Potato Tissue Research Articles

Transcriptome analysis and identification of leaf, tuberous root and fibrous root tissue-specific high temperature stress-responsive genes in sweet potato

Sweet Potato is an important food crop, and its production is affected by environmental stresses, including high temperature. The gene expression patterns and molecular responses in different tissues of sweet potato under high temperature stress were studied using microarray data sets. Analysis revealed that modulation in the expression of key genes and pathways associated with various proteins including enzymes under high temperature stress in leaf, fibrous root and storage root tissues. Tissue-specific responses, with both common and unique cellular responses were observed among the tissues. Pathway analysis revealed the differential regulation of genes involved in DNA replication, metabolism, transport, signaling, and stress response during high temperature stress. Six genes viz., DnaJ-domain protein (IpDnaJ), nuclear protein (IpELF5), heat shock protein 90.1 (IpHsp90.1), ABC transporter (IpABC) hydrolase (IpNUDX1) and alternative oxidase 1a (IpAO1a), were up-regulated in the leaf, fibrous root and tuberous root tissues. These six genes might play an important role in imparting high temperature stress tolerance in the leaf, fibrous root and tuberous root tissues of sweet potato. The information generated provides valuable insights on leaf, tuberous root and fibrous root tissue-specific high temperature stress-responsive genes in sweet potato. These datasets will be helpful in selecting candidate genes and pathways for further functional and genomic analyses, facilitating the genetic improvement of sweet potato with enhanced stress tolerance.

CRISPR/Cas9-mediated Inhibition of Vacuolar Invertase (VInv) Gene in Potato

Potato is the third most important food crop worldwide after the wheat and rice. It has potential to overcome the issues of world’s food security. Potato crop faces some challenges during storage as Cold Induce Sweetening (CIS). During cold storage, the accumulation of reducing sugars such as fructose and glucose takes place in potato tubers. These reducing sugars later react with free amino acid and produce dark-brown pigmentation on potato products during frying. That leads towards reduction of potato quality and consumption. The increased quantity of sucrose is further hydrolyzed by Vacuolar Invertase (VInv) gene into reducing sugars. VInv gene acts as a key player in inducing CIS in potato. The objective of study was cloning of CRISPR/Cas9 construct and successful inhibition of VInv gene function in potato. Agrobacterium-mediated transformation of VInv gene in potato tissues was performed. The knockout of VInv gene in transformed plants was analyzed by using specific primers through polymerase chain reaction (PCR). Real time polymerase chain reaction (RT-PCR) was carried out to analyze the expression of transgene in transgenic potato plants. The knockout of VInv gene using CRISPR/Cas9 strategy could maintain the quality of potato tubers during cold storage.

Prediction of potato dry matter content by FT-NIR spectroscopy: Impact of tuber tissue on model performance

Potato, an important cash crop, is critically affected by supply chain losses that require attention of both research and industry to ensure sustainable production (SDG 12.3). Within potato supply chain management, dry matter (DM) determination is a key factor affecting the harvest quality, storability, food losses, designated user and tuber prices. Even though rapid methods like near-infrared spectroscopy (NIR) enable operators to carry out fast, reliable in situ measurements, the prediction results are often unsatisfactory due to inherent variability of tuber's composition. Thus, this study aims to evaluate Fourier Transformed-NIR based DM prediction in different potato tissues: i) periderm, ii) cortex, iii) outer medulla and iv) inner medulla of 12 different cultivars. The DM prediction models developed using standard chemometrics approaches (i.e., partial least squares, PLS; and interval-PLS, iPLS) showed that features selection by iPLS allowed for better performances. Among the evaluated tissues, the inner medulla had more precise and reliable measurements with RMSE and R2 prediction values of 0.93% and 0.90, respectively. This information can be used to develop more advanced systems inclusive of portable tools and advanced technologies for in situ evaluation to support operators and ensure better pre- and post-harvest management of potatoes.

