Convergent evolution of immune receptors underpins distinct elicitin recognition in closely related Solanaceous plants.

Elicitins are a large family of secreted proteins in Phytophthora. Clade 1 elicitins were identified decades ago as potent elicitors of immune responses in Nicotiana species, but the mechanisms underlying elicitin recognition are largely unknown. Here we identified an elicitin receptor in Nicotiana benthamiana that we named REL for Responsive to ELicitins. REL is a receptor-like protein (RLP) with an extracellular leucine-rich repeat (LRR) domain that mediates Phytophthora resistance by binding elicitins. Silencing or knocking out REL in N. benthamiana abolished elicitin-triggered cell death and immune responses. Domain deletion and site-directed mutagenesis revealed that the island domain (ID) located within the LRR domain of REL is crucial for elicitin recognition. In addition, sequence polymorphism in the ID underpins the genetic diversity of REL homologs in various Nicotiana species in elicitin recognition and binding. Remarkably, REL is phylogenetically distant from the elicitin response (ELR) protein, an LRR-RLP that was previously identified in the wild potato species Solanum microdontum and REL and ELR differ in the way they bind and recognize elicitins. Our findings provide insights into the molecular basis of plant innate immunity and highlight a convergent evolution of immune receptors towards perceiving the same elicitor.

Pangenome analyses reveal impact of transposable elements and ploidy on the evolution of potato species.

Potato (Solanum sp., family Solanaceae) is the most important noncereal food crop globally. It has over 100 wild relatives in the Solanum section Petota, which features species with both sexual and asexual reproduction and varying ploidy levels. A pangenome of Solanum section Petota composed of 296 accessions was constructed including diploids and polyploids compared via presence/absence variation (PAV). The Petota core (genes shared by at least 97% of the accessions) and shell genomes (shared by 3 to 97%) are enriched in basic molecular and cellular functions, while the cloud genome (genes present in less than 3% of the member accessions) showed enrichment in transposable elements (TEs). Comparison of PAV in domesticated vs. wild accessions was made, and a phylogenetic tree was constructed based on PAVs, grouping accessions into different clades, similar to previous phylogenies produced using DNA markers. A cladewise pangenome approach identified abiotic stress response among the core genes in clade 1+2 and clade 3, and flowering/tuberization among the core genes in clade 4. The TE content differed between the clades, with clade 1+2, which is composed of species from North and Central America with reproductive isolation from species in other clades, having much lower TE content compared to other clades. In contrast, accessions with in vitro propagation history were identified and found to have high levels of TEs. Results indicate a role for TEs in adaptation to new environments, both natural and artificial, for Solanum section Petota.

Solanum pennellii (LA5240) backcross inbred lines (BILs) for high resolution mapping in tomato.

Wild species are an invaluable source of new traits for crop improvement. Over the years, the tomato community bred cultivated lines that carry introgressions from different species of the tomato tribe to facilitate trait discovery and mapping. The next phase in such projects is to find the genes that drive the identified phenotypes. This can be achieved by genotyping a few thousand individuals resulting in fine mapping that can potentially identify the causative gene. To couple trait discovery and fine mapping, we are presenting large, recombination-rich, Backcross Inbred Line (BIL) populations involving an unexplored accession of the wild, green-fruited species Solanum pennellii (LA5240; the 'Lost' Accession) with two modern tomato inbreds: LEA, determinate, and TOP, indeterminate. The LEA and TOP BILs are in BC2F6-8 generation and include 1400 and 500 lines, respectively. The BILs were genotyped with 5000 SPET markers, showing that in the euchromatic regions there was one recombinant every 17-18 Kb while in the heterochromatin a recombinant every 600-700 Kb (TOP and LEA respectively). To gain perspective on the topography of recombination we compared five independent members of the Self-pruning gene family with their respective neighboring genes; based on PCR markers, in all cases we found recombinants. Further mapping analysis of two known morphological mutations that segregated in the BILs (self-pruning and hairless) showed that the maximal delimited intervals were 73 Kb and 210 Kb, respectively, and included the known causative genes. The 'Lost'_BILs provide a solid framework to study traits derived from a drought-tolerant wild tomato.

Transcription factor SlWRKY50 enhances cold tolerance in tomato by activating the jasmonic acid signaling.

