Salicylic acid carboxyl methyltransferase induced in hairy root cultures of Atropa belladonna after treatment with exogeneously added salicylic acid

Prediction of leaf nitrogen in sugarcane (Saccharum spp.) by Vis-NIR-SWIR spectroradiometry

Nitrogen is one of the essential nutrients for the production of agricultural crops, participating in a complex interaction among soil, plant and the atmosphere. Therefore, its monitoring is important both economically and environmentally. The aim of this work was to estimate the leaf nitrogen contents in sugarcane from hyperspectral reflectance data during different vegetative stages of the plant. The assessments were performed from an experiment designed in completely randomized blocks, with increasing nitrogen doses (0, 60, 120 and 180 kg ha-1). The acquisition of the spectral data occurred at different stages of crop development (67, 99, 144, 164, 200, 228, 255 and 313 days after cutting; DAC). In the laboratory, the hyperspectral responses of the leaves and the Leaf Nitrogen Contents (LNC) were obtained. The hyperspectral data and the LNC values were used to generate spectral models employing the technique of Partial Least Squares Regression (PLSR) Analysis, also with the calculation of the spectral bands of greatest relevance, by the Variable Importance in Projection (VIP). In general, the increase in LNC promoted a smaller reflectance in all wavelengths in the visible (400-680 nm). Acceptable models were obtained (R2 > 0.70 and RMSE <1.41 g kg-1), the most robust of which were those generated from spectra in the visible (400-680 nm) and red-edge (680-750 nm), with values of R2 > 0.81 and RMSE <1.24 g kg-1. An independent validation, leave-one-date-out cross validation (LOOCV), was performed using data from other collections, which confirmed the robustness and the possibility of LNC prediction in new data sets, derived, for instance, from samplings subsequent to the period of study.

Overexpression of salicylic acid methyltransferase reduces salicylic acid-mediated pathogen resistance in poplar

Salicylic acid (SA) is generally considered to be a critical signal transduction factor in plant defenses against pathogens. It could be converted to methyl salicylate (MeSA) for remote signals by salicylic acid methyltransferase (SAMT) and converted back to SA by SA-binding protein 2 (SABP2). In order to verify the function of SAMT in poplar plants, we isolated the full-length cDNA sequence of PagSAMT from 84K poplar and cultivated PagSAMT overexpression lines (OE-2 isolate) to test its role in SA-mediated defenses against the virulent fungal pathogen Botryosphaeria dothidea. Our results showed that after inoculation with B. dothidea, OE-2 significantly increased MeSA content and reduced SA content which is associated with increased expression of SAMT in both infected and uninfected leaves, when compared against the wild type (WT). Additionally, SAMT overexpression plant lines (OE-2) exhibited higher expression of pathogenesis-related genes PR-1 and PR-5, but were still susceptible to B. dothidea suggesting that in poplar SA might be responsible for resistance against this pathogen. This study expands the current understanding of joint regulation of SAMT and SABP2 and the balance between SA and MeSA in poplar responses to pathogen invasion.

Increased phenolic acid and tanshinone production and transcriptional responses of biosynthetic genes in hairy root cultures of Salvia przewalskii Maxim. treated with methyl jasmonate and salicylic acid

The purpose of this study is to reveal the impact of the plant hormone salicylic acid (SA) and methyl jasmonate (MeJA) on the growth, effective components accumulation, and related gene expression of the hairy root of Salvia przewalskii Maxim. Various concentrations of SA (0, 25, 50, 100, 200 μM) or MeJA (0, 50, 100, 200, 400, 600 μM) were added to the culture medium of Salvia przewalskii Maxim. Low concentrations of SA promoted the growth of hairy root, while a high concentration inhibited it. 0 to 400 μM MeJA promoted the growth of hairy root, but 600 μM MeJA starts to inhibit its growth. 50 μM SA and 400 μM MeJA significantly enhanced the production of caffeic acid, rosmarinic acid, salvianolic acid B, cryptotanshinone, and tanshinone IIA. In general, 50 μM SA can be used to accumulate of tanshinone in hairy roots of S. przewalskii with 6 days. 400 μM MeJA can be used to accumulate of phenolic acids in hairy roots of S. przewalskii with 3 days. The selected genes in the tanshinone and phenolic acid biosynthetic pathway were upregulated with elicitation. To obtain a higher yield and content of secondary metabolites, it is advisable to use 50 μM SA or 400 μM MeJA as the optimal doses to cultivate the hairy root of S. przewalskii. This study provides, for the first time, an efficient tanshinone and phenolic acid production method for S. przewalskii.

