Characterisation and mapping of a Globodera pallida resistance derived from the wild potato species Solanum spegazzinii.

KEY MESSAGE: A new resistance locus acting against the potato cyst nematode Globodera pallida was mapped to chromosome VI in the diploid wild potato species Solanum spegazzinii CPC 7195. The potato cyst nematodes (PCN) Globodera pallida and Globodera rostochiensis are economically important potato pests in almost all regions where potato is grown. One important management strategy involves deployment through introgression breeding into modern cultivars of new sources of naturally occurring resistance from wild potato species. We describe a new source of resistance to G. pallida from wild potato germplasm. The diploid species Solanum spegazzinii Bitter accession CPC 7195 shows resistance to G. pallida pathotypes Pa1 and Pa2/3. A cross and first backcross of S. spegazzinii with Solanum tuberosum Group Phureja cultivar Mayan Gold were performed, and the level of resistance to G. pallida Pa2/3 was determined in progeny clones. Bulk-segregant analysis (BSA) using generic mapping enrichment sequencing (GenSeq) and genotyping-by-sequencing were performed to identify single-nucleotide polymorphisms (SNPs) that are genetically linked to the resistance, using S. tuberosum Group Phureja clone DM1-3 516 R44 as a reference genome. These SNPs were converted into allele-specific PCR assays, and the resistance was mapped to an interval of roughly 118 kb on chromosome VI. This newly identified resistance, which we call Gpa VIlspg, can be used in future efforts to produce modern cultivars with enhanced and broad-spectrum resistances to the major pests and pathogens of potato.

StCoExpNet: a global co-expression network analysis facilitates identifying genes underlying agronomic traits in potatoes.

KEY MESSAGE: We constructed a gene expression atlas and co-expression network for potatoes and identified several novel genes associated with various agronomic traits. This resource will accelerate potato genetics and genomics research. Potato (Solanum tuberosum L.) is the world's most crucial non-cereal food crop and ranks third in food production after wheat and rice. Despite the availability of several potato transcriptome datasets at public databases like NCBI SRA, an effort has yet to be put into developing a global transcriptome atlas and a co-expression network for potatoes. The objectives of our study were to construct a global expression atlas for potatoes using publicly available transcriptome datasets, identify housekeeping and tissue-specific genes, construct a global co-expression network and identify co-expression clusters, investigate the transcriptional complexity of genes involved in various essential biological processes related to agronomic traits, and provide a web server (StCoExpNet) to easily access the newly constructed expression atlas and co-expression network to investigate the expression and co-expression of genes of interest. In this study, we used data from 2299 publicly available potato transcriptome samples obtained from 15 different tissues to construct a global transcriptome atlas. We found that roughly 87% of the annotated genes exhibited detectable expression in at least one sample. Among these, we identified 281 genes with consistent and stable expression levels, indicating their role as housekeeping genes. Conversely, 308 genes exhibited marked tissue-specific expression patterns. We exemplarily linked some co-expression clusters to important agronomic traits of potatoes, such as self-incompatibility, anthocyanin biosynthesis, tuberization, and defense responses against multiple pathogens. The dataset compiled here constitutes a new resource (StCoExpNet), which can be accessed at https://stcoexpnet.julius-kuehn.de . This transcriptome atlas and the co-expression network will accelerate potato genetics and genomics research.

StMAPKK5 Positively Regulates Response to Drought and Salt Stress in Potato.