Field surveys indicate taxonomically diverse Pectobacterium species inducing soft rot of vegetables and annual crops in Iran

AbstractSoft rot‐inducing bacterial pathogens are considered among the main biotic constraints on vegetables and annual crops. Most of the bacterial soft rot pathogens are members of Pectobacterium spp. and Dickeya, with the former genus encompassing a continuously increasing number of species varying in geographic distribution and host of isolation. In Iran, Pectobacterium species have rarely been investigated using high‐throughput nucleotide sequence‐based techniques, leaving the genetic diversity of these pathogens mostly undetermined. During 2021, vegetables and annual crops with symptoms of soft rot and maceration were collected from Fars, Hamedan, Isfahan, Khuzestan and Kohgiluyeh‐Boyer‐Ahmad provinces of Iran. Forty‐four pectinolytic bacterial strains were isolated from symptomatic tissues of bell pepper, cabbage, carrot, lettuce, potato and zucchini. The bacterial strains were subjected to pathogenicity and host range assays, specific PCR tests and phylogenetic analysis of three housekeeping genes (dnaX, gapA and leuS). All strains were pathogenic on their host of isolation. Among the 44 pectinolytic strains, 26 strains were identified as members of Pectobacterium based on PCR using the primer pair Y1/Y2. Multilocus sequence analysis confirmed the latter bacterial strains belonging to the genus Pectobacterium and revealed that the strains scattered into four species: P. brasiliense (five strains), P. carotovorum (eight strains), P. polaris (five strains) and P. versatile (eight strains). P. polaris and P. versatile have not previously been reported in the country. Host range assays showed that P. brasiliense and P. carotovorum have a broader host range than the other two species.

Genome-Wide Identification of the NPR1-like Gene Family in Solanum tuberosum and Functional Characterization of StNPR1 in Resistance to Ralstonia solanacearum.

The NPR1 (nonexpressor of pathogenesis-related genes 1) gene is an activator of the systemic acquisition of resistance (SAR) in plants and is one of the central factors in their response to pathogenic bacterial infestation, playing an important role in plant disease resistance. Potato (Solanum tuberosum) is a crucial non-grain crop that has been extensively studied. However, the identification and analysis of the NPR1-like gene within potato have not been understood well. In this study, a total of six NPR1-like proteins were identified in potato, and phylogenetic analysis showed that the six NPR1-like proteins in Solanum tuberosum could be divided into three major groups with NPR1-related proteins from Arabidopsis thaliana and other plants. Analysis of the exon-intron patterns and protein domains of the six NPR1-like genes from potato showed that the exon-intron patterns and protein domains of the NPR1-like genes belonging to the same Arabidopsis thaliana subfamily were similar. By performing quantitative real-time PCR (qRT-PCR) analysis, we found that six NPR1-like proteins have different expression patterns in different potato tissues. In addition, the expression of three StNPR1 genes was significantly downregulated after being infected by Ralstonia solanacearum (RS), while the difference in the expression of StNPR2/3 was insignificant. We also established potato StNPR1 overexpression lines that showed a significantly increased resistance to R. solanacearum and elevated activities of chitinase, β-1,3-glucanase, and phenylalanine deaminase. Increased peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) activities, as well as decreased hydrogen peroxide, regulated the dynamic balance of reactive oxygen species (ROS) in the StNPR1 overexpression lines. The transgenic plants activated the expression of the genes associated with the Salicylic acid (SA) defense response but suppressed the expression of the genes associated with Jasmonic acid (JA) signaling. This resulted in resistance to Ralstonia solanacearum.

The Expression of the StNRAMP2 Gene Determined the Accumulation of Cadmium in Different Tissues of Potato.

