Search Results (29)

The growing emphasis on food safety and healthier lifestyles, driven by industrial expansion and scientific priorities, has highlighted the necessity of managing harmful microorganisms to guarantee food quality. A significant challenge in this domain is the control of pathogens that are capable of forming biofilms, entering a sessile state that enhances their resistance to broad-spectrum antibiotics. Essential oils, renowned for their antibacterial properties, present a promising natural alternative for food preservation. In this study, we analyzed the chemical composition of Santalum album essential oil (SAEO) using GC-MS, identifying (Z)-α-santalol (57.1%) as the primary constituent. Antimicrobial activity was confirmed through disc diffusion and minimum inhibitory concentration (MIC) assays against Gram-positive and Gram-negative bacteria and yeast from the genus Candida. Additionally, in situ experiments demonstrated that vapor-phase SAEO effectively inhibited Serratia marcescens on the food model, supporting its potential as a natural preservative. MBIC assays, crystal violet staining, and MALDI-TOF MS analysis on S. enterica biofilms were used to further evaluate the antibiofilm effects of SAEO. The crystal violet assay revealed a strong antibiofilm effect, while the MALDI-TOF MS analysis showed changes in the bacterial protein profiles on both glass and plastic surfaces. SAEO also showed significant anti-Salmonella activity on vacuum-packed carrot slices. SAEO outperformed the control samples. The insecticidal activity against Megabruchidius dorsalis was also studied in this work, and the best insecticidal activity was found at the highest concentrations. These findings indicate that SAEO could serve as a valuable component in food preservation, with notable antibacterial and antibiofilm benefits. Full article

The primary constituents of the essential oil derived from Santalum album L. are (Z)-α-santalol, (Z)-β-santalol, (Z)-α-exo-bergamotol, and (Z)-epi-β- santalol. SaCYP736A167 plays a pivotal role in the biosynthesis of these sesquiterpene alcohols within S. album, but the mechanisms governing the expression of the SaCYP736A167 gene is far from being deciphered. In this research, a promoter sequence of the SaCYP736A167 gene, spanning 2808 base pairs, was isolated from S. album. A bioinformatics analysis of the 2384-bp SaCYP736A167 promoter (PSaCYP736A167) showed that abundant stress-inducible cis-acting elements were distributed in different regions of PSaCYP736A167. The histochemical β-glucuronidase (GUS) staining of T1 transgenic Nicotiana tabacum plants harboring PSaCYP736A167 demonstrated that the predominant GUS activity was exhibited in the parenchyma cells of the stem cortex and phloem, suggesting that PSaCYP736A167 is a tissue-specific expression promoter. GUS fluorometric assays of transiently transgenic N. benthamiana leaves revealed that seven distinct segments of PSaCYP736A167 exhibited notably varied levels of GUS activity. A 936-base pair sequence upstream of the transcription initiation codon ATG constitutes the core promoter section of PSaCYP736A167. Our findings shed light on the regulatory mechanisms controlling the transcription of the SaCYP736A167 gene, potentially serving as a novel tissue-specific promoter for applications in transgenic plant biotechnology. Full article

The main components of sandalwood heartwood essential oil are terpenoids, approximately 80% of which are α-santalol and β-santalol. In the synthesis of the main secondary metabolites of sandalwood heartwood, the key gene, santalene synthase (SaSSY), can produce α-santalene and β-santalene by catalyzed (E, E)-FPP. Furthermore, santalene is catalyzed by the cytochrome monooxygenase SaCYP736A167 to form sandalwood essential oil, which then produces a fragrance. However, the upstream regulatory mechanism of the key gene santalene synthase remains unclear. In this study, SaSSY (Sal3G10690) promoter transcription factors and SaSSY cis-elements were screened. The results showed that the titer of the sandalwood cDNA library was 1.75 × 10⁷ CFU/mL, 80% of the inserted fragments identified by PCR were over 750 bp in length, and the positivity rate of the library was greater than 90%. The promoter region of the SaSSY gene was shown to have the structural basis for potential regulatory factor binding. After sequencing and bioinformatics analysis, we successfully obtained 51 positive clones and identified four potential SaSSY transcriptional regulators. Sal6G03620 was annotated as the transcription factor MYB36-like, and Sal8G07920 was annotated as the small heat shock protein HSP20 in sandalwood. Sal1G00910 was annotated as a hypothetical protein of sandalwood. Sal4G10880 was annotated as a homeobox-leucine zipper protein (ATHB-15) in sandalwood. In this study, a cDNA library of sandalwood was successfully constructed using a yeast one-hybrid technique, and the transcription factors that might interact with SaSSY gene promoters were screened. This study provides a foundation for exploring the molecular regulatory mechanism involved in the formation of sandalwood heartwood. Full article

