Structure and development of root gall induced by Meloidogyne javanica in Glycine max L.

Abstract

Galls formed by root-knot nematodes have been studied in several cultivated species focusing on understanding the intimate relationship between parasite and the host plant. Species of Meloidogyne induce the development of a feeding site in the cortex or vascular cylinder of the host plant and are totally dependent on this site formation to complete their life cycle. Therefore, we focused on anatomical, cytological and histochemical changes during the establishment and development of galls and giant cells induced by Meloidogyne javanica in the roots of Glycine max. Seeds of soybean (susceptible cultivar M8372 IPRO) were sown in trays with coconut fibre substrate and the seedlings were removed ten days after the seeds emerged for nematode inoculation. The roots from inoculated and non-inoculated (control) were sampled at different stages of development until 55 days after inoculation. Histological, cytological, histochemical analysis were performed in light and electron microscopy in non-galled tissue and galls induced by M. javanica. The galls showed different shapes and abundance in the roots inoculated by M. javanica. The induction of galls occurs by hypertrophy of the root cortex shortly after the initial infection process. Giant cells were formed 18 days after nematode inoculation. These giant or nourishing cells are multinucleated, and have a dense cytoplasm, a thick wall with invaginations, many mitochondria and small vacuoles. The anatomical sections indicated a disorganisation of the cells of the cortex and vascular cylinder in relation to the control root.

Rhizophagus clarus controls Meloidogyne javanica and enhances the activity of defense-related enzymes in tomato

“…Such an effect is provided by the extension of hyphae in soil (Prasad et al, 2017). Nematode parasitism results in the disorganization of the central cylinder of plant roots (Wanderley & Santos, 2004;Vitela et al, 2019), thereby limiting the absorption of soil solution. R. clarus increased plant phytomass even in the presence of nematodes, evidence of the benefits that the fungus may provide in the control of M. javanica.…”

“…infection (Pinheiro et al, 2019). Females of these sedentary endoparasites establish a complex parasitic relationship with hosts, inducing feeding sites characterized by the presence of multinucleated giant cells (Vitela et al, 2019). Adjacent cells undergo hyperplasia and hypertrophy, resulting in the occurrence of nodosities in roots, a symptom also known as galls (Jones et al, 2013).…”

Plasmodesmata play pivotal role in sucrose supply to Meloidogyne graminicola‐caused giant cells in rice

“…and Heterodera spp., infect host roots and establish feeding sites within the root tissues (Kyndt et al., 2013). It has been suggested that plant sugars are transported into the feeding sites and are stored as starch for nematodes’ carbohydrate needs (Hofmann et al., 2008; Vilele et al., 2019). Two different mechanisms on sucrose supply to feeding sites of sedentary plant‐parasitic nematodes have been uncovered in Arabidopsis .…”

Effects of yeast fermentation broths on the Meloidogyne incognita population in soybean

“…Gall formation results from the hypertrophy of root cortex cells with the differentiation of vascular cylinder cells into giant cells, but it is not a fundamental factor for the success of rootknot nematodes (Vilela et al 2019). Success occurs when the nematode establishes a well-defined feeding site, the coenocyte, and the gall may appear before the coenocyte (Ferraz and Brown 2016).…”