Eggplant transcription factor SmMYB5 integrates jasmonate and light signaling during anthocyanin biosynthesis.

Low light conditions severely suppress anthocyanin synthesis in fruit skins, leading to compromised fruit quality in eggplant (Solanum melongena L.) production. In this study, we found that exogenous methyl-jasmonate (MeJA) application can effectively rescue the poor coloration of the eggplant pericarp under low light conditions. However, the regulatory relationship between jasmonate and light signaling for regulating anthocyanin synthesis remains unclear. Here, we identified a JA response factor, SmMYB5, as an anthocyanin positive regulator by applying RNA-sequencing and characterization of transgenic plants. Firstly, we resolved that SmMYB5 can interact with TRANSPARENT TESTA8 (SmTT8), an anthocyanin-promoted BASIC HELIX-LOOP-HELIX (bHLH) transcription factor, to form the SmMYB5-SmTT8 complex and activate CHALCONE SYNTHASE (SmCHS), FLAVANONE-3-HYDROXYLASE (SmF3H), and ANTHOCYANIN SYNTHASE (SmANS) promoters by direct binding. Secondly, we revealed that JA signaling repressors JASMONATE ZIM DOMAIN5 (SmJAZ5) and SmJAZ10 can interfere with the stability and transcriptional activity of SmMYB5-SmTT8 by interacting with SmMYB5. JA can partially rescue the transcriptional activation of SmF3H and SmANS promoters by inducing SmJAZ5/10 degradation. Thirdly, we demonstrated that the protein abundance of SmMYB5 is regulated by light. CONSTITUTIVELY PHOTOMORPHOGENIC1 (SmCOP1) interacts with SmMYB5 to trigger SmMYB5 degradation via the 26S proteasome pathway. Finally, we delineated a light-dependent JA-SmMYB5 signaling pathway that promotes anthocyanin synthesis in eggplant fruit skins. These results provide insights into the mechanism of the integration of JA and light signals in regulating secondary metabolite synthesis in plants.

Single-cell RNA sequencing identifies eggplant as a regulator of germ cell development in Drosophila.

Drosophila ovarian germline stem cells (GSCs) are a powerful model for stem cell research. In this study, we use single-cell RNA sequencing (scRNA-seq), an RNAi screen and bioinformatic analysis, to identify genes involved in germ cell differentiation, including 34 genes with upregulated expression during early germ cell development and 19 genes that may regulate germ cell differentiation. Among these, a gene we have named eggplant (eggpl) is highly expressed in GSCs and downregulated in early daughter cells. RNAi knockdown of eggpl causes germ cell proliferation and differentiation defects. In flies fed a rich yeast diet, the expression of eggpl is significantly lower and knockdown or knockout of eggpl phenocopies a rich diet. In addition, eggpl knockdown suppresses the reduction in germ cell proliferation caused by inhibition of the insulin effector PI3K. These findings suggest that downregulation of eggpl links nutritional status to germ cell proliferation and differentiation. Collectively, this study provides new insights into the signaling networks that regulate early germ cell development and identifies eggpl as a key player in this process.

New insight into protective effect against oxidative stress and biosynthesis of exopolysaccharides produced by Lacticaseibacillus paracasei NC4 from fermented eggplant.

Fermented eggplant is a traditional fermented food, however lactic acid bacteria capable of producing exopolysaccharide (EPS) have not yet been exploited. The present study focused on the production and protective effects against oxidative stress of an EPS produced by Lacticaseibacillus paracasei NC4 (NC4-EPS), in addition to deciphering its genomic features and EPS biosynthesis pathway. Among 54 isolates tested, strain NC4 showed the highest EPS yield and antioxidant activity. The maximum EPS production (2.04 ± 0.11 g/L) was achieved by culturing in MRS medium containing 60 g/L sucrose at 37 °C for 48 h. Under 2 mM H2O2 stress, the survival of a yeast model Saccharomyces cerevisiae treated with 0.4 mg/mL NC4-EPS was 2.4-fold better than non-treated cells, which was in agreement with the catalase and superoxide dismutase activities measured from cell lysates. The complete genome of NC4 composed of a circular chromosome of 2,888,896 bp and 3 circular plasmids. The NC4 genome comprises more genes with annotated function in nitrogen metabolism, phosphorus metabolism, cell division and cell cycle, and iron acquisition and metabolism as compared to other reported L. paracasei. Of note, the eps gene cluster is not conserved across L. paracasei. Pathways of sugar metabolism for EPS biosynthesis were proposed for the first time, in which gdp pathway only present in few plant-derived bacteria was identified. These findings shed new light on the cell-protective activity and biosynthesis of EPS produced by L. paracasei, paving the way for future efforts to enhance yield and tailor-made EPS production for food and pharmaceutical industries.