Identification and analysis of key genes involved in methyl salicylate biosynthesis in different birch species

Species of the perennial woody plant genus Betula dominate subalpine forests and play a significant role in preserving biological diversity. In addition to their conventional benefits, birches synthesize a wide range of secondary metabolites having pharmacological significance. Methyl salicylate (MeSA) is one of these naturally occurring compounds constitutively produced by different birch species. MeSA is therapeutically important in human medicine for muscle injuries and joint pain. However, MeSA is now mainly produced synthetically due to a lack of information relating to MeSA biosynthesis and regulation. In this study, we performed a comprehensive bioinformatics analysis of two candidate genes mediating MeSA biosynthesis, SALICYLIC ACID METHYLTRANSFERASE (SAMT) and SALICYLIC ACID-BINDING PROTEIN 2 (SABP2), of high (B. lenta, B. alleghaniensis, B. medwediewii, and B. grossa) and low (B. pendula, B. utilis, B. alnoides, and B. nana) MeSA-producing birch species. Phylogenetic analyses of SAMT and SABP2 genes and homologous genes from other plant species confirmed their evolutionary relationships. Multiple sequence alignments of the amino acid revealed the occurrence of important residues for substrate specificity in SAMT and SABP2. The analysis of cis elements in different birches indicated a functional multiplicity of SAMT and SABP2 and provided insights into the regulation of both genes. We successfully developed six prominent single nucleotide substitution markers that were validated with 38 additional birch individuals to differentiate high and low MeSA-producing birch species. Relative tissue-specific expression analysis of SAMT in leaf and bark tissue of two high and two low MeSA-synthesizing birches revealed a high expression in the bark of both high MeSA-synthesizing birches. In contrast, SABP2 expression in tissues revealed indifferent levels of expression between species belonging to the two groups. The comparative expression and bioinformatics analyses provided vital information that could be used to apply plant genetic engineering technology in the mass production of organic MeSA.

Involvement of CsWRKY70 in salicylic acid-induced citrus fruit resistance against Penicillium digitatum

Penicillium digitatum causes serious losses in postharvest citrus fruit. Exogenous salicylic acid (SA) can induce fruit resistance against various pathogens, but the mechanism remains unclear. Herein, a transcriptome-based approach was used to investigate the underlying mechanism of SA-induced citrus fruit resistance against P. digitatum. We found that CsWRKY70 and genes related to methyl salicylate (MeSA) biosynthesis (salicylate carboxymethyltransferase, SAMT) were induced by exogenous SA. Moreover, significant MeSA accumulation was detected in the SA-treated citrus fruit. The potential involvement of CsWRKY70 in regulating CsSAMT expression in citrus fruit was studied. Subcellular localization, dual luciferase, and electrophoretic mobility shift assays and an analysis of transient expression in fruit peel revealed that the nucleus-localized transcriptional activator CsWRKY70 can activate the CsSAMT promoter by recognizing the W-box element. Taken together, the findings from this study offer new insights into the transcriptional regulatory mechanism of exogenous SA-induced disease resistance in Citrus sinensis fruit.

Functional Characterization of Salicylic Acid Carboxyl Methyltransferase from Camellia sinensis, Providing the Aroma Compound of Methyl Salicylate during the Withering Process of White Tea

Methyl salicylate (MeSA) is one of the volatile organic compounds (VOCs) that releases floral scent and plays an important role in the sweet flowery aroma of tea. During the withering process for white tea producing, MeSA was generated by salicylic acid carboxyl methyltransferase (SAMT) with salicylic acid (SA), and the specific floral scent was formed. In this study, we first cloned a CsSAMT from tea leaves (GenBank accession no. MG459470) and used Escherichia coli and Saccharomyces cerevisiae to express the recombinant CsSAMT. The enzyme activity in prokaryotic and eukaryotic expression systems was identified, and the protein purification, substrate specificity, pH, and temperature optima were investigated. It was shown that CsSAMT located in the chloroplast, and the gene expression profiles were quite different in tea organs. The obtained results might give a new understanding for tea aroma formation, optimization, and regulation and have great significance for improving the specific quality of white tea.

