Improving Potato Stress Tolerance and Tuber Yield Under a Climate Change Scenario - A Current Overview

Maladaptation in cereal crop landraces following a soot-producing climate catastrophe

Aerosol-producing global catastrophes such as nuclear war, super-volcano eruption, or asteroid strike, although rare, pose a serious threat to human survival. Light-absorbing aerosols would sharply reduce temperature and solar radiation reaching the earth's surface, decreasing crop productivity including for locally adapted traditional crop varieties, i.e. landraces. Here, we test post-catastrophic climate impacts on barley, maize, rice, and sorghum, four crops with extensive landrace cultivation, under a range of nuclear war scenarios that differ in the amount of black carbon aerosol (soot) injected into the climate model. We used a crop growth model to estimate gradients of environmental stressors that drive local adaptation. We then fit genotype environment associations using high density genomic markers with gradient forest offset (GF offset) methods and predicted maladaptation through time. As a validation, we found that our GF models successfully predicted local adaptation of maize landraces in multiple common gardens across Mexico. We found strong concordance between GF offset and disruptions in climate, and landraces of all tested crop species were predicted to be the most maladapted across space and time where soot-induced climate change was the greatest. We further used our GF models to identify landrace varieties best matched to specific post-catastrophic conditions, indicating potential substitutions for agricultural resilience. We found the best landrace genotype was often far away or in another nation, though countries with more climatic diversity had better within-country substitutions. Our results highlight that a soot-producing catastrophe would result in the global maladaptation of landraces and suggest that current landrace adaptive diversity is insufficient for agricultural resilience in the case of the soot scenarios with the greatest change to climate.

Potato starch quality in relation to the treatments and long-term storage of tubers

Starch is the most important component of potato tubers, the structure and composition of which play a key role in their utilization as well as processing and storage. Potato seed treatment may play the biggest role in ensuring proper plant growth and development. Isolated starch from tubers of different potato varieties for food processing was evaluated immediately after harvesting and after long-term storage with consideration of different products for potato seed treatment. The quality of starch was evaluated in terms of starch grain size, total starch content, pH, starch stability after freezing, gelatinization temperature as well as phosphorus and amylose content. The varieties differed significantly in starch content and quality. The Beo variety had the highest starch content in dry tuber weight (77.8%) and the best starch quality characteristics (the lowest starch stability after freezing - 18.0% and highest gelatinization temperature - 64.0 ℃ onset and 68.4 ℃ end). Simultaneous treatment of tubers with Supporter and Moncut 460 SC contributed to the highest starch content in tubers (77.6% d. m.) as well as increasing its stability after freezing (20.8%) and decreasing its gelatinization temperatures (61.7 ℃ onset and 66.0 ℃ end). This may be due to the increased proportion of large starch grains and higher amylose and phosphorus content. A slight decrease in starch quality traits was shown after long-term storage of tubers. Maintaining constant conditions during storage along with the applied treatments contributed to this. It is recommended to use products for potato seed treatment in the production technology of potato for consumption and for starch production.

Assessment of salicylic acid and potassium nitrate to mitigate frost stress in autumn-sown potato crop cv. Sutlej

Potato is cultivated all the year round in Pakistan. However, the major crop is the autumn crop which is planted in mid-October and contributes 80-85% of the total production. The abrupt climate change has affected the weather patterns all over the world, resulting in the reduction of the mean air temperature in autumn by almost 1.6 °C in Pakistan, which in turn, has adversely affected the crop performance and tuber yield. This trial, therefore, was conducted to optimize and evaluate the concentration of salicylic acid (SA) and potassium nitrate (KNO3) for inducing frost stress tolerance in an autumn-sown potato crop cv. Sutlej. The findings revealed that the foliar application of 0.5 mM SA significantly enhanced the growth, yield, fluorescent, and biochemical indices of potato plants outperforming 100 mM KNO₃ application in comparison with the control. This included increased plant height by 14% and 17.6%, leaf area index by 6.3% and 26.3%, shoot biomass by 15.4% and 46.2%, crop growth rate by 16.7% and 43.3%, average tuber weight by 8.2% and 23%, tuber diameter by 6.8% and 12.2%, tuber yield by 26.1% and 46.3%, leaf angle by 16.2% and 21.6%, quantum yield of photosystem II by 20.6% and 28.2%, photosynthetically active radiations by 20.5% and 32.4%, chlorophyll content by 6.3% and 14.6%, leaf thickness by 14% and 29%, linear electron flow by 20% and 32.7%, O-2 by 6% and 14.4%, H2O2 by 11.7% and 27.6%, enzyme activities of catalase by 20.7% and 28.5%, superoxide dismutase by 28.6% and 28.5%, peroxidase by 8.3% and 13.5%, ascorbate peroxidase by 17.2% and 37.8%, total protein by 21% and 37%, proline by 36.2% and 114%, and phenolic content by 33% and 63.3% with a reduction in non-photochemical quenching by 12.7% and 29.6%, non-regulatory energy dissipation by 169.5% and 268.5%, and leaf electrolyte leakage by 57.5% and 180%, compared to KNO3 and the control, respectively. Based on the above findings, it can be concluded and recommended that 0.5 mM foliar spray of SA can be utilized on potato crop cv. Sutlej in frost-sensitive regions. However, the application rate of KNO3 needs to be optimized in order to use its maximal frost stress tolerance potential.

The physiological and molecular responses of potato tuberization to projected future elevated temperatures

Potato (Solanum tuberosum L.) is one of the most important food crops globally and is especially vulnerable to heat stress. However, substantial knowledge gaps remain in our understanding of the developmental mechanisms associated with tuber responses to heat stress. This study used whole-plant physiology, transcriptomics, and phytohormone profiling to elucidate how heat stress affects potato tuber development. When plants were grown in projected future elevated temperature conditions, abscisic acid (ABA) levels decreased in leaf and tuber tissues, whereas rates of leaf carbon assimilation and stomatal conductance were not significantly affected compared to those plants grown in historical temperature conditions. While plants grown in projected future elevated temperature conditions initiated more tubers per plant on average, there was a 66% decrease in mature tubers at the final harvest compared to those plants grown in historical temperature conditions. We hypothesize that reduced tuber yields at elevated temperatures are not due to reduced tuber initiation, but due to impaired tuber filling. Transcriptomic analysis detected significant changes in the expression of genes related to ABA response, heat stress, and starch biosynthesis. The tuberization repressor genes SELF-PRUNING 5G (StSP5G) and CONSTANS-LIKE1 (StCOL1) were differentially expressed in tubers grown in elevated temperatures. Two additional known tuberization genes, IDENTITY OF TUBER 1 (StIT1) and TIMING OF CAB EXPRESSION 1 (StTOC1), displayed distinct expression patterns under elevated temperatures compared to historical temperature conditions but were not differentially expressed. This work highlights potential gene targets and key developmental stages associated with tuberization to develop potatoes with greater heat tolerance.

Balancing the scales: assessing the impact of irrigation and pathogen burden on potato blackleg disease and soil microbial communities

BACKGROUND

Understanding the interaction between environmental conditions, crop yields, and soil health is crucial for sustainable agriculture in a changing climate. Management practices to limit disease are a balancing act. For example, in potato production, dry conditions favour common scab (Streptomyces spp.) and wet conditions favour blackleg disease (Pectobacterium spp.). The exact mechanisms involved and how these link to changes in the soil microbiome are unclear. Our objectives were to test how irrigation management and bacterial pathogen load in potato seed stocks impact: (i) crop yields; (ii) disease development (blackleg or common scab); and (iii) soil microbial community dynamics.

METHODS

We used stocks of seed potatoes with varying natural levels of Pectobacterium (Jelly [high load], Jelly [low load] and Estima [Zero - no Pectobacterium]). Stocks were grown under four irrigation regimes that differed in the timing and level of watering. The soil microbial communities were profiled using amplicon sequencing at 50% plant emergence and at harvest. Generalised linear latent variable models and an annotation-free mathematical framework approach (ensemble quotient analysis) were then used to show the interacting microbes with irrigation regime and Pectobacterium pathogen levels.

RESULTS

Irrigation increased blackleg symptoms in the plots planted with stocks with low and high levels of Pectobacterium (22-34%) but not in the zero stock (2-6%). However, withholding irrigation increased common scab symptoms (2-5%) and reduced crop yields. Irrigation did not impact the composition of the soil microbiome, but planting stock with a high Pectobacterium burden resulted in an increased abundance of Planctomycetota, Anaerolinea and Acidobacteria species within the microbiome. Ensemble quotient analysis highlighted the Anaerolinea taxa were highly associated with high levels of Pectobacterium in the seed stock and blackleg symptoms in the field.