Tomato (Solanum lycopersicum) is a cold-sensitive crop but frequently experiences low-temperature stimuli. However, tomato responses to cold stress are still poorly understood. Our previous studies have shown that using wild tomato (Solanum habrochaites) as rootstock can significantly enhance the cold resistance of grafted seedlings, in which a high concentration of jasmonic acids (JAs) in scions exerts an important role, but the mechanism of JA accumulation remains unclear. Herein, we discovered that tomato SlWRKY50, a Group II WRKY transcription factor that is cold inducible, responds to cold stimuli and plays a key role in JA biosynthesis. SlWRKY50 directly bound to the promoter of tomato allene oxide synthase gene (SlAOS), and overexpressing SlWRKY50 improved tomato chilling resistance, which led to higher levels of Fv/Fm, antioxidative enzymes, SlAOS expression, and JA accumulation. SlWRKY50-silenced plants, however, exhibited an opposite trend. Moreover, diethyldithiocarbamate acid (a JA biosynthesis inhibitor) foliar treatment drastically reduced the cold tolerance of SlWRKY50-overexpression plants to wild-type levels. Importantly, SlMYC2, the key regulator of the JA signaling pathway, can control SlWRKY50 expression. Overall, our research indicates that SlWRKY50 promotes cold tolerance by controlling JA biosynthesis and that JA signaling mediates SlWRKY50 expression via transcriptional activation by SlMYC2. Thus, this contributes to the genetic knowledge necessary for developing cold-resistant tomato varieties.

Solanum aculeatissimum and Solanum torvum chloroplast genome sequences: a comparative analysis with other Solanum chloroplast genomes.

BACKGROUND: Solanum aculeatissimum and Solanum torvum belong to the Solanum species, and they are essential plants known for their high resistance to diseases and adverse conditions. They are frequently used as rootstocks for grafting and are often crossbred with other Solanum species to leverage their resistance traits. However, the phylogenetic relationship between S. aculeatissimum and S. torvum within the Solanum genus remains unclear. Therefore, this paper aims to sequence the complete chloroplast genomes of S. aculeatissimum and S. torvum and analyze them in comparison with 29 other previously published chloroplast genomes of Solanum species. RESULTS: We observed that the chloroplast genomes of S. aculeatissimum and S. torvum possess typical tetrameric structures, consisting of one Large Single Copy (LSC) region, two reverse-symmetric Inverted Repeats (IRs), and one Small Single Copy (SSC) region. The total length of these chloroplast genomes ranged from 154,942 to 156,004 bp, with minimal variation. The highest GC content was found in the IR region, while the lowest was in the SSC region. Regarding gene content, the total number of chloroplast genes and CDS genes remained relatively consistent, ranging from 128 to 134 and 83 to 91, respectively. Nevertheless, there was notable variability in the number of tRNA genes and rRNAs. Relative synonymous codon usage (RSCU) analysis revealed that both S. aculeatissimum and S. torvum preferred codons that utilized A and U bases. Analysis of the IR boundary regions indicated that contraction and expansion primarily occurred at the junction between SSC and IR regions. Nucleotide polymorphism analysis and structural variation analysis demonstrated that chloroplast variation in Solanum species mainly occurred in the LSC and SSC regions. Repeat sequence analysis revealed that A/T was the most frequent base pair in simple repeat sequences (SSR), while Palindromic and Forward repeats were more common in long sequence repeats (LSR), with Reverse and Complement repeats being less frequent. Phylogenetic analysis indicated that S. aculeatissimum and S. torvum belonged to the same meristem and were more closely related to Cultivated Eggplant. CONCLUSION: These findings enhance our comprehension of chloroplast genomes within the Solanum genus, offering valuable insights for plant classification, evolutionary studies, and potential molecular markers for species identification.

CAGEE: Computational Analysis of Gene Expression Evolution.

