Plant hormones have been extensively studied for their roles in the regulation of various aspects of plant development. However, in the last decade important new insights have been made into their action during development and ripening, in both dry and fleshy fruits. Emerging evidence suggests that relative functions of plant hormones are not restricted to a particular stage, and a complex network of more than one plant hormone is involved in controlling various aspects of fruit development. Though some areas are extensively covered, considerable gaps in our knowledge and understanding still exist in the control of hormonal networks and crosstalk between different hormones during fruit expansion, maturation, and various other aspects of ripening. Here, we evaluate the new knowledge on their relative roles during tomato fruit development with a view to understand their mechanism of action in fleshy fruits. For a better understanding, pertinent evidences available on hormonal crosstalk during fruit development in other species are also discussed. We envisage that such detailed knowledge will help design new strategies for effective manipulation of fruit ripening.

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Role of plant hormones and their interplay in development and ripening of fleshy fruits

Drought stress is one of the most destructive environmental factors that affect tomato plants adversely. Mitogen-activated protein kinases (MAPKs) are important signaling molecules that respond to drought stress. In this study, SlMAPK3 was induced by drought stress, and the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (CRISPR/Cas9) system was utilized to generate slmapk3 mutants. Two independent T1 transgenic lines and wild-type (WT) tomato plants were used for analysis of drought tolerance. Compared with WT plants, slmapk3 mutants exhibited more severe wilting symptom, higher hydrogen peroxide content, lower antioxidant enzymes activities, and suffered more membrane damage under drought stress. Furthermore, knockout of SlMAPK3 led to up- or down-regulated expressions of drought stress-responsive genes including SlLOX, SlGST, and SlDREB. The results suggest that SlMAPK3 is involved in drought response in tomato plants by protecting cell membranes from oxid...

Reduced Drought Tolerance by CRISPR/Cas9-Mediated SlMAPK3 Mutagenesis in Tomato Plants.

In the field, plants constantly face a plethora of abiotic and biotic stresses that can impart detrimental effects on plants. In response to multiple stresses, plants can rapidly reprogram their transcriptome through a tightly regulated and highly dynamic regulatory network where WRKY transcription factors can act as activators or repressors. WRKY transcription factors have diverse biological functions in plants, but most notably are key players in plant responses to biotic and abiotic stresses. In tomato there are 83 WRKY genes identified. Here we review recent progress on functions of these tomato WRKY genes and their homologs in other plant species, such as Arabidopsis and rice, with a special focus on their involvement in responses to abiotic and biotic stresses. In particular, we highlight WRKY genes that play a role in plant responses to a combination of abiotic and biotic stresses.

The Role of Tomato WRKY Genes in Plant Responses to Combined Abiotic and Biotic Stresses.

Many mushrooms have been used as foods and medicines for a long time. Mushrooms contain polyphenols, polysaccharides, vitamins and minerals. Studies show that mushrooms possess various bioactivities, such as antioxidant, anti-inflammatory, anticancer, immunomodulatory, antimicrobial, hepatoprotective, and antidiabetic properties, therefore, mushrooms have attracted increasing attention in recent years, and could be developed into functional food or medicines for prevention and treatment of several chronic diseases, such as cancer, cardiovascular diseases, diabetes mellitus and neurodegenerative diseases. The present review summarizes the bioactivities and health benefits of mushrooms, and could be useful for full utilization of mushrooms.

Bioactivities and Health Benefits of Mushrooms Mainly from China

Chilling stress is the main constraint in tomato ( Solanum lycopersicum) production, as this is a chilling-sensitive horticultural crop. The highly conserved C-repeat binding factors (CBFs) are cold-response-system components found in many species. In this study, we generated slcbf1 mutants using the CRISPR-Cas9 system and investigated the role of SlCBF1 in tomato-plant chilling tolerances. The slcbf1 mutants exhibited more severe chilling-injury symptoms with higher electrolyte leakage and malondialdehyde levels than wild-type (WT) plants. Additionally, slcbf1 mutants showed lower proline and protein contents and higher hydrogen peroxide contents and activities of antioxidant enzymes than WT plants. Knockout of SlCBF1 significantly increased indole acetic acid contents but decreased methyl jasmonate, abscisic acid, and zeatin riboside contents. The reduced chilling tolerance of the slcbf1 mutants was further reflected by the down-regulation of CBF-related genes. These results contribute to a better understanding of the molecular basis underlying SlCBF1 mediation of tomato chilling sensitivity.

Reduction of Tomato-Plant Chilling Tolerance by CRISPR-Cas9-Mediated SlCBF1 Mutagenesis

Bacillus subtilis strain B154, isolated from Agaricus bisporus mushroom compost infected by red bread mold, exhibited antagonistic activities against Neurospora sitophila. Antifungal activity against phytopathogenic fungi was also observed. The maximum antifungal activity was reached during the stationary phase. This antifungal activity was stable over a wide pH and temperature range and was not affected by proteases. Assay of antifungal activity in vitro indicated that a purified antifungal substance could strongly inhibit mycelia growth and spore germination of N. sitophila. In addition, treatment with strain B154 in A. bisporus mushroom compost infected with N. sitophila significantly increased the yield of bisporus mushrooms. Ultraviolet scan spectroscopy, tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis, matrix-associated laser desorption ionization time-of-flight mass spectrometry, and electrospray ionization tandem mass spectrometry analyses revealed a molecular weight consistent with 1498.7633 Da. The antifungal compound might belong to a new type of lipopeptide fengycin.