MAPKKs, as one of the main members of the mitogen-activated protein kinase (MAPK) cascade pathway, are located in the middle of the cascade and are involved in many physiological processes of plant growth and development, as well as stress tolerance. Previous studies have found that StMAPKK5 is responsive to drought and salt stress. To further investigate the function and regulatory mechanism of StMAPKK5 in potato stress response, potato variety 'Atlantic' was subjected to drought and NaCl treatments, and the expression of the StMAPKK5 gene was detected by qRT-PCR. StMAPKK5 overexpression and RNA interference-mediated StMAPKK5 knockdown potato plants were constructed. The relative water content, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities, as well as proline (Pro) and malondialdehyde (MDA) contents of plant leaves, were also assayed under drought and NaCl stress. The StMAPKK5 interacting proteins were identified and validated by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC). The results showed that the expression of StMAPKK5 was significantly up-regulated under drought and NaCl stress conditions. The StMAPKK5 protein was localized in the nucleus, cytoplasm, and cell membrane. The expression of StMAPKK5 affected the relative water content, the enzymatic activities of SOD, CAT, and POD, and the proline and MDA contents of potatoes under drought and salt stress conditions. These results suggest that StMAPKK5 plays a significant role in regulating drought and salt tolerance in potato crop. Yeast two-hybrid (Y2H) screening identified four interacting proteins: StMYB19, StZFP8, StPUB-like, and StSKIP19. BiFC confirmed the authenticity of the interactions. These findings suggest that StMAPKK5 is crucial for potato growth, development, and response to adversity.

RNA three-dimensional structure drives the sequence organization of potato spindle tuber viroid quasispecies.

RNA viruses and viroids exist and evolve as quasispecies due to error-prone replication. Quasispecies consist of a few dominant master sequences alongside numerous variants that contribute to genetic diversity. Upon environmental changes, certain variants within quasispecies have the potential to become the dominant sequences, leading to the emergence of novel infectious strains. However, the emergence of new infectious variants remains unpredictable. Using mutant pools prepared by saturation mutagenesis of selected stem and loop regions, our study of potato spindle tuber viroid (PSTVd) demonstrates that mutants forming local three-dimensional (3D) structures similar to the wild type (WT) are more likely to accumulate in PSTVd quasispecies. The selection mechanisms underlying this biased accumulation are likely associated with cell-to-cell movement and long-distance trafficking. Moreover, certain trafficking-defective PSTVd mutants can be spread by functional sister genomes in the quasispecies. Our study reveals that the RNA 3D structure of stems and loops constrains the evolution of viroid quasispecies. Mutants with a structure similar to WT have a higher likelihood of being maintained within the quasispecies and can potentially give rise to novel infectious variants. These findings emphasize the potential of targeting RNA 3D structure as a more robust approach to defend against viroid infections.

Potato miR394 targets StA/N-INVE and StLCR to negatively regulate late blight resistance.

MicroRNAs (miRNAs) are small noncoding RNAs in eukaryotes. Plant endogenous miRNAs play pivotal roles in regulating plant development and defense responses. MicroRNA394 (miR394) has been reported to regulate plant development, abiotic stresses and defense responses. Previous reports showed that miR394 responded to P. infestans inoculation in potato, indicating that miR394 may be involved in defense responses. In this study, we further investigated its role in potato defense against P. infestans. Stable expression of miR394 in tobacco and potato enhances the susceptibility to P. infestans, which is accompanied with the reduced accumulation of ROS and down-regulation of the PTI (pattern-triggered immunity) marker genes. Besides well-known target StLCR, miR394 also targets StA/N-INVE, which encodes a chloroplast Alkaline/Neutral Invertases (A/N-INVE). Both StLCR and StA/N-INVE positively regulate late blight resistance, while miR394 degrades them. Interestingly, StA/N-INVE is located in the chloroplast, indicating that miR394 may manipulate chloroplast immunity. Degradation of StA/N-INVE may affect the chloroplast function and hence lead to the compromised ROS (reactive oxygen species) burst and reduced retrograde signaling from the chloroplast to the nucleus and cytoplasm. In summary, this study provides new information that miR394 targets and degrades StA/N-INVE and StLCR, which are positive regulators, to enhance potato susceptibility to P. infestans.

Assessing small RNA profiles in potato diploid hybrid and its resynthesized allopolyploid reveals conserved abundance with distinct genomic distribution.