Despite the increasing abundance of whole transcriptome data, few methods are available to analyze global gene expression across phylogenies. Here, we present a new software package (Computational Analysis of Gene Expression Evolution [CAGEE]) for inferring patterns of increases and decreases in gene expression across a phylogenetic tree, as well as the rate at which these changes occur. In contrast to previous methods that treat each gene independently, CAGEE can calculate genome-wide rates of gene expression, along with ancestral states for each gene. The statistical approach developed here makes it possible to infer lineage-specific shifts in rates of evolution across the genome, in addition to possible differences in rates among multiple tissues sampled from the same species. We demonstrate the accuracy and robustness of our method on simulated data and apply it to a data set of ovule gene expression collected from multiple self-compatible and self-incompatible species in the genus Solanum to test hypotheses about the evolutionary forces acting during mating system shifts. These comparisons allow us to highlight the power of CAGEE, demonstrating its utility for use in any empirical system and for the analysis of most morphological traits. Our software is available at https://github.com/hahnlab/CAGEE/.

De novo assembly of the complete mitochondrial genome of pepino (Solanum muricatum) using PacBio HiFi sequencing: insights into structure, phylogenetic implications, and RNA editing.

BACKGROUND: Solanum muricatum is an emerging horticultural fruit crop with rich nutritional and antioxidant properties. Although the chromosome-scale genome of this species has been sequenced, its mitochondrial genome sequence has not been reported to date. RESULTS: PacBio HiFi sequencing was used to assemble the circular mitogenome of S. muricatum, which was 433,466 bp in length. In total, 38 protein-coding, 19 tRNA, and 3 rRNA genes were annotated. The reticulate mitochondrial conformations with multiple junctions were verified by polymerase chain reaction, and codon usage, sequence repeats, and gene migration from chloroplast to mitochondrial genome were determined. A collinearity analysis of eight Solanum mitogenomes revealed high structural variability. Overall, 585 RNA editing sites in protein coding genes were identified based on RNA-seq data. Among them, mttB was the most frequently edited (52 times), followed by ccmB (46 times). A phylogenetic analysis based on the S. muricatum mitogenome and those of 39 other taxa (including 25 Solanaceae species) revealed the evolutionary and taxonomic status of S. muricatum. CONCLUSIONS: We provide the first report of the assembled and annotated S. muricatum mitogenome. This information will help to lay the groundwork for future research on the evolutionary biology of Solanaceae species. Furthermore, the results will assist the development of molecular breeding strategies for S. muricatum based on the most beneficial agronomic traits of this species.

Diversity of the Rysto gene conferring resistance to potato virus Y in wild relatives of potato.

BACKGROUND: Potato virus Y (PVY) is among the economically most damaging viral pathogen in production of potato (Solanum tuberosum) worldwide. The gene Rysto derived from the wild potato relative Solanum stoloniferum confers extreme resistance to PVY. RESULTS: The presence and diversity of Rysto were investigated in wild relatives of potato (298 genotypes representing 29 accessions of 26 tuber-bearing Solanum species) using PacBio amplicon sequencing. A total of 55 unique Rysto-like sequences were identified in 72 genotypes representing 12 accessions of 10 Solanum species and six resistant controls (potato cultivars Alicja, Bzura, Hinga, Nimfy, White Lady and breeding line PW363). The 55 Rysto-like sequences showed 89.87 to 99.98% nucleotide identity to the Rysto reference gene, and these encoded in total 45 unique protein sequences. While Rysto-like26 identified in Alicja, Bzura, White Lady and Rysto-like16 in PW363 encode a protein identical to the Rysto reference, the remaining 44 predicted Rysto-like proteins were 65.93 to 99.92% identical to the reference. Higher levels of diversity of the Rysto-like sequences were found in the wild relatives of potato than in the resistant control cultivars. The TIR and NB-ARC domains were the most conserved within the Rysto-like proteins, while the LRR and C-JID domains were more variable. Several Solanum species, including S. antipoviczii and S. hougasii, showed resistance to PVY. This study demonstrated Hyoscyamus niger, a Solanaceae species distantly related to Solanum, as a host of PVY. CONCLUSIONS: The new Rysto-like variants and the identified PVY resistant potato genotypes are potential resistance sources against PVY in potato breeding. Identification of H. niger as a host for PVY is important for cultivation of this plant, studies on the PVY management, its ecology, and migrations. The amplicon sequencing based on PacBio SMRT and the following data analysis pipeline described in our work may be applied to obtain the nucleotide sequences and analyze any full-length genes from any, even polyploid, organisms.

