Effect of Phytoparasitic Nematodes on Agricultural Yield: Current Progress and Challenges

Introduction

The coexistence of nematodes and plants over millions of years has led to the emergence of the plant-parasitic nematode. Broadly dispersed pathogens of vascular plants, enormous losses in yields have been ascribed to the nearness of nematodes. The complicated relationship between the parasitic nematode and plant has culminated in an “evolutionary arms race”. Phytoparasitic nematodes have advanced procedures to have resistant reactions for the improvement of feeding sites. In turn, plants have created particular molecules to recognize pathogens signaling for immune response. Declining utilize of chemical pesticides has brought incredible consideration to inquire about in elective strategies of nematode control. A successful strategy for nematode management includes the utilization and usage of nematode-resistant cultivars into crop breeding programs. So Genetic sequencing analyses are broadly utilized in the recognizable proof of molecular components of nematode parasitism and are also used to distinguish nematode-resistant and susceptible plant genotypes. These detailed investigations have essentially contributed to our generally understanding of the energetic and complex nature of plant-nematode interactions. Plant-parasitic nematodes are called plant-parasitic since supplements they get come straight forwardly from plants. They have a needle-like structure called a stylet that helps them to penetrate the plant cell wall and reach the juicy substance on which they nourish (Bernard et al., 2017). Correct identification of nematode species is fundamental for choosing the right strategies of control. The morphology based scientific classification of nematodes is complex due to intraspecific variety, but the tools and methodologies based on biochemical and atomic markers can effectively analyze a wide range of nematode species (Carneiro et al., 2017). The economic consequence of crop losses caused by nematodes come in numerous varieties and are associated with a reduction in crops production and yields quality

Plant-parasitic nematodes are recognized as one of the most noteworthy threats to crops globally. It has been found that nematodes, alone or in combination with other soil microorganisms, caused disease almost each part of the plant, consisting roots, stems, fruits, leaves and seeds. Although globally identification of nematodes as critical cause of plant infections did not happen until the mid of the last century, nematodes were examined more than 150 years earlier. The foremost harming plant-parasitic nematodes are considered to be the root-knot nematodes (RKNs), Meloidogyne sp. (Almohithef et al., 2018), which are responsible for losses in vegetable crops worldwide and determine the common utilize of chemical pesticides (Sikandar et al., 2020).

The common indications of nematode disease are the root development decrease, expanded shriveling, mineral deficiency-like symptoms, diminished winter toughness, and dieback in perennial plants. Although these indications are related to root disability, a few species of nematodes (Anguina spp.) can moreover influence other parts of the plant, leading to the cause of gall on seeds, leaves, and stems (Kumar et al., 2020). By definition, the seed gall nematodes cause seed gall, though the stem gall nematodes cause swelling and twisting of stems, and the leaf nematodes cause leaf discoloration. However, the terrestrial indications of nematode infection are predominantly circuitous and or maybe unpretentious; among them are diminished vitality, hindered development, decreased yield, and leaf chlorosis. India is one of the twelve mega biodiversity regions with 7.7% genetic resources of the world. Nematodes, as one component of the soil ecosystem, interact with biotic and abiotic factors and adapt themselves to their environment even if the environment threatens to change. If they are not able to do so, they become extinct in due course. So, they are considered as important biological indicators because of their tremendous diversity. The plant parasitic nematodes are distributed worldwide and possess a broad host range of economically important crops. They are recognized as causing more economic damage to food crops. Damage due to plant parasitic nematode causes poor growth, decline in the quality and yield of the crop and reduction in the resistance to stressors, such as, drought, diseases, etc. Damaged roots fail to absorb water and nutrients effectively, leading to additional losses.