Biocontrol Activity of Bacillus subtilis Isolated from Agaricus bisporus Mushroom Compost Against Pathogenic Fungi

Nitric oxide (NO) and mitogen-activated protein kinases (MAPKs) are signal molecules involved in the disease resistance of plants. To investigate the role of tomato MAPKs in the NO-mediated defense response, mature green tomatoes (Lycopersicon esculentum Mill. cv. Qian-xi) were treated with a MAPKs inhibitor (1,4-diamino-2,3-dicyano-1,4-bis(o-amino-phenylmercapto) butadiene (U0126)), NO donor sodium nitroprusside (SNP), and SNP plus U0126. Treatment with U0126 increased the incidence of disease and size of lesion areas in the tomato fruits after being inoculated with Botrytis cinerea. NO enhanced the resistance of the tomato fruits against Botrytis cinerea invasion and the activities of nitric oxide synthase, Chitinase, β-1,3-glucanase, polyphenol oxidase, and phenylalanine ammonia-lyase. However, the effects of NO on disease resistance were weakened by the MAPKs inhibitor. Meanwhile, the relative expression of LeMAPK1, LeMAPK2, and LeMAPK3 in the (SNP + U0126)-treated fruits was lower than that in the SN...

LeMAPK1, LeMAPK2, and LeMAPK3 are associated with nitric oxide-induced defense response against Botrytis cinerea in the Lycopersicon esculentum fruit.

Mitogen-activated protein kinases (MAPKs) are major components of defense signaling pathways that transduce extracellular stimuli into intracellular responses in plants. Our previous study indicated that SlMPK1/2/3 were associated with nitric oxide-induced defense response in tomato fruit. In this study, we determine whether SlMPK1/2/3 influence the tomato fruit's innate immunity and whether plant hormones and reactive oxygen species (ROS) are involved in SlMPK1/2/3 defense signaling pathways. Treatment with 10 μM U0126 significantly inhibited the relative expression of SlMPK1, SlMPK2, and SlMPK3 (P < 0.05). U0126-treated fruit showed higher concentrations of auxin indole acetic acid (IAA), abscisic acid (ABA), and gibberellic acid (GA), but a lower concentration of methyl jasmonate (MeJA). The activities of defense enzymes, including β-1,3-glucanases (GLU), chitinase (CHI), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO), decreased after U0126 treatment. Meanwhile, H2O2 content increased, and catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POD) activities decreased after U0126 treatment. U0126 treatment enhanced the susceptibility of tomato fruit to Botrytis cinerea and resulted in more severe gray mold rot. These results demonstrate that inhibition of SlMPK1/2/3 disrupts tomato fruit defense signaling pathways and enhances the susceptibility to B. cinerea and also that plant hormones and ROS are associated with SlMPK1/2/3 defense signaling pathways.

Inhibition of SlMPK1, SlMPK2, and SlMPK3 Disrupts Defense Signaling Pathways and Enhances Tomato Fruit Susceptibility to Botrytis cinerea.

Characterization of WRKY transcription factors in Solanum lycopersicum reveals collinearity and their expression patterns under cold treatment.

Hydrogen peroxide (H2O2) acts as a signaling molecule in response to cold stress. Mitogen-activated protein kinases (MAPKs) and C-repeat/dehydration-responsive factor (CBF) play important roles in cold response regulation. To investigate the roles of MAPKs and CBF in H2O2-induced chilling tolerance, tomato (Solanum lycopersicum cv. Ailsa Craig) plants were treated with 1 mM H2O2 before chilling treatment. The results showed that H2O2 treatment protected subcellular structure, increased concentrations of abscisic acid (ABA), zeatin riboside (ZR), and methyl jasmonate (MeJA), but decreased the concentration of gibberellic acid (GA3). Furthermore, 1 mM H2O2 treatment enhanced the activities of antioxidant enzymes. Meanwhile, relative expressions of SlMAPK1/2/3 and SlCBF1 in H2O2-treated plants were higher than those in the control. Our findings suggest that H2O2 treatment might enhance the chilling tolerance of tomato plants by activating SlMAPK1/2/3 and SlCBF1 gene expression and by regulating phytohormone ...

Yanyan Zheng

Papers

Biocontrol Activity of Bacillus subtilis Isolated from Agaricus bisporus Mushroom Compost Against Pathogenic Fungi

LeMAPK1, LeMAPK2, and LeMAPK3 are associated with nitric oxide-induced defense response against Botrytis cinerea in the Lycopersicon esculentum fruit.

Inhibition of SlMPK1, SlMPK2, and SlMPK3 Disrupts Defense Signaling Pathways and Enhances Tomato Fruit Susceptibility to Botrytis cinerea.

Characterization of WRKY transcription factors in Solanum lycopersicum reveals collinearity and their expression patterns under cold treatment.

SlMAPK1/2/3 and Antioxidant Enzymes Are Associated with H2O2-Induced Chilling Tolerance in Tomato Plants.