Plants inevitably encounter a diverse array of constantly changing environmental stresses, and drought stands out as one of the most severe threats to plants. Abscisic acid (ABA) and jasmonic acid (JA) work synergistically to increase plant drought tolerance, but their interplay during drought response remains elusive. Here, we uncovered that ABA induced the degradation of a negative transcription regulator, ethylene responsive factor (ERF.D2), in tomato drought tolerance. We identified that ERF.D2 was phosphorylated at Ser-52 by calcium-dependent protein kinase 27 (CPK27) in an ABA-dependent manner and underwent subsequent PUB22-mediated ubiquitination. Degradation of ERF.D2 leads to the increase of the transcript levels of JA biosynthesis genes, allene oxide cyclase (AOC) and 12-oxophytodienoic acid reductase 3 (OPR3), and endogenous concentration of JA, thus enhancing tomato plant drought tolerance. These findings demonstrate a novel insight into the molecular mechanism of ABA-JA synergistic interaction during tomato drought tolerance.
Summary Plant secreted peptides RAPID ALKALINISATION FACTORs (RALFs), which act through the receptor FERONIA (FER), play important roles in plant growth. However, it remains unclear whether and how RALF‐FER contributes to the trade‐off of plant growth–defense. Here, we used a variety of techniques such as CRISPR/Cas9, protein–protein interaction and transcriptional regulation methods to investigate the role of RALF2 and its receptor FER in regulating lignin deposition, root growth, and defense against Fusarium oxysporum f. sp. lycopersici (Fol) in tomato (Solanum lycopersicum). The ralf2 and fer mutants show reduced primary root length, elevated lignin accumulation, and enhanced resistance against Fol than the wild‐type. FER interacts with and phosphorylates MYB63 to promote its degradation. MYB63 serves as an activator of lignin deposition by regulating the transcription of dirigent protein gene DIR19. Mutation of DIR19 suppresses lignin accumulation, and reverses the short root phenotype and Fol resistance in ralf2 or fer mutant. Collectively, our results demonstrate that the RALF2‐FER‐MYB63 module fine‐tunes root growth and resistance against Fol through regulating the deposition of lignin in tomato roots. The study sheds new light on how plants maintain the growth–defense balance via RALF‐FER.
Drought is a major environmental stress threatening plant growth and productivity. Calcium-dependent protein kinases (CPKs) are plant-specific Ca2+ sensors with multifaceted roles in signaling drought responses. Nonetheless, the mechanisms underpinning how CPKs transmit downstream drought signaling remain unresolved. Through genetic investigations, our study unveiled that knocking out CPK27 reduced drought tolerance in tomato (Solanum lycopersicum) plants and impaired abscisic acid (ABA)-orchestrated plant response to drought stress. Proteomics and phosphoproteomics revealed that CPK27-dependent drought-induced proteins were highly associated with the sugar metabolism pathway, which was further verified by reduced soluble sugar content in the cpk27 mutant under drought conditions. Using protein-protein interaction assays and phosphorylation assessments, we demonstrated that CPK27 directly interacted with and phosphorylated tonoplast sugar transporter 2 (TST2), promoting intercellular soluble sugar accumulation during drought stress. Furthermore, Ca2+ and ABA enhanced CPK27-mediated interaction and phosphorylation of TST2, thus revealing a role of TST2 in tomato plant drought tolerance. These findings extend the toolbox of potential interventions for enhancing plant drought stress tolerance and provide a target to improve drought tolerance by manipulating CPK27-mediated soluble sugar accumulation for rendering drought tolerance in a changing climate. A tomato calcium-dependent protein kinase controls soluble sugar accumulation, which enhances drought tolerance, by phosphorylating a tonoplast sugar transporter.
