Gamma Phytotron: A New Chronic Gamma Irradiation Facility

Genetic improvement by chronic irradiation is another important option of mutation breeding technique, especially when a wide array of mutants and minimal growth arrest are needed. Therefore, a chronic irradiation of living plant materials has been favored to induce useful mutants in mutation breeding. Unfortunately, these kinds of facilities are scarce and only a few Asian countries including Japan, Malaysia, and Thailand have operational chronic irradiation facilities such as gamma field, gamma greenhouse, and gamma phytotron, respectively. There are still many factors to consider when operating these types of facilities such as security and management issues. For this purpose, we constructed a new gamma phytotron in the Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), Jeongeup, Jeonbuk, Rep. of Korea. The gamma phytotron in ARTI can be occupied with living pot plants or cultured callus during long periods of chronic irradiation at lower doses. The ionizing source is 60Co with the radioactivity strength of about 400 curies. The facility consists of an irradiation room, a non-irradiation room, a glasshouse for acclimation, an operating room, and an office. The total area of the irradiation room is about 104.16m2. The target plant materials for a gamma ray irradiation can be arranged from 2m (612.9 mGy/h) to 7m (60.1 mGy/h) from the 60Co source at present. For safety reasons, the building, where the 60Co source is located, is surrounded by concrete walls with 1.2m depth and a twofold lead shielded door between the control room and the irradiation room. Moreover, the irradiation room is equipped with two CCD camera systems, which enable an inner situation check of the control room. The irradiation room and non-irradiation control room have automatic control systems for various ranges of temperature (15∼35oC), humidity (50∼80%) and light condition (maximum 30,000lux), which can be finely set up according to the growth conditions of targeted plants. The difference of mutagenic effects of the acute and chronic irradiation can be compared using the same treatment dose. To date, we have finished the chronic irradiation of Arabidopsis, rice, tobacco and many ornamental plants to examine the biological effect. Also, microarray experiments were designed to compare expression shift of target genes responding to the acute and chronic irradiation in Arabidopsis and rice. It is expected that the heavy applications of the chronic gamma phytotron in ARTI will be extended to other crops and plants, which are eventually provided to domestic and global communities for mutation breeding and fundamental research