ABSTRACT
ß-cyclocitral (ßCC) is one of the significant oxidative products of ß-carotene. It primes plants for multiple stress acclimation without compromising plant growth. Metabolic reorganization is necessary to maintain a balance between growth and defense. However, the ßCC-mediated changes in a plant's metabolic network are unknown. Here, we demonstrate how ßCC-induced metabolic changes enable Solanum lycopersicum L. (tomato) plants to promote defense and maintain growth under stress. An analysis of early (0-240 min) and late (72 h) changes in the tomato metabolome after ßCC-treatment using liquid chromatography and tandem mass spectrometry identified 57 compounds. A principal coordinate analysis suggested that ßCC treatment significantly changes the metabolite profile. A variable importance in projection (VIP) analysis revealed 16 and 19 discriminant metabolites from early and late samples, respectively (VIP ≥ 1.0). Upregulated metabolites were mainly amino acids and phytophenols. Pathway enrichment analysis showed that ßCC treatment influenced amino acid metabolism at early and later times; however, phenylpropanoid and isoquinoline biosynthesis were influenced only at the later time. A 66.6% similarity in the upregulated metabolites of ßCC- and simulated-herbivory-treated plants confirmed ßCC's role against herbivores. We conclude that ßCC steers a temporal separation in amino acids and defense metabolite accumulation that optimizes resource allocation to growth and defense.
ABSTRACT
ß-cyclocitral (ßCC), a major apocarotenoid of ß-carotene, enhances plants' defense against environmental stresses. However, the knowledge of ßCC's involvement in the complex stress-signaling network is limited. Here we demonstrate how ßCC reprograms the transcriptional responses that enable Solanum lycopersicum L. (tomato) plants to endure a plethora of environmental stresses. Comparative transcriptome analysis of control and ßCC-treated tomato plants was done by generating RNA sequences in the BGISEQ-500 platform. The trimmed sequences were mapped on the tomato reference genome that identifies 211 protein-coding differentially expressed genes. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis and their enrichment uncovered that only upregulated genes are attributed to the stress response. Moreover, 80% of the upregulated genes are functionally related to abiotic and biotic stresses. Co-functional analysis of stress-responsive genes revealed a network of 18 genes that code for heat shock proteins, transcription factors (TFs), and calcium-binding proteins. The upregulation of jasmonic acid (JA)-dependent TFs (MYC2, MYB44, ERFs) but not the JA biosynthetic genes is surprising. However, the upregulation of DREB3, an abscisic acid (ABA)-independent TF, validates the unaltered expression of ABA biosynthetic genes. We conclude that ßCC treatment upregulates multiple stress-responsive genes without eliciting JA and ABA biosynthesis.
ABSTRACT
Voltage-gated sodium channel NaV1.7 is a genetically validated target for pain. Identification of NaV1.7 inhibitors with all of the desired properties to develop as an oral therapeutic for pain has been a major challenge. Herein, we report systematic structure-activity relationship (SAR) studies carried out to identify novel sulfonamide derivatives as potent, selective, and state-dependent NaV1.7 inhibitors for pain. Scaffold hopping from benzoxazine to chroman and indane bicyclic system followed by thiazole replacement on sulfonamide led to identification of lead molecules with significant improvement in solubility, selectivity over NaV1.5, and CYP2C9 inhibition. The lead molecules 13, 29, 32, 43, and 51 showed a favorable pharmacokinetics (PK) profile across different species and robust efficacy in veratridine and formalin-induced inflammatory pain models in mice. Compound 51 also showed significant effects on the CCI-induced neuropathic pain model. The profile of 51 indicated that it has the potential for further evaluation as a therapeutic for pain.