Cadmium (Cd) is a toxic metal that threatens human health when enriched in crops. NRAMPs are a family of natural macrophage proteins reported to play a key role in Cd transport in plants. In order to explore the gene regulation mechanism of potato under Cd stress and the role of NRAMPs family in it, this study analyzed the gene expression differences of two different Cd accumulation levels in potato after 7 days of 50 mg/kg Cd stress and screened out the key genes that may play a major role in the differential accumulation of Cd in different varieties. Additionally, StNRAMP2 was selected for verification. Further verification showed that the StNRAMP2 gene plays an important role in the accumulation of Cd in potato. Interestingly, silencing StNRAMP2 increased Cd accumulation in tubers but significantly decreased Cd accumulation in other sites, suggesting a critical role of StNRAMP2 in Cd uptake and transport in potatoes. To further confirm this conclusion, we performed heterologous expression experiments in which overexpression of StNRAMP2 gene in tomato resulted in a threefold increase in Cd content, which further confirmed the important role of StNRAMP2 in the process of Cd accumulation compared with wild-type plants. In addition, we found that the addition of Cd to the soil increased the activity of the plant antioxidant enzyme system, and silencing StNRAMP2 partially reversed this effect. This suggests that the StNRAMP2 gene plays an important role in plant stress tolerance, and future studies could further explore the role of this gene in other environmental stresses. In conclusion, the results of this study improve the understanding of the mechanism of Cd accumulation in potato and provide experimental basis for remediation of Cd pollution.

Identification of a Comprehensive Gene Co-Expression Network Associated with Autotetraploid Potato (Solanum tuberosum L.) Development Using WGCNA Analysis.

The formation and development of potato tissues and organs is a complex process regulated by a variety of genes and environmental factors. The regulatory mechanisms underlying the growth and development are still unclear. In this work, we aimed to explore the changes in gene expression patterns and genetic characteristics of potato tissues throughout different developmental stages. To achieve this, we used autotetraploid potato JC14 as an experimental subject to analyze the transcriptome of the root, stem, and leaf at the seedling, tuber formation, and tuber expansion stages. The results revealed thousands of differentially expressed genes, predominantly involved in defense response and carbohydrate metabolism according to KEGG pathway enrichment analysis. Weighted gene co-expression network analysis (WGCNA) revealed a total of 12 co-expressed gene modules, with 4 modules showing the highest correlation with potato stem development. By calculating the connectivity of genes within the module, hub genes were identified, and functional annotations were subsequently performed. A total of 40 hub genes from the four modules were identified, and their functions were found to be related to carbohydrate metabolism, defense response, and transcription factors. These findings provide important insights for further understanding of the molecular regulation and genetic mechanisms involved in potato tissue development.

Genotypic and phenotypic uniformity among the population of Pectobacterium atrosepticum strains isolated during three growing seasons from potato fields in Poland

Pectobacterium atrosepticum (Pba)are phytopathogenic, pectinolytic, non-sporulating, gram-negative rods causing blackleg and soft rot diseases in potato. They are ubiquitously present under temperate climate conditions and contribute to significant economic losses. Currently, there are no efficient control methods against soft rot Pectobacteriaceae (SRP). As limitation of the spread of SRP is solely prevention-based, we undertook broad characterization on both genotypic and phenotypic levels of the P. atrosepticum isolates acquired during monitoring of potato fields in Poland in 2013, 2014 and 2016. Of REP, ERIC and BOX-based genomic fingerprinting, the BOX-based approach turned out to be the most informative and allowed for classification of 118 Pba strains into six groups. The present study indicated that IV and I BOX profiles dominated among the investigated population. Finally, 23 Pba strains representing all BOX groups and originating from various growing seasons were selected for genotypic, phylogenetic and phenotypic studies. rpoS-based phylogeny revealed intraspecies variation (16 SNP sites) among the studied Pba strains, in contrast to the analyses relying on gyrA (1 SNP) and recA (0 SNP) sequences. Pba strains showed higher potency to macerate potato tissue at 20 °C than 28 °C. These isolates exhibited rather uniform production of plant cell wall degrading enzymes (pectinases, cellulases and proteases), lipases, siderophores and biofilm, however in the majority of cases inferior in comparison to Dickeya solani and Pectobacterium carotovorum strains. In conclusion, this study revealed genotypic and phenotypic uniformity in addition to high virulence potential of Pba strains isolated from potato fields during several growing seasons in Poland.

