits varied significantly among the 128 eggplants, highlighting variation in response to abiotic stresses. Broad-sense heritability was high (> 0.60) for chlorophyll content, plant biomass and performance index, electrolyte leakage, and total leaf area. Positive and significant relationships existed between biomass and photosynthetic parameters, but a negative association existed between electrolyte leakage and morpho-physiological traits. The plants underwent more significant stress when drought and heat stress were imposed concurrently than under single stresses, with the impact of drought on the plants being more detrimental than heat. There were antagonistic effects on the morphophysiology of the eggplants when heat and drought stress were applied together. Resilient genotypes such as RV100503, RV100501, JAMBA, LOC3, RV100164, RV100169, LOC 3, RV100483, GH5155, RV100430, GH1087, GH1087*, RV100388, RV100387, RV100391 maintained high relative water content, low electrolyte leakage, high Fv/Fm ratio and performance index, and increased biomass production under abiotic stress conditions. The antagonistic interactions between heat and drought observed here may be retained or enhanced during several stress combinations typical of plants' environments and must be factored into efforts to develop climate change-resilient crops. This paper demonstrates improvised climate chambers for high throughput, reliable, rapid, and cost-effective screening for heat and drought and combined stress tolerance in plants.

Antioxidant Response, Phenolic Compounds and Yield of Solanum tuberosum Tubers Inoculated with Arbuscular Mycorrhizal Fungi and Growing under Water Stress

Solanum tuberosum (potato) is one of the most common crops worldwide; however, it is sensitive to water stress, which necessitates the identification of alternative tools to improve their production. Here, we evaluated the inoculation of two arbuscular mycorrhizal fungi (AMF) strains, Claroideoglomus claroideum (CC), Claroideoglomus lamellosum (HMC26), and the MIX (CC + HMC26) in yield and phenolic and antioxidant response using chromatographic and spectroscopic methods in potato crops, at increasing levels of water stress, namely, with 100% (0), 70% (S1), and 40% (S2) soil humidity. Two caffeoylquinic acid isomers were detected and their levels showed a tendency to increase under stress together with the AMF inoculation, reaching up to 19.2 mg kg-1 of 5-caffeoylquinic acid and 7.4 mg kg-1 of caffeoylquinic acid isomer when CC was inoculated, and potato plants grew at the highest water starvation condition (S2). Regarding antioxidant activities, a differentiated response was detected depending on the AMF strain, highlighting the effect of HMC26 on Trolox equivalent antioxidant capacity (TEAC) method and CC in cupric reducing antioxidant capacity (CUPRAC) method, reaching up to 1.5 μmol g-1 of TEAC in plants inoculated with HMC26 and 0.9 μmol g-1 of CUPRAC in plants inoculated with CC, both in potato tubers of plants growing under the S2 stress condition. Meanwhile, the use of AMF did not influence the number and biomass of the tubers, but significant changes in the biochemical properties of tubers were observed. The results suggest that specific AMF adaptations to water stress must be considered when inoculation procedures are planned to improve the yield and quality of tubers in potato crops.

Optimization of a simple, low-cost one-step reverse transcription recombinase polymerase amplification method for real-time detection of potato virus A in potato leaves and tubers

Vegetative propagation of potatoes makes it possible for potato viruses to be transmitted through tubers. Potato virus A (PVA) is one of these viruses, which belongs to the Potyvirus genus in the Potyviridae family. Potato tuber yield can be reduced by 30-40% by PVA alone. Losses can be further exacerbated by potato virus X and/or potato virus Y infection. PVA is transmitted primarily by several species of aphids in non-persistent manner. With the aim of resolving this problem, we developed one-step reverse transcription-recombinase polymerase amplification (RT-RPA), a highly sensitive and cost-effective method for detecting PVA in both potato tubers and leaves. Detection and amplification are performed using isothermal conditions in this method. There was good amplification of the coat protein gene in PVA with all three primers tested. To conduct this study, a primer set that can amplify specific 185 base pair (bp) product was selected. PVA detection was optimized by 30-min amplification reactions, which showed no cross-reactivity with other potato viruses. A simple heating block or water bath was used to amplify PVA product using RT-RPA at a temperature range of 38-42 °C. In comparison to conventional reverse transcription-polymerase chain reaction (RT-PCR), the newly developed RT-RPA protocol exhibited high sensitivity for both potato leaves and tuber tissues. Using cellular paper-based simple RNA extraction procedure, the virus was detected in leaf samples as efficiently as purified total RNA. We also found that combining LiCl-based RNA precipitation with cellular paper discs allowed us to successfully optimize RNA extraction for one-step RT-RPA for detecting PVA in tubers. Tests using this simplified one-step RT-RPA method were successfully applied to 300 samples of both leaves and tubers from various potato cultivars. In our knowledge, this is the first report of an RT-RPA assay utilizing simple RNA obtained from either cellular disc paper or LiCl coupled with cellular disc paper to detect PVA. As a result, this method was equally sensitive and specific for detecting PVA in potatoes. The developed RT-RPA assay is more versatile, durable, and do not require highly purified RNA templates, thus providing an effective alternative to RT-PCR assays for screening of germplasm, certifying planting materials, breeding for virus resistance, and real-time monitoring of PVA.