Carotenoids in tomatoes confer significant health benefits to humans but with the disadvantage of the carotenoids from raw tomatoes not being easily absorbed for utilization. Thus, this study aimed to investigate the effects of different cooking processes on carotenoid release and human gut microbiota composition during in vitro simulated gastrointestinal digestion of tomatoes. The results showed that stir-frying significantly increased the release of lycopene and β-carotene during gastrointestinal digestion, with boiling being the second most effective treatment. The boiling-treated tomatoes enhanced the carotenoid release during in vitro fermentation. Gut microbiota analysis revealed that the digestion of the raw and boiled tomatoes promoted the growth of potentially beneficial microbiota while reducing the ratio of Firmicutes/Bacteroides, which potentially helps prevent obesity. Boiling treatment significantly reduced the growth of Peptostreptococcus and was negatively correlated with carotenoid release. Overall, the boiling-treated tomatoes were more effective than the raw or stir-fried tomatoes in terms of both colon health benefits and carotenoid release.
As a potential protein kinase C inhibitor, the fungus metabolite balanol has become more attractive in recent decades. In our previous work, we revealed its biosynthetic pathway through overexpression of the cluster-situated regulator gene blnR in Chinese herb fungus Tolypocladium ophioglossoides. However, information on the regulation of blnR is still largely unknown. In this study, we further investigated the regulation of balanol biosynthesis by BlnR through the analysis of affinity binding using EMSA and RNA-seq analysis. The results showed that BlnR positively regulates balanol biosynthesis through binding to all promoters of bln gene members, including its own promoter. Microscopic observation revealed blnR overexpression also affected spore development and hypha growth. Furthermore, RNA-seq analysis suggested that BlnR can regulate other genes outside of the balanol biosynthetic gene cluster, including those involved in conidiospore development. Finally, balanol production was further improved to 2187.39 mg/L using the optimized medium through statistical optimization based on response surface methodology.
Tolypocladium ophioglossoides is a rare and valuable fungus extensively used in Chinese medicine for relieving postmenopausal syndrome in women yet its bioactive molecules are unknown. To explore its molecular mechanisms, we have developed a reliable Agrobacterium-mediated transformation system using the selective marker: the chlorimuron ethyl-resistance gene sur. For this purpose, we firstly constructed a T-DNA binary vector system and then improved the transformation efficiency by optimizing conditional parameters including the Agrobacterium tumefaciens concentration, the conidia number of T. ophioglossoides, the co-culture time and the concentration of acetosyringone. Furthermore, we have knocked-out the ku70 gene,which is a key gene in non-homologous end joining (NHEJ) DNA repair pathway,and the effect of the length of the homologous arms (HA) on the genetic transformation efficacy was also examined, which increased by 60% when HA was about 3 kb in length. Our results suggest that the genetic transformation system is efficient and feasible for the truffle-parasite fungus T. ophioglossoides, which can further be used in large-scale experiments for characterization of genes of interest in future work.
A cryptic gene cluster, bln, was activated by genome mining in Tolypocladium ophioglossoides. This activation led to the production of balanol and eight other metabolites. Gene disruption and metabolite profile analysis showed that the biosynthesis of balanol involved the convergence of independent PKS and NRPS pathways, and a biosynthetic pathway for balanol was proposed.
One of the main characteristics of tomato (Solanum lycopersicum) fruit ripening is a massive accumulation of carotenoids (mainly lycopene), which may contribute to the nutrient quality of tomato fruit and its role in chemoprevention. Previous studies have shown that ethylene (ET) plays a central role in promoting fruit ripening. In this study, the role of jasmonic acid (JA) in controlling lycopene accumulation in tomato fruits was analysed by measuring fruit lycopene content and the expression levels of lycopene biosynthetic genes in JA-deficient mutants (spr2 and def1) and a 35S::prosystemin transgenic line (35S::prosys) with increased JA levels and constitutive JA signalling. The lycopene content was significantly decreased in the fruits of spr2 and def1, but was enhanced in 35S::prosys fruits. Simultaneously, the expression of lycopene biosynthetic genes followed a similar trend. Lycopene synthesis in methyl jasmonate (MeJA) vapour-treated fruits showed an inverted U-shaped dose response, which significantly enhanced the fruit lycopene content and restored lycopene accumulation in spr2 and def1 at a concentration of 0.5 µM. The results indicated that JA plays a positive role in lycopene biosynthesis. In addition, the role of ET in JA-induced lycopene accumulation was also examined. Ethylene production in tomato fruits was depressed in spr2 and def1 while it increased in 35S::prosys. However, the exogenous application of MeJA to Never ripe (Nr), the ET-insensitive mutant, significantly promoted lycopene accumulation, as well as the expression of lycopene biosynthetic genes. Based on these results, it is proposed that JA might function independently of ethylene to promote lycopene biosynthesis in tomato fruits.