Analysis of the scented components of the art installation House of Hope by Montien Boonma, including eight bags of unlabeled or poorly labeled powder and five strands of aromatic beads, was completed to facilitate its display at the Museum of Modern Art (MoMA). Though an olfactory experience is central to the piece, limited information was available concerning the origin of the object’s scent. Identification of the aromas from the powders and beads, some of which were nearly 30 years old, was accomplished through visual assessment, attenuated total reflectance–Fourier-transform infrared spectroscopy (ATR-FTIR), and static headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GCMS) and confirmed using controls. Challenges included spices that had lost some of their potency or become cross-contaminated. The contents of five of the eight bags of powder were successfully identified as black pepper (two bags), clove, turmeric, and white sandalwood (Santalum album). All beads contained nutmeg, peppermint, ginger, and turmeric, while licorice root, thyme, cardamom, and clove were noted in some. The beads were bound using pine honey, a unique type of honey produced by bees that feed on aphid excretions. Identifying the scented components informs current and future installations so that the artist’s original intent is more closely approximated. Full article

The SAUR (small auxin-up RNA) family constitutes a category of genes that promptly respond to the hormone auxin and play a pivotal role in diverse biological processes encompassing plant growth and the response to abiotic stress. Santalum album L., a semi-parasitic evergreen tree, is renowned for its economically valuable essential oils, positioning it among the most prized tree species. In this study, a meticulous identification and comprehensive analysis of 43 SAUR genes was conducted within S. album. Based on phylogenetic relationships, the SaSAUR genes were systematically categorized into five groups. A collinearity analysis revealed intriguing insights, disclosing 14 segmental duplications and 9 tandem duplications within the SaSAUR genes, emphasizing the pivotal role of duplication in the expansion of this gene family. Noteworthy variations in the expression levels of SaSAUR genes were observed by delving into the SaSAUR transcriptome data from various tissues, including leaves, roots, and heartwood, as well as under salt-stress conditions. Notably, SaSAUR08 and SaSAUR13 were significantly upregulated in heartwood compared with roots and leaves, while SaSAUR18 was markedly more expressed in roots compared with heartwood and leaves. Furthermore, SaSAUR27 and SaSAUR28 were found to respond closely to salt stress, hinting at their potential involvement in the salt-stress response mechanism. This research offers a comprehensive investigation of SAUR genes in S. album and establishes a foundation for future exploration of the SAUR gene family, particularly its relation to growth and salt-stress responses. Full article

Salinity is one of the most significant abiotic stress that affects the growth and development of high-value tree species, including sandalwood, which can also be managed effectively on saline soils with the help of suitable host species. Therefore, the current investigation was conducted to understand the physiological processes and antioxidant mechanisms in sandalwood along the different salinity gradients to explore the host species that could support sandalwood growth in salt-affected agro-ecosystems. Sandalwood seedlings were grown with ten diverse host species with saline water irrigation gradients (EC_iw~3, 6, and 9 dS m⁻¹) and control (EC_iw~0.82 dS m⁻¹). Experimental findings indicate a decline in the chlorophyll content (13–33%), relative water content (3–23%), photosynthetic (27–61%) and transpiration rate (23–66%), water and osmotic potential (up to 137%), and ion dynamics (up to 61%) with increasing salinity levels. Conversely, the carotenoid content (23–43%), antioxidant activity (up to 285%), and membrane injury (82–205%) were enhanced with increasing salinity stress. Specifically, among the hosts, Dalbergia sissoo and Melia dubia showed a minimum reduction in chlorophyll content, relative water content, and plant water relation and gas exchange parameters of sandalwood plants. Surprisingly, most of the host tree species maintained K⁺/Na⁺ of sandalwood up to moderate water salinity of EC_iw~6 dS m⁻¹; however, a further increase in water salinity decreased the K⁺/Na⁺ ratio of sandalwood by many-fold. Salinity stress also enhanced the antioxidative enzyme activity, although the maximum increase was noted with host plants M. dubia, followed by D. sissoo and Azadirachta indica. Overall, the investigation concluded that sandalwood with the host D. sissoo can be successfully grown in nurseries using saline irrigation water and, with the host M. dubia, it can be grown using good quality irrigation water. Full article