Floral scent changes in response to pollen removal are rare in buzz-pollinated Solanum.

MAIN CONCLUSION: One of seven Solanum taxa studied displayed associations between pollen presence and floral scent composition and volume, suggesting buzz-pollinated plants rarely use scent as an honest cue for foraging pollinators. Floral scent influences the recruitment, learning, and behaviour of floral visitors. Variation in floral scent can provide information on the amount of reward available or whether a flower has been visited recently and may be particularly important in species with visually concealed rewards. In many buzz-pollinated flowers, tubular anthers opening via small apical pores (poricidal anthers) visually conceal pollen and appear similar regardless of pollen quantity within the anther. We investigated whether pollen removal changes floral scent composition and emission rate in seven taxa of buzz-pollinated Solanum (Solanaceae). We found that pollen removal reduced both the overall emission of floral scent and the emission of specific compounds (linalool and farnesol) in S. lumholtzianum. Our findings suggest that in six out of seven buzz-pollinated taxa studied here, floral scent could not be used as a signal by visitors as it does not contain information on pollen availability.

A highly resolved nuclear phylogeny uncovers strong phylogenetic conservatism and correlated evolution of fruit color and size in Solanum L.

Mutualisms between plants and fruit-eating animals were key to the radiation of angiosperms. Still, phylogenetic uncertainties limit our understanding of fleshy-fruit evolution, as in the case of Solanum, a genus with remarkable fleshy-fruit diversity, but with unresolved phylogenetic relationships. We used 1786 nuclear genes from 247 species, including 122 newly generated transcriptomes/genomes, to reconstruct the Solanum phylogeny and examine the tempo and mode of the evolution of fruit color and size. Our analysis resolved the backbone phylogeny of Solanum, providing high support for its clades. Our results pushed back the origin of Solanum to 53.1 million years ago (Ma), with most major clades diverging between 35 and 27 Ma. Evolution of Solanum fruit color and size revealed high levels of trait conservatism, where medium-sized berries that remain green when ripe are the likely ancestral form. Our analyses revealed that fruit size and color are evolutionary correlated, where dull-colored fruits are two times larger than black/purple and red fruits. We conclude that the strong phylogenetic conservatism shown in the color and size of Solanum fruits could limit the influences of fruit-eating animals on fleshy-fruit evolution. Our findings highlight the importance of phylogenetic constraints on the diversification of fleshy-fruit functional traits.

Cuscuta campestris fine-tunes gene expression during haustoriogenesis as an adaptation to different hosts.

The Cuscuta genus comprises obligate parasitic plants that have an unusually wide host range. Whether Cuscuta uses different infection strategies for different hosts or whether the infection strategy is mechanistically and enzymatically conserved remains unknown. To address this, we investigated molecular events during the interaction between field dodder (Cuscuta campestris) and two host species of the Solanum genus that are known to react differently to parasitic infection. We found that host gene induction, particularly of cell wall fortifying genes, coincided with a differential induction of genes for cell wall degradation in the parasite in the cultivated tomato (Solanum lycopersicum) but not in a wild relative (Solanum pennellii). This indicates that the parasite can adjust its gene expression in response to its host. This idea was supported by the increased expression of C. campestris genes encoding an endo-ß-1,4-mannanase in response to exposure of the parasite to purified mono- and polysaccharides in a host-independent infection system. Our results suggest multiple key roles of the host cell wall in determining the outcome of an infection attempt.

Specialized metabolism by trichome-enriched Rubisco and fatty acid synthase components.