KEY MESSAGE: The shock produced by the allopolyploidization process on a potato interspecific diploid hybrid displays a non-random remobilization of the small RNAs profile on a variety of genomic features. Allopolyploidy, a complex process involving interspecific hybridization and whole genome duplication, significantly impacts plant evolution, leading to the emergence of novel phenotypes. Polyploids often present phenotypic nuances that enhance adaptability, enabling them to compete better and occasionally to colonize new habitats. Whole-genome duplication represents a genomic "shock" that can trigger genetic and epigenetic changes that yield novel expression patterns. In this work, we investigate the polyploidization effect on a diploid interspecific hybrid obtained through the cross between the cultivated potato Solanum tuberosum and the wild potato Solanum kurtzianum, by assessing the small RNAs (sRNAs) profile of the parental diploid hybrid and its derived allopolyploid. Small RNAs are key components of the epigenetic mechanisms involved in silencing by RNA-directed DNA Methylation (RdDM). A sRNA sequencing (sRNA-Seq) analysis was performed to individually profile the 21 to 22 nucleotide (21 to 22-nt) and 24-nt sRNA size classes due to their unique mechanism of biogenesis and mode of function. The composition and distribution of different genomic features and differentially accumulated (DA) sRNAs were evaluated throughout the potato genome. We selected a subset of genes associated with DA sRNAs for messenger RNA (mRNA) expression analysis to assess potential impacts on the transcriptome. Interestingly, we noted that 24-nt DA sRNAs that exclusively mapped to exons were correlated with differentially expressed mRNAs between genotypes, while this behavior was not observed when 24-nt DA sRNAs were mapped to intronic regions. These findings collectively emphasize the nonstochastic nature of sRNA remobilization in response to the genomic shock induced by allopolyploidization.

Using drone-retrieved multispectral data for phenomic selection in potato breeding.

Predictive breeding approaches, like phenomic or genomic selection, have the potential to increase the selection gain for potato breeding programs which are characterized by very large numbers of entries in early stages and the availability of very few tubers per entry in these stages. The objectives of this study were to (i) explore the capabilities of phenomic prediction based on drone-derived multispectral reflectance data in potato breeding by testing different prediction scenarios on a diverse panel of tetraploid potato material from all market segments and considering a broad range of traits, (ii) compare the performance of phenomic and genomic predictions, and (iii) assess the predictive power of mixed relationship matrices utilizing weighted SNP array and multispectral reflectance data. Predictive abilities of phenomic prediction scenarios varied greatly within a range of - 0.15 and 0.88 and were strongly dependent on the environment, predicted trait, and considered prediction scenario. We observed high predictive abilities with phenomic prediction for yield (0.45), maturity (0.88), foliage development (0.73), and emergence (0.73), while all other traits achieved higher predictive ability with genomic compared to phenomic prediction. When a mixed relationship matrix was used for prediction, higher predictive abilities were observed for 20 out of 22 traits, showcasing that phenomic and genomic data contained complementary information. We see the main application of phenomic selection in potato breeding programs to allow for the use of the principle of predictive breeding in the pot seedling or single hill stage where genotyping is not recommended due to high costs.

Allelic variation in the autotetraploid potato: genes involved in starch and steroidal glycoalkaloid metabolism as a case study.

BACKGROUND: Tuber starch and steroidal glycoalkaloid (SGA)-related traits have been consistently prioritized in potato breeding, while allelic variation pattern of genes that underlie these traits is less explored. RESULTS: Here, we focused on the genes involved in two important metabolic pathways in the potato: starch metabolism and SGA biosynthesis. We identified 119 genes consisting of 81 involved in starch metabolism and 38 in the biosynthesis of steroidal glycoalkaloids, and discovered 96,166 allelic variants among 2,169 gene haplotypes in six autotetraploid potato genomes. Comparative analyses revealed an uneven distribution of allelic variants among gene haplotypes and that the vast majority of deleterious mutations in these genes are retained in heterozygous state in the autotetraploid potato genomes. Leveraging full-length cDNA sequencing data, we find that approximately 70% of haplotypes of the 119 genes are transcribable. Population genetic analyses identify starch and SGA biosynthetic genes that are potentially conserved or diverged between potato varieties with varying starch or SGA content. CONCLUSIONS: These results deepen the understanding of haplotypic diversity within functionally important genes in autotetraploid genomes and may facilitate functional characterization of genes or haplotypes contributing to traits related to starch and SGA in potato.