In the search for new bioactive agents against the infectious pathogen responsible for the neglected tropical disease (NTD) mycetoma, we tested a collection of 27 essential oils (EOs) in vitro against Madurella mycetomatis, the primary pathogen responsible for the fungal form of mycetoma, termed eumycetoma. Among this series, the EO of Santalum album (Santalaceae), i.e., East Indian sandalwood oil, stood out prominently with the most potent inhibition in vitro. We, therefore, directed our research toward 15 EOs of Santalum species of different geographical origins, along with two samples of EOs from other plant species often commercialized as “sandalwood oils”. Most of these EOs displayed similar strong activity against M. mycetomatis in vitro. All tested oils were thoroughly analyzed by GC-QTOF MS and most of their constituents were identified. Separation of the sandalwood oil into the fractions of sesquiterpene hydrocarbons and alcohols showed that its activity is associated with the sesquiterpene alcohols. The major constituents, the sesquiterpene alcohols (Z)-α- and (Z)-β-santalol were isolated from the S. album oil by column chromatography on AgNO₃-coated silica. They were tested as isolated compounds against the fungus, and (Z)-α-santalol was about two times more active than the β-isomer. Full article

AREB/ABF/ABI5 (ABA-responsive element-binding protein/ABRE binding factors and ABA INSENSITIVE 5) transcription factors are involved in regulating the expression of ABA (abscisic acid)-related genes and improving plant adaptability to environmental stress. To explore the influence of AREB/ABF transcription factors on santalol synthesis, we conducted a genome-wide analysis of the AREB gene family in sandalwood, identified 10 SaAREB genes, and divided them into five subfamilies. We found that all SaAREB genes encoded unstable hydrophilic proteins and the subcellular localization prediction of SaAREBs was that they are located in the nucleus. AREB/ABF genes belong to the bZIP-A subfamily and we found that the 10 AREB proteins all contained bZIP (basic region leucine zipper) and four potential phosphorylation sites (RXXS/T). According to the collinearity analysis results, four of the SaAREB genes were involved in two fragment duplication events. Through qRT-PCR (real-time fluorescence quantitative PCR), we explored the expression profile of SaAREB in different tissues; the effects of ABA treatment and drought treatment on AREB transcription factors were predicted. From the expression of different tissues, we found that SaAREB1 not only responded to prolonged drought but also was highly expressed in stems. Moreover, SaAREB3, SaAREB7, and SaAREB8 specifically respond to ABA treatment. Based on RNA-seq (RNA sequencing) data, we found that SaAREB6 and SaAREB8 were highly expressed in the sapwood and transition regions. Regarding SaCYP736A167, as a key gene in santalol synthesis, its promoter contains the most ABRE cis-reactive elements. These results provide a basis for further analysis of the role of the Santalum album L. (S. album) ABRE/ABF/ABI5 genes in the formation of santalols. Full article

The natural populations of East Indian sandalwood (Santalum album L.) are very confined and are facing a drastic decline over the past three decades due to overexploitation. Santalum album L. seeds, in general, have poor and staggered germination, which is the major constraint in raising seedlings in nursery and establishing plantations. In the present investigation, we studied the impact of hydro- and osmopriming on the germination attributes and seedling performance of Santalum album L. The Polyethylene glycol (PEG-6000) solutions at four concentrations of 5, 10, 15, and 20% and four durations of 2, 4, 6, and 8 days and hydropriming for the same durations were applied. Results indicated that the osmopriming of seeds at PEG solutions at 5% concentrations for 2 days recorded the highest germination (79%), which is 42% higher than the control group. Longer priming times (6–8 days) had no effect or negatively affected the germination and growth. Moreover, hydropriming had no significant impact on the germination percentage of sandalwood seeds. The positive growth after osmopriming was connected with higher β-amylase content, higher carbohydrate and fat content, and lower electrical conductance of the seeds. Osmopriming can be recommended as a suitable and low-cost technology in enhancing the seed germination and seedling growth of Santalum album L. to produce quality planting material. Further testing of osmoprimed seedlings under abiotic stress conditions may help to explore its possible acclimation potential for stress resistance. Full article

This research work focuses on the potential application of an organic compound, santalol, obtained from santalum album, in the inhibition of the enzyme tyrosinase, which is actively involved in the biosynthesis of melanin pigment. Over-production of melanin causes undesirable pigmentation in humans as well as other organisms and significantly downgrades their aesthetic value. The study is designed to explain the purification of tyrosinase from the mushroom Agaricus bisporus, followed by activity assays and enzyme kinetics to give insight into the santalol-modulated tyrosinase inhibition in a dose-dependent manner. The multi-spectroscopic techniques such as UV-vis, fluorescence, and isothermal calorimetry are employed to deduce the efficiency of santalol as a potential candidate against tyrosinase enzyme activity. Experimental results are further verified by molecular docking. Santalol, derived from the essential oils of santalum album, has been widely used as a remedy for skin disorders and a potion for a fair complexion since ancient times. Based on enzyme kinetics and biophysical characterization, this is the first scientific evidence where santalol inhibits tyrosinase, and santalol may be employed in the agriculture, food, and cosmetic industries to prevent excess melanin formation or browning. Full article