Acylsugars, specialized metabolites with defense activities, are secreted by trichomes of many solanaceous plants. Several acylsugar metabolic genes (AMGs) remain unknown. We previously reported multiple candidate AMGs. Here, using multiple approaches, we characterized additional AMGs. First, we identified differentially expressed genes between high- and low-acylsugar-producing F2 plants derived from a cross between cultivated tomato (Solanum lycopersicum) and a wild relative (Solanum pennellii), which produce acylsugars that are ∼1% and ∼20% of leaf dry weight, respectively. Expression levels of many known and candidate AMGs positively correlated with acylsugar amounts in F2 individuals. Next, we identified lycopersicum-pennellii putative orthologs with higher nonsynonymous to synonymous substitutions. These analyses identified four candidate genes, three of which showed enriched expression in stem trichomes compared to underlying tissues (shaved stems). Virus-induced gene silencing confirmed two candidates, Sopen05g009610 [beta-ketoacyl-(acyl-carrier-protein) reductase; fatty acid synthase component] and Sopen07g006810 (Rubisco small subunit), as AMGs. Phylogenetic analysis indicated that Sopen05g009610 is distinct from specialized metabolic cytosolic reductases but closely related to two capsaicinoid biosynthetic reductases, suggesting evolutionary relationship between acylsugar and capsaicinoid biosynthesis. Analysis of publicly available datasets revealed enriched expression of Sopen05g009610 orthologs in trichomes of several acylsugar-producing species. Similarly, orthologs of Sopen07g006810 were identified as solanaceous trichome-enriched members, which form a phylogenetic clade distinct from those of mesophyll-expressed "regular" Rubisco small subunits. Furthermore, δ13C analyses indicated recycling of metabolic CO2 into acylsugars by Sopen07g006810 and showed how trichomes support high levels of specialized metabolite production. These findings have implications for genetic manipulation of trichome-specialized metabolism in solanaceous crops.

Beneath the blooms: Unearthing the effect of rhizospheric bacteria on floral signals and pollinator preferences.

The relationship between plants and pollinators is known to be influenced by ecological interactions with other community members. While most research has focused on aboveground communities affecting plant-pollinator interactions, it is increasingly recognized that soil-dwelling organisms can directly or indirectly impact these interactions. Although studies have examined the effects of arbuscular mycorrhizal fungi on floral traits, there is a gap in research regarding similar effects associated with plant growth-promoting rhizobacteria (PGPR), particularly concerning floral scent. Our study aimed to investigate the influence of the PGPR Bacillus amyloliquefaciens on the floral traits of wild (Solanum habrochaites, Solanum pimpinellifolium and Solanum peruvianum) and cultivated tomato (Solanum lycopersicum), as well as the impact of microbially-driven changes in floral scent on the foraging behaviour of the stingless bee Melipona quadrifasciata. Our findings revealed that inoculating tomatoes with PGPR led to an increased number of flowers and enhanced overall floral volatile emission. Additionally, we observed higher flower biomass and pollen levels in all species, except S. peruvianum. Importantly, these changes in volatile emissions influenced the foraging behaviour of M. quadrifasciata significantly. Our results highlight the impact of beneficial soil microbes on plant-pollinator interactions, shedding light on the multiple effects that plant-microbial interactions can have on aboveground organisms.

Antibacterial and antibiofilm efficacy of Solanum lasiocarpum root extract synthesized silver/silver chloride nanoparticles against Staphylococcus haemolyticus associated with bovine mastitis.

Staphylococcus haemolyticus is a cause of bovine mastitis, leading to inflammation in the mammary gland. This bacterial infection adversely affects animal health, reducing milk quality and yield. Its emergence has been widely reported, representing a significant economic loss for dairy farms. Interestingly, S. haemolyticus exhibits higher levels of antimicrobial resistance than other coagulase-negative Staphylococci. In this study, we synthesized silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Solanum lasiocarpum root extract and evaluated their antibacterial and antibiofilm activities against S. haemolyticus. The formation of the Ag/AgCl-NPs was confirmed using UV-visible spectroscopy, which revealed maximum absorption at 419 nm. X-ray diffraction (XRD) analysis demonstrated the crystalline nature of the Ag/AgCl-NPs, exhibiting a face-centered cubic lattice. Fourier transform infrared (FT-IR) spectroscopy elucidated the functional groups potentially involved in the Ag/AgCl-NPs synthesis. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the Ag/AgCl-NPs was 10 nm. Antimicrobial activity results indicated that the minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) of the Ag/AgCl-NPs treatment were 7.82-15.63 µg/mL towards S. haemolyticus. Morphological changes in bacterial cells treated with the Ag/AgCl-NPs were observed under scanning electron microscopy (SEM). The Ag/AgCl-NPs reduced both the biomass of biofilm formation and preformed biofilm by approximately 20.24-94.66 % and 13.67-88.48 %. Bacterial viability within biofilm formation and preformed biofilm was reduced by approximately 21.56-77.54 % and 18.9-71.48 %, respectively. This study provides evidence of the potential of the synthesized Ag/AgCl-NPs as an antibacterial and antibiofilm agent against S. haemolyticus.