CONCLUSIONS

We conclude that planting seed stocks with a high Pectobacterium burden alters the abundance of specific microbial species within the soil microbiome and suggest that managing pathogen load in seed stocks could substantially affect soil communities, affecting crop health and productivity. Video Abstract.

StEPF2 and StEPFL9 Play Opposing Roles in Regulating Stomatal Development and Drought Tolerance in Potato (Solanum tuberosum L.)

Stomata are essential for photosynthesis and water-use efficiency in plants. When expressed in transgenic Arabidopsis thaliana plants, the potato (Solanum tuberosum) proteins EPIDERMAL PATTERNING FACTOR 2 (StEPF2) and StEPF-LIKE9 (StEPFL9) play antagonistic roles in regulating stomatal density. Little is known, however, about how these proteins regulate stomatal development, growth, and response to water deficit in potato. Transgenic potato plants overexpressing StEPF2 (E2 plants) or StEPFL9 (ST plants) were generated, and RT-PCR and Western blot analyses were used to select two lines overexpressing each gene. E2 plants showed reduced stomatal density, whereas ST plants produced excessive stomata. Under well-watered conditions, ST plants displayed vigorous growth with improved leaf gas exchange and also showed increased biomass/yields compared with non-transgenic and E2 plants. E2 plants maintained lower H2O2 content and higher levels of stomatal conductance and photosynthetic capacity than non-transgenic and ST plants, which resulted in higher water-use efficiency and biomass/yields during water restriction. These results suggest that StEPF2 and StEPFL9 functioned in pathways regulating stomatal development. These genes are thus promising candidates for use in future breeding programs aimed at increasing potato water-use efficiency and yield under climate change scenarios.

Non-thermal plasma enhances growth and salinity tolerance of bok choy (Brassica rapa subsp. chinensis) in hydroponic culture

In this study, we aimed to examine the growth, physiological and biochemical status, and responses to salinity stress of bok choy (Brassica rapa subsp. chinensis) cultivated in a hydroponic system with a plasma-treated solution. Plasma gas generated using a cylindrical dielectric barrier discharge or air (control) was injected into Hoagland nutrient solution once a week for different durations (0, 5, and 10 min). After 4 weeks, the length of the shoots and roots, number of leaves, and dry weight of bok choy plants significantly increased in individuals grown with Hoagland solution treated with plasma gas for 10 min. An increase in dry weight of individual plants of approximately 80.5% was observed in plants in the plasma-treated group compared to those in a control group. The levels of chlorophyll, total soluble proteins, and nitrogen uptake, and transcription of genes related to salinity stress tolerance-WRKY2, HHP3, and ABI1- were also significantly elevated in bok choy grown with plasma treated Hoagland solution. Moreover, when exposed to 20 mM NaCl, plant length and leaf number were significantly increased, in the group grown with Hoagland solution treated with plasma gas for 10 min. Level of H2O2 was significantly elevated in the treated nutrient solutions. In plants grown with the treated nutrient solution, intracellular NO was highly detected in the cell division and elongation zone of roots. Our findings suggest that plasma treatment of nutrient solutions in hydroponic culture systems may improve the growth, physiological and biochemical status, and tolerance to salinity stress in plants, and a crucial role of H2O2 generated in the treated nutrient solutions may play in this improvement.

Genome-wide characterization of the GRF transcription factors in potato (Solanum tuberosum L.) and expression analysis of StGRF genes during potato tuber dormancy and sprouting

Growth-regulating factors (GRFs) are transcription factors that play a pivotal role in plant growth and development. This study identifies 12 Solanum tuberosum GRF transcription factors (StGRFs) and analyzes their physicochemical properties, phylogenetic relationships, gene structures and gene expression patterns using bioinformatics. The StGRFs exhibit a length range of 266 to 599 amino acids, with a molecular weight of 26.02 to 64.52 kDa. The majority of StGRFs possess three introns. The promoter regions contain a plethora of cis-acting elements related to plant growth and development, as well as environmental stress and hormone response. All the members of the StGRF family contain conserved WRC and QLQ domains, with the sequences of these two conserved domain modules exhibiting high levels of conservation. Transcriptomic data indicates that StGRFs play a significant role in the growth and development of stamens, roots, young tubers, and other tissues or organs in potatoes. Furthermore, a few StGRFs exhibit differential expression patterns in response to Phytophthora infestans, chemical elicitors, heat, salt, and drought stresses, as well as multiple hormone treatments. The results of the expression analysis indicate that StGRF1, StGRF2, StGRF5, StGRF7, StGRF10 and StGRF12 are involved in the process of tuber sprouting, while StGRF4 and StGRF9 may play a role in tuber dormancy. These findings offer valuable insights that can be used to investigate the roles of StGRFs during potato tuber dormancy and sprouting.

Physiological and Enzymatic Antioxidant Responses of Solanum tuberosum Leaves to Arbuscular Mycorrhizal Fungal Inoculation under Water Stress

Solanum tuberosum is one of the most widely cropped plant species worldwide; unfortunately, drought is one of the major constraints on potato productivity because it affects the physiology, biochemical processes, and yield. The use of arbuscular mycorrhizal fungi (AMF) has exhibited beneficial effects on plants during drought. The objective of this study was to analyse the effect of AMF inoculation on two genotypes of potato plants exposed to water stress, and the photosynthetic traits, enzymatic antioxidant activity, and exudation of low-molecular-weight organic acids (LMWOAs) of potato plants inoculated with two strains of AMF, Claroideoglomus claroideum (CC) and Claroideoglomus lamellosum (HMC26), were evaluated. Stomatal conductance exhibited a similar trend in the CC and HMC26 treatments for both potato genotypes; moreover, the photosynthetic rate significantly increased by 577.9% between the 100% soil humidity (S0) and 40% soil humidity (S2) stress levels for the VR808 genotype under the CC treatment. The activities of the enzymes catalase (CAT) and ascorbate peroxidase (APX) showed similar trends. In this study, there were different responses among genotypes and treatments. Inoculation with CC under S2 stress levels is a promising potential approach for improving potato growth under drought conditions.

Whole-genome sequencing of tetraploid potato varieties reveals different strategies for drought tolerance

Climate changes leading to increasingly longer seasonal drought periods in large parts of the world increase the necessity for breeding drought-tolerant crops. Cultivated potato (Solanum tuberosum), the third most important vegetable crop worldwide, is regarded as drought-sensitive due to its shallow root architecture. Two German tetraploid potato cultivars differing in drought tolerance and their F1-progeny were evaluated under various drought scenarios. Bulked segregant analyses were combined with whole-genome sequencing (BSA-Seq) using contrasting bulks of drought-tolerant and drought-sensitive F1-clones. Applying QTLseqr, 15 QTLs comprising 588,983 single nucleotide polymorphisms (SNPs) in 2325 genes associated with drought stress tolerance were identified. SeqSNP analyses in an association panel of 34 mostly starch potato varieties using 1-8 SNPs for each of 188 selected genes narrowed the number of candidate genes down to 10. In addition, ent-kaurene synthase B was the only gene present under QTL 10. Eight of the identified genes (StABP1, StBRI1, StKS, StLEA, StPKSP1, StPKSP2, StYAB5, and StZOG1) address plant development, the other three genes (StFATA, StHGD and StSYP) contribute to plant protection under drought stress. Allelic variation in these genes might be explored in future breeding for drought-tolerant potato varieties.

Multivariate Analysis Compares and Evaluates Heat Tolerance of Potato Germplasm

High temperature is the most important environmental factor limiting potato (Solanum tuberosum L.) yield. The tuber yield has been used to evaluate the heat tolerance of some potato cultivars, but potato yield was closely correlated with the maturation period. Therefore, it is necessary to employ different parameters to comprehensively analyze and evaluate potato tolerance to heat stress. This study aimed to investigate physiologic changes during growth and development, and develop accurate heat tolerance evaluation methods of potato cultivars under heat stress. About 93 cultivars (including foreign elite lines, local landraces and cultivars) were screened using an in vitro tuber-inducing system (continuous darkness and 8% sucrose in the culture medium) under heat stress (30 °C) and normal (22 °C) conditions for 30 days. The tuber yield and number decreased significantly under heat stress compared to the control. A total of 42 cultivars were initially selected depending on tuber formation, after in vitro screening, further testing of selected cultivars was conducted in ex vitro conditions. The screened cultivars were further exposed to heat stress (35 °C/28 °C, day/night) for 60 days. Heat stress led to an increase in the plant height growth rate, fourth internode growth rate, and membrane damage, and due to heat-induced damage to chloroplasts, decrease in chlorophyll biosynthesis and photosynthetic efficiency. Three principal components were extracted by principal component analysis. Correlation and regression analysis showed that heat tolerance is positively correlated with the plant height growth rate, fourth internode growth rate, the content of chlorophyll b, photosynthetic rate, stomatal conductance, transpiration rate, tuber number, and tuber yield, and negatively correlated with the cell membrane injury level. The nine traits are accurate and representative indicators for evaluating potato tolerance to heat stress and could determine a relatively high mean forecast accuracy of 100.0% for the comprehensive evaluation value. Through cluster analysis and screening, cultivar FA, D73, and C132 had the highest heat comprehensive evaluation value, which could be further selected as heat-resistant varieties. This study provides insights into the different physiological mechanisms and accurate evaluation methods of potato cultivars under heat stress, which could be valuable for further research and breeding.

