Plant defense responses to stress have attracted interest because of their similarity to reported mammalian stress responses. To investigate plant responses to abiotic stress, caspase 10-like enzymatic activities of Lycopersicon hirsutum and Lycopersicon esculentum were assayed in response to copper chloride and paraquat induction. Caspase 10-like activity was greatest at 40 mM CuCl2 at 9 h after elicitation in both L. hirsutum and L. esculentum, for which respective response slopes (Δ absorbance per Δ minute) were 0.0054 and 0.0022 . The response for L. hirsutum was less variable and significantly greater than for L. esculentum. Elicitation of caspase 10-like activity by paraquat was greatest at around 2 h after treatment in both species with slopes of 0.013 and 0.0012, respectively for L. hirsutum and L. esculentum. The direct determination of caspase 10-like activity in tomato seedlings treated with copper and paraquat, using a specific substrate for mammals, suggested that the observed responses were related to apoptosis processes under abiotic induction.
Lycopersicon; abiotic elicitation; apoptosis; caspase activity