Quantifying terpenes in tomato leaf extracts from different species using gas chromatography-mass spectrometry (GC-MS).

Terpenes play a vital role in plant defense; tomato plants produce a diverse range of terpenes within specialized glandular trichomes, influencing interactions with herbivores, predators, and pollinators. This study employed two distinct methods, namely leaf dip and maceration, to extract trichomes from tomato leaves. Terpene quantification was carried out using Gas Chromatography-Mass Spectrometry (GC-MS). The leaf dip method proved effective in selectively targeting trichome content, revealing unique extraction patterns compared to maceration. The GC-MS method demonstrated high linearity, accuracy, sensitivity, and low limits of detection and quantification. Application of the method to different tomato species (Solanum pennellii, Solanum pimpinellifolium, Solanum galapagense, Solanum habrochaites, and Solanum lycopersicum) identified significant variation in terpene content among these species, highlighting the potential of specific accessions for breeding programs. Notably, the terpene α-zingiberene, known for its repellency against whiteflies, was found in high quantities (211.90-9155.13 µg g-1) in Solanum habrochaites accession PI209978. These findings provide valuable insights into terpenoid diversity for plant defense mechanisms, guiding future research on developing pest-resistant tomato cultivars. Additionally, the study underscores the broader applications of terpenes in agriculture.

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.

Chromosome-scale assembly and gene editing of Solanum americanum genome reveals the basis for thermotolerance and fruit anthocyanin composition.

Solanum americanum serves as a promising source of resistance genes against potato late blight and is considered as a leafy vegetable for complementary food and nutrition. The limited availability of high-quality genome assemblies and gene annotations has hindered the exploration and exploitation of stress-resistance genes in S. americanum. Here, we present a chromosome-level genome assembly of a thermotolerant S. americanum ecotype and identify a crucial heat-inducible transcription factor gene, SaHSF17, essential for heat tolerance. The CRISPR/Cas9 system-mediated knockout of SaHSF17 results in remarkably reduced thermotolerance in S. americanum, exhibiting a significant suppression of multiple HSP gene expressions under heat treatment. Furthermore, our transcriptome analysis and anthocyanin component investigation of fruits indicated that delphinidins are the major anthocyanins accumulated in the mature dark-purple fruits. The accumulation of delphinidins and other pigment components during fruit ripening in S. americanum coincides with the transcriptional regulation of key genes, particularly the F3'5'H and F3'H genes, in the anthocyanin biosynthesis pathway. By integrating existing knowledge, the development of this high-quality reference genome for S. americanum will facilitate the identification and utilization of novel abiotic and biotic stress-resistance genes for improvement of Solanaceae and other crops.

Evidence for human-caused founder effect in populations of Solanum jamesii at archaeological sites: II. Genetic sequencing establishes ancient transport across the Southwest USA.

PREMISE: The domestication of wild plant species can begin with gathering and transport of propagules by Indigenous peoples. The effect on genomic composition, especially in clonal, self-incompatible perennials would be instantaneous and drastic with respect to new, anthropogenic populations subsequently established. Reductions in genetic diversity and mating capability would be symptomatic and the presence of unique alleles and genetic sequences would reveal the origins and ancestry of populations associated with archaeological sites. The current distribution of the Four Corners potato, Solanum jamesii Torr. in the Southwestern USA, may thus reflect the early stages of a domestication process that began with tuber transport. METHODS: Herein genetic sequencing (GBS) data are used to further examine the hypothesis of domestication in this culturally significant species by sampling 25 archaeological and non-archaeological populations. RESULTS: Archaeological populations from Utah, Colorado and northern Arizona have lower levels of polymorphic loci, unique alleles, and heterozygosity than non-archaeological populations from the Mogollon region of central Arizona and New Mexico. Principle components analysis, Fst values, and structure analysis revealed that genetic relationships among archaeological populations did not correspond to geographic proximity. Populations in Escalante, Utah were related to those on the Mogollon Rim (400 km south) and had multiple origins and significant disjunctions with those populations in Bears Ears, Chaco Canyon, and Mesa Verde sites. CONCLUSIONS: Movement of tubers from the Mogollon region may have occurred many times and in multiple directions during the past, resulting in the complex genetic patterns seen in populations from across the Four Corners region.