Kinetic modeling identifies targets for engineering improved photosynthetic efficiency in potato (Solanum tuberosum cv. Solara)

Potato (Solanum tuberosum) is a significant non-grain food crop in terms of global production. However, its yield potential might be raised by identifying means to release bottlenecks within photosynthetic metabolism, from the capture of solar energy to the synthesis of carbohydrates. Recently, engineered increases in photosynthetic rates in other crops have been directly related to increased yield - how might such increases be achieved in potato? To answer this question, we derived the photosynthetic parameters Vcmax and Jmax to calibrate a kinetic model of leaf metabolism (e-Photosynthesis) for potato. This model was then used to simulate the impact of manipulating the expression of genes and their protein products on carbon assimilation rates in silico through optimizing resource investment among 23 photosynthetic enzymes, predicting increases in photosynthetic CO2 uptake of up to 67%. However, this number of manipulations would not be practical with current technologies. Given a limited practical number of manipulations, the optimization indicated that an increase in amounts of three enzymes - Rubisco, FBP aldolase, and SBPase - would increase net assimilation. Increasing these alone to the levels predicted necessary for optimization increased photosynthetic rate by 28% in potato.

A deep learning model for predicting risks of crop pests and diseases from sequential environmental data

Crop pests reduce productivity, so managing them through early detection and prevention is essential. Data from various modalities are being used to predict crop diseases by applying machine learning methodology. In particular, because growth environment data is relatively easy to obtain, many attempts are made to predict pests and diseases using it. In this paper, we propose a model that predicts diseases through previous growth environment information of crops, including air temperature, relative humidity, dew point, and CO2 concentration, using deep learning techniques. Using large-scale public data on crops of strawberry, pepper, grape, tomato, and paprika, we showed the model can predict the risk score of crop pests and diseases. It showed high predictive performance with an average AUROC of 0.917, and based on the predicted results, it can help prevent pests or post-processing. This environmental data-based crop disease prediction model and learning framework are expected to be universally applicable to various facilities and crops for disease/pest prevention.

Biological control of potato common scab and growth promotion of potato by Bacillus velezensis Y6

Potato common scab, caused mainly by Streptomyces scabies, causes surface necrosis and reduces the economic value of potato tubers, but effective chemical control is still lacking. In this study, an attempt was made to control potato common scab by inoculating potatoes with Bacillus velezensis (B. velezensis) and to further investigate the mechanism of biological control. The results showed that B. velezensis Y6 could reduce the disease severity of potato common scab from 49.92 ± 25.74% [inoculated with Streptomyces scabies (S. scabies) only] to 5.56 ± 1.89% (inoculated with S. scabies and Y6 on the same day) and increase the potato yield by 37.32% compared with the control under pot experiment in this study. Moreover, in the field trial, it was found that Y6 could also significantly reduce disease severity from 13.20 ± 1.00% to 4.00 ± 0.70% and increase the potato yield from 2.07 ± 0.10 ton/mu to 2.87 ± 0.28 ton/mu (p < 0.01; Tukey's test). Furthermore, RNA-seq analysis indicated that 256 potato genes were upregulated and 183 potato genes were downregulated in response to B. velezensis Y6 inoculation. In addition, strain Y6 was found to induce the expression of plant growth-related genes in potato, including cell wall organization, biogenesis, brassinosteroid biosynthesis, and plant hormone transduction genes, by 1.01-4.29 times. As well as up-regulate hydroquinone metabolism-related genes and several transcription factors (bHLH, MYB, and NAC) by 1.13-4.21 times. In summary, our study will help to understand the molecular mechanism of biological control of potato common scab and improve potato yield.

StHsfB5 Promotes Heat Resistance by Directly Regulating the Expression of Hsp Genes in Potato

With global warming, high temperatures have become a major environmental stress that inhibits plant growth and development. Plants evolve several mechanisms to cope with heat stress accordingly. One of the important mechanisms is the Hsf (heat shock factor)-Hsp (heat shock protein) signaling pathway. Therefore, the plant transcription factor Hsf family plays important roles in response to heat stress. All Hsfs can be divided into three classes (A, B, and C). Usually, class-A Hsfs are transcriptional activators, while class-B Hsfs are transcriptional repressors. In potato, our previous work identified 27 Hsfs in the genome and analyzed HsfA3 and HsfA4C functions that promote potato heat resistance. However, the function of HsfB is still elusive. In this study, the unique B5 member StHsfB5 in potato was obtained, and its characterizations and functions were comprehensively analyzed. A quantitative real-time PCR (qRT-PCR) assay showed that StHsfB5 was highly expressed in root, and its expression was induced by heat treatment and different kinds of phytohormones. The subcellular localization of StHsfB5 was in the nucleus, which is consistent with the characterization of transcription factors. The transgenic lines overexpressing StHsfB5 showed higher heat resistance compared with that of the control nontransgenic lines and inhibitory lines. Experiments on the interaction between protein and DNA indicated that the StHsfB5 protein can directly bind to the promoters of target genes small Hsps (sHsp17.6, sHsp21, and sHsp22.7) and Hsp80, and then induce the expressions of these target genes. All these results showed that StHsfB5 may be a coactivator that promotes potato heat resistance ability by directly inducing the expression of its target genes sHsp17.6, sHsp21, sHsp22.7, and Hsp80.

The enhancement of photosynthetic performance, water use efficiency and potato yield under elevated CO2 is cultivar dependent

As a fourth major food crop, potato could fulfill the nutritional demand of the growing population. Understanding how potato plants respond to predicted increase in atmospheric CO2 at the physiological, biochemical and molecular level is therefore important to improve potato productivity. Thus, the main objectives of the present study are to investigate the effects of elevated CO2 on the photosynthetic performance, water use efficiency and tuber yield of various commercial potato cultivars combined with biochemical and molecular analyses. We grew five potato cultivars (AC Novachip, Atlantic, Kennebec, Russet Burbank and Shepody) at either ambient CO2 (400 μmol CO2 mol-1) or elevated (750 μmol CO2 mol-1) CO2. Compared to ambient CO2-grown counterparts, elevated CO2-grown Russet Burbank and Shepody exhibited a significant increase in tuber yield of 107% and 49% respectively, whereas AC Novachip, Atlantic and Kennebec exhibited a 16%, 6% and 44% increment respectively. These differences in CO2-enhancement of tuber yield across the cultivars were mainly associated with the differences in CO2-stimulation of rates of photosynthesis. For instance, elevated CO2 significantly stimulated the rates of gross photosynthesis for AC Novachip (30%), Russet Burbank (41%) and Shepody (28%) but had minimal effects for Atlantic and Kennebec when measured at growth light. Elevated CO2 significantly increased the total tuber number for Atlantic (40%) and Shepody (83%) but had insignificant effects for other cultivars. Average tuber size increased for AC Novachip (16%), Kennebec (30%) and Russet Burbank (80%), but decreased for Atlantic (25%) and Shepody (19%) under elevated versus ambient CO2 conditions. Although elevated CO2 minimally decreased stomatal conductance (6-22%) and transpiration rates (2-36%), instantaneous water use efficiency increased by up to 79% in all cultivars suggesting that enhanced water use efficiency was mainly associated with increased photosynthesis at elevated CO2. The effects of elevated CO2 on electron transport rates, non-photochemical quenching, excitation pressure, and leaf chlorophyll and protein content varied across the cultivars. We did not observe any significant differences in plant growth and morphology in elevated versus ambient CO2-grown plants. Taken all together, we conclude that the CO2-stimulation of photosynthetic performance, water use efficiency and tuber yield of potatoes is cultivar dependent.