Deciphering desiccation tolerance in wild eggplant species: insights from chlorophyll fluorescence dynamics.

BACKGROUND: Climate change exacerbates abiotic stresses, which are expected to intensify their impact on crop plants. Drought, the most prevalent abiotic stress, significantly affects agricultural production worldwide. Improving eggplant varieties to withstand abiotic stress is vital due to rising drought from climate change. Despite the diversity of wild eggplant species that thrive under harsh conditions, the understanding of their drought tolerance mechanisms remains limited. In the present study, we used chlorophyll fluorescence (ChlaF) imaging, which reveals a plant's photosynthetic health, to investigate desiccation tolerance in eggplant and its wild relatives. Conventional fluorescence measurements lack spatial heterogeneity, whereas ChlaF imaging offers comprehensive insights into plant responses to environmental stresses. Hence, employing noninvasive imaging techniques is essential for understanding this heterogeneity. RESULTS: Desiccation significantly reduced the leaf tissue moisture content (TMC) across species. ChlaF and TMC displayed greater photosystem II (PSII) efficiency after 54 h of desiccation in S. macrocarpum, S. torvum, and S. indicum, with S. macrocarpum demonstrating superior efficiency due to sustained fluorescence. PSII functions declined gradually in S. macrocarpum and S. torvum, unlike those in other species, which exhibited abrupt declines after 54 h of desiccation. However, after 54 h, PSII efficiency remained above 50% of its initial quantum yield in S. macrocarpum at 35% leaf RWC (relative water content), while S. torvum and S. indicum displayed 50% decreases at 31% and 33% RWC, respectively. Conversely, the susceptible species S. gilo and S. sisymbriifolium exhibited a 50% reduction in PSII function at an early stage of 50% RWC, whereas in S. melongena, this reduction occurred at 40% RWC. CONCLUSION: Overall, our study revealed notably greater leaf desiccation tolerance, especially in S. macrocarpum, S. torvum, and S. indicum, attributed to sustained PSII efficiency at low TMC levels, indicating that these species are promising sources of drought tolerance.

Effect of salinity on growth and biochemical responses of brinjal varieties: implications for salt tolerance and antioxidant mechanisms.

Salinity poses significant challenges to agricultural productivity, impacting crops' growth, morphology and biochemical parameters. A pot experiment of three months was conducted between February to April 2023 in the Department of Botany, The Islamia University of Bahawalpur. Four brinjal (eggplant) varieties: ICS-BR-1351, HBR-313-D, HBR-314-E, and HBR-334-D were selected and assessed for the effects of salinity on various growth and biochemical attributes. The experiment was completely randomized in design with three replicates each. This study revealed that increased salinity significantly reduced the shoot length, root length, and leaf number across all varieties, with maximum adverse effects observed at a 300mM NaCl concentration. Among the tested varieties, ICS-BR-1351 demonstrated superior performance in most growth parameters, suggesting potential salt tolerance. Biochemically, salinity decreased chlorophyll content across all varieties, with the sharpest decline observed at the highest salt concentration. V4 (HBR-334-D) showed a 57% decrease in chlorophyll followed by V3 (HBR-314-E) at 56%, V2 (HBR-313-D) at 54%, and V1 (ICS-BR-1351) at 33% decrease at maximum salt levels as compared to control. Conversely, carotenoid content increased up to -42.11% in V3 followed by V2 at -81.48%, V4 at -94.11%, and - 233% in V1 at 300mM NaCl stress as compared to respective controls. V3 (HBR-314-E) has the maximum value for carotenoids while V1 has the lowest value for carotenoids as compared to the other three brinjal varieties. In addition to pigments, the study indicated a salinity-induced decrease in total proteins and total soluble sugar, whereas total amino acids and flavonoids increased. Total proteins showed a decrease in V2 (49.46%) followed by V3 (36.44%), V4 (53.42%), and V1 (53.79%) at maximum salt concentration as compared to plants treated with tap water only. Whereas, total soluble sugars showed a decrease of 52.07% in V3, 41.53% in V2, 19.49% in V1, and 18.99% in V4 at the highest salt level. While discussing total amino acid, plants showed a -9.64% increase in V1 as compared to V4 (-31.10%), V2 (-36.62%), and V3 (-22.61%) with high salt levels in comparison with controls. Plant flavonoid content increased in V3 (-15.61%), V2 (-19.03%), V4 (-18.27%) and V1 (-27.85%) at 300mM salt concentration. Notably, salinity elevated the content of anthocyanin, lycopene, malondialdehyde (MDA), and hydrogen peroxide (H2O2) across all varieties. Antioxidant enzymes like peroxidase, catalase, and superoxide dismutase also increased under salt stress, suggesting an adaptive response to combat oxidative damage. However, V3 (HBR-314-E) has shown an increase in anthocyanin at -80.00%, lycopene at -24.81%, MDA at -168.04%, hydrogen peroxide at -24.22%, POD at -10.71%, CAT as-36.63 and SOD as -99.14% at 300mM NaCl stress as compared to control and other varieties. The enhanced accumulation of antioxidants and other protective compounds suggests an adaptive mechanism in brinjal to combat salt-induced oxidative stress. The salt tolerance of different brinjal varieties was assessed by principal component analysis (PCA), and the order of salt tolerance was V1 (ICS-BR-1351) > V4 (HBR-334-D), > V2 (HBR-313-D) > V3 (HBR-314-E). Among the varieties studied, ICS-BR-1351 demonstrated resilience against saline conditions, potentially offering a promising candidate for saline-prone agricultural areas.