Differentially-expressed genes in rice infected by Xanthomonas oryzae pv. oryzae relative to a flagellin-deficient mutant reveal potential functions of flagellin in host-pathogen interactions

BACKGROUND

Plants have evolved a sensitive defense response system that detects and recognizes various pathogen-associated molecular patterns (PAMPs) (e.g. flagellin) and induces immune responses to protect against invasion. Transcriptional responses in rice to PAMPs produced by Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen, have not yet been defined.

RESULTS

We characterized transcriptomic responses in rice inoculated with the wildtype (WT) Xoo and flagellin-deficient mutant ∆fliC through RNA-seq analysis. Digital gene expression (DGE) analysis based on Solexa/Illumina sequencing was used to investigate transcriptomic responses in 30 day-old seedlings of rice (Oryza sativa L. cv. Nipponbare). 1,680 genes were differentially-expressed (DEGs) in rice inoculated with WT relative to ∆fliC; among which 1,159 genes were up-regulated and 521 were down-regulated. Expression patterns of 12 randomly-selected DEGs assayed by quantitative real time PCR (qRT-PCR) were similar to those detected by DGE analyses, confirming reliability of the DGE data. Functional annotations revealed the up-regulated DEGs are involved in the cell wall, lipid and secondary metabolism, defense response and hormone signaling, whereas the down-regulated ones are associated with photosynthesis. Moreover, 57 and 21 specifically expressed genes were found after WT and ∆fliC treatments, respectively.

CONCLUSIONS

DEGs were identified in rice inoculated with WT Xoo relative to ∆fliC. These genes were predicted to function in multiple biological processes, including the defense response and photosynthesis in rice. This study provided additional insights into molecular basis of rice response to bacterial infection and revealed potential functions of bacterial flagellin in the rice-Xoo interactions.

Effective elicitors and process strategies for enhancement of secondary metabolite production in hairy root cultures

This chapter reviews the various biotic and abiotic elicitors applied to hairy root cultures and their stimulating effects on the accumulation of secondary metabolites. Elicitors generally refer to the agents that stimulate the defense responses of plants. As a major response of plants to biotic and abiotic stress, the accumulation of secondary metabolites in plant tissue cultures can be stimulated by the elicitors. Among the many elicitors applied to hairy root cultures as well as plant cell suspension cultures, the most common and effective elicitors are fungal cell extracts, polysaccharides from fungal and plant cells, and heavy metal salts. With the crude fungal cell extracts, it is essential to observe the preparation conditions carefully for achieving reproducible effects. In addition to the chemical agents, UV-radiation, hyperosmotic stress and temperature shift have been shown effective for some plant species/metabolites. Elicitor type, dose, and treatment schedule are major factors determining the effects on the secondary metabolite production. In addition to the accumulation of products in roots, elicitor treatments often stimulate the release of intracellular products. Although elicitation is mainly effective to increase specific product yield on per unit mass of roots, the incorporation of nutrient feeding strategies can be applied to enhance the volumetric product yield. The integration of in situ product recovery from the roots/liquid medium is another synergistic strategy with the elicitor treatment to improve the process.

Herbivore-induced SABATH methyltransferases of maize that methylate anthranilic acid using s-adenosyl-L-methionine

Volatile methyl esters are common constituents of plant volatiles with important functions in plant defense. To study the biosynthesis of these compounds, especially methyl anthranilate and methyl salicylate, we identified a group of methyltransferases that are members of the SABATH enzyme family in maize (Zea mays). In vitro biochemical characterization after bacterial expression revealed three S-adenosyl-L-methionine-dependent methyltransferases with high specificity for anthranilic acid as a substrate. Of these three proteins, Anthranilic Acid Methyltransferase1 (AAMT1) appears to be responsible for most of the S-adenosyl-L-methionine-dependent methyltransferase activity and methyl anthranilate formation observed in maize after herbivore damage. The enzymes may also be involved in the formation of low amounts of methyl salicylate, which are emitted from herbivore-damaged maize. Homology-based structural modeling combined with site-directed mutagenesis identified two amino acid residues, designated tyrosine-246 and glutamine-167 in AAMT1, which are responsible for the high specificity of AAMTs toward anthranilic acid. These residues are conserved in each of the three main clades of the SABATH family, indicating that the carboxyl methyltransferases are functionally separated by these clades. In maize, this gene family has diversified especially toward benzenoid carboxyl methyltransferases that accept anthranilic acid and benzoic acid.

