The jasmonate biosynthesis Gene OsOPR7 can mitigate salinity induced mitochondrial oxidative stress

Cadmium induced defense enhance the invasive potential of Wedelia trilobata under herbivore infestation

Cadmium (Cd) pollution is on the rise due to rapid urbanization, which emphasize the potential adverse effects on plant biodiversity and human health. Wedelia as a dominant invasive species, is tested for its tolerance to Cd-toxicity and herbivore infestation. We investigate defense mechanism system of invasive Wedelia trilobata and its native congener Wedelia chinensis against the Cd-pollution and Spodoptera litura infestation. We found that Cd-toxicity significantly increase hydrogen peroxide (H2O2), Malondialdehyde (MDA) and hydroxyl ions (O2•) in W. chinensis 20.61%, 4.78% and 15.68% in leave and 27.44%, 25.52% and 30.88% in root, respectively. The photosynthetic pigments (Chla, Chla and Caro) and chlorophyll florescence (Fo and Fv/Fm) declined by (60.23%, 58.48% and 51.96%), and (73.29% and 55.75%) respectively in W. chinensis and (44.76%, 44.24% and 44.30%), and (54.66% and 45.36%) in W. trilobata under Cd treatment and S. litura. Invasive W. trilobata had higher enzymatic antioxidant SOD 126.9/71.64%, POD 97.24/94.92%, CAT 53.99/25.62% and APX 82.79/50.19%, and nonenzymatic antioxidant ASA 10.47/16.87%, DHA 15.07/27.88%, GSH 15.91/10.03% and GSSG 13.56/17.93% activity in leaf/root, respectively. Overall, W. trilobata accumulate higher Cd content 55.41%, 50.61% and 13.95% in root, shoot and leaf tissues respectively, than its native congener W. chinensis. While, nutrient profile of W. chinensis reveals less uptake of Fe, Cu and Zn than W. trilobata. W. trilobata showed efficient alleviation of oxidative damage through upregulating the genes related to key defense such as SOD, POD, CAT, APX, GR, PROL, FLV, ABA and JAZ, and metal transporter in leaves, shoot and root tissues, respectively. Conclusively, W. trilobata efficiently employed Cd-triggered defense for successful invasion, even under S. litura infestation, in Cd-contaminated soil.

SlWRKY81 regulates Spd synthesis and Na+ /K+ homeostasis through interaction with SlJAZ1 mediated JA pathway to improve tomato saline-alkali resistance

Saline-alkali stress is an important abiotic stress factor affecting tomato (Solanum lycopersicum L.) plant growth. Although the involvement of the tomato SlWRKY gene family in responses to saline-alkali stress has been well established, the mechanism underlying resistance to saline-alkali stress remains unclear. In this study, we investigated the role of SlWRKY81 in conferring saline-alkali stress resistance by using overexpression and knockout tomato seedlings obtained via genetic modification. We demonstrated that SlWRKY81 improves the ability of tomato to withstand saline-alkali stress by enhancing antioxidant capacity, root activity, and proline content while reducing malondialdehyde levels. Saline-alkali stress induces an increase in jasmonic acid (JA) content in tomato seedlings, and the SlWRKY81 promoter responds to JA signaling, leading to an increase in SlWRKY81 expression. Furthermore, the interaction between SlJAZ1 and SlWRKY81 represses the expression of SlWRKY81. SlWRKY81 binds to W-box motifs in the promoter regions of SlSPDS2 and SlNHX4, thereby positively regulating their expression. This regulation results in increased spermidine (Spd) content and enhanced potassium (K+ ) absorption and sodium (Na+ ) efflux, which contribute to the resistance of tomato to saline-alkali stress. However, JA and SlJAZ1 exhibit antagonistic effects. Elevated JA content reduces the inhibitory effect of SlJAZ1 on SlWRKY81, leading to the release of additional SlWRKY81 protein and further augmenting the resistance of tomato to saline-alkali stress. In summary, the modulation of Spd synthesis and Na+ /K+ homeostasis mediated by the interaction between SlWRKY81 and SlJAZ1 represents a novel pathway underlying tomato response to saline-alkali stress.

