A STUDY ON CYTOTOXIC IONS SEQUESTRATION AND K+/Na+ LEVELS AS SALT TOLERANT INDICATORS IN TOMATO (Solanum lycospersicum L.)

*Gumi, A.M and Aliero, A.A

Department of Biological Sciences

Usmanu Danfodiyo University, Sokoto

E-mail: muhammadag@yahoo.co.uk, amgumi@udusok.edu.ng

ABSTRACT

The study on ion homeostasis and cytotoxic ion sequestration in tomato (Solanum lycospersicum L.) was investigated. Salinity stress did not show a significant effect (P>0.05) on dry matter accumulation of shoots and roots of tomato. The accumulation of sodium ion (Na⁺) in root of tomato increased in salt treated groups (50 mM, 75 mM and 100 mM) while in shoot of tomato, the Na⁺ accumulation was highest (6 times higher than the control) in 75 mM treatment. Potassium (K⁺) uptake was salt concentration dependent in both shoot and root and 50 mM treatment of each organ yielded highest K⁺ content. The Na⁺/K⁺ levels in shoot and root increased with increasing concentrations but the magnitude of this level is lower in shoot than in root due to the high level of K⁺ content in the shoot tissues. It can be concluded from these findings that Na⁺ was compartmentalised both in shoot and root of tomato by membrane transporters and that low level of Na⁺/K⁺ level was a good indicator of salt tolerance property in the tomato genotype studied.

Keywords: Sequestration; Solanum lycospersicum; Salinity stress; ion homeostasis; membrane transporters, cytotoxic ions