Changes in the Lycopersicum esculentum root proteome with Cd stress
Rodríguez-Celma, J., López-Millán, A. F., Abadía, A., Abadía, J.
Plant Stress Physiology Group, Dept. of Plant Nutrition, Aula Dei Experimental Station
(CSIC), Zaragoza, Spain
Heavy metals constitute a heterogeneous group of essential and non-essential elements. Non-
essential heavy metals such as Cd and Zn behave as phytotoxic elements, even when present
at low concentrations (1, 2). The aim of this work was to investigate the changes in the root
proteome to further understand the physiological responses of tomato plants to Cd. An
experiment was carried out in the growth chamber in hydroponics with five different batches
of tomato plants supplied with 0, 10 or 100 µM Cd in nutrient solution. Cadmium in the
nutrient solution decreased root and shoot fresh and dry weight when compared to control
plants (1). Plants grown with Cd had brownish roots and showed necrotic lesions in the leaf
blades (1). Cd concentrations in roots from plants grown with 0, 10 and 100 µM Cd were 0.7,
1607 and 4731 µg g-1 dry weight. Bidimensional separation of root extracts from plants grown
with 0, 10, 100 µM Cd resolved 194, 193 and 162 spots, respectively. The comparison of
averaged maps (5 replicates) indicated that 10 µM Cd caused increases and decreases in
signal intensity in 22 and 7 spots, respectively, whereas 1 and 6 spots were only detected in
Cd-free and 10 µM Cd treated plants, respectively. When analyzing root extracts from plants
grown with 100 µM Cd, 9 and 24 spots increased and decreased in signal intensity, whereas 2
and 6 spots were only detected in the 100 µM Cd and Cd-free grown plants, respectively.
From the spots whose intensity changed with Cd supply, 3 increased their signal intensity in
both 10 and 100 µM Cd treatment, while 6 decreased in both. Up to 72% of the spots where
identified by MALDI-TOF analysis. Our results suggest that the 10 µM Cd treatment caused
up-regulation of proteins involved in sugar and energy metabolism (glycolysis, TCA-cycle…)
and down-regulation of proteins involved in starch and amino-sugar metabolism. However,
the 100 µM Cd treatment induced up-regulation of chaperone-like proteins, and proteins
involved in amino-sugar metabolism and cell redox homeostasis, whereas proteins related to
glycolysis, TCA-cycle and starch-sucrose metabolism were down-regulated.
This study was supported by the Spanish Ministry of Science and Innovation (project AGL2007-
61948, co-financed with FEDER), and the Aragón Government (group A03).
(1) López-Millán A-F, Sagardoy R, Solanas M, Abadía A, Abadía J (2009) Cadmium toxicity in
tomato (Lycopersicon esculentum) plants grown in hydroponics. Environ Exp Bot 65, 376-385.
(2) Sagardoy R, Morales F, López-Millán A-F, Abadía A, Abadía J (2009) Effects of Zinc toxicity in
sugar beet (Beta vulgaris L.) plants grown in hydroponics. Plant Biol, in press.