SlWRKY80-mediated jasmonic acid pathway positively regulates tomato resistance to saline-alkali stress by enhancing spermidine content and stabilizing Na+/K+ homeostasis

Saline-alkali is an important abiotic stressor influencing tomato production. Exogenous methyl jasmonate (MeJA) is well known to increase tomato resistance to a variety of stresses, although its exact mechanism is yet unknown. In this study we confirmed that 22.5 μmol/l MeJA could significantly improve the saline-alkali stress resistance of tomato. Saline-alkali (300 mM) stress increased the endogenous MeJA and jasmonic acid (JA) contents of tomato by 18.8 and 13.4%, respectively. Exogenous application of 22.5 μmol/l MeJA increased the endogenous MeJA and JA contents in tomato by 15.2 and 15.9%, respectively. Furthermore, we found an important transcription factor, SlWRKY80, which responded to MeJA, and constructed its overexpressing and knockout lines through genetic transformation. It was found that SlWRKY80 actively regulated tomato resistance to saline-alkali stress, and the spraying of exogenous MeJA (22.5 μmol/l) reduced the sensitivity of SlWRKY80 knockout lines to saline-alkali stress. The SlWRKY80 protein directly combines with the promoter of SlSPDS2 and SlNHX4 to positively regulate the transcription of SlSPDS2 and SlNHX4, thereby promoting the synthesis of spermidine and Na+/K+ homeostasis, actively regulating saline-alkali stress. The augmentation of JA content led to a notable reduction of 70.6% in the expression of SlJAZ1, and the release of the SlWRKY80 protein interacting with SlJAZ1. In conclusion, we revealed the mechanism of exogenous MeJA in tomato stress resistance through multiple metabolic pathways, elucidated that exogenous MeJA further promotes spermidine synthesis and Na+/K+ homeostasis by activating the expression of SlWRKY80, which provides a new theoretical basis for the study of the JA stress resistance mechanism and the production of tomato.

Functional analysis of a rice 12-oxo-phytodienoic acid reductase gene (OsOPR1) involved in Cd stress tolerance

BACKGROUND

The accumulation of cadmium (Cd) in plants may compromise the growth and development of plants, thereby endangering human health through the food chain. Understanding how plants respond to Cd is important for breeding low-Cd rice cultivars.

METHODS

In this study, the functions of 12-oxo-phytodienoic acid reductase 1 (OsOPR1) were predicted through bioinformatics analysis. The expression levels of OsOPR1 under Cd stress were analyzed by using qRT-PCR. Then, the role that OsOPR1 gene plays in Cd tolerance was studied in Cd-sensitive yeast strain (ycf1), and the Cd concentration of transgenic yeast was analyzed using inductively coupled plasma mass spectrometry (ICP-MS).

RESULTS

Bioinformatics analysis revealed that OsOPR1 was a protein with an Old yellow enzyme-like FMN (OYE_like_FMN) domain, and the cis-acting elements which regulate hormone synthesis or responding abiotic stress were abundant in the promoter region, which suggested that OsOPR1 may exhibit multifaceted biological functions. The expression pattern analysis showed that the expression levels of OsOPR1 were induced by Cd stress both in roots and roots of rice plants. However, the induced expression of OsOPR1 by Cd was more significant in the roots compared to that in roots. In addition, the overexpression of OsOPR1 improved the Cd tolerance of yeast cells by affecting the expression of antioxidant enzyme related genes and reducing Cd content in yeast cells.

CONCLUSION

Overall, these results suggested that OsOPR1 is a Cd-responsive gene and may has a potential for breeding low-Cd or Cd-tolerant rice cultivars and for phytoremediation of Cd-contaminated in farmland.

Transcriptomic analysis reveals that methyl jasmonate confers salt tolerance in alfalfa by regulating antioxidant activity and ion homeostasis

Introduction

Alfalfa, a globally cultivated forage crop, faces significant challenges due to its vulnerability to salt stress. Jasmonates (JAs) play a pivotal role in modulating both plant growth and response to stressors.

Methods

In this study, alfalfa plants were subjected to 150 mM NaCl with or without methyl jasmonate (MeJA). The physiological parameters were detected and a transcriptomic analysis was performed to elucidate the mechanisms underlying MeJA-mediated salt tolerance in alfalfa.