Evaluating the impact of modeling the family effect for clonal selection in potato-breeding programs

Because of its wide distribution, high yield potential, and short cycle, the potato has become essential for global food security. However, the complexity of tetrasomic inheritance, the high level of heterozygosity of the parents, the low multiplication rate of tubers, and the genotype-by-environment interactions impose severe challenges on tetraploid potato-breeding programs. The initial stages of selection take place in experiments with low selection accuracy for many of the quantitative traits of interest, for example, tuber yield. The goal of this study was to investigate the contribution of incorporating a family effect in the estimation of the total genotypic effect and selection of clones in the initial stage of a potato-breeding program. The evaluation included single trials (STs) and multi-environment trials (METs). A total of 1,280 clones from 67 full-sib families from the potato-breeding program at Universidade Federal de Lavras were evaluated for the traits total tuber yield and specific gravity. These clones were distributed in six evaluated trials that varied according to the heat stress level: without heat stress, moderate heat stress, and high heat stress. To verify the importance of the family effect, models with and without the family effect were compared for the analysis of ST and MET data for both traits. The models that included the family effect were better adjusted in the ST and MET data analyses for both traits, except when the family effect was not significant. Furthermore, the inclusion of the family effect increased the selective efficiency of clones in both ST and MET analyses via an increase in the accuracy of the total genotypic value. These same models also allowed the prediction of clone effects more realistically, as the variance components associated with family and clone effects within a family were not confounded. Thus, clonal selection based on the total genotypic value, combining the effects of family and clones within a family, proved to be a good alternative for potato-breeding programs that can accommodate the logistic and data tracking required in the breeding program.

Variability in morpho-biochemical, photosynthetic pigmentation, enzymatic and quality attributes of potato for salinity stress tolerance

Salt stress has emerged as a growing global concern, exerting a significant impact on agricultural productivity. The challenges of salt stress on potatoes are crucial for ensuring food security and sustainable agriculture. To address this issue a pot trial was executed to evaluate the impacts of NaCl in the soil on the growth, photosynthetic pigments, and quality attributes of potato, plants were grown in soil spiked with various concentrations of NaCl (0, 1, 3, 5, 7 g kg-1 of soil). Results revealed that salt stress have negative impacts on the growth, biomass, photosynthesis and quality attributes of potato. Lower level of salt stress 1 g kg-1 of soil improved the fresh and dry biomass of leaves (78.70 and 47.74%) and tubers (86.04 and 88.92%) as compared to control, respectively. Higher levels of salt stress (7 g kg-1) increased lipid peroxidation in leaves and improved the enzymatic antioxidants. It was observed that enzyme activities i.e., SOD (134.97%), POD (101.02%), and CAT (28.87%) increased in leaves and are inversely related to the NaCl concentration. The combination of reduction in chlorophyll contents and soluble sugars resulted in lower levels of quality attributes i.e., amylose (68.90%) and amylopectin (16.70%) of potato. Linear relationship in growth, biomass and physiological attributes showed the strong association with increased salt stress. Furthermore, the PCA-heatmap synergy offers identifying clusters of co-regulated attributes, which pinpoint the physiological responses that exhibit the strongest correlation with increasing salt stress levels. Findings indicate that potato can be grown successfully with (1 g kg-1 of NaCl in soil) without negative impacts on plant quality. Furthermore, this study contributes valuable insights into the complexities of salt stress on potato plants and provides a foundation for developing strategies to enhance their resilience in salt-affected environments.

Identification of genes associated with abiotic stress tolerance in sweetpotato using weighted gene co-expression network analysis

Sweetpotato, Ipomoea batatas (L.), a key food security crop, is negatively impacted by heat, drought, and salinity stress. The orange-fleshed sweetpotato cultivar "Beauregard" was exposed to heat, salt, and drought treatments for 24 and 48 h to identify genes responding to each stress condition in leaves. Analysis revealed both common (35 up regulated, 259 down regulated genes in the three stress conditions) and unique sets of up regulated (1337 genes by drought, 516 genes by heat, and 97 genes by salt stress) and down regulated (2445 genes by drought, 678 genes by heat, and 204 genes by salt stress) differentially expressed genes (DEGs) suggesting common, yet stress-specific transcriptional responses to these three abiotic stressors. Gene Ontology analysis of down regulated DEGs common to both heat and salt stress revealed enrichment of terms associated with "cell population proliferation" suggestive of an impact on the cell cycle by the two stress conditions. To identify shared and unique gene co-expression networks under multiple abiotic stress conditions, weighted gene co-expression network analysis was performed using gene expression profiles from heat, salt, and drought stress treated 'Beauregard' leaves yielding 18 co-expression modules. One module was enriched for "response to water deprivation," "response to abscisic acid," and "nitrate transport" indicating synergetic crosstalk between nitrogen, water, and phytohormones with genes encoding osmotin, cell expansion, and cell wall modification proteins present as key hub genes in this drought-associated module. This research lays the groundwork for exploring to a further degree, mechanisms for abiotic stress tolerance in sweetpotato.

New potential roles of StDREB1 and VvWRKY2 transcription factors in potato dormancy and sprouting patterns

In a previous study, transgenic potato plants overexpressing the StDREB1 or the VvWRKY2 transcription factor (TF) proved to have higher productivity and ameliorated tuber quality in comparison to wildtype (WT; the BF15 variety) plants. Interestingly, when stored at 4 °C, we noticed that the tubers of transgenic potato plants exhibited a delay in sprouting, hence a longer dormancy period. Therefore, we decided to study the dormancy and sprouting of these tubers (the two transgenic and the WT lines) through a physiological and biochemical characterization. WT and genetically modified (GM) tubers were stored at 4 °C for different periods (0, 30, 90, 180, and 240 days) followed by placing them in a germination chamber and the sprouting parameters were then monitored. According to our findings, the overexpression of these two TFs led to modifications in the sprouting kinetic of tubers through an extension of the dormancy period and changes in the sprouting process. Indeed, WT tubers emitted apical and lateral sprouts while those from GM plants showed mainly apical sprouts. In addition, higher reactive oxygen species (ROS) rates, indicators of tuber aging, were recorded in WT tubers compared to GM ones. The higher antioxidant enzyme activities in GM tubers seem to be responsible for aging modification in comparison to WT. The above results suggest the first report on new roles of the StDREB1 and VvWRKY2 TF which seemed to be involved in the regulation of potato tuber aging via a reduction of the main biochemical factors concentration and the ROS content leading to a longer dormancy period and a modified sprouting pattern.

RNA-seq provides insights into potato deubiquitinase responses to drought stress in seedling stage

Ubiquitination is a specific protein degradation and reversible post-translational modification process that can be reversed by deubiquitinase (DUBs). DUBs can hydrolyze and release ubiquitin in the substrate protein so that the substrate can avoid degradation or change its activity, and it has an impact on plant growth and development, cell cycle, abiotic stress response, and other biological processes. Transcript sequences of potato varieties "DM1-3", "Atlantic" and "Cooperation-88" downloaded from Potato Genome Resources were used for genome-wide identification of the DUB gene family using Hidden Markov Models and verified in the NCBI CD-Search tool. The characteristics of DUB genes from different potato varieties were analyzed including subcellular localization, gene structural motifs, phylogenetic tree, and sequence homology. Polyethylene glycol 6000 (PEG6000) induced drought stress transcriptome analysis was performed on the "Atlantic", and differentially expressed genes were screened, with emphasis on the characterization of deubiquitinase. DUB genes have a complex gene structure, often with a large number of exons and alternative splicing. Their promoters contain abundant abiotic stress-responsive elements, such as 425 MYC, 325 ABRE, and 320 MYB. There are also a large number of orthologous genes in the DUBs of the three potato varieties, and these genes are often clustered in similar regions on the genome. We performed transcriptome sequencing of the potato under PEG-induced drought stress and analyzed it for the first time using the Atlantic as a reference genome. We identified a total of 6067 down-regulated differentially expressed genes (DEGs) and 4950 up-regulated DEGs under PEG-induced drought stress. We screened the expression of DUBs and observed that 120 DUBs were up-regulated where most of them functioned in the nucleus, and the interacting proteins of DUBs were also localized in the nucleus. We have comprehensively identified and analyzed potato DUBs, and the accurately aligned transcriptome data which will further deepen the understanding of DUBs involved in the regulation of osmotic stress.

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.

Integrating Full-Length Transcriptome and RNA Sequencing of Siberian Wildrye (Elymus sibiricus) to Reveal Molecular Mechanisms in Response to Drought Stress

Drought is one of the most significant limiting factors affecting plant growth and development on the Qinghai-Tibet Plateau (QTP). Mining the drought-tolerant genes of the endemic perennial grass of the QTP, Siberian wildrye (Elymus sibiricus), is of great significance to creating new drought-resistant varieties which can be used in the development of grassland livestock and restoring natural grassland projects in the QTP. To investigate the transcriptomic responsiveness of E. sibiricus to drought stress, PEG-induced short- and long-term drought stress was applied to two Siberian wildrye genotypes (drought-tolerant and drought-sensitive accessions), followed by third- and second-generation transcriptome sequencing analysis. A total of 40,708 isoforms were detected, of which 10,659 differentially expressed genes (DEGs) were common to both genotypes. There were 2107 and 2498 unique DEGs in the drought-tolerant and drought-sensitive genotypes, respectively. Additionally, 2798 and 1850 DEGs were identified in the drought-tolerant genotype only under short- and long-term conditions, respectively. DEGs numbering 1641 and 1330 were identified in the drought-sensitive genotype only under short- and long-term conditions, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that all the DEGs responding to drought stress in E. sibiricus were mainly associated with the mitogen-activated protein kinase (MAKP) signaling pathway, plant hormone signal transduction, the linoleic acid metabolism pathway, the ribosome pathway, and plant circadian rhythms. In addition, Nitrate transporter 1/Peptide transporter family protein 3.1 (NPF3.1) and Auxin/Indole-3-Acetic Acid (Aux/IAA) family protein 31(IAA31) also played an important role in helping E. sibiricus resist drought. This study used transcriptomics to investigate how E. sibiricus responds to drought stress, and may provide genetic resources and references for research into the molecular mechanisms of drought resistance in native perennial grasses and for breeding drought-tolerant varieties.