Biosynthesis and emission of insect-induced methyl salicylate and methyl benzoate from rice

Two benzenoid esters, methyl salicylate (MeSA) and methyl benzoate (MeBA), were detected from insect-damaged rice plants. By correlating metabolite production with gene expression analysis, five candidate genes encoding putative carboxyl methyltransferases were identified. Enzymatic assays with Escherichia coli-expressed recombinant proteins demonstrated that only one of the five candidates, OsBSMT1, has salicylic acid (SA) methyltransferase (SAMT) and benzoic acid (BA) methyltransferase (BAMT) activities for producing MeSA and MeBA, respectively. Whereas OsBSMT1 is phylogenetically relatively distant from dicot SAMTs, the three-dimensional structure of OsBSMT1, which was determined using homology-based structural modeling, is highly similar to those of characterized SAMTs. Analyses of OsBSMT1 expression in wild-type rice plants under various stress conditions indicate that the jasmonic acid (JA) signaling pathway plays a critical role in regulating the production and emission of MeSA in rice. Further analysis using transgenic rice plants overexpressing NH1, a key component of the SA signaling pathway in rice, suggests that the SA signaling pathway also plays an important role in governing OsBSMT1 expression and emission of its products, probably through a crosstalk with the JA signaling pathway. The role of the volatile products of OsBSMT1, MeSA and MeBA, in rice defense against insect herbivory is discussed.

Enzymatic, expression and structural divergences among carboxyl O-methyltransferases after gene duplication and speciation in Nicotiana

Methyl salicylate and methyl benzoate have important roles in a variety of processes including pollinator attraction and plant defence. These compounds are synthesized by salicylic acid, benzoic acid and benzoic acid/salicylic acid carboxyl methyltransferases (SAMT, BAMT and BSMT) which are members of the SABATH gene family. Both SAMT and BSMT were isolated from Nicotiana suaveolens, Nicotiana alata, and Nicotiana sylvestris allowing us to discern levels of enzyme divergence resulting from gene duplication in addition to species divergence. Phylogenetic analyses showed that Nicotiana SAMTs and BSMTs evolved in separate clades and the latter can be differentiated into the BSMT1 and the newly established BSMT2 branch. Although SAMT and BSMT orthologs showed minimal change coincident with species divergences, substantial evolutionary change of enzyme activity and expression patterns occurred following gene duplication. After duplication, the BSMT enzymes evolved higher preference for benzoic acid (BA) than salicylic acid (SA) whereas SAMTs maintained ancestral enzymatic preference for SA over BA. Expression patterns are largely complementary in that BSMT transcripts primarily accumulate in flowers, leaves and stems whereas SAMT is expressed mostly in roots. A novel enzyme, nicotinic acid carboxyl methyltransferase (NAMT), which displays a high degree of activity with nicotinic acid was discovered to have evolved in N. gossei from an ancestral BSMT. Furthermore a SAM-dependent synthesis of methyl anthranilate via BSMT2 is reported and contrasts with alternative biosynthetic routes previously proposed. While BSMT in flowers is clearly involved in methyl benzoate synthesis to attract pollinators, its function in other organs and tissues remains obscure.

Occurrence of theobromine synthase genes in purine alkaloid-free species of Camellia plants

Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are purine alkaloids that are present in high concentrations in plants of some species of Camellia. However, most members of the genus Camellia contain no purine alkaloids. Tracer experiments using [8-(14)C]adenine and [8-(14)C]theobromine showed that the purine alkaloid pathway is not fully functional in leaves of purine alkaloid-free species. In five species of purine alkaloid-free Camellia plants, sufficient evidence was obtained to show the occurrence of genes that are homologous to caffeine synthase. Recombinant enzymes derived from purine alkaloid-free species showed only theobromine synthase activity. Unlike the caffeine synthase gene, these genes were expressed more strongly in mature tissue than in young tissue.

Biosynthesis and Catabolism of Purine Alkaloids in Camellia Plants

A few Camellia plants accumulate caffeine, theobromine and theacrine. The present article reviews the distribution of purine alkaloids and biosynthetic pathways, including properties and genes of the caffeine synthase family of enzymes, and catabolism. Plant physiological studies and ecology-related studies are also summarized briefly.