Application of coumarin concentrations and number of nodes on induction potato (Solanum tuberosum L.) micro tuber in vitro

Potato is a horticultural commodity with good prospects for development. Potato tissue culture technology is one of the efforts to produce virus- and disease-free potato seeds. The aim of this experiment was to see if there was an interaction between the administration of multiple coumarin concentrations and the number of nodes and at what concentration of coumarin and at what number of nodes gives optimal results for induction of potato micro tuber. This experiment was arranged according to a two-factor factorial Completely Randomized Design with 3 replications. The 1st factor was multiple coumarin concentrations with 4 levels (30, 60, 90, 120 mg/l) and the 2nd factor was the number of nodes with 3 levels (1 node, 2 nodes, and 3 nodes). The results showed that there was an interaction between the administration of multiple concentrations of coumarin and the number of nodes, showing the best interaction when the coumarin concentration was 120 mg/l with 2 nodes that could form tubers with a percentage of 94.44%. The 120 mg/l coumarin concentration gave the highest of plantlets forming micro-tubers, the highest number of micro tuber and the largest micro-tuber diameter. The two-node treatment increased the percentage of plantlets forming micro tubers, the number of micro tubers, and the diameter of the micro tuber.

Screening and Identification of Potato StSPS1, a Potential Crucial Gene Regulating Seed Potato Vigor

Sucrose phosphate synthase (SPS), a crucial rate-limiting enzyme that catalyzes the synthesis of precursors of sucrose, plays an indispensable role in the regulation of seed potato vigor. Nonetheless, the genes that encode SPS in potato have not undergone complete analysis, and the primary genes responsible for the regulation of seed potato vigor have not been screened and identified. In this study, four StSPS family members were identified by comparing the potato genome database with homologous proteins. Using bioinformatics, the physicochemical properties, subcellular localization, sequence structure, conserved motifs, and phylogenetics of StSPS were analyzed. The expression levels of StSPS in different potato tissues, from dormancy to sprouting in the seed potato tubers, were measured via qRT-PCR. The expression data from the potato genome database and previous transcriptome and proteome studies of dormancy to sprouting were also compared. After combining the analysis of SPS enzyme activity in diverse tuber tissues and the correlation analysis between multiple varieties with different dormancy periods and the expression of StSPS1, the primary gene StSPS1 that might regulate seed potato vigor was identified. This study set a theoretical and experimental groundwork for further verification and clarification of the regulatory function of StSPS1 in alterations in seed potato vigor.

Effect of Coconut Water and Benzyl Adenine with Different Concentrations on Potato Tissue Culture (Solanum tuberosum L.) Var. Granola

This study aimed to determine the effect of giving coconut water and the right concentration of benzyl adenine in MS media for potato tissue culture of Granola variety. The study was carried out from November to January 2022, in the Plant Tissue Culture Laboratory of the Faculty of Agriculture, Pattimura University, Ambon. This study used a 2-factor completely randomized design (CRD); the first factor was the concentration of coconut water 0 with 100 ml/l, and the second factor was the concentration of BA consisting of 0.1,2,3,4 mg/l. The study was conducted with 7 replicates and each replication consisted of 5 explants in each culture bottle, so that there were 350 cultures as the unit of observation. The variables observed in this study included the number of shoots, the number of internodes, the number of branches, and the number of roots per plantlet. The results showed that the concentration of coconut water 0 and 100 ml/l had an effect on the number of internodes and the number of roots at 4 weeks after planting. Benzyl adenine at 0, 1, 2, 3 and 4 mg/l had an effect on the variable number of shoots at 8 WAP and the number of internodes at 2 - 8 WAP; which also applies to the number of roots. Whereas, the interaction between both factors affected the number of internodes at 4, 6, and 8 weeks, which also applies to the number of roots.