Genome-wide characterization of SOS1 gene family in potato (Solanum tuberosum) and expression analyses under salt and hormone stress

Salt Overly Sensitive 1 (SOS1) is one of the members of the Salt Overly Sensitive (SOS) signaling pathway and plays critical salt tolerance determinant in plants, while the characterization of the SOS1 family in potato (Solanum tuberosum) is lacking. In this study, 37 StSOS1s were identified and found to be unevenly distributed across 10 chromosomes, with most of them located on the plasma membrane. Promoter analysis revealed that the majority of these StSOS1 genes contain abundant cis-elements involved in various abiotic stress responses. Tissue specific expression showed that 21 of the 37 StSOS1s were widely expressed in various tissues or organs of the potato. Molecular interaction network analysis suggests that 25 StSOS1s may interact with other proteins involved in potassium ion transmembrane transport, response to salt stress, and cellular processes. In addition, collinearity analysis showed that 17, 8, 1 and 5 of orthologous StSOS1 genes were paired with those in tomato, pepper, tobacco, and Arabidopsis, respectively. Furthermore, RT-qPCR results revealed that the expression of StSOS1s were significant modulated by various abiotic stresses, in particular salt and abscisic acid stress. Furthermore, subcellular localization in Nicotiana benthamiana suggested that StSOS1-13 was located on the plasma membrane. These results extend the comprehensive overview of the StSOS1 gene family and set the stage for further analysis of the function of genes in SOS and hormone signaling pathways.

Systematic Analysis of Galactinol Synthase and Raffinose Synthase Gene Families in Potato and Their Expression Patterns in Development and Abiotic Stress Responses

Raffinose family oligosaccharides (RFOs) are very important for plant growth, development, and abiotic stress tolerance. Galactinol synthase (GolS) and raffinose synthase (RFS) are critical enzymes involved in RFO biosynthesis. However, the whole-genome identification and stress responses of their coding genes in potato remain unexplored. In this study, four StGolS and nine StRFS genes were identified and classified into three and five subgroups, respectively. Remarkably, a total of two StGolS and four StRFS genes in potato were identified to form collinear pairs with those in both Arabidopsis and tomato, respectively. Subsequent analysis revealed that StGolS4 exhibited significantly high expression levels in transport-related tissues, PEG-6000, and ABA treatments, with remarkable upregulation under salt stress. Additionally, StRFS5 showed similar responses to StGolS4, but StRFS4 and StRFS8 gene expression increased significantly under salt treatment and decreased in PEG-6000 and ABA treatments. Overall, these results lay a foundation for further research on the functional characteristics and molecular mechanisms of these two gene families in response to ABA, salt, and drought stresses, and provide a theoretical foundation and new gene resources for the abiotic-stress-tolerant breeding of potato.

Abiotic Stress in Crop Production

The vast majority of agricultural land undergoes abiotic stress that can significantly reduce agricultural yields. Understanding the mechanisms of plant defenses against stresses and putting this knowledge into practice is, therefore, an integral part of sustainable agriculture. In this review, we focus on current findings in plant resistance to four cardinal abiotic stressors—drought, heat, salinity, and low temperatures. Apart from the description of the newly discovered mechanisms of signaling and resistance to abiotic stress, this review also focuses on the importance of primary and secondary metabolites, including carbohydrates, amino acids, phenolics, and phytohormones. A meta-analysis of transcriptomic studies concerning the model plant Arabidopsis demonstrates the long-observed phenomenon that abiotic stressors induce different signals and effects at the level of gene expression, but genes whose regulation is similar under most stressors can still be traced. The analysis further reveals the transcriptional modulation of Golgi-targeted proteins in response to heat stress. Our analysis also highlights several genes that are similarly regulated under all stress conditions. These genes support the central role of phytohormones in the abiotic stress response, and the importance of some of these in plant resistance has not yet been studied. Finally, this review provides information about the response to abiotic stress in major European crop plants—wheat, sugar beet, maize, potatoes, barley, sunflowers, grapes, rapeseed, tomatoes, and apples.

Analysis of Genome Structure and Its Variations in Potato Cultivars Grown in Russia

Solanum tuberosum L. (common potato) is one of the most important crops produced almost all over the world. Genomic sequences of potato opens the way for studying the molecular variations related to diversification. We performed a reconstruction of genomic sequences for 15 tetraploid potato cultivars grown in Russia using short reads. Protein-coding genes were identified; conserved and variable parts of pan-genome and the repertoire of the NBS-LRR genes were characterized. For comparison, we used additional genomic sequences for twelve South American potato accessions, performed analysis of genetic diversity, and identified the copy number variations (CNVs) in two these groups of potato. Genomes of Russian potato cultivars were more homogeneous by CNV characteristics and have smaller maximum deletion size in comparison with South American ones. Genes with different CNV occurrences in two these groups of potato accessions were identified. We revealed genes of immune/abiotic stress response, transport and five genes related to tuberization and photoperiod control among them. Four genes related to tuberization and photoperiod were investigated in potatoes previously (phytochrome A among them). A novel gene, homologous to the poly(ADP-ribose) glycohydrolase (PARG) of Arabidopsis, was identified that may be involved in circadian rhythm control and contribute to the acclimatization processes of Russian potato cultivars.

Potato root-associated microbiomes adapt to combined water and nutrient limitation and have a plant genotype-specific role for plant stress mitigation

BACKGROUND

Due to climate change and reduced use of fertilizers combined stress scenarios are becoming increasingly frequent in crop production. In a field experiment we tested the effect of combined water and phosphorus limitation on the growth performance and plant traits of eight tetraploid and two diploid potato varieties as well as on root-associated microbiome diversity and functional potential. Microbiome and metagenome analysis targeted the diversity and potential functions of prokaryotes, fungi, plasmids, and bacteriophages and was linked to plant traits like tuber yield or timing of canopy closure.

RESULTS

The different potato genotypes responded differently to the combined stress and hosted distinct microbiota in the rhizosphere and the root endosphere. Proximity to the root, stress and potato genotype had significant effects on bacteria, whereas fungi were only mildly affected. To address the involvement of microbial functions, we investigated well and poorly performing potato genotypes (Stirling and Desirée, respectively) under stress conditions and executed a metagenome analysis of rhizosphere microbiomes subjected to stress and no stress conditions. Functions like ROS detoxification, aromatic amino acid and terpene metabolism were enriched and in synchrony with the metabolism of stressed plants. In Desirée, Pseudonocardiales had the genetic potential to take up assimilates produced in the fast-growing canopy and to reduce plant stress-sensing by degrading ethylene, but overall yield losses were high. In Stirling, Xanthomonadales had the genetic potential to reduce oxidative stress and to produce biofilms, potentially around roots. Biofilm formation could be involved in drought resilience and nutrient accessibility of Stirling and explain the recorded low yield losses. In the rhizosphere exposed to combined stress, the relative abundance of plasmids was reduced, and the diversity of phages was enriched. Moreover, mobile elements like plasmids and phages were affected by combined stresses in a genotype-specific manner.

CONCLUSION

Our study gives new insights into the interconnectedness of root-associated microbiota and plant stress responses in the field. Functional genes in the metagenome, phylogenetic composition and mobile elements play a role in potato stress adaption. In a poor and a well performing potato genotype grown under stress conditions, distinct functional genes pinpoint to a distinct stress sensing, water availability and compounds in the rhizospheres.

Ectopic expression of the AtCDF1 transcription factor in potato enhances tuber starch and amino acid contents and yield under open field conditions

INTRODUCTION

Cycling Dof transcription factors (CDFs) have been involved in different aspects of plant growth and development. In Arabidopsis and tomato, one member of this family (CDF1) has recently been associated with the regulation of primary metabolism and abiotic stress responses, but their roles in crop production under open field conditions remain unknown.

METHODS

In this study, we compared the growth, and tuber yield and composition of plants ectopically expressing the CDF1 gene from Arabidopsis under the control of the 35S promoter with wild-type (WT) potato plants cultured in growth chamber and open field conditions.