Results

Results showed that exogenous MeJA regulated alfalfa seed germination and primary root growth in a dose-dependent manner, with 5µM MeJA exerting the most efficient in enhancing salt tolerance. MeJA at this concentration elavated the salt tolerance of young alfalfa seedlings by refining plant growth, enhancing antioxidant capacity and ameliorating Na+ overaccumulation. Subsequent transcriptomic analysis identified genes differentially regulated by MeJA+NaCl treatment and NaCl alone. PageMan analysis revealed several significantly enriched categories altered by MeJA+NaCl treatment, compared with NaCl treatment alone, including genes involved in secondary metabolism, glutathione-based redox regulation, cell cycle, transcription factors (TFs), and other signal transductions (such as calcium and ROS). Further weighted gene co-expression network analysis (WGCNA) uncovered that turquoise and yellow gene modules were tightly linked to antioxidant enzymes activity and ion content, respectively. Pyruvate decar-boxylase (PDC) and RNA demethylase (ALKBH10B) were identified as the most central hub genes in these two modules. Also, some TFs-hub genes were identified by WGCNA in these two modules highly positive-related to antioxidant enzymes activity and ion content.

Discussion

MeJA triggered a large-scale transcriptomic remodeling, which might be mediated by transcriptional regulation through TFs or post-transcriptional regulation through demethylation. Our findings contributed new perspectives for understanding the underneath mechanisms by which JA-mediated salt tolerance in alfalfa.

Effects of drought and rehydration on root gene expression in seedlings of Pinus massoniana Lamb

The mechanisms underlying plant response to drought involve the expression of numerous functional and regulatory genes. Transcriptome sequencing based on the second- and/or third-generation high-throughput sequencing platforms has proven to be powerful for investigating the transcriptional landscape under drought stress. However, the full-length transcriptomes related to drought responses in the important conifer genus Pinus L. remained to be delineated using the third-generation sequencing technology. With the objectives of identifying the candidate genes responsible for drought and/or rehydration and clarifying the expression profile of key genes involved in drought regulation, we combined the third- and second-generation sequencing techniques to perform transcriptome analysis on seedling roots under drought stress and rewatering in the drought-tolerant conifer Pinus massoniana Lamb. A sum of 294,114 unique full-length transcripts were produced with a mean length of 3217 bp and N50 estimate of 5075 bp, including 279,560 and 124,438 unique full-length transcripts being functionally annotated and Gene Ontology enriched, respectively. A total of 4076, 6295 and 18,093 differentially expressed genes (DEGs) were identified in three pair-wise comparisons of drought-treatment versus control transcriptomes, including 2703, 3576 and 8273 upregulated and 1373, 2719 and 9820 downregulated DEGs, respectively. Moreover, 157, 196 and 691 DEGs were identified as transcription factors in the three transcriptome comparisons and grouped into 26, 34 and 44 transcription factor families, respectively. Gene Ontology enrichment analysis revealed that a remarkable number of DEGs were enriched in soluble sugar-related and cell wall-related processes. A subset of 75, 68 and 97 DEGs were annotated to be associated with starch, sucrose and raffinose metabolism, respectively, while 32 and 70 DEGs were associated with suberin and lignin biosynthesis, respectively. Weighted gene co-expression network analysis revealed modules and hub genes closely related to drought and rehydration. This study provides novel insights into root transcriptomic changes in response to drought dynamics in Masson pine and serves as a fundamental work for further molecular investigation on drought tolerance in conifers.

12-Oxophytodienoate Reductase Overexpression Compromises Tolerance to Botrytis cinerea in Hexaploid and Tetraploid Wheat

12-Oxophytodienoate reductase is the enzyme involved in the biosynthesis of phytohormone jasmonates, which are considered to be the major regulators of plant tolerance to biotic challenges, especially necrotrophic pathogens. However, we observe compromised tolerance to the necrotrophic fungal pathogen Botrytis cinerea in transgenic hexaploid bread wheat and tetraploid emmer wheat plants overexpressing 12-OXOPHYTODIENOATE REDUCTASE-3 gene from Arabidopsis thaliana, while in Arabidopsis plants themselves, endogenously produced and exogenously applied jasmonates exert a strong protective effect against B. cinerea. Exogenous application of methyl jasmonate on hexaploid and tetraploid wheat leaves suppresses tolerance to B. cinerea and induces the formation of chlorotic damages. Exogenous treatment with methyl jasmonate in concentrations of 100 µM and higher causes leaf yellowing even in the absence of the pathogen, in agreement with findings on the role of jasmonates in the regulation of leaf senescence. Thereby, the present study demonstrates the negative role of the jasmonate system in hexaploid and tetraploid wheat tolerance to B. cinerea and reveals previously unknown jasmonate-mediated responses.