Genetic Loci of Plant Pathogenic Dickeya solani IPO 2222 Expressed in Contact with Weed-Host Bittersweet Nightshade (Solanum dulcamara L.) Plants.

Dickeya solani, belonging to the Soft Rot Pectobacteriaceae, are aggressive necrotrophs, exhibiting both a wide geographic distribution and a wide host range that includes many angiosperm orders, both dicot and monocot plants, cultivated under all climatic conditions. Little is known about the infection strategies D. solani employs to infect hosts other than potato (Solanum tuberosum L.). Our earlier study identified D. solani Tn5 mutants induced exclusively by the presence of the weed host S. dulcamara. The current study assessed the identity and virulence contribution of the selected genes mutated by the Tn5 insertions and induced by the presence of S. dulcamara. These genes encode proteins with functions linked to polyketide antibiotics and polysaccharide synthesis, membrane transport, stress response, and sugar and amino acid metabolism. Eight of these genes, encoding UvrY (GacA), tRNA guanosine transglycosylase Tgt, LPS-related WbeA, capsular biosynthesis protein VpsM, DltB alanine export protein, glycosyltransferase, putative transcription regulator YheO/PAS domain-containing protein, and a hypothetical protein, were required for virulence on S. dulcamara plants. The implications of D. solani interaction with a weed host, S. dulcamara, are discussed.

Knockout of SlDCL2b attenuates the resistance of tomato to potato spindle tuber viroid infection.

RNA interference, or RNA silencing, is an important defence mechanism against viroid infection in plants. Plants encode multiple DICER-LIKE (DCL) proteins that are key components of the RNA silencing pathway. However, the roles of different DCLs in defence responses against viroid infection remain unclear. Here, we determined the function of tomato DCL2b (SlDCL2b) in defence responses against potato spindle tuber viroid (PSTVd) infection using SlDCL2b loss-of-function tomato mutant plants. Compared with wild-type plants, mutant plants were more susceptible to PSTVd infection, developing more severe symptoms earlier and accumulating higher levels of PSTVd RNAs. Moreover, we verified the feedback mechanism for the regulation of SlDCL2b expression by miR6026. Functional blocking of tomato miR6026, by expressing its target mimics, can enhance resistance to PSTVd infection in tomato plants. These findings deepen the current understanding of RNAi-based resistance against viroid infection and provide a potentially new strategy for viroid control.

Screening and functional analysis of StMYB transcription factors in pigmented potato under low-temperature treatment.

MYB transcription factors play an extremely important regulatory role in plant responses to stress and anthocyanin synthesis. Cloning of potato StMYB-related genes can provide a theoretical basis for the genetic improvement of pigmented potatoes. In this study, two MYB transcription factors, StMYB113 and StMYB308, possibly related to anthocyanin synthesis, were screened under low-temperature conditions based on the low-temperature-responsive potato StMYB genes family analysis obtained by transcriptome sequencing. By analyzed the protein properties and promoters of StMYB113 and StMYB308 and their relative expression levels at different low-temperature treatment periods, it is speculated that StMYB113 and StMYB308 can be expressed in response to low temperature and can promote anthocyanin synthesis. The overexpression vectors of StMYB113 and StMYB308 were constructed for transient transformation tobacco. Color changes were observed, and the expression levels of the structural genes of tobacco anthocyanin synthesis were determined. The results showed that StMYB113 lacking the complete MYB domain could not promote the accumulation of tobacco anthocyanins, while StMYB308 could significantly promote the accumulation involved in tobacco anthocyanins. This study provides a theoretical reference for further study of the mechanism of StMYB113 and StMYB308 transcription factors in potato anthocyanin synthesis.

