Identification And Postharvest Physiology Analysis Of Tomato Plants Expressing Antisense LeEIL2

Ethylene is a phytohorone with simple structure and is involved in many physiological processed, including growth development, stress response, fruit ripening and senescence. Ethylene biosynthesis pathway has been studied intensely in 70' of 20th century and the whole pathway has been elucidated. Ethylene signaling model has been established in last 20 years as follows: C₂H₂→ETR→CTR→EIN2→ EIN3→ERF→ethylene response. EIN3 was first cloned in Arabidopsis thalina mutant, and it has been suggested that EIN3 acted downstream to CTR located in nuclear and encoded transcription factors. LeEIL2 was a EIN3 gene cloned from tomato leaves. Researchers in our lab has cloned the whole sequence of LeEIL2, constructed it into an anti-sense vector, transformed the vector and 98 transformed tomato plants were obtained.This study focused on the identification and physiology analysis of tomato expressing anti-sense LeEIL2, in order to provide more information about the role of LeEIL2 in ripening and senescence and ethylene signaling pathway.(1) Transplant and identification of tomato expressing antisense LeEIL2: 72 tomato plants were selected as positive according PCR test from 98 plants. 58 plants were tested as tomato expressing antisense LeEIL2 in further selection using Southern blotting.(2) Postharvest physiological characteristics of tomato fruits expressing antisense LeEIL2: some parameters about fruit ripening, nutritional character and storage performance were measured, including ethylene production, respiration rate, flesh firmness, lycopene content, phytohormone concertration and ACS and ACO activities, and results suggested that, compared with wild tomato fruit, tomato fruit expressing antisense LeEIL2 showed a delayed ripening process, promoted nutritional value and storage duration.(3) Physiological character of excised leaves of tomato expressing antisense LeEIL2: wound ethylene, membrane permeability and chlorophyll content were measured and results indicated that wound ethylene in excised leaves was inhibited, while chlorophyll content was higher than that of wild tomato, and membrane permeability was lower. These results suggested that senescence was inhibited and stability of cytolemma was strengthenned in tomato leaves expressing antisense LeEIL2.