Growth and antioxidant responses to water stress in eggplant MAGIC population parents, F1 hybrids and a subset of recombinant inbred lines.

BACKGROUND: The generation of new eggplant (Solanum melongena L.) cultivars with drought tolerance is a main challenge in the current context of climate change. In this study, the eight parents (seven of S. melongena and one of the wild relative S. incanum L.) of the first eggplant MAGIC (Multiparent Advanced Generation Intercrossing) population, together with four F1 hybrids amongst them, five S5 MAGIC recombinant inbred lines selected for their genetic diversity, and one commercial hybrid were evaluated in young plant stage under water stress conditions (30% field capacity; FC) and control conditions (100% FC). After a 21-day treatment period, growth and biomass traits, photosynthetic pigments, oxidative stress markers, antioxidant compounds, and proline content were evaluated. RESULTS: Significant effects (p < 0.05) were observed for genotype, water treatments and their interaction in most of the traits analyzed. The eight MAGIC population parental genotypes displayed a wide variation in their responses to water stress, with some of them exhibiting enhanced root development and reduced foliar biomass. The commercial hybrid had greater aerial growth compared to root growth. The four F1 hybrids among MAGIC parents differed in their performance, with some having significant positive or negative heterosis in several traits. The subset of five MAGIC lines displayed a wide diversity in their response to water stress. CONCLUSION: The results show that a large diversity for tolerance to drought is available among the eggplant MAGIC materials, which can contribute to developing drought-tolerant eggplant cultivars.

Comparative physiology and transcriptome response patterns in cold-tolerant and cold-sensitive varieties of Solanum melongena.