RESULTS

In growth chambers, the 35S::AtCDF1 plants showed a greater tuber yield than the WT by increasing the biomass partition for tuber development. Under field conditions, the ectopic expression of CDF1 also promoted the sink strength of the tubers, since 35S::AtCDF1 plants exhibited significant increases in tuber size and weight resulting in higher tuber yield. A metabolomic analysis revealed that tubers of 35S::AtCDF1 plants cultured under open field conditions accumulated higher levels of glucose, starch and amino acids than WT tubers. A comparative proteomic analysis of tubers of 35S::AtCDF1 and WT plants cultured under open field conditions revealed that these changes can be accounted for changes in the expression of proteins involved in energy production and different aspects of C and N metabolism.

DISCUSSION

The results from this study advance our collective understanding of the role of CDFs and are of great interest for the purposes of improving the yield and breeding of crop plants.

Flavonoids and Phenolic Acids Content in Cultivation and Wild Collection of European Cranberry Bush Viburnum opulus L

Guelder rose (Viburnum opulus L.) is known for its health benefits. V. opulus contains phenolic compounds (flavonoids and phenolic acids), a group of plant metabolites with wide biological activities. They are good sources of natural antioxidants in human diets owing to their prevention of the oxidative damage responsible for many diseases. In recent years, observations have shown that an increase in temperature can change the quality of plant tissues. So far, little research has addressed the problem of the common impact of temperature and place of occurrence. Towards a better understanding of phenolics concentration that could indicate their potentials as therapeutic agents and towards predicting and controlling the quality of medicinal plants, the aim of this study was to compare phenolic acids and flavonoids content in the leaves of cultivation and wild collection V. opulus, and to examine the impacts of temperature and place of occurrence on their content and composition. Total phenolics were determined using the spectrophotometric method. Phenolic composition of V. opulus was determined using high-performance liquid chromatography (HPLC). The following hydroxybenzoic acids there were identified: gallic, p-hydroxybenzoic, syringic, salicylic, benzoic, as well as hydroxycinnamic acids: chlorogenic, caffeic, p-coumaric, ferulic, o-coumaric and t-cinnamic. The analysis of extracts from V. opulus leaves has indicated the presence of the following flavonoids: flavanols: (+)-catechin and (-)-epicatechin; flavonols: quercetin, rutin, kaempferol, myricetin; and flavones: luteolin, apigenin and chrysin. The dominant phenolic acids were p-coumaric and gallic acids. The major flavonoids found in V. opulus leaves were myricetin and kaempferol. Temperature and plant location affected the concentration of tested phenolic compounds. The present study shows the potential of naturally grown and wild V. opulus for the human.

Combined nitrogen and drought stress leads to overlapping and unique proteomic responses in potato

Nitrogen deficient and drought-tolerant or sensitive potatoes differ in proteomic responses under combined (NWD) and individual stresses. The sensitive genotype 'Kiebitz' exhibits a higher abundance of proteases under NWD. Abiotic stresses such as N deficiency and drought affect the yield of Solanum tuberosum L. tremendously. Therefore, it is of importance to improve potato genotypes in terms of stress tolerance. In this study, we identified differentially abundant proteins (DAPs) in four starch potato genotypes under N deficiency (ND), drought stress (WD), or combined stress (NWD) in two rain-out shelter experiments. The gel-free LC-MS analysis generated a set of 1177 identified and quantified proteins. The incidence of common DAPs in tolerant and sensitive genotypes under NWD indicates general responses to this stress combination. Most of these proteins were part of the amino acid metabolism (13.9%). Three isoforms of S-adenosyl methionine synthase (SAMS) were found to be lower abundant in all genotypes. As SAMS were found upon application of single stresses as well, these proteins appear to be part of the general stress response in potato. Interestingly, the sensitive genotype 'Kiebitz' showed a higher abundance of three proteases (subtilase, carboxypeptidase, subtilase family protein) and a lower abundance of a protease inhibitor (stigma expressed protein) under NWD stress compared to control plants. The comparably tolerant genotype 'Tomba', however, displayed lower abundances of proteases. This indicates a better coping strategy for the tolerant genotype and a quicker reaction to WD when previously stressed with ND.

Genome-Wide Association Study of Agronomic and Physiological Traits Related to Drought Tolerance in Potato

Potato (Solanum tuberosum L.) is often considered a water-sensitive crop and its production can be threatened by drought events, making water stress tolerance a trait of increasing interest. In this study, a panel of 144 tetraploid potato genotypes was evaluated for two consecutive years (2019 and 2020) to observe the variation of several physiological traits such as chlorophyll content and fluorescence, stomatal conductance, NDVI, and leaf area and circumference. In addition, agronomic parameters such as yield, tuber fresh weight, tuber number, starch content, dry matter and reducing sugars were determined. GGP V3 Potato array was used to genotype the population, obtaining a total of 18,259 high-quality SNP markers. Marker-trait association was performed using GWASpoly package in R software and Q + K linear mixed models were considered. This approach allowed us to identify eighteen SNP markers significantly associated with the studied traits in both treatments and years, which were related to genes with known functions. Markers related to chlorophyll content and number of tubers under control and stress conditions, and related to stomatal conductance, NDVI, yield and reducing sugar content under water stress, were identified. Although these markers were distributed throughout the genome, the SNPs associated with the traits under control conditions were found mainly on chromosome 11, while under stress conditions they were detected on chromosome 4. These results contribute to the knowledge of the mechanisms of potato tolerance to water stress and are useful for future marker-assisted selection programs.

Study of High-Temperature-Induced Morphological and Physiological Changes in Potato Using Nondestructive Plant Phenotyping

Potato (Solanum tuberosum L.) is vulnerable to high temperatures, which are expected to increase in frequency and duration due to climate change. Nondestructive phenotyping techniques represent a promising technology for helping the adaptation of agriculture to climate change. In this study, three potato cultivars (Agria, Bellarosa and Desiree) were grown under four temperature treatments: 20/15 °C (T1), 25/20 °C (T2), 30/25 °C (T3), and 35/30 °C (T4). Multispectral and chlorophyll fluorescence imaging, 3D multispectral scanning, and gas exchange analysis were used to study the effect of moderate heat stress on potato morphology and physiology and select phenotypic traits most responsive to increased temperatures. The most responsive morphological traits to increased temperatures are related to decreased leaf area, which were detected already at T2. Increased temperatures (already T2) also changed leaf spectral characteristics, indicated by increased red, green, and blue reflectance and decreased far-red reflectance and anthocyanin index (ARI). Regarding chlorophyll fluorescence, increasing temperatures (T2) caused an increase in minimal fluorescence of both dark-adapted (F₀) and light-adapted (F₀') plants. Stomatal conductance, transpiration rate, photosynthetic rate, instantaneous water use efficiency (WUE), and intrinsic water use efficiency increased from T1 to T3 and decreased again in T4. Using recursive partitioning analysis, the most responsive potato phenotypic traits to increased temperature were leaf area projected (LAP), ARI, F₀, and WUE. These traits could be considered marker traits for further studying potato responses to increased temperatures.

Genome-wide identification and gene expression analysis of the 14-3-3 gene family in potato (Solanum tuberosum L.)

BACKGROUND

14-3-3 proteins are essential in regulating various biological processes and abiotic stress responses in plants. Although 14-3-3 proteins have been studied in model plants such as Arabidopsis thaliana and Oryza sativa, there is a lack of research on the 14-3-3 gene family in potatoes (Solanum tuberosum L.).

RESULTS

A total of 18 14-3-3 genes encoding proteins containing a typical conserved PF00244 domain were identified by genome-wide analysis in potatoes. The St14-3-3 gene family members were unevenly distributed across the chromosomes, and gene structure analysis showed that gene length and intron number varied greatly among the members. Phylogenetic analysis of 14-3-3 proteins in potatoes and other plant species showed that they could be divided into two distinct groups (ε and non-ε). Members in the ε group tended to have similar exon-intron structures and conserved motif patterns. Promoter sequence analysis showed that the St14-3-3 gene promoters contained multiple hormone-, stress-, and light-responsive cis-regulatory elements. Synteny analysis suggested that segmental duplication events contributed to the expansion of the St14-3-3 gene family in potatoes. The observed syntenic relationships between some 14-3-3 genes from potato, Arabidopsis, and tomato suggest that they evolved from a common ancestor. RNA-seq data showed that St14-3-3 genes were expressed in all tissues of potatoes but that their expression patterns were different. qRT-PCR assays revealed that the expression levels of nearly all tested St14-3-3 genes were affected by drought, salt, and low-temperature stresses and that different St14-3-3 genes had different responses to these stresses.