Genome-Wide Identification and Expression Analysis of C3H Zinc Finger Family in Potato (Solanum tuberosum L.)

Transcription factors containing a CCCH structure (C3H) play important roles in plant growth and development, and their stress response, but research on the C3H gene family in potato has not been reported yet. In this study, we used bioinformatics to identify 50 C3H genes in potato and named them StC3H-1 to StC3H-50 according to their location on chromosomes, and we analyzed their physical and chemical properties, chromosome location, phylogenetic relationship, gene structure, collinearity relationship, and cis-regulatory element. The gene expression pattern analysis showed that many StC3H genes are involved in potato growth and development, and their response to diverse environmental stresses. Furthermore, RT-qPCR data showed that the expression of many StC3H genes was induced by high temperatures, indicating that StC3H genes may play important roles in potato response to heat stress. In addition, Some StC3H genes were predominantly expressed in the stolon and developing tubers, suggesting that these StC3H genes may be involved in the regulation of tuber development. Together, these results provide new information on StC3H genes and will be helpful for further revealing the function of StC3H genes in the heat stress response and tuber development in potato.

The Impact of Heavy Metal Accumulation on Some Physiological Parameters in Silphium perfoliatum L. Plants Grown in Hydroponic Systems

Heavy metals like cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn), resulting from anthropogenic activities, are elements with high persistence in nature, being able to accumulate in soils, water, and plants with significant impact to human and animal health. This study investigates the phytoremediation capacity of Silphium perfoliatum L. as a specific heavy metal hyperaccumulator and the effects of Cu, Zn, Cd, and Pb on some physiological and biochemical indices by growing plants under floating hydroponic systems in nutrient solutions under the presence of heavy metals. One-year-old plants of S. perfoliatum grown for 20 days in Hoagland solution with the addition of (ppm) Cu-400, Zn-1200, Cd-20, Pb-400, and Cu+Zn+Cd+Pb (400/1200/20/400) were investigated with respect to the control. The level of phytoremediation, manifested by the ability of heavy metal absorption and accumulation, was assessed. In addition, the impact of stress on the proline content, photosynthetic pigments, and enzymatic activity, as being key components of metabolism, was determined. The obtained results revealed a good absorption and selective accumulation capacity of S. perfoliatum plants for the studied heavy metals. Therefore, Cu and Zn mainly accumulate in the stems, Cd in the roots and stems, while Pb mainly accumulates in the roots. The proline tended to increase under stress conditions, depending on the pollutant and its concentration, with higher values in leaves and stems under the associated stress of the four metals and individually for Pb and Cd. In addition, the enzymatic activity recorded different values depending on the plant organ, its type, and the metal concentration on its substrate. The obtained results indicate a strong correlation between the metal type, concentration, and the mechanisms of absorption/accumulation of S. perfoliatum species, as well as the specific reactions of metabolic response.

Development of Reverse Transcription Recombinase Polymerase Amplification (RT-RPA): A Methodology for Quick Diagnosis of Potato Leafroll Viral Disease in Potato

Potatoes are developed vegetatively from tubers, and therefore potato virus transmission is always a possibility. The potato leafroll virus (PLRV) is a highly devastating virus of the genus Polerovirus and family Luteoviridae and is regarded as the second-most destructive virus after Potato virus Y. Multiple species of aphids are responsible for the persistent and non-propagating transmission of PLRV. Due to intrinsic tuber damage (net necrosis), the yield and quality are drastically diminished. PLRV is mostly found in phloem cells and in extremely low amounts. Therefore, we have attempted to detect PLRV in both potato tuber and leaves using a highly sensitive, reliable and cheap method of one-step reverse transcription-recombinase polymerase amplification (RT-RPA). In this study, an isothermal amplification and detection approach was used for efficient results. Out of the three tested primer sets, one efficiently amplified a 153-bp product based on the coat protein gene. In the present study, there was no cross-reactivity with other potato viruses and the optimal amplification reaction time was thirty minutes. The products of RT-RPA were amplified at a temperature between 38 and 42 °C using a simple heating block/water bath. The present developed protocol of one-step RT-RPA was reported to be highly sensitive for both leaves and tuber tissues equally in comparison to the conventional reverse transcription-polymerase chain reaction (RT-PCR) method. By using template RNA extracted employing a cellular disc paper-based extraction procedure, the method was not only simplified but it detected the virus as effectively as purified total RNA. The simplified one-step RT-RPA test was proven to be successful by detecting PLRV in 129 samples of various potato cultivars (each consisting of leaves and tubers). According to our knowledge, this is the first report of a one-step RT-RPA performed using simple RNA extracted from cellular disc paper that is equally sensitive and specific for detecting PLRV in potatoes. In terms of versatility, durability and the freedom of a highly purified RNA template, the one-step RT-RPA assay exceeds the RT-PCR assay, making it an effective alternative for the certification of planting materials, breeding for virus resistance and disease monitoring.