Effects of lindane on cell structure of pea roots

Abstract

Lindane affected growth of pea plants (Pisum sativum L.). Threshold concentrations of the insecticide at which no inhibitory effects could be noticed were established to be between 1 and 2 ppm. Below that level, plant development was stimulated, while above it primary roots were shortened, thickened, club-shaped, and lacked secondary root and root-hair development. Growth of the green plant parts was also significantly reduced.Changes in root morphology associated with lindane phytotoxicity were examined by scanning electron microscopy. A lack of secondary root and root-hair development, disruptions of the epidermal layer, "extraneous" surface tissue on roots grown in lindane-treated sand, as well as increased vacuolation in the region of elongation, were noticed. The disorganization and enlargement of the pericycle and lateral root initials created mechanical stresses which resulted in the disruption and breaking of cortical and epidermal tissue.Cytological changes in pea root tissue were investigated using light and transmission and scanning electron microscopy. The occurrence of anomalous cell wall development, both as simple cellulosic bars projecting into or traversing a cell and as random networks of material in the lumen of the cell, was noticed. The possible misinterpretation of multinucleate cells, as seen by light microscopy, is projected in view of the greatly enlarged and lobed nuclei identified through transmission electron microscopy. These nuclei were seen to inhabit more than one cell simultaneously by virtue of incomplete wall formation. Intramitochondrial crystals were identified; the frequency of their occurrence increased with increased lindane concentration in sand.