Several recent studies have reported on the role of mitogen-activated protein kinase (MAPK3) in plant immune responses. However, little is known about how MAPK3 functions in tomato (Solanum lycopersicum L.) infected with tomato yellow leaf curl virus (TYLCV). There is also uncertainty about the connection between plant MAPK3 and the salicylic acid (SA) and jasmonic acid (JA) defense-signaling pathways. The results of this study indicated that SlMAPK3 participates in the antiviral response against TYLCV. Tomato seedlings were inoculated with TYLCV to investigate the possible roles of SlMAPK1, SlMAPK2, and SlMAPK3 against this virus. Inoculation with TYLCV strongly induced the expression and the activity of all three genes. Silencing of SlMAPK1, SlMAPK2, and SlMAPK3 reduced tolerance to TYLCV, increased leaf H₂O₂ concentrations, and attenuated expression of defense-related genes after TYLCV infection, especially in SlMAPK3-silenced plants. Exogenous SA and methyl jasmonic acid (MeJA) both significantly induced SlMAPK3 expression in tomato leaves. Over-expression of SlMAPK3 increased the transcript levels of SA/JA-mediated defense-related genes (PR1, PR1b/SlLapA, SlPI-I, and SlPI-II) and enhanced tolerance to TYLCV. After TYLCV inoculation, the leaves of SlMAPK3 over-expressed plants compared with wild type plants showed less H₂O₂ accumulation and greater superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activity. Overall, the results suggested that SlMAPK3 participates in the antiviral response of tomato to TYLCV, and that this process may be through either the SA or JA defense-signaling pathways.

Changing climate, food shortage, water scarcity and rapidly increasing population are some of the emerging challenges globally. Drought stress is the most devastating threat for agricultural productivity. Natural plant growth substances are intensively used to improve the productivity of crop plants grown under stressed and benign environments. The current study evaluated whether leaf extract of different moringa (Moringa oleiferaL.) could play a role in improving drought-tolerance of rice (Oryza sativaL.). Rice plants were grown under three drought conditions, i.e., no, moderate and severe drought (100, 75 and 50% field capacity, respectively). Moringa leaf extract (MLE) obtained from four landraces (Multan, Faisalabad, D. G. Khan and exotic landrace from India) was applied during critical crop growth stages, i.e., tillering, panicle initiation and grain filling. Drought stress adversely affected the gas exchange attributes, photosynthetic pigments, antioxidant enzymes’ activities, yield and quality parameters of rice. Application of MLE from all landraces significantly improved physiological, biochemical and yield parameters under stressed and normal environmental conditions. The highest improvement in gas exchange traits (photosynthetic rate, stomatal conductance and respiration rate), photosynthetic pigments (chlorophylla,band carotenoids) and enzymatic activities (superoxide dismutase, catalase) and oxidative marker (H₂O₂) was recorded with MLE obtained from Faisalabad landrace. The application of MLE of Faisalabad landrace also improved yield and grain quality of rice grown under drought stress as well as drought-free environment. Thus, MLE of Faisalabad can be successfully used to improve growth, productivity and grain quality of rice under drought stress.

Drought is a major threat to agriculture production worldwide. Mitogen-activated protein kinases (MAPKs) play a pivotal role in sensing and converting stress signals into appropriate responses so that plants can adapt and survive. To examine the function of MAPKs in the drought tolerance of tomato plants, we silenced the SpMPK1, SpMPK2, and SpMPK3 genes in wild-type plants using the virus-induced gene silencing (VIGS) method. The results indicate that silencing the individual genes or co-silencing SpMPK1, SpMPK2, and SpMPK3 reduced the drought tolerance of tomato plants by varying degrees. Co-silencing SpMPK1 and SpMPK2 impaired abscisic acid (ABA)-induced and hydrogen peroxide (H₂O₂)-induced stomatal closure and enhanced ABA-induced H₂O₂ production. Similar results were observed when silencing SpMPK3 alone, but not when SpMPK1 and SpMPK2 were individually silenced. These data suggest that the functions of SpMPK1 and SpMPK2 are redundant, and they overlap with that of SpMPK3 in drought stress signaling pathways. In addition, we found that SpMPK3 may regulate H₂O₂ levels by mediating the expression of CAT1. Hence, SpMPK1, SpMPK2, and SpMPK3 may play crucial roles in enhancing tomato plants’ drought tolerance by influencing stomatal activity and H₂O₂ production via the ABA-H₂O₂ pathway.

Contamination by petroleum hydrocarbons (PHs) is a great threat to environment due to the higher persistence and bio-toxicity of PHs. Therefore, removal of PHs from contaminated environment and strategies to reduce their toxic effects on living organisms are crucial for environmental safety and human health. The toxic effects of PHs from the polluted soil can be reduced by the addition of microbes and biochar. In this study, a pot trial was carried out to evaluate the effects of sugarcane bagasse (SB) biochar and Bacillus sp. MN54 addition on phytoremediation of PHs and growth of maize (Zea mays L.) in soil artificially contaminated with diesel. Maize seeds were sown in uncontaminated or contaminated (with PHs) soil, treated with biochar and Bacillus sp. MN54. The results revealed that PHs showed significant phytotoxicity to maize plants and the application of strain MN54 and biochar greatly reduced the toxic effects of PHs on plants growth and physiology by increasing the nutrients uptake in PHs contaminated soil. Interestingly, the phytotoxicity of PHs on maize plants was further reduced in the co-supplementation of strain MN54 and biochar. Plants physiological (25–48%) and agronomic (38–47%) attributes were significantly higher as compared to only PHs contaminated soil in the co-supplementation of strain MN54 and biochar. Similarly, nitrogen (41%), phosphorus (43%) and potassium (37%) concentrations were also increased in the co-supplementation of strain MN54 and biochar. Furthermore, maize plants successfully phytoremediate a considerable amount of PHs from soil particularly in the presence of strain MN54 and biochar, and this PHs removal was further enhanced in the co-supplementation of strain MN54 and biochar (i.e., 46% and 77% of initial PHs were removed in unplanted and planted treatments, respectively). The present results indicate that co-supplementation of biochar and Bacillus sp. MN54 could be effective in enhancing the degradation of PHs and improving plant growth in the hydrocarbons contaminated soil.