CONCLUSIONS

In summary, genome-wide identification, evolutionary, and expression analyses of the 14-3-3 gene family in potato were conducted. These results provide important information for further studies on the function and regulation of St14-3-3 gene family members in potatoes.

Transcriptome Analysis of Two Tetraploid Potato Varieties under Water-Stress Conditions

Potato (Solanum tuberosum L.) is one of the most important crops worldwide, but due to its sensitivity to drought, its production can be affected by water availability. In this study, the varieties Agria and Zorba were used to determine the expression differences between control and water-stressed plants. For this purpose, they were sequenced by RNAseq, obtaining around 50 million transcripts for each variety and treatment. When comparing the significant transcripts obtained from control and drought-stressed plants of the Agria variety, we detected 931 genes that were upregulated and 2077 genes that were downregulated under stress conditions. When both treatments were compared in Zorba plants, 735 genes were found to be upregulated and 923 genes were found to be downregulated. Significantly more DEGs were found in the Agria variety, indicating a good stress response of this variety. "Abscisic acid and environmental stress-inducible protein TAS14-like" was the most overexpressed gene under drought conditions in both varieties, but expression differences were also found in numerous transcription factors and heat shock proteins. The principal GO term found was "cellular components", more specifically related to the cell membrane and the cell wall, but other metabolic pathways such as carbohydrate metabolism and osmotic adjustment were also identified. These results provide valuable information related to the molecular mechanisms of tolerance to water stress in order to establish the basis for breeding new, more tolerant varieties.

The appropriate expression and coordination of glycolate oxidase and catalase are vital to the successful construction of the photorespiratory metabolic pathway

Photorespiration has emerged as a hotspot in the evolution of photosynthesis owing to the energy loss during the process. To ensure the physiological functions of photorespiration such as light protection, H₂O₂ signaling, and stress resistance, separate the photorespiration glycolic acid flow, and minimize photorespiration loss, a balance must be maintained during the construction of photorespiratory metabolic branch. In this study, glycolate oxidase (GLO) and catalase (CAT) were introduced into potato (Solanum tuberosum) chloroplasts through the expression of fusion protein. Through the examination of phenotypic characteristics, photosynthesis, anatomical structure, and enzyme activity, the efficiency of the photorespiration pathway was demonstrated. The results showed that certain transgenic lines plants had shorter plant height and deformed leaves and tubers in addition to the favorable photosynthetic phenotypes of thicker leaves and larger and denser mesophyll cells. By Diaminobenzidine (DAB) staining analysis of the leaves, the intermediate H₂O₂ could not be decomposed in time to cause biomass decline and malformation, and the excessive glycolate shunt formed by the overexpression of the fusion protein affected other important physiological activities. Hence, the appropriate and coordinated expression of glycolate oxidase and catalase is essential for the establishment of photorespiration pathways in chloroplasts.

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

Most cultivated potatoes are tetraploid, and the tuber is the main economic part that is consumed due to its calorific and nutritional values. Recent trends in climate change led to the frequent occurrence of heat and drought stress in major potato-growing regions worldwide. The optimum temperature for tuber production is 15-20 °C. High-temperature and water-deficient conditions during the growing season result in several morphological, physiological, biochemical, and molecular alterations. The morphological changes under stress conditions may affect the process of stolon formation, tuberization, and bulking, ultimately affecting the tuber yield. This condition also affects the physiological responses, including an imbalance in the allocation of photoassimilates, respiration, water use efficiency, transpiration, carbon partitioning, and the source-sink relationship. The biochemical responses under stress conditions involve maintaining ionic homeostasis, synthesizing heat shock proteins, achieving osmolyte balance, and generating reactive oxygen species, ultimately affecting various biochemical pathways. Different networks that include both gene regulation and transcription factors are involved at the molecular level due to the combination of hot and water-deficient conditions. This article attempts to present an integrative content of physio-biochemical and molecular responses under the combined effects of heat and drought, prominent factors in climate change. Taking into account all of these aspects and responses, there is an immediate need for comprehensive screening of germplasm and the application of appropriate approaches and tactics to produce potato cultivars that perform well under drought and in heat-affected areas.

Transcriptome analysis reveals the proline metabolic pathway and its potential regulation TF-hub genes in salt-stressed potato

Potato (Solanum tuberosum) is currently the third most important food crop in the world. However, the production of potato is seriously threatened by salt stress, which often occurs in the facility cultivation environment, and the mining of salt tolerance genes in potato remains to be further studied. In this study, test-tube plantlets of DM potato were treated with 200-mM NaCl to simulate salt stress, and 15 cDNA libraries were constructed for RNA-seq analysis. A total of 8383 DEGs were identified, of which 3961 DEGs were shared among all the salt treatments, and 264 (7.15%) TF-coding genes were identified from these shared DEGs. KEGG enrichment analysis showed that most DEGs identified from the "arginine and proline metabolism" (ko00330) were enriched in the proline metabolic pathway, and their functions almost covered the whole proline metabolic process. Further analysis showed that expression levels of all the 13 structural DEGs in the pathway were significantly up-regulated and proline accumulation was also significantly increased under salt stress, and 13 TF-hub genes were discovered by WGCNA in the lightcyan and tan modules which were highly positively correlated with the proline contents. Correlation analysis revealed that the four TF-hub genes of the lightcyan module and seven structural DEGs of the proline metabolic pathway might be the potential candidate genes, especially the potential and novel regulatory gene StGLK014720. Furthermore, the dual-luciferase reporter assay confirmed that the key protein StGLK014720 could activate the promoters of both structural genes StAST021010 and StAST017480. In conclusion, these results lay the foundation for further study on the salt tolerance mechanism of potato, and provide a theoretical basis and new genetic resources for salt tolerance breeding of potato.

Biotechnological Advances to Improve Abiotic Stress Tolerance in Crops

The major challenges that agriculture is facing in the twenty-first century are increasing droughts, water scarcity, flooding, poorer soils, and extreme temperatures due to climate change. However, most crops are not tolerant to extreme climatic environments. The aim in the near future, in a world with hunger and an increasing population, is to breed and/or engineer crops to tolerate abiotic stress with a higher yield. Some crop varieties display a certain degree of tolerance, which has been exploited by plant breeders to develop varieties that thrive under stress conditions. Moreover, a long list of genes involved in abiotic stress tolerance have been identified and characterized by molecular techniques and overexpressed individually in plant transformation experiments. Nevertheless, stress tolerance phenotypes are polygenetic traits, which current genomic tools are dissecting to exploit their use by accelerating genetic introgression using molecular markers or site-directed mutagenesis such as CRISPR-Cas9. In this review, we describe plant mechanisms to sense and tolerate adverse climate conditions and examine and discuss classic and new molecular tools to select and improve abiotic stress tolerance in major crops.

Transcriptome profiling shows a rapid variety-specific response in two Andigenum potato varieties under drought stress

Potato is a drought-sensitive crop whose global sustainable production is threatened by alterations in water availability. Whilst ancestral Solanum tuberosum Andigenum landraces retain wild drought tolerance mechanisms, their molecular bases remain poorly understood. In this study, an aeroponic growth system was established to investigate stress responses in leaf and root of two Andigenum varieties with contrasting drought tolerance. Comparative transcriptome analysis revealed widespread differences in the response of the two varieties at early and late time points of exposure to drought stress and in the recovery after rewatering. Major differences in the response of the two varieties occurred at the early time point, suggesting the speed of response is crucial. In the leaves and roots of the tolerant variety, we observed rapid upregulation of ABA-related genes, which did not occur until later in the susceptible variety and indicated not only more effective ABA synthesis and mobilization, but more effective feedback regulation to limit detrimental effects of too much ABA. Roots of both varieties showed differential expression of genes involved in cell wall reinforcement and remodeling to maintain cell wall strength, hydration and growth under drought stress, including genes involved in lignification and wall expansion, though the response was stronger in the tolerant variety. Such changes in leaf and root may help to limit water losses in the tolerant variety, while limiting the reduction in photosynthetic rate. These findings provide insights into molecular bases of drought tolerance mechanisms and pave the way for their reintroduction into modern cultivars with improved resistance to drought stress and yield stability under drought conditions.

Root system architecture for abiotic stress tolerance in potato: Lessons from plants

The root is an important plant organ, which uptakes nutrients and water from the soil, and provides anchorage for the plant. Abiotic stresses like heat, drought, nutrients, salinity, and cold are the major problems of potato cultivation. Substantial research advances have been achieved in cereals and model plants on root system architecture (RSA), and so root ideotype (e.g., maize) have been developed for efficient nutrient capture to enhance nutrient use efficiency along with genes regulating root architecture in plants. However, limited work is available on potatoes, with a few illustrations on root morphology in drought and nitrogen stress. The role of root architecture in potatoes has been investigated to some extent under heat, drought, and nitrogen stresses. Hence, this mini-review aims to update knowledge and prospects of strengthening RSA research by applying multi-disciplinary physiological, biochemical, and molecular approaches to abiotic stress tolerance to potatoes with lessons learned from model plants, cereals, and other plants.