BACKGROUND: Climate change has led to severe cold events, adversely impacting global crop production. Eggplant (Solanum melongena L.), a significant economic crop, is highly susceptible to cold damage, affecting both yield and quality. Unraveling the molecular mechanisms governing cold resistance, including the identification of key genes and comprehensive transcriptional regulatory pathways, is crucial for developing new varieties with enhanced tolerance. RESULTS: In this study, we conducted a comparative analysis of leaf physiological indices and transcriptome sequencing results. The orthogonal partial least squares discriminant analysis (OPLS-DA) highlighted peroxidase (POD) activity and soluble protein as crucial physiological indicators for both varieties. RNA-seq data analysis revealed that a total of 7024 and 6209 differentially expressed genes (DEGs) were identified from variety "A" and variety "B", respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment of DEGs demonstrated that the significant roles of starch and sucrose metabolism, glutathione metabolism, terpenoid synthesis, and energy metabolism (sucrose and starch metabolism) were the key pathways in eggplant. Weighted gene co-expression network analysis (WGCNA) shown that the enrichment of numerous cold-responsive genes, pathways, and soluble proteins in the MEgrep60 modules. Core hub genes identified in the co-expression network included POD, membrane transporter-related gene MDR1, abscisic acid-related genes, growth factor enrichment gene DELLA, core components of the biological clock PRR7, and five transcription factors. Among these, the core transcription factor MYB demonstrated co-expression with signal transduction, plant hormone, biosynthesis, and metabolism-related genes, suggesting a pivotal role in the cold response network. CONCLUSION: This study integrates physiological indicators and transcriptomics to unveil the molecular mechanisms responsible for the differences in cold tolerance between the eggplant cold-tolerant variety "A" and the cold-sensitive variety "B". These mechanisms include modulation of reactive oxygen species (ROS), elevation in osmotic carbohydrate and free proline content, and the expression of terpenoid synthesis genes. This comprehensive understanding contributes valuable insights into the molecular underpinnings of cold stress tolerance, ultimately aiding in the improvement of crop cold tolerance.

FeONPs alleviate cadmium toxicity in Solanum melongena through improved morpho-anatomical and physiological attributes, along with oxidative stress and antioxidant defense regulations.

In this study, various constraints of Cd toxicity on growth, morpho-anatomical characters along with physiological and biochemical metabolic processes of Solanum melongena L. plants were analyzed. Conversely, ameliorative role of iron oxide nanoparticles (FeONPs) was examined against Cd stress. For this purpose, the following treatments were applied in completely randomized fashion; 3 mM CdCl2 solution applied with irrigation water, 40 and 80 ppm solutions of FeONPs applied via foliar spray. Regarding the results, Cd caused oxidative damage to plants' photosynthetic machinery, resulting in elevated levels of stress-markers like malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolytic leakage (EL) along with slight increase in antioxidants activities, including glutathione (GsH), ascorbate (AsA), catalases (CAT), peroxidases (POD), superoxide dismutase (SOD), and ascorbate peroxidases (APX). Also, high Cd level in plants disturb ions homeostasis and reduced essential minerals uptake, including Ca and K. This ultimately reduced growth and development of S. melongena plants. In contrast, FeONPs supplementations improved antioxidants (enzymatic and non-enzymatic) defenses which in turn limited ROS generation and lowered the oxidative damage to photosynthetic machinery. Furthermore, it maintained ionic balance resulting in enhanced uptake of Ca and K nutrients which are necessary for photosynthesis, hence also improved photosynthesis rate of S. melongena plants. Overall, FeONPs foliar spray effectively mitigated Cd toxicity imposed on S. melongena plants.

Copper mitigates salinity stress by regulating water status, photosynthetic pigments and ion homeostasis and increases the yield of Eggplant (Solanum melongena).

Eggplant (Solanum melongena) is moderately sensitive to salinity. Seed priming and exogenous supplementation are technique that enhances germination, growth, and crop yield by overcoming salt stress. Therefore, this study was designed to understand the role of seed priming and copper (Cu) supplementation in modulating salt tolerance in eggplant. When exposed to salt stress, eggplant seedlings showed significantly higher Na+ content, an increased Na/K ratio, prolonged mean germination time, higher relative water loss, more days to flower bud initiation and first flowering, along with decreased germination rate, growth factors, water content, photosynthetic pigments, ionic contents (K+, Ca2+, Mg2+), and yield. The results demonstrated that the germination rate, final germination percentage, germination index, germination energy, and seed vigor index significantly improved, while the mean germination time decreased in Cu-primed seeds. The results also revealed that Cu supplementations increased seedling traits, leaf water content, photosynthetic pigment contents, ionic contents (K+, Ca2+, and Mg2+), and yield while decreasing the contents of Na+, and Na/K ratio, mean germination time, relative water loss, days to flower bud initiation, and days to 1st flowering under salt stress. Germination of seeds, seedlings growth traits, plant water status, plant pigments, yield, and ionic contents with the NaCl and Cu treatments were found to substantially interact with each other according to both hierarchical clustering and PCA. Overall, Cu seed priming and exogenous supplementation emerged as a promising strategy to enhance salt tolerance and promote germination, growth, and yield by regulating water status, photosynthetic pigments, and ion homeostasis in eggplant seedlings under NaCl stress. These findings provide valuable insights into the mechanisms of Cu-mediated stress alleviation in eggplant, with implications for sustainable crop production in saline environments.