Siderophore of plant growth promoting rhizobacterium origin reduces reactive oxygen species mediated injury in Solanum spp. caused by fungal pathogens.

AIMS: The study aims to explore antifungal properties of bacillibactin siderophore produced by the plant growth-promoting rhizobacterium (PGPR) Bacillus subtilis against fungal phytopathogens Alternaria porri and Fusarium equiseti isolated from Solanum lycopersicum and Solanum melongena plants. METHODS AND RESULTS: Alternaria porri and F. equiseti were isolated from infected plants of eggplant and tomato, respectively. A plate assay was employed to assess the effect of bacillibactin against the phytopathogens. The antifungal potential of the PGPR was evaluated by estimation of dry fungal biomass, visualization of cellular deformity using compound and scanning electron microscopy, antioxidative enzyme assay and analysis of membrane damage via using lipid peroxidation. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was employed to investigate changes in intracellular iron content. The impact of bacillibactin on pathogenesis was evaluated by infecting detached leaves of S. lycopersicum and S. melongena plants with both the pathogens and treating the infected leaves with bacillibactin. Leaves were further investigated for ROS accumulation, extent of necrosis and cell death. Our findings revealed significant damage to the hyphal structure of A. porri and F. equiseti following treatment with bacillibactin. Biomass reduction, elevated antioxidative enzyme levels, and membrane damage further substantiated the inhibitory effects of the siderophore on fungal growth. ICP-AES analysis indicates an increase in intracellular iron content suggesting enhanced iron uptake facilitated by bacillibactin. Moreover, application of 1500 µg ml-1 bacillibactin on infected leaves demonstrated a substantial inhibition of ROS accumulation, necrosis, and cell death upon bacillibactin treatment. CONCLUSIONS: This study confirms the potent antagonistic activity of bacillibactin against both the phytopathogens A. porri and F. equiseti growth, supporting its potential as a promising biological control agent for fungal plant diseases. Bacillibactin-induced morphological, physiological, and biochemical alterations in the isolated fungi and pathogen-infected leaves highlight the prospects of bacillibactin as an effective and sustainable solution to mitigate economic losses associated with fungal infections in vegetable crops.

Tradeoffs between pH, dissolved organic carbon, and mineral ions regulate cadmium uptake by Solanum hyperaccumulators in calcareous soil.

Soil solution pH and dissolved organic carbon (DOC) influence cadmium (Cd) uptake by hyperaccumulators but their tradeoff in calcareous soils is unclear. This study investigated the mechanisms of Solanum nigrum L. and Solanum alatum Moench in calcareous soil using a combination of concentration gradient experiments (0.6-100 mg Cd kg-1) and soil solution composition analysis. The results showed that the soil solution pH of S. nigrum remained stable despite Cd stress. On average, the soil solution pH of S. alatum was 0.23 units higher than that of S. nigrum, although pH decreased significantly under high Cd stress. In addition, the concentrations of potassium (K) and calcium (Ca) in the soil solution of S. nigrum increased and decreased under low and high levels of Cd stress, respectively. In S. alatum, the K and Ca concentrations in the soil solution generally increased with increasing Cd stress levels. Moreover, the level of DOC in the soil solution of both plants was higher under Cd stress compared to the control, and a gradually increasing trend with Cd stress level was observed in S. alatum. Consequently, the bioconcentration factors of the roots (2.62-19.35) and shoots (1.20-9.59) of both plants were >1, while the translocation factors were <1, showing an obstacle of Solanum hyperaccumulators in transferring Cd into their aboveground parts. Redundancy analysis revealed that the Cd concentration in S. nigrum roots was significantly negatively correlated with the soil solutions of K and Ca. In contrast, Cd concentrations in S. alatum roots and shoots were significantly positively correlated with soil solution DOC, K, and Ca but negatively correlated with pH. Our results suggest that calcareous soil neutralizes the acidity of released protons but does not affect cation exchange, inhibiting DOC in assisting the translocation of Cd within plants.