Heavy Metal Analysis and Health Risk Assessment of Potato (Solanum tuberosum L.) Cultivars irrigated with Fly Ash-Treated Acid Mine Drainage

In water-scant regions, the reuse of (un)treated acid mine drainage effluent (AMD) water for crop irrigation has turned into a prerequisite. The study assesses the levels of heavy metals, and health risk assessment in two potato crop cultivars, namely, Fianna and Lady rosetta (both determinate and indeterminate) when exposed to irrigation with different fly ash: acid mine drainage amelioration ratios. The study investigates the health risk assessment in the potato tissues namely, stem, tubers, new and old leaves of the potato cultivars. The treatments constituted a control, 50% FA: AMD, 75% FA: AMD ratio, and 100% AMD (untreated AMD). The results showed that the heavy metals of plants irrigated with AMD mixed with FA was significantly affected differently at harvest. In summary, the concentration of Cd was over the WHO acceptable standards in untreated acid mine drainage water. Fianna recorded 1.34 mg/kg while a notably decrease was observed in Lady rosetta with (1.01 mg/kg). In any case, FA was proven to significantly lessen the Cd particles in both FA-AMD ratios: Cd content was 0.98 mg/kg and 0.84 mg/kg in 50% FA: AMD treatment for Fianna and Lady rosetta separately, while the recommended maximum limit is 0.1 mg/kg. With the readings recorded, they are slightly high according to the CODEX general standard for food contaminants and toxins in food and feed (CODEX STAN 193-1995). Then again, in 75% FA: AMD ratio, the Cd concentration was 0.04 mg/kg and 0.03 mg/kg for Fianna and Lady rosetta exclusively. It is in this way obvious that FA adsorbed the Cd ions, and the two cultivars fulfill the CODEX guideline, nonetheless the potato crop irrigated with a 75% FA: AMD ratio can be consumed by humans without causing any detrimental effects.

Small G Protein StRab5b positively regulates potato resistance to Phytophthora infestans.

Rabproteins are the largest members of the small G protein family and are widely distributed in eukaryotes. It comprises eight subfamilies and is responsible for regulating vesicle transport, plant growth and development, and biotic and abiotic stress responses. In this study, the small G protein gene StRab5b was cloned from potato, and its biological information, expression profile and induced expression level, overexpression and gene silencing were examined on regulating potato resistance to Phytophthora infestans using PCR, qPCR and Virus-induced gene silencing (VIGS). Our results indicate that the amino acid of StRab5b shows the highest and lowest homology with NbRab5b in N. benthamiana and StRab in potato respectively. StRab5b expression varied among different potato tissues and varieties, and was induced by P. infestans infection. Transiently ectopic expression of StRab5b in N. benthamiana enhanced its resistance to P. infestans, whereas, silencing of StRab5b and its homologous gene facilitated pathogen infection in potato and N. benthamiana respectively. Furthermore, stable expression of the StRab5b gene in potatoes enhanced its redox-stress response capacity, as manifested by the accumulation of H2O2 in infected leaves and subsequent increase in the activity and expression of ROS scavenging enzymes, thereby attenuating the development of P. infestans and ultimately reducing the lesions on infected potato leaves. In addition, the LOX gene transcripts and JA level were upregulated rapidly after inoculation with P. infestans. Collectively, our results suggest that StRab5b positively regulates the resistance against potato late blight (PLB) via JA-mediated defense signaling pathway.

Genome-Wide Identification of 14-3-3 gene family reveals their diverse responses to abiotic stress by interacting with StABI5 in Potato (Solanum tuberosum L.).

The 14-3-3 genes are widely present in plants and participate in a wide range of cellular and physiological processes. In the current study, twelve 14-3-3s were identified from potato genome. According to phylogenetic evolutionary analysis, potato 14-3-3s were divided into ϵ and non-ϵ groups. Conserved motif and gene structure analysis displayed a distinct class-specific divergence between the ϵ group and non-ϵ group. Multiple sequence alignments and three-dimensional structure analysis of 14-3-3 proteins indicated all the members contained nine conservative antiparallel α-helices. The majority of 14-3-3s had transcript accumulation in each detected potato tissue, implying their regulatory roles across all stages of potato growth and development. Numerous cis-acting elements related to plant hormones and abiotic stress response were identified in the promoter region of potato 14-3-3s, and the transcription levels of these genes fluctuated to different degrees under exogenous ABA, salt and drought stress, indicating that potato 14-3-3s may be involved in different hormone signaling pathways and abiotic stress responses. In addition, eight potato 14-3-3s were shown to interact with StABI5, which further demonstrated that potato 14-3-3s were involved in the ABA-dependent signaling pathway. This study provides a reference for the identification of the 14-3-3 gene family in other plants, and provides important clues for cloning potential candidates in response to abiotic stresses in potato.

