Phenol and antioxidant enzymatic activity in root knot nematode, Meloidogyne incognita infected tomato plants treated with chitosan nanoparticles

Abstract

Root knot nematode, Meloidogyne spp. causes severe yield losses in vegetable crops. Chitosan is one of the most abundant biopolymer available worldwide next to cellulose. It is known to have anti-nemic, anti-fungal and anti-bacterial properties. Application of chitosan induces systemic resistance in tomato plants against pathogens by increasing phenolic content and antioxidant enzymes viz., Polyphenol oxidase, Superoxide dismutase and phytoalexins. A study was conducted to study the phenol content and activity of antioxidant enzymes, polyphenol oxidase and peroxidase activities in root knot nematode infected tomato plants treated with chiotsan nanoparticles. The antioxidant enzymatic activities were recorded after 25 th day of nematode inoculation. It was observed that the phenolic content increased due to the application of chitosan nanoparticle in nematode infected plants (174.32 µg/g of root) compared to 160.37 µg/g of root in untreated plants. Similarly the peroxidase and polyphenol oxidase activity also increased in chitosan nanoparticle treated nematode infected plants. The study revealed that chitosan nano particles protect plants from root knot nematode infection by increasing the phenol content, peroxidase and polyphenol oxidase activity and induce systemic resistance against nemayodes. Introduction Insects, pathogens and nematodes are more prevalent in both agricultural and horticultural crops. Among nematodes, the endoparasitic nematodes like Root knot and Cyst nematodes causes severe yield losses in vegetable crops (Khan and Sharma, 2020) [14]. Plant parasitic nematodes interact with the root pathogens like Fusarium spp., Phytophthora spp., Rhizoctonia spp. and Pythium spp and increase disease severity. Several measures are taken to manage the pest, pathogen and nematode attacks. Nanotechnology is one of the recent technologies that can be used to develop several tools for drought, pest and disease resistance (Yanat and Schroen, 2021) [30]. Chitosan biopolymer is reported to possess anti-nemic, anti-fungal and anti-bacterial properties (Goy et al., 2016) [9]. It elicits enormous defense response related to biotic and abiotic stress (Malerba and Cerana, 2015) [16]. Pichyangkura and Chadhawan, 2015 [16, 24] , studied the chitosan mechanism in plants and signaling molecules were induced by chitosan involving H 2 O 2 via octadecanoid pathway and nitric oxide. Nitric oxide regulated phosphatidic acid through phospholipase and diacyglycerol kinase pathways. Those pathways activated the biotic stress responsive genes. Sathiyabama et al., 2014 [25] reported that phenolic compounds, Poly Phenol Oxidase activites, Super Oxide Dismutase activities and phytoalexins activities in tomato plants increased by chitosan which gives resistance mechanism to Alternaria solani. Hidangmayum et al. (2019) [11] found that chitin or chitosan specific receptors in plant cell membrane enhance the defense responses. The defense responses includes production of phytoalexins, pathogenesis related proteins (chitinase, β-glucanase, proteinase and induction stress response gene). It induced the signaling molecules in plants such as specific cellular receptor which is transduced by secondary messanger. The secondary messengers includes Reactive Oxygen Species (ROS), H 2 O 2 , Ca 2+ , nitric oxide and phytohormones. Chandra et al. (2015) [5] reported that chitosan nanoparticles induce plant immunity and defense related enzymes in plants. With this background a study was carried out to assess the phenol content and antioxidant enzyme activity in M. incognita infected tomato treated with chitosan nanoparticles.