Aromatase represents an important target for the treatment of hormone-dependent breast cancer. In the present study, nine alkaloids from the dichloromethane extract of Corydalis yanhusuo were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS) and tested for their aromatase binding activities using an ultrafiltration LC-MS method by investigating the differences of peak areas of compounds before and after incubations with aromatase. It was demonstrated that the quaternary protoberberine alkaloids and the tertiary protoberberine alkaloids exhibited potent aromatase binding activities. The quaternary ammonium group and the methyl group at C-13 position of tertiary protoberberine alkaloids might be necessary for the activity. The findings should provide guidance for the discovery of potential aromatase inhibitors from natural products.
In the present study, we examined the potential chemopreventive activity of dichloromethane extract of Eurycorymbus cavaleriei by investigating the change of constitutions after incubation with glutathione (GSH). The major constitutions in the dichloromethane extract of E. cavaleriei were cumarin compounds and their cleavage pattern was examined by LC–MS-MS and the characteristic product ions at m/z 206 and 207 were helpful to determine the substitutions of coumarinolignoid compounds. The mechanism of conjugations of 5′-demethylaquillochin and its isomer with GSH was discussed and validated through analysis of the conjugations of reference compound 6-hydroxy-7-methoxycoumarin with GSH by LC–MS-MS and NMR spectrum. The relative ability to induce the detoxification enzyme, NAD(P)H:quinone oxidoreductase 1 (NQO1) of nine coumarin compounds was tested which also showed 5′-demethylaquillochin exhibited the most potential chemopreventive ability. These observations suggest that 5′-demethylaquillochin and its isomer from the dichloromethane extract of E. cavaleriei have potential as chemopreventive agents through induction of detoxification enzymes.
Quinone reductase (QR) induction is a reliable biomarker of phase II enzyme induction. In this study, glutathione (GSH) was employed and a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was introduced to reveal the chemical constituents with QR activity from the ethyl acetate extract of roots Salvia miltiorrhiza ('Danshen') and nine tanshinones (9, 13, 17-19, 21, 24-26), which could conjugate with GSH, were characterized by LC/MS/MS and considered to have QR activities. Then, thirteen tanshinones, including six compounds (17, 18, 21, 24-26) of the above nine tanshinones, were isolated to conduct QR induction evaluation, and it was found that miltirone and its derivatives (18, 20, 24, 26) exhibited significant activities. The GSH conjugate abilities of the isolated tanshinones were also examined; this showed that compounds 18, 20, 24 and 26 had good conjugating abilities with GSH. Compared with the in vitro bioactivity screening results, this proved that conjugate ability is related with QR activity, so an LC/MS/MS method can be applied to find more active compounds.
The crude ethanol extract of Pulsatilla chinensis (Bunge) Regel roots was extracted successively with light petroleum, dichloromethane and n -butanol. The light petroleum fraction (PEF) exhibited potent anti-proliferation activity on HL60 cells with an IC 50 value of 14 μg/mL. As a result, ICR mice transplanted with tumor strain S180 were employed for testing the effectiveness of drug administration of PEF. The tumor inhibitory rate was 36.7% at a dose of 20 mg/kg/d, which was higher than the positive control, which produced 31.5% inhibition. However, an unusual phenomenon was observed in that the tumor inhibitory response was reverse dose-dependent since tumor inhibition was only 19.5% at a dose of 180 mg/kg/d. GC-MS revealed that the main components of the PEF were C-19 and C-22 polyunsaturated fatty acids. Previous studies had revealed that polyunsaturated fatty acids exhibit either anti-tumor or tumor promoting activities, and so it is proposed that the effects of PEF on tumor growth is dependent on dosage.