Plant-specific Rac/Rop small GTPases, also known as Rop, belong to the Rho subfamily. Rac proteins can be divided into two types according to their C-terminal motifs: Type I Rac proteins have a typical CaaL motif at the C-terminal, whereas type II Rac proteins lack this motif but retain a cysteine-containing element for membrane anchoring. The Rac gene family participates in diverse signal transduction events, cytoskeleton morphogenesis, reactive oxygen species (ROS) production and hormone responses in plants as molecular switches. S. album is a popular semiparasitic plant that absorbs nutrients from the host plant through the haustoria to meet its own growth and development needs. Because the whole plant has a high use value, due to the high production value of its perfume oils, it is known as the “tree of gold”. Based on the full-length transcriptome data of S. album, nine Rac gene members were named SaRac1-9, and we analyzed their physicochemical properties. Evolutionary analysis showed that SaRac1-7, AtRac1-6, AtRac9 and AtRac11 and OsRac5, OsRacB and OsRacD belong to the typical plant type I Rac/Rop protein, while SaRac8-9, AtRac7, AtRac8, AtRac10 and OsRac1-4 belong to the type II Rac/ROP protein. Tissue-specific expression analysis showed that nine genes were expressed in roots, stems, leaves and haustoria, and SaRac7/8/9 expression in stems, haustoria and roots was significantly higher than that in leaves. The expression levels of SaRac1, SaRac4 and SaRac6 in stems were very low, and the expression levels of SaRac2 and SaRac5 in roots and SaRac2/3/7 in haustoria were very high, which indicated that these genes were closely related to the formation of S. album haustoria. To further analyze the function of SaRac, nine Rac genes in sandalwood were subjected to drought stress and hormone treatments. These results establish a preliminary foundation for the regulation of growth and development in S. album by SaRac. Full article

Auxin response factors (ARFs) are essential transcription factors in plants that play an irreplaceable role in controlling the expression of auxin response genes and participating in plant growth and stress. The ARF gene family has been found in Arabidopsis thaliana, apple (Malus domestica), poplar (Populus trichocarpa) and other plants with known whole genomes. However, S. album (Santalum album L.), has not been studied. In this study, we analyzed and screened the whole genome of S. album and obtained 18 S. album ARFs (SaARFs), which were distributed on eight chromosomes. Through the prediction of conserved domains, we found that 13 of the 18 SaARFs had three intact conserved domains, named DBD, MR, Phox and Bem1 (PB1), while the extra five SaARFs (SaARF3, SaARF10, SaARF12, SaARF15, SaARF17) had only two conserved domains, and the C-terminal PB1 domain was missing. By establishing a phylogenetic tree, 62 ARF genes in S. album, poplar and Arabidopsis were divided into four subgroups, named Ⅰ, Ⅱ, Ⅲ and Ⅳ. According to the results of collinearity analysis, we found that ten of the eighteen ARF genes were involved in five segmental duplication events and these genes had short distance intervals and high homology in the SaARF gene family. Finally, tissue-specific and drought-treatment expression of SaARF genes was observed by quantitative real-time polymerase chain reaction (qRT-PCR), and six genes were significantly overexpressed in haustorium. Meanwhile we found SaARF5, SaARF10, and SaARF16 were significantly overexpressed under drought stress. These results provide a basis for further analysis of the related functions of the S. album ARF gene and its relationship with haustorium formation. Full article