Eggplant NAC domain transcription factor SmNST1 as an activator promotes secondary cell wall thickening.

NAC-domain transcription factors (TFs) are plant-specific transcriptional regulators playing crucial roles in plant secondary cell wall (SCW) biosynthesis. SCW is important for plant growth and development, maintaining plant morphology, providing rigid support, ensuring material transportation and participating in plant stress responses as a protective barrier. However, the molecular mechanisms underlying SCW in eggplant have not been thoroughly explored. In this study, the NAC domain TFs SmNST1 and SmNST2 were cloned from the eggplant line 'Sanyue qie'. SmNST1 and SmNST2 expression levels were the highest in the roots and stems. Subcellular localization analysis showed that they were localized in the cell membrane and nucleus. Their overexpression in transgenic tobacco showed that SmNST1 promotes SCW thickening. The expression of a set of SCW biosynthetic genes for cellulose, xylan and lignin, which regulate SCW formation, was increased in transgenic tobacco. Bimolecular fluorescence and luciferase complementation assays showed that SmNST1 interacted with SmNST2 in vivo. Yeast one-hybrid, electrophoretic mobility shift assay (EMSA) and Dual-luciferase reporter assays showed that SmMYB26 directly bound to the SmNST1 promoter and acted as an activator. SmNST1 and SmNST2 interact with the SmMYB108 promoter and repress SmMYB108 expression. Altogether, we showed that SmNST1 positively regulates SCW formation, improving our understanding of SCW biosynthesis transcriptional regulation.

Effects of different rootstocks grafting on selenium accumulation in Cyphomandra betacea Sendt. seedlings under selenium-contaminated soil.

The effects of rootstocks tomato (Solanum lycopersicum L.), eggplant (Solanum melongena L.), and nightshade (Solanum nigrum L.) grafting on the growth and selenium (Se) accumulation of Cyphomandra betacea Sendt. seedlings were studied to identify the most suitable rootstock for increasing Se uptake of fruit trees grown in Se-contaminated soil. The rootstocks of tomato, eggplant, and nightshade grafting increased the scion biomass of C. betacea seedlings by 146.1%, 23.2%, and 94.5%, respectively, compared with the un-grafted seedlings. Moreover, tomato, eggplant, and nightshade rootstocks grafting increased the photosynthesis, superoxide dismutase activity, and peroxidase activity, while reducing the catalase activity and soluble protein content of C. betacea seedlings. Although all three rootstocks grafting decreased Se contents in rootstock roots and stems, only nightshade rootstock grafting increased Se content in the scions of C. betacea seedlings. Notably, root biomass, catalase activity, soluble protein content, rootstock root Se content, and rootstock stem Se content were closely related to the scion Se content. These findings suggest that only grafting onto nightshade rootstock significantly enhances Se uptake in C. betacea, whereas tomato and eggplant rootstocks grafting have no effect on Se uptake.

This study shows that under selenium (Se)-contaminated soil conditions, tomato, eggplant, and nightshade rootstocks can promote the growth of C. betacea seedlings and improve their stress resistance. The nightshade rootstock stands out for its ability to promote Se uptake in C. betacea seedlings, suggesting its suitability as a promising rootstock to enhance both growth and Se uptake in C. betacea.

Identification and Molecular Characterization of the CAMTA Gene Family in Solanaceae with a Focus on the Expression Analysis of Eggplant Genes under Cold Stress.

Calmodulin-binding transcription activator (CAMTA) is an important calmodulin-binding protein with a conserved structure in eukaryotes which is widely involved in plant stress response, growth and development, hormone signal transduction, and other biological processes. Although CAMTA genes have been identified and characterized in many plant species, a systematic and comprehensive analysis of CAMTA genes in the Solanaceae genome is performed for the first time in this study. A total of 28 CAMTA genes were identified using bioinformatics tools, and the biochemical/physicochemical properties of these proteins were investigated. CAMTA genes were categorized into three major groups according to phylogenetic analysis. Tissue-expression profiles indicated divergent spatiotemporal expression patterns of SmCAMTAs. Furthermore, transcriptome analysis of SmCAMTA genes showed that exposure to cold induced differential expression of many eggplant CAMTA genes. Yeast two-hybrid and bimolecular fluorescent complementary assays suggested an interaction between SmCAMTA2 and SmERF1, promoting the transcription of the cold key factor SmCBF2, which may be an important mechanism for plant cold resistance. In summary, our results provide essential information for further functional research on Solanaceae family genes, and possibly other plant families, in the determination of the development of plants.