UHPLC-MS/MS Analysis of the Accumulation and Excretion of Steroidal Glycoalkaloids Consumed by Potato Tuber Moth (Phthorimaea operculella) Larvae under Different Feeding Treatments.

Food poisoning caused by potato glycoside alkaloids (SGA) remains a critical factor that affects potato production safety. The potato tuber moth (Phthorimaea operculella) is a notorious pest that displays good adaptability to SGA in potato tissues. Studies that explore the mechanisms underlying SGA homeostasis in potato tuber moth larvae are urgently needed. In this study, ultra-high-performance liquid chromatography (UHPLC)-triple quadrupole mass spectrometry (MS/MS) was applied to detect the dominant SGA substances α-solanine and α-chaconine in potato leaves and PTM larval tissues. From the highest to lowest SGA concentrations, the potato cultivars studied were ranked as follows: DS47, LS6, DS23 and QS9. To exclude the influence of nutrients within different potato varieties, different SGA containing (0%, 0.1%, 0.2%, 0.3% and 0.4%) the artificial diet treatment groups were added. DS47 and 0.3% SGA-containing artificial diets presented the best conditions for PTM growth, development and reproduction compared to other potato cultivars and artificial diet controls. The potato tuber moth larva tissues were dissected and the SGA content within different tissues were detected using an UHPLC machine. The results showed that α-chaconine was dispersed in the feces, midgut, hindgut, head and cuticle, and α-solanine was distributed only in the feces and midgut. Antibiotic-treated insects exhibited higher concentrations of SGA than the normal microbiome group. Furthermore, the SGA concentrations of 100 newly-hatched PTM larvae and puparia were detected, with both of them found to contain small amounts of SGA. The results showed that ecdysis and the excretion process were effective approaches used by the potato tuber moth to equilibrate internal SGA accumulation. The microorganism-decreased SGA concentrations were excited in their gut. SGA may transfer from adults to the next generation, and SGAs in PTM are inheritable. In this study, we demonstrated that the potato tuber moth possessed an effective method to preliminarily decrease high SGA accumulation in potato.

Effect of Phosphorus and Potassium Fertilizers Application on Soil Chemical Characteristics and Their Accumulation in Potato Plant Tissues

Applications of nutrients are determined by the plant’s nutritional requirements and the soil’s available nutrients; however, the precise nutrient application is difficult. At Assosa, a field experiment was conducted to determine how soil chemical characteristics and accumulation of phosphorus and potassium in potato tissue responded to phosphorus and potassium fertilizers application. The treatments included four potassium levels (0, 100, 200, and 300 kg·K2O ha−1) and six phosphorus levels (0, 46, 92, 138, 184, and 230 kg·P2O5 ha−1). The experiment was set up as a factorial randomized complete block design (RCBD) and was repeated three times. According to the preplanting soil analysis, the cropping area’s soil has a medium CEC, low accessible phosphorus, and very low exchangeable potassium. The application of phosphorus had a highly significant influence on accessible phosphorus, exchangeable potassium, and CEC, the concentration of phosphorus in the leaf and tuber tissue of the potato plant. While potassium had a significant effect on exchangeable potassium, CEC, phosphorus concentration in potato plant tuber tissue, and potassium level in both the leaf and the tuber, the interaction effect of phosphorus and potassium on all of the above-mentioned soil chemical properties, as well as the amount of P and K in potato plant tissues, was observed. The critical potassium level in the leaf blade for optimum crop yield tissue content was determined to be 100 kg·K2O ha−1, while the critical level of phosphorus was determined to be 184 kg·P2O5 ha−1.