Responses of transformed Catharanthus roseus roots to femtomolar concentrations of salicylic acid

Catharanthus roseus transformed roots were cultured in the presence of salicylic acid (SA) at concentrations between 0.1 fM and 100 pM and the effect on root growth was evaluated. Significant morphological changes in the lateral roots were recorded on day two in the SA treatment. Presence of SA increased root cap size and caused the appearance of lateral roots closer to the root tip. The bioassay was sensitive enough to allow testing of low concentrations of other growth regulators that may affect root morphology and physiology.

OsBISAMT1, a gene encoding S-adenosyl-L-methionine: salicylic acid carboxyl methyltransferase, is differentially expressed in rice defense responses

We isolated and identified a full-length cDNA, OsBISAMT1 [Oryza sativa L. benzothiadiazole (BTH)-induced SAMT 1], which encodes a putative S-adenosyl-L: -methionine:salicylic acid carboxyl methyltransferase (SAMT) from rice. OsBISAMT1 contains an ORE of 1128 bp, which predicts to encode a 375 aa protein. The OsBISAMT1 protein sequence shows a high level of identity to known plant SAMTs and contains a conserved characteristic methyltransferase domain. OsBISAMT1 is a member of a small gene family in the rice genome. Expression of OsBISAMT1 in rice leaves was induced by treatments with benzothiadiazole and salicylic acid, which are capable of inducing rice disease resistance. OsBISAMT1 was also up-regulated in both incompatible and compatible interactions between rice and the blast fungus, Magnaporthe grsiea, but the induced expression of OsBISAMT1 was greater and more rapid in the incompatible interaction than that in the compatible one. Moreover, mechanical wounding also activated OsBISAMT1 expression. The results suggest that OsBISAMT1 may be involved in disease resistance responses as well as in wound response in rice.

Substrate specificity of N-methyltransferase involved in purine alkaloids synthesis is dependent upon one amino acid residue of the enzyme

Caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) are the major purine alkaloids in plants. To investigate the diversity of N-methyltransferases involved in purine alkaloid biosynthesis, we isolated the genes homologous for caffeine synthase from theobromine-accumulating plants. The predicted amino acid sequences of N-methyltransferases in theobromine-accumulating species in Camellia were more than 80% identical to caffeine synthase in C. sinensis. However, there was a little homology among the N-methyltransferases between Camellia and Theobroma. The recombinant enzymes derived from theobromine-accumulating plants had only 3-N-methyltransferase activity. The accumulation of purine alkaloids was, therefore, dependent on the substrate specificity of N-methyltransferase determined by one amino acid residue in the central part of the protein.

Floral benzenoid carboxyl methyltransferases: from in vitro to in planta function

Benzenoid carboxyl methyltransferases synthesize methyl esters (e.g., methyl benzoate and methyl salicylate), which are constituents of aromas and scents of many plant species and play important roles in plant communication with the surrounding environment. Within the past five years, eleven such carboxyl methyltransferases were isolated and most of them were comprehensively investigated at the biochemical, molecular and structural level. Two types of enzymes can be distinguished according to their substrate preferences: the SAMT-type enzymes isolated from Clarkia breweri, Stephanotis floribunda, Antirrhinum majus, Hoya carnosa, and Petunia hybrida, which have a higher catalytic efficiency and preference for salicylic acid, while BAMT-type enzymes from A. majus, Arabidopsis thaliana, Arabidopsis lyrata, and Nicotiana suaveolens prefer benzoic acid. The elucidation of C. breweri SAMT's three-dimensional structure allowed a detailed modelling of the active sites of the carboxyl methyltransferases and revealed that the SAM binding pocket is highly conserved among these enzymes while the methyl acceptor binding site exhibits some variability, allowing a classification into SAMT-type and BAMT-type enzymes. The analysis of expression patterns coupled with biochemical characterization showed that these carboxyl methyltransferases are involved either in floral scent biosynthesis or in plant defense responses. While the latter can be induced by biotic or abiotic stress, the genes responsible for floral scent synthesis exhibit developmental and rhythmic expression pattern. The nature of the product and efficiency of its formation in planta depend on the availability of substrates, the catalytic efficiency of the enzyme toward benzoic acid and/or salicylic acid, and the transcriptional, translational, and post-translational regulation at the enzyme level. The biochemical properties of benzenoid carboxyl methyltransferases suggest that the genes involved in plant defenses might represent the ancestor for the presently existing floral genes which during evolution gained different expression profiles and encoded enzymes with the ability to accept structurally similar substrates.