Fine Mapping of Candidate Gene Controlling Anthocyanin Biosynthesis for Purple Peel in Solanum melongena L.

Fruit color is an intuitive quality of horticultural crops that can be used as an evaluation criterion for fruit ripening and is an important factor affecting consumers' purchase choices. In this study, a genetic population from the cross of green peel 'Qidong' and purple peel '8 guo' revealed that the purple to green color of eggplant peel is dominant and controlled by a pair of alleles. Bulked segregant analysis (BSA), SNP haplotyping, and fine genetic mapping delimited candidate genes to a 350 kb region of eggplant chromosome 10 flanked by markers KA2381 and CA8828. One ANS gene (EGP22363) was predicted to be a candidate gene based on gene annotation and sequence alignment of the 350-kb region. Sequence analysis revealed that a single base mutation of 'T' to 'C' on the exon green peel, which caused hydrophobicity to become hydrophilic serine, led to a change in the three-level spatial structure. Additionally, EGP22363 was more highly expressed in purple peels than in green peels. Collectively, EGP22363 is a strong candidate gene for anthocyanin biosynthesis in purple eggplant peels. These results provide important information for molecular marker-assisted selection in eggplants, and a basis for analyzing the regulatory pathways responsible for anthocyanin biosynthesis in eggplants.

Genetic and Biotechnological Approaches to Improve Fruit Bioactive Content: A Focus on Eggplant and Tomato Anthocyanins.

Anthocyanins are a large group of water-soluble flavonoid pigments. These specialized metabolites are ubiquitous in the plant kingdom and play an essential role not only in plant reproduction and dispersal but also in responses to biotic and abiotic stresses. Anthocyanins are recognized as important health-promoting and chronic-disease-preventing components in the human diet. Therefore, interest in developing food crops with improved levels and compositions of these important nutraceuticals is growing. This review focuses on work conducted to elucidate the genetic control of the anthocyanin pathway and modulate anthocyanin content in eggplant (Solanum melongena L.) and tomato (Solanum lycopersicum L.), two solanaceous fruit vegetables of worldwide relevance. While anthocyanin levels in eggplant fruit have always been an important quality trait, anthocyanin-based, purple-fruited tomato cultivars are currently a novelty. As detailed in this review, this difference in the anthocyanin content of the cultivated germplasm has largely influenced genetic studies as well as breeding and transgenic approaches to improve the anthocyanin content/profile of these two important solanaceous crops. The information provided should be of help to researchers and breeders in devising strategies to address the increasing consumer demand for nutraceutical foods.

Genome-Wide Identification of Glutathione S-Transferase Genes in Eggplant (Solanum melongena L.) Reveals Their Potential Role in Anthocyanin Accumulation on the Fruit Peel.

Anthocyanins are ubiquitous pigments derived from the phenylpropanoid compound conferring red, purple and blue pigmentations to various organs of horticultural crops. The metabolism of flavonoids in the cytoplasm leads to the biosynthesis of anthocyanin, which is then conveyed to the vacuoles for storage by plant glutathione S-transferases (GST). Although GST is important for transporting anthocyanin in plants, its identification and characterization in eggplant (Solanum melongena L.) remains obscure. In this study, a total of 40 GST genes were obtained in the eggplant genome and classified into seven distinct chief groups based on the evolutionary relationship with Arabidopsis thaliana GST genes. The seven subgroups of eggplant GST genes (SmGST) comprise: dehydroascorbate reductase (DHAR), elongation factor 1Bγ (EF1Bγ), Zeta (Z), Theta(T), Phi(F), Tau(U) and tetra-chlorohydroquinone dehalogenase TCHQD. The 40 GST genes were unevenly distributed throughout the 10 eggplant chromosomes and were predominantly located in the cytoplasm. Structural gene analysis showed similarity in exons and introns within a GST subgroup. Six pairs of both tandem and segmental duplications have been identified, making them the primary factors contributing to the evolution of the SmGST. Light-related cis-regulatory elements were dominant, followed by stress-related and hormone-responsive elements. The syntenic analysis of orthologous genes indicated that eggplant, Arabidopsis and tomato (Solanum lycopersicum L.) counterpart genes seemed to be derived from a common ancestry. RNA-seq data analyses showed high expression of 13 SmGST genes with SmGSTF1 being glaringly upregulated on the peel of purple eggplant but showed no or low expression on eggplant varieties with green or white peel. Subsequently, SmGSTF1 had a strong positive correlation with anthocyanin content and with anthocyanin structural genes like SmUFGT (r = 0.9), SmANS (r = 0.85), SmF3H (r = 0.82) and SmCHI2 (r = 0.7). The suppression of SmGSTF1 through virus-induced gene silencing (VIGs) resulted in a decrease in anthocyanin on the infiltrated fruit surface. In a nutshell, results from this study established that SmGSTF1 has the potential of anthocyanin accumulation in eggplant peel and offers viable candidate genes for the improvement of purple eggplant. The comprehensive studies of the SmGST family genes provide the foundation for deciphering molecular investigations into the functional analysis of SmGST genes in eggplant.

