Amino Acid Uptake by Tomato Leaf Tissue Under Chilling Stress: Uptake Conditions and a Comparison of Lycopersicon Species of Different Chilling Resistance

Abstract

Uptake of [³H]leucine by leaf fragments and roots from Lycopersicon esculentum (domestic tomato) and L. hirsutum (a wild tomato) was compared. Uptake of amino acids was affected by metabolic inhibitors and temperature. The L. esculentum cultivars studied, Rutgers and PI.341985, showed similar uptake rates above 12°C. After preincubation at the uptake temperatures below 12°C, the Q₁₀ for uptake for PI.341985 was about 25 while for Rutgers it was about 125. The temperature response was similar for root and leaf material and for material grown at different temperatures (24/18 and 15/5°C). The temperature response of the uptake by leaf fragments of the wild races of L. hirsutum was related to the altitude of origin. The race from the highest altitude (3100 m) showed little change in slope in a plot of tog uptake rate versus temperature over the range 4-20°C. The race from the lowest altitude (30 m) resembled the cultivars of L. esculentum in its response to temperature and showed an increasing slope below 10°C. The race of L. hirsutum from 1500 m responded to temperature in an intermediate fashion. It is concluded that the decrease in the rate of uptake of amino acids during incubation at chilling temperatures can be related to genetic adaptation to the temperature of the native habitat and chilling resistance of the variety of Lycopersicon used.