Indian sandalwood (Santalum album Linn.), an evergreen tree, indigenous to the Indian peninsula, is known for its fragrant heartwood worldwide. Sandalwood plantations are gaining importance throughout the Indian subcontinent, demanding large-scale production and the establishment of nurseries with quality planting material (QPM). However, sandalwood seedlings succumb to devastating diseases at nurseries, leading to high mortality of the plant stock. Therefore, there is a dire need for the effective management of these diseases. In our study, we isolated and identified phytopathogenic fungi, such as Fusarium solani causing wilt disease with seedling mortality of 25% and Colletotrichum siamense causing anthracnose disease with a disease incidence of 75%. We identified and characterized a total of 90 fungal endophytic isolates from leaf, stem, and root tissues of disease escaped or apparently healthy seedlings of sandalwood. Total fungal endophytes isolated from the disease-escaped sandalwood seedlings comprised 33.3% Colletotrichum siamense, 26.6% Diaporthe melonis, 13.3% Aspergillus sclerotiorum, 13.3% Fusarium oxysporum, 13.3 Paraphoma radicina, 6.6% Alternaria alternata, and 6.6% Pestalotiopsis microspora. Molecular identification using the nuclear ribosomal DNA internal transcribed spacer (ITS) sequences was performed, and those species which could not be resolved with ITS sequence were subjected to multi-locus gene (beta-tubulin (TUB2), the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene, the chitin synthase 1 gene (CHS-1), the actin gene (ACT), and the glutamine synthetase (GS) gene) analysis, and the sequences were deposited to GenBank. Dual culture test assay revealed that the fungal endophytes Aspergillus sclerotiorum and Diaporthe melonis showed the highest percent inhibition of 63.08% and 61.54%, respectively, against Fusarium solani and Diaporthe melonis, and Fusarium oxysporum showed the highest percent inhibition of 55.38% and 67.69% in the case of the pathogen Colletotrichum siamense. This study will be useful for the management of seed, soil, and airborne pathogens of Indian sandalwood. Full article

Santalum album is a semi parasitic plant and its growth is often restricted due to a lack of a host or water during plantation establishment. In this study, the effects of water and the host on the growth of S. album seedlings were studied in pot culture. The results showed that the net photosynthetic rate and height of S. album seedlings decreased significantly under drought stress. Compared with the seedlings of S. album grown without a host, the host could significantly increase the growth of S. album seedlings. The contents of soluble sugar and proline in S. album leaves increased significantly under drought stress. Drought stress resulted in a significant accumulation of malondialdehyde, increments of antioxidant enzymes activity, and non-enzymatic antioxidant substances. Antioxidant capacity was stronger and malondialdehyde content was lower in the seedling leaves of S. album with a host than in the seedlings without a host. RNA-seq was used to analyze the transcription expression profiles of S. album leaves and the results were consistent with the physiological data. These results indicate that the host can promote the seedling growth of S. album and it can increase the antioxidant capacity and osmotic adjustment substance content of the seedlings of S. album, alleviating the damage caused by drought. Full article

Santalum album L., a semi-parasitic evergreen tree, contains economically important essential oil, rich in sesquiterpenoids, such as (Z) α- and (Z) β-santalol. However, their transcriptional regulations are not clear. Several studies of other plants have shown that basic-helix-loop-helix (bHLH) transcription factors (TFs) were involved in participating in the biosynthesis of sesquiterpene synthase genes. Herein, bHLH TF genes with similar expression patterns and high expression levels were screened by co-expression analysis, and their full-length ORFs were obtained. These bHLH TFs were named SaMYC1, SaMYC3, SaMYC4, SaMYC5, SabHLH1, SabHLH2, SabHLH3, and SabHLH4. All eight TFs had highly conserved bHLH domains and SaMYC1, SaMYC3, SaMYC4, and SaMYC5, also had highly conserved MYC domains. It was indicated that the eight genes belonged to six subfamilies of the bHLH TF family. Among them, SaMYC1 was found in both the nucleus and the cytoplasm, while SaMYC4 was only localized in the cytoplasm and the remaining six TFs were localized in nucleus. In a yeast one-hybrid experiment, we constructed decoy vectors pAbAi-SSy1G-box, pAbAi-CYP2G-box, pAbAi-CYP3G-box, and pAbAi-CYP4G-box, which had been transformed into yeast. We also constructed pGADT7-SaMYC1 and pGADT7-SabHLH1 capture vectors and transformed them into bait strains. Our results showed that SaMYC1 could bind to the G-box of SaSSy, and the SaCYP736A167 promoter, which SaSSy proved has acted as a key enzyme in the synthesis of santalol sesquiterpenes and SaCYP450 catalyzed the ligation of santalol sesquiterpenes into terpene. We have also constructed pGreenII 62-SK-SaMYC1, pGreenII 0800-LUC-SaSSy and pGreenII 0800-LUC-SaCYP736A167 via dual-luciferase fusion expression vectors and transformed them into Nicotiana benthamiana using an Agrobacterium-mediated method. The results showed that SaMYC1 was successfully combined with SaSSy or SaCYP736A167 promoter and the LUC/REN value was 1.85- or 1.55-fold higher, respectively, than that of the control group. Therefore, we inferred that SaMYC1 could activate both SaSSy and SaCYP736A167 promoters. Full article