Picolinic acid spray stimulates the antioxidative metabolism and minimizes impairments on photosynthesis on wheat leaves infected by Pyricularia oryzae

Impact of Isonicotinic Acid Blending in Chitosan/Polyvinyl Alcohol on Ripening-Dependent Changes of Green Stage Tomato

The effect of isonicotinic acid (INA) in a chitosan (CS)/polyvinyl alcohol (PVA) blend on ripening-dependent changes of preserved green tomatoes (Solanum lycopersicum L.) was examined at room temperature. The results showed that CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations retarded firmness loss and delayed the pigmentation parameters i.e., lycopene (LYP), total carotenes (TCs), and titratable acidity (TA). The CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations were able to delay the increase in malondialdehyde (MDA) and total polyphenol (TP) contents. Furthermore, the peroxidase (POD), polyphenoloxidase (PPO), and phenylalanine ammonia-lyase (PAL) activities of tomatoes coated with CS/PVA/INA 0.5 mM and CS/PVA/INA 1.0 mM formulations were lower than those in other treatments. Meanwhile, the CS/PVA blend had the highest TP content, as well as the highest PPO and PAL activities, at the late stage of maturation. The UV analysis showed that the CS/PVA/INA blend film is a promising UV-protective food packaging material. The pure CS, PVA, and INA formulations, as well as the CS/PVA, CS/PVA/INA 0.5 mM, and CS/PVA/INA 1.0 mM formulations, were characterized by infrared (FTIR). The three polymer formulations showed strong antifungal activity against Alternaria alternata and Botrytis cinerea.

Modern Approaches for the Development of New Herbicides Based on Natural Compounds

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.

Wheat Blast: A Disease Spreading by Intercontinental Jumps and Its Management Strategies

Wheat blast (WB) caused by Magnaporthe oryzae pathotype Triticum (MoT) is an important fungal disease in tropical and subtropical wheat production regions. The disease was initially identified in Brazil in 1985, and it subsequently spread to some major wheat-producing areas of the country as well as several South American countries such as Bolivia, Paraguay, and Argentina. In recent years, WB has been introduced to Bangladesh and Zambia via international wheat trade, threatening wheat production in South Asia and Southern Africa with the possible further spreading in these two continents. Resistance source is mostly limited to 2NS carriers, which are being eroded by newly emerged MoT isolates, demonstrating an urgent need for identification and utilization of non-2NS resistance sources. Fungicides are also being heavily relied on to manage WB that resulted in increasing fungal resistance, which should be addressed by utilization of new fungicides or rotating different fungicides. Additionally, quarantine measures, cultural practices, non-fungicidal chemical treatment, disease forecasting, biocontrol etc., are also effective components of integrated WB management, which could be used in combination with varietal resistance and fungicides to obtain reasonable management of this disease.

Metabolomic analysis reveals dose-dependent alteration of maize (Zea mays L.) metabolites and mineral nutrient profiles upon exposure to zerovalent iron nanoparticles

Nanoscale zero-valent iron (nZVI) has been widely applied in the environmental field to degrade organic pollutants. The potential risk posed from nZVI on crop species is not well understood and is critical for sustainable application in the future. In this study, maize (Zea mays L.) plants were cultivated in field soils mixed with nZVI at 0, 50, and 500 mg/kg soil for four weeks. Upon exposure to 500 mg/kg nZVI, ICP-MS results showed that Fe accumulated by roots and translocated to leaves was increased by 36% relative to untreated controls. At 50 mg/kg, root elongation was enhanced by 150-200%; at 500 mg/kg, pigments, lipid peroxidation, and polyphenolic levels in leaves were increased by 12, 87 and 23%, respectively, whereas the accumulation of Al, Ca, and P were decreased by 62.2%, 19.7%, and 13.3%, respectively. A gas chromatography-mass spectrometry (GC-MS) based metabolomics analysis of maize roots revealed that antioxidants and stress signaling-associated metabolites were downregulated at 50 mg/kg, but were upregulated at 500 mg/kg. At 50 mg/kg, the content of glutamate was increased by 11-fold, whereas glutamine was decreased by 99% with respect to controls. Interestingly, eight metabolic pathways were disturbed at 50 mg/kg, but none at 500 mg/kg. This metabolic reprogramming at the lower dose represented potential risks to the health of exposed plants, which could be particularly important although no phenotypic impacts were noted. Overall, metabolites analysis provides a deeper understanding at the molecular level of plant response to nZVI and is a powerful tool for full characterization of risk posed to crop species as part of food safety assessment.

Nicotinamide Effectively Suppresses Fusarium Head Blight in Wheat Plants

Pyridine nucleotides such as a nicotinamide adenine dinucleotide (NAD) are known as plant defense activators. We previously reported that nicotinamide mononucleotide (NMN) enhanced disease resistance against fungal pathogen Fusarium graminearum in barley and Arabidopsis. In this study, we reveal that the pretreatment of nicotinamide (NIM), which does not contain nucleotides, effectively suppresses disease development of Fusarium Head Blight (FHB) in wheat plants. Correspondingly, deoxynivalenol (DON) mycotoxin accumulation was also significantly decreased by NIM pretreatment. A metabolome analysis showed that several antioxidant and antifungal compounds such as trigonelline were significantly accumulated in the NIM-pretreated spikes after inoculation of F. graminearum. In addition, some metabolites involved in the DNA hypomethylation were accumulated in the NIM-pretreated spikes. On the other hand, fungal metabolites DON and ergosterol peroxide were significantly reduced by the NIM pretreatment. Since NIM is relative stable and inexpensive compared with NMN and NAD, it may be more useful for the control of symptoms of FHB and DON accumulation in wheat and other crops.