Transcriptomics reveals the molecular mechanisms of flesh colour differences in eggplant (Solanum melongena).

BACKGROUND: Fruit flesh colour is not only an important commodity attribute of eggplant but is also closely related to maturity. However, very little is known about its formation mechanism in eggplant. RESULTS: Two inbred lines of eggplant, green 'NC7' and white 'BL', were used in this study to explain the differences in flesh colour. Transcriptome sequencing results revealed a total of 3304 differentially expressed genes (DEGs) in NC7 vs. BL. Of the DEGs obtained, 2050 were higher and 1254 were lower in BL. These DEGs were annotated to 126 pathways, where porphyrin and chlorophyll metabolism, flavonoid biosynthesis, and photosynthesis-antenna proteins play vital roles in the colour formation of eggplant flesh. At the same time, Gene Ontology (GO) enrichment significance analysis showed that a large number of unigenes involved in the formation of chloroplast structure were lower in BL, which indicated that the formation of chloroplasts in white-fleshed eggplant was blocked. This was confirmed by transmission electron microscopy (TEM), which found only leucoplasts but no chloroplasts in the flesh cells of white-fleshed eggplant. Several genes encoding ERF and bHLH transcription factors were predicted to participate in the regulation of chlorophyll biosynthetic genes. CONCLUSIONS: The results of this study indicated that differences in the gene expression of the chlorophyll metabolic pathway were the main cause of the different flesh colour formations. These findings will increase our understanding of the genetic basis in eggplant flesh colors formation mechanism.

Genome-Wide Analysis of the Mads-Box Transcription Factor Family in Solanum melongena.

The MADS-box transcription factors are known to be involved in several aspects of plant growth and development, especially in floral organ specification. However, little is known in eggplant. Here, 120 eggplant MADS-box genes were identified and categorized into type II (MIKCC and MIKC*) and type I (Mα, Mß, and Mγ) subfamilies based on phylogenetic relationships. The exon number in type II SmMADS-box genes was greater than that in type I SmMADS-box genes, and the K-box domain was unique to type II MADS-box TFs. Gene duplication analysis revealed that segmental duplications were the sole contributor to the expansion of type II genes. Cis-elements of MYB binding sites related to flavonoid biosynthesis were identified in three SmMADS-box promoters. Flower tissue-specific expression profiles showed that 46, 44, 38, and 40 MADS-box genes were expressed in the stamens, stigmas, petals, and pedicels, respectively. In the flowers of SmMYB113-overexpression transgenic plants, the expression levels of 3 SmMADS-box genes were co-regulated in different tissues with the same pattern. Correlation and protein interaction predictive analysis revealed six SmMADS-box genes that might be involved in the SmMYB113-regulated anthocyanin biosynthesis pathway. This study will aid future studies aimed at functionally characterizing important members of the MADS-box gene family.

Genome-Wide Identification of Catalase Gene Family and the Function of SmCAT4 in Eggplant Response to Salt Stress.