Jasmonic acid is a key regulator of spider mite-induced volatile terpenoid and methyl salicylate emission in tomato

The tomato (Lycopersicon esculentum) mutant def-1, which is deficient in induced jasmonic acid (JA) accumulation upon wounding or herbivory, was used to study the role of JA in the direct and indirect defense responses to phytophagous mites (Tetranychus urticae). In contrast to earlier reports, spider mites laid as many eggs and caused as much damage on def-1 as on wild-type plants, even though def-1 lacked induction of proteinase inhibitor activity. However, the hatching-rate of eggs on def-1 was significantly higher, suggesting that JA-dependent direct defenses enhanced egg mortality or increased the time needed for embryonic development. As to gene expression, def-1 had lower levels of JA-related transcripts but higher levels of salicylic acid (SA) related transcripts after 1 d of spider mite infestation. Furthermore, the indirect defense response was absent in def-1, since the five typical spider mite-induced tomato-volatiles (methyl salicylate [MeSA], 4,8,12-trimethyltrideca-1,3,7,11-tetraene [TMTT], linalool, trans-nerolidol, and trans-beta-ocimene) were not induced and the predatory mite Phytoseiulus persimilis did not discriminate between infested and uninfested def-1 tomatoes as it did with wild-type tomatoes. Similarly, the expression of the MeSA biosynthetic gene salicylic acid methyltransferase (SAMT) was induced by spider mites in wild type but not in def-1. Exogenous application of JA to def-1 induced the accumulation of SAMT and putative geranylgeranyl diphosphate synthase transcripts and restored MeSA- and TMTT-emission upon herbivory. JA is therefore necessary to induce the enzymatic conversion of SA into MeSA. We conclude that JA is essential for establishing the spider mite-induced indirect defense response in tomato.

Six genes strongly regulated by mercury in Pisum sativum roots

Suppression subtractive hybridisation was used to isolate heavy metal-induced genes from Pisum sativum roots hydroponically exposed to 5 microM HgCl2 and 10 microM EDTA. Six genes were induced out of which one, PsHMIP6B, was novel. The other genes (PsSAMT, PsI2'H, PsNDA, PsAPSR, PsPOD) had not previously been isolated from pea and sequenced. All six genes were also induced after exposure to 5 microM HgCl2 in the absence of EDTA. The induction pattern was in some cases different for the two Hg species, demonstrating a quicker response to-free Hg2+ than Hg-EDTA. The stress-specificity of the gene regulation was investigated by hydroponically adding 5 microM Cd2+. Most Hg-induced cDNAs were also induced by Cd2+ but to a smaller extent than after Hg exposure. In addition, the gene expression was also probed for tissue specificity, which showed that all six genes were expressed in roots and not in leaves.

An Arabidopsis thaliana gene for methylsalicylate biosynthesis, identified by a biochemical genomics approach, has a role in defense

Emission of methylsalicylate (MeSA), and occasionally of methylbenzoate (MeBA), from Arabidopsis thaliana leaves was detected following the application of some forms of both biotic and abiotic stresses to the plant. Maximal emission of MeSA was observed following alamethicin treatment of leaves. A gene (AtBSMT1) encoding a protein with both benzoic acid (BA) and salicylic acid (SA) carboxyl methyltransferase activities was identified using a biochemical genomics approach. Its ortholog (AlBSMT1) in A. lyrata, a close relative of A. thaliana, was also isolated. The AtBSMT1 protein utilizes SA more efficiently than BA, whereas AlBSMT1 catalyzes the methylation of SA less effectively than that of BA. The AtBSMT1 and AlBSMT1 genes showed expression in leaves under normal growth conditions and were more highly expressed in the flowers. In A. thaliana leaves, the expression of AtBSMT1 was induced by alamethicin, Plutella xylostella herbivory, uprooting, physical wounding, and methyl jasmonate. SA was not an effective inducer. Using a beta-glucuronidase (GUS) reporter approach, the promoter activity of AtBSMT1 was localized to the sepals of flowers, and also to leaf trichomes and hydathodes. Upon thrip damage to leaves, AtBSMT1 promoter activity was induced specifically around the lesions.