“The false root-knot nematode: Modification of the root anatomy and alteration of the physiological performance in tomato plants”

Abstract

This work relates the biological cycle of the plant-parasitic nematode Nacobbus aberrans and its impact on the morphology and physiology of tomato (Solanum lycopersicum L) plants. Tomato var. platense plants were grown in 10 L pots in a greenhouse using a previously sterilized substrate. Half of the plants were inoculated at the time of transplanting with 5000 eggs of the nematode (parasitized treatment) and the other half remained noninoculated (control). Histological sections performed 75 days after inoculation showed that the establishment of adult females of N. aberrans in roots caused a displacement of the xylem and phloem. This alteration induced a series of changes and symptoms in parasitized plants compared to control plants. Stomatic conductance, photosystem II efficiency, and CO2 fixation (net photosynthesis) showed significantly lower values in parasitized plants. Leaf chlorophyll content and soluble protein content were also reduced. Plants inoculated with the nematode showed a higher accumulation of osmoregulatory metabolites such as proline and sugars as well as malondialdehyde, an indicator of cell membrane damage. Results indicate that the symptoms and alterations caused by this phytoparasite are consistent with those of a plant subjected to water stress.