Gene expression analysis of potato drought-responsive genes under drought stress in potato (Solanum tuberosum L.) cultivars.

The potato (Solanum tuberosum L.), an important field crop consumed extensively worldwide, is adversely affected by abiotic stress factors especially drought. Therefore, it is vital to understand the genetic mechanism under drought stress to decrease loose of yield and quality . This trial aimed to screen drought-responsive gene expressions of potato and determine the drought-tolerant potato cultivar. The trial pattern is a completely randomized block design (CRBD) with four replications under greenhouse conditions. Four cultivars (Brooke, Orwell, Vr808, Shc909) were irrigated with four different water regimes (control and three stress conditions), and the gene expression levels of 10 potato genes were investigated. The stress treatments as follows: Control = 100% field capacity; slight drought = 75% field capacity; moderate drought = 50% field capacity, and severe drought 25% field capacity. To understand the gene expression under drought stress in potato genotypes, RT-qPCR analysis was performed and results showed that the genes most associated with drought tolerance were the StRD22 gene, MYB domain transcription factor, StERD7, Sucrose Synthase (SuSy), ABC Transporter, and StDHN1. The StHSP100 gene had the lowest genetic expression in all cultivars. Among the cultivars, the Orwell exhibited the highest expression of the StRD22 gene under drought stress. Overall, the cultivar with the highest gene expression was the Vr808, closely followed by the Brooke cultivar. As a result, it was determined that potato cultivars Orwell, Vr808, and Brooke could be used as parents in breeding programs to develop drought tolerant potato cultivars.

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.

Genome-Wide Identification of LOX Gene Family and Its Expression Analysis under Abiotic Stress in Potato (Solanum tuberosum L.).

The lipoxygenases (LOXs) are non-heme iron-containing dioxygenases that play an important role in plant growth and defense responses. There is scarce knowledge regarding the LOX gene family members and their involvement in biotic and abiotic stresses in potato. In this study, a total of 17 gene family members (StLOXs) in potato were identified and clustered into three subfamilies: 9-LOX type I, 13-LOX type I, and 13-LOX type II, with eleven, one, and five members in each subfamily based on phylogenetic analysis. By exploiting the RNA-seq data in the Potato Genome Sequencing Consortium (PGSC) database, the tissue-specific expressed and stress-responsive StLOX genes in double-monoploid (DM) potato were obtained. Furthermore, six candidate StLOX genes that might participate in drought and salt response were determined via qPCR analysis in tetraploid potato cultivars under NaCl and PEG treatment. Finally, the involvement in salt stress response of two StLOX genes, which were significantly up-regulated in both DM and tetraploid potato under NaCl and PEG treatment, was confirmed via heterologous expression in yeast under salt treatment. Our comprehensive analysis of the StLOX family provides a theoretical basis for the potential biological functions of StLOXs in the adaptation mechanisms of potato to stress conditions.

DNA-Binding with One Finger (Dof) Transcription Factor Gene Family Study Reveals Differential Stress-Responsive Transcription Factors in Contrasting Drought Tolerance Potato Species.

DNA-binding with one finger (Dof) proteins comprise a large family that play central roles in stress tolerance by regulating the expression of stress-responsive genes via the DOFCORE element or by interacting with other regulatory proteins. Although the Dof TF has been identified in a variety of species, its systemic analysis in potato (Solanum tuberosum L.) is lacking and its potential role in abiotic stress responses remains unclear. A total of 36 potential Dof genes in potato were examined at the genomic and transcriptomic levels in this work. Five phylogenetic groups can be formed from these 36 Dof proteins. An analysis of cis-acting elements revealed the potential roles of Dofs in potato development, including under numerous abiotic stress conditions. The cycling Dof factors (CDFs) might be the initial step in the abiotic stress response signaling cascade. In potato, five CDFs (StCDF1/StDof19, StCDF2/StDof4, StCDF3/StDof11, StCDF4/StDof24, and StCDF5/StDof15) were identified, which are homologs of Arabidopsis CDFs. The results revealed that these genes were engaged in a variety of abiotic reactions. Moreover, an expression analysis of StDof genes in two potato cultivars ('Long10' (drought tolerant) and 'DXY' (drought susceptible)) of contrasting tolerances under drought stress was carried out. Further, a regulatory network mediated by lncRNA and its target Dofs was established. The present study provides fundamental knowledge for further investigation of the roles of Dofs in the adaptation of potato to drought stress, aiming to provide insights into a viable strategy for crop improvement and stress-resistance breeding.