An atlas of small RNAs from potato.

Small RNAs, including microRNAs (miRNAs), phased secondary small interfering RNAs (phasiRNA), and heterochromatic small interfering RNAs (hc-siRNA) are an essential component of gene regulation. To establish a broad potato small RNA atlas, we constructed an expression atlas of leaves, flowers, roots, and tubers of Desiree and Eva, which are commercially important potato (Solanum tuberosum) cultivars. All small RNAs identified were observed to be conserved between both cultivars, supporting the hypothesis that small RNAs have a low evolutionary rate and are mostly conserved between lineages. However, we also found that a few miRNAs showed differential accumulation between the two potato cultivars, and that hc-siRNAs have a tissue specific expression. We further identified dozens of reproductive and non-reproductive phasiRNAs originating from coding and noncoding regions that appeared to exhibit tissue-specific expression. Together, this study provides an extensive small RNA profiling of different potato tissues that might be used as a resource for future investigations.

Cutting Efficiency of a Newly Developed Incubator-Based Laser Cutting Method and Its Effects on Potato Tissue Culture Plantlet Growth

Cutting Efficiency of a Newly Developed Incubator-Based Laser Cutting Method and Its Effects on Potato Tissue Culture Plantlet Growth

Multifunctional Microelectrode for Low-Voltage Pulsed Field Ablation in Atrial Fibrillation

Pulsed field ablation is an emerging technique for the treatment of atrial fibrillation, and it can specifically damage cardiomyocytes without destroying surrounding tissues. However, current single-function ablation electrodes apply electric pulses at thousands of volts, which is potentially harmful to the heart. In this letter, we propose a multifunctional microelectrode for low-voltage pulsed field ablation and effect evaluation. By using finite element analysis and tests on potato tissues and in vivo experiments, we show that the soft microelectrode in multiplexed array format supports two orders of magnitude reduction in ablation voltage compared with the state of the art. Meanwhile, the electrode-tissue equivalent circuit before and after irreversible electroporation is established, and we find that the ablation effect could be evaluated by impedance. In the future, the microelectrode integrated with a medical balloon can be applied to minimally invasive surgery for improving the success rate of pulsed field ablation.

A Systematic Study of Estimating Potato N Concentrations Using UAV-Based Hyper- and Multi-Spectral Imagery

Potato growth depends largely on nitrogen (N) availability in the soil. However, the shallow-root crop coupled with its common cultivation in coarse-textured soils leads to its poor N use efficiency. Fast and accurate estimations of potato tissue N concentrations are urgently needed to assist the decision making in precision fertilization management. Remote sensing has been utilized to evaluate the potato N status by correlating spectral information with lab tests on leaf N concentrations. In this study, a systematic comparison was conducted to quantitatively evaluate the performance of hyperspectral and multispectral images in estimating the potato N status, providing a reference for the trade-off between sensor costs and performance. In the experiment, two potato varieties were planted under four fertilization rates with replicates. UAV images were acquired multiple times during the season with a narrow-band hyperspectral imager. Multispectral reflectance was simulated by merging the relevant narrow bands into broad bands to mimic commonly used multispectral cameras. The whole leaf total N concentration and petiole nitrate-N concentration were obtained from 160 potato leaf samples. A partial least square regression model was developed to estimate the two N status indicators using different groups of image features. The best estimation accuracies were given by reflectance of the full spectra with 2.2 nm narrow, with the coefficient of determination (R2) being 0.78 and root mean square error (RMSE) being 0.41 for the whole leaf total N concentration; while, for the petiole nitrate-N concentration, the 10 nm bands had the best performance (R2 = 0.87 and RMSE = 0.13). Generally, the model performance decreased with an increase of the spectral bandwidth. The hyperspectral full spectra largely outperformed all three multispectral cameras, but there was no significant difference among the three brands of multispectral cameras. The results also showed that spectral bands in the visible regions (400–700 nm) were the most highly correlated with potato N concentrations.