The MYB33, MYB65, and MYB101 transcription factors affect Arabidopsis and potato responses to drought by regulating the ABA signaling pathway

Drought is one of the main climate threats limiting crop production. Potato is one of the four most important food crop species worldwide and is sensitive to water shortage. The CBP80 gene was shown to affect Arabidopsis and potato responses to drought by regulating the level of microRNA159 and, consequently, the levels of the MYB33 and MYB101 transcription factors (TFs). Here, we show that three MYB TFs, MYB33, MYB65, and MYB101, are involved in plant responses to water shortage. Their downregulation in Arabidopsis causes stomatal hyposensitivity to abscisic acid (ABA), leading to reduced tolerance to drought. Transgenic Arabidopsis and potato plants overexpressing these genes, with a mutated recognition site in miR159, show hypersensitivity to ABA and relatively high tolerance to drought conditions. Thus, the MYB33, MYB65, and MYB101 genes may be potential targets for innovative breeding to obtain crops with relatively high tolerance to drought.

Genome sequencing of adapted diploid potato clones

Cultivated potato is a vegetatively propagated crop, and most varieties are autotetraploid with high levels of heterozygosity. Reducing the ploidy and breeding potato at the diploid level can increase efficiency for genetic improvement including greater ease of introgression of diploid wild relatives and more efficient use of genomics and markers in selection. More recently, selfing of diploids for generation of inbred lines for F1 hybrid breeding has had a lot of attention in potato. The current study provides genomics resources for nine legacy non-inbred adapted diploid potato clones developed at Agriculture and Agri-Food Canada. De novo genome sequence assembly using 10× Genomics and Illumina sequencing technologies show the genome sizes ranged from 712 to 948 Mbp. Structural variation was identified by comparison to two references, the potato DMv6.1 genome and the phased RHv3 genome, and a k-mer based analysis of sequence reads showed the genome heterozygosity range of 1 to 9.04% between clones. A genome-wide approach was taken to scan 5 Mb bins to visualize patterns of heterozygous deleterious alleles. These were found dispersed throughout the genome including regions overlapping segregation distortions. Novel variants of the StCDF1 gene conferring earliness of tuberization were found among these clones, which all produce tubers under long days. The genomes will be useful tools for genome design for potato breeding.

Construction of drought stress regulation networks in potato based on SMRT and RNA sequencing data

BACKGROUND

Potato (Solanum tuberosum) is the fourth most important food crop in the world and plays an important role in food security. Drought stress has a significantly negative impact on potato growth and production. There are several publications involved drought stress in potato, this research contributes to enrich the knowledge.

RESULTS

In this study, next-generation sequencing (NGS) and single-molecule real-time (SMRT) sequencing technology were used to study the transcription profiles in potato in response to 20%PEG6000 simulates drought stress. The leaves of the variety "Désirée" from in vitro plantlets after drought stress at six time points from 0 to 48 hours were used to perform NGS and SMRT sequencing. According to the sequencing data, a total of 12,798 differentially expressed genes (DEGs) were identified in six time points. The real-time (RT)-PCR results are significantly correlated with the sequencing data, confirming the accuracy of the sequencing data. Gene ontology and KEGG analysis show that these DEGs participate in response to drought stress through galactose metabolism, fatty acid metabolism, plant-pathogen interaction, glutathione metabolism and other pathways. Through the analysis of alternative splicing of 66,888 transcripts, the functional pathways of these transcripts were enriched, and 51,098 transcripts were newly discovered from alternative splicing events and 47,994 transcripts were functionally annotated. Moreover, 3445 lncRNAs were predicted and enrichment analysis of corresponding target genes was also performed. Additionally, Alternative polyadenylation was analyzed by TADIS, and 26,153 poly (A) sites from 13,010 genes were detected in the Iso-Seq data.

CONCLUSION

Our research greatly enhanced potato drought-induced gene annotations and provides transcriptome-wide insights into the molecular basis of potato drought resistance.

Identification and Characterization of Potato Zebra Chip Resistance Among Wild Solanum Species

Potato zebra chip (ZC) disease, associated with the uncultured phloem-limited bacterium, Candidatus Liberibacter solanacearum (CLso), is transmitted by the potato psyllid Bactericera cockerelli. Potato ZC disease poses a significant threat to potato production worldwide. Current management practices mainly rely on the control of the psyllid to limit the spread of CLso. The present study investigated new sources of ZC resistance among wild Solanum species. A taxonomically diverse collection of tuber-bearing Solanum species was screened; one ZC-resistant accession and three ZC-tolerant accessions were identified among the 52 screened accessions. Further characterization of the resistant accession showed that the resistance was primarily associated with antibiosis effects due to differences in leaf trichome density and morphology of the wild accession, which could limit the psyllid feeding and oviposition. This germplasm offers a good resource for further understanding ZC and psyllid resistance mechanisms, contributing to potato breeding efforts to develop ZC resistance cultivars. Alternatively, it could be used as a potential trap crop to manage psyllid and control ZC disease.

Salinity Stress Tolerance in Potato Cultivars: Evidence from Physiological and Biochemical Traits

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.

From Soil Amendments to Controlling Autophagy: Supporting Plant Metabolism under Conditions of Water Shortage and Salinity

Crop resistance to environmental stress is a major issue. The globally increasing land degradation and desertification enhance the demand on management practices to balance both food and environmental objectives, including strategies that tighten nutrient cycles and maintain yields. Agriculture needs to provide, among other things, future additional ecosystem services, such as water quantity and quality, runoff control, soil fertility maintenance, carbon storage, climate regulation, and biodiversity. Numerous research projects have focused on the food–soil–climate nexus, and results were summarized in several reviews during the last decades. Based on this impressive piece of information, we have selected only a few aspects with the intention of studying plant–soil interactions and methods for optimization. In the short term, the use of soil amendments is currently attracting great interest to cover the current demand in agriculture. We will discuss the impact of biochar at water shortage, and plant growth promoting bacteria (PGPB) at improving nutrient supply to plants. In this review, our focus is on the interplay of both soil amendments on primary reactions of photosynthesis, plant growth conditions, and signaling during adaptation to environmental stress. Moreover, we aim at providing a general overview of how dehydration and salinity affect signaling in cells. With the use of the example of abscisic acid (ABA) and ethylene, we discuss the effects that can be observed when biochar and PGPB are used in the presence of stress. The stress response of plants is a multifactorial trait. Nevertheless, we will show that plants follow a general concept to adapt to unfavorable environmental conditions in the short and long term. However, plant species differ in the upper and lower regulatory limits of gene expression. Therefore, the presented data may help in the identification of traits for future breeding of stress-resistant crops. One target for breeding could be the removal and efficient recycling of damaged as well as needless compounds and structures. Furthermore, in this context, we will show that autophagy can be a useful goal of breeding measures, since the recycling of building blocks helps the cells to overcome a period of imbalanced substrate supply during stress adjustment.

Physiology and Gene Expression Analysis of Potato (Solanum tuberosum L.) in Salt Stress

The production of potato (Solanum tuberosum L.) faces a severe challenge due to the salinization of arable land worldwide. The cultivation of salt-tolerant potatoes is of great significance to ensure food security. In this study, two cultivars of 'Longshu 5' and 'Qingshu 9' were compared for physiological responses to salt stress, and then the salt tolerance of the two cultivars were assessed via principal component analysis. Furthermore, the Na⁺, K⁺, and Ca²⁺ flux of the cultivars under salt stress was recorded. Finally, the expression levels of ion transport-related genes and transcription factors in salt-tolerant cultivars were explored under NaCl stress. The results showed that the seven physiological indicators of salt tolerance were differed between the cultivars. Interestingly, soluble protein and sugar were early responsive to salt stress than proline in the salt-tolerance cultivar. Peroxidase and superoxide dismutase activity were significantly different in 'Longshu 5' under NaCl stress and without being significantly different in 'Qingshu9'. In addition, the salt tolerance of 'Longshu 5' was more tolerant than 'Qingshu 9' based on principal component evaluation. Meanwhile, the strong efflux of Na⁺, the stability of K⁺, and the high absorption of Ca²⁺ in 'Longshu 5' indicated salt adaption mechanisms in the salt-tolerant potato. In addition, we found that ion transport-related genes and transcription factors, such as StSOS1, StNHX4, StAKT1, StNAC24, and StCYP707A, played a role in the salt tolerance of 'Longshu 5'. In conclusion, the salt-tolerant potato can regulate physiological substances to adapt to salt stress, and ion transport related genes and transcription factors play a role in improving salt tolerance.