Genome-wide characterization of the CPA gene family in potato and a preliminary functional analysis of its role in NaCl tolerance.

BACKGROUND: The cation/proton antiporter (CPA) superfamily plays a crucial role in regulating ion homeostasis and pH in plant cells, contributing to stress resistance. However, in potato (Solanum tuberosum L.), systematic identification and analysis of CPA genes are lacking. RESULTS: A total of 33 StCPA members were identified and classified into StNHX (n = 7), StKEA (n = 6), and StCHX (n = 20) subfamilies. StCHX owned the highest number of conserved motifs, followed by StKEA and StNHX. The StNHX and StKEA subfamilies owned more exons than StCHX. NaCl stress induced the differentially expression of 19 genes in roots or leaves, among which StCHX14 and StCHX16 were specifically induced in leaves, while StCHX2 and StCHX19 were specifically expressed in the roots. A total of 11 strongly responded genes were further verified by qPCR. Six CPA family members, StNHX1, StNHX2, StNHX3, StNHX5, StNHX6 and StCHX19, were proved to transport Na+ through yeast complementation experiments. CONCLUSIONS: This study provides comprehensive insights into StCPAs and their response to NaCl stress, facilitating further functional characterization.

A sustainable strategy for biosynthesis of Rebaudioside D using a novel glycosyltransferase of Solanum tuberosum.

Bioconversion of Rebaudioside D faces high-cost obstacles. Herein, a novel glycosyltransferase StUGT converting Rebaudioside A to Rebaudioside D was screened and characterized, which exhibits stronger affinity and substrate specificity for Rebaudioside A than previously reported enzymes. A whole-cell catalytic system was thus developed using the StUGT strain. The production of Rebaudioside D was enhanced significantly by enhancing cell permeability, and the maximum production of 6.12 g/L and the highest yield of 98.08% by cell catalyst was obtained by statistical-based optimization. A new cascade process utilizing this recombinant strain and E. coli expressing sucrose synthase was further established to reduce cost through replacing expensive UDPG with sucrose. A StUGT-GsSUS1 system exhibited high catalytic capability, and 5.27 g L-1 Rebaudioside D was achieved finally without UDPG addition by systematic optimization. This is the best performance reported in cell-cascaded biosynthesis, which paves a new cost-effective strategy for sustainable synthesis of scarce premium sweeteners from biomass.

Comprehensive Characterization of the C3HC4 RING Finger Gene Family in Potato (Solanum tuberosum L.): Insights into Their Involvement in Anthocyanin Biosynthesis.

