Bioregenerative Life Support Systems in the space (BLSS): effects of radiation on plants

The growth of plants in Space is a fundamental issue for Space exploration. Plants play an important role in the Bioregenerative Life Support Systems (BLSS) needed to sustain human permanence in extraterrestrial environments. From this perspective, plants are basic elements for oxygen and fresh food production, air regeneration as well as providing psychological support to the crew. The potential of plant survival and reproduction in space is limited by the same factors that act on Earth (e.g. light, temperature and relative humidity) and by additional factors such as altered gravity and ionizing radiation. This paper analyzes plant response to