Salinity is an important abiotic stress, damaging plant tissues by causing a burst of reactive oxygen species (ROS). Catalase (CAT) enzyme coded by Catalase (CAT) genes are potent in reducing harmful ROS and hydrogen peroxide (H2O2) produced. Herein, we performed bioinformatics and functional characterization of four SmCAT genes, retrieved from the eggplant genome database. Evolutionary analysis CAT genes revealed that they are divided into subgroups I and II. The RT-qPCR analysis of SmCAT displayed a differential expression pattern in response to abiotic stresses. All the CAT proteins of eggplant were localized in the peroxisome, except for SmCAT4, which localized in the cytomembrane and nucleus. Silencing of SmCAT4 compromised the tolerance of eggplant to salt stress. Suppressed expression levels of salt stress defense related genes SmTAS14 and SmDHN1, as well as increase of H2O2 content and decrease of CAT enzyme activity was observed in the SmCAT4 silenced eggplants. Our data provided insightful knowledge of CAT gene family in eggplant. Positive regulation of eggplant response to salinity by SmCAT4 provides resource for future breeding programs.

Fine mapping and characterization of the dominant gene SmFTSH10 conferring non-photosensitivity in eggplant (Solanum melongena L.).

KEY MESSAGE: A candidate non photosensitive gene S m F TS H10 was identified by combining bulked segregant analysis and map­based cloning. Low light condition often leads to poor coloration of photosensitive eggplant. Here, we obtained a non-photosensitive eggplant that can synthesize large amount of anthocyanin under shading conditions. Genetic analysis of F1 and F2 populations revealed that the phenotype of non-photosensitivity was regulated by a single dominant nuclear gene, herein temporarily designated SmFTSH10. Through Bulked segregant analysis (BSA), SNP haplotyping and fine genetic mapping delimited SmFTSH10 to a 290 kb region of eggplant chromosome 10 flanking by markers dCAPS21 and dCAPS32. Sequence analysis revealed C-base deletion in the fourth exon of SmFTSH10 resulted in premature termination of translation. The expression level of SmFTSH10 decreased significantly in anthocyanin-rich parts of mutant '145' compared with the wild-type 'LSHX'. Sequencing of 10 recombinants revealed that the C-base deletion in the 4th exon of SmFTSH10 was co-segregated with the non-photosensitive phenotype, and the sequencing analysis of the natural population of eggplant also showed that the Indel in SmFTSH10 had a high accuracy in the identification of the photosensitivity of eggplant. Light-responsive expression patterns analysis suggests that it has the same expression trend as the genes involved in eggplant anthocyanin biosynthesis, which supports SmFTSH10 as the most possible candidate gene of non-photosensitivity. These findings provide a new insight into understanding the molecular mechanisms of anthocyanin biosynthesis in non-photosensitive eggplant.

Organophosphorus insecticides mineralizing endophytic and rhizospheric soil bacterial consortium influence eggplant growth-promotion.

This study was aimed to evaluate eggplant's growth-enhancing activity of chlorpyrifos and diazinon-degrading endophytic and rhizospheric soil bacteria isolated from cauliflower and tomato roots and the rhizospheric soil of rice roots, respectively. The identified endophytes belong to the Acinetobacter, Enterobacter and Klebsiella genera, while rhizospheric soil isolates belong to Pantoea, Acinetobacter, Kosakonia, Morganella, Enterobacter, and Klebsiella genera with species variation and genetic distances. All the strain's consumed 100% (50 mg/5 mL) chlorpyrifos and diazinon after 14 days of exposure, except for Pantoea sp. HSTU-Sny4 (84%) and Kosakonia sp. HSTU-ASn39 (42%). The strain's exhibited N-fixation, P-solubilization, indole-3-acetic acid (IAA), and ACC-deaminase production capabilities. The individual strain's and consortium treatment enhanced eggplant growth at germination, seedling, vegetative and reproductive stages. Plant growth-promoting genes, e.g., nif-cluster, chemotaxis, phosphates, sulfur, abiotic stress, chemotaxis, biofilm formation and organophosphorus insecticide-degrading genes were annotated in Klebsiella sp. HSTU-Sny5 and Morganella sp. HSTU-ASny43 genomes. Importantly, the mixed consortium supplemented with 40% urea-treated eggplants demonstrated similar growth parameters compared to the 100% urea eggplants. Plenty of insecticide-degrading proteins belonged to HSTU-Sny5 and HSTU-ASny43 strain's and had interacted with 100 different insecticides as confirmed in virtual screening. This research has a significant role in reducing the application of chemical fertilizer and bioremediation of pesticides in agriculture.