The C3HC4 RING finger gene (RING-HC) family is a zinc finger protein crucial to plant growth. However, there have been no studies on the RING-HC gene family in potato. In this study, 77 putative StRING-HCs were identified in the potato genome and grouped into three clusters based on phylogenetic relationships, the chromosome distribution, gene structure, conserved motif, gene duplication events, and synteny relationships, and cis-acting elements were systematically analyzed. By analyzing RNA-seq data of potato cultivars, the candidate StRING-HC genes that might participate in tissue development, abiotic stress, especially drought stress, and anthocyanin biosynthesis were further determined. Finally, a StRING-HC gene (Soltu.DM.09G017280 annotated as StRNF4-like), which was highly expressed in pigmented potato tubers was focused on. StRNF4-like localized in the nucleus, and Y2H assays showed that it could interact with the anthocyanin-regulating transcription factors (TFs) StbHLH1 of potato tubers, which is localized in the nucleus and membrane. Transient assays showed that StRNF4-like repressed anthocyanin accumulation in the leaves of Nicotiana tabacum and Nicotiana benthamiana by directly suppressing the activity of the dihydroflavonol reductase (DFR) promoter activated by StAN1 and StbHLH1. The results suggest that StRNF4-like might repress anthocyanin accumulation in potato tubers by interacting with StbHLH1. Our comprehensive analysis of the potato StRING-HCs family contributes valuable knowledge to the understanding of their functions in potato development, abiotic stress, hormone signaling, and anthocyanin biosynthesis.

Transcriptome Analysis Reveals the Molecular Mechanisms of BR Negative Regulatory Factor StBIN2 Maintaining Tuber Dormancy.

Potato is an important food crop. After harvest, these tubers will undergo a period of dormancy. Brassinosteroids (BRs) are a new class of plant hormones that regulate plant growth and seed germination. In this study, 500 nM of BR was able to break the dormancy of tubers. Additionally, exogenous BR also upregulated BR signal transduction genes, except for StBIN2. StBIN2 is a negative regulator of BR, but its specific role in tuber dormancy remains unclear. Transgenic methods were used to regulate the expression level of StBIN2 in tubers. It was demonstrated that the overexpression of StBIN2 significantly prolonged tuber dormancy while silencing StBIN2 led to premature sprouting. To further investigate the effect of StBIN2 on tuber dormancy, RNA-Seq was used to analyze the differentially expressed genes in OE-StBIN2, RNAi-StBIN2, and WT tubers. The results showed that StBIN2 upregulated the expression of ABA signal transduction genes but inhibited the expression of lignin synthesis key genes. Meanwhile, it was also found that StBIN2 physically interacted with StSnRK2.2 and StCCJ9. These results indicate that StBIN2 maintains tuber dormancy by mediating ABA signal transduction and lignin synthesis. The findings of this study will help us better understand the molecular mechanisms underlying potato tuber dormancy and provide theoretical support for the development of new varieties using related genes.

Transcriptome profiling and characterization of genes associated with tuberization under high temperature in aeroponics in potato cv. Kufri Anand.

BACKGROUND: High temperature stress is an important abiotic factor, which affects tuberization and ultimately causes heavy yield reduction in potato. OBJECTIVES: Identification and characterization of genes associated with tuberization under high temperature stress is essential for future management through biotechnology. METHODOLOGY: Two contrasting potato varieties Kufri Anand (profuse tuber-bearing) versus Kufri Frysona (very less/scanty tuber-bearing, control) were cultivated in aeroponics under high temperature stress, and transcriptomes were analyzed. RESULTS: Potato cv. Kufri Anand was found superior over control (Kufri Frysona) for tuber yield and its component traits along with root morphology under aeroponics. Transcriptomes of tuber and leaf tissues were analyzed. Statistically significant (p < 0.05) differentially expressed genes (DEGs) were categorised into up-regulated (> 2 log2 fold change, FC) and down-regulated (< -2 log2 FC) genes. DEGs were annotated by gene ontology and KEGG pathways. A few selected up-regulated genes of both tissues were identified, and phylogeny tree and motif analysis were analysed based on 36 peptide sequences representing 15 selected DEGs in this study. Further, gene expression markers were developed and validated by real time qPCR analysis for the identification of high temperature tolerant genotypes. CONCLUSION: A few key genes associated in tuberization under high temperature conditions were heat shock proteins (e.g. 18.5 kDa class I heat shock protein), sugar metabolism (e.g. glucosyltransferase), transcription factor (e.g. WRKY), and phytohormones (e.g. auxin-induced beta-glucosidase). Our study provides an overview of key genes involved in tuberization under high temperature stress in potato cv. Kufri Anand under aeroponics.