Morpho-physiological Alterations in Capsicum annuum L. by the False Root-knot Nematode Nacobbus aberrans

Abstract

Nacobbus aberrans is a phytoparasitic nematode responsible for significant losses in numerous horticultural crops. For this reason, it is considered a major economic pest in several countries. This work focuses on the morphological, biochemical, and physiological changes in pepper plants due to N. aberrans parasitism. The experiment was conducted under controlled conditions. A significant reduction in growth was observed in the inoculated plants, showing less accumulation of dry matter in aerial parts and roots. The leaves of the inoculated plants showed lower chlorophyll and soluble protein contents than the non-inoculated plants. Net photosynthesis and transpiration decreased, thus reducing water use efficiency in the inoculated plants. Stomatal conductance in the inoculated plants was also lower. The penetration of mobile forms of N. aberrans in the roots damaged cell membranes, as evidenced by a more profuse release of electrolytes that, in turn, increased relative conductivity. Malondialdehyde content was higher in the roots and leaves of inoculated plants than in plants without nematodes. An increase in the catalase activity and peroxidase enzymes was observed in plants infected by N. aberrans. The loss of functionality in inoculated roots caused drought stress and culminated in reduced plant growth. This was also confirmed by a greater accumulation of proline and sugars, metabolites used as osmoregulators in water-deficit situations.