Abstract: Cadmium is one of the most serious heavy metal pollutions in agricultural soils in China. Three-day-old tomato seedlings were treated with 0.01–1.00 mmol L^–1 Cd²⁺ for 72 h. The results showed that seedling growth was obviously inhibited and seedling height was decreased from 4.76±0.5 cm (in control) to 3.79±0.05 cm (in 0.01 mmol L^–1 Cd²⁺ treatment, P<0.01) and 1.77±0.15 cm (in 0.03 mmol L^–1 Cd²⁺ treatment, P<0.01). In addition, root length was also decreased from 6.07±0.04 cm (in control) to 4.77±0.58 cm (in 0.01 mmol L^–1 Cd²⁺ treatment, P<0.01) and 3.65±0.66 cm (in 0.03 mmol L^–1Cd²⁺ treatment, P<0.01). The chlorophyll contents decreased in the treatment with 0.1 mmol L^–1 Cd²⁺. Ten protein spots in roots and twenty one protein spots in leaves were altered when the seedlings were treated with 0.05 mmol L^–1 Cd²⁺. Total ten protein spots in roots were identified by MS/MS. Four new proteins were induced in roots, including spot 1: ribosomal protein L 20, spot 2: F-box /LRR repeat protein, spot 4: ribosomal protein small submit 4 and spot 5: CBL-interacting protein kinase. In the leaves, two protein spots disappeared and four new protein spots were induced, including spot 16, ABC transporter; spot 17, maturase-like protein; spot 1, chalcone synthase; spot 3, a hypothetical protein; spot 4, an unknown protein and spot 6, a predicated protein. These Cd²⁺ responsive proteins identified could be involved in protein biosynthesis, mRNA transcription regulation and protein transport. The above results showed that tomato is one of the highly sensitive crops to Cd²⁺ and could be used as a model to study the adaptation and tolerance mechanisms to heavy metals at physiological and biochemical levels.

Key words: Cd²⁺-stress, Proteome, Partial amino acid sequence, MALDI-TOF-MS, Tomato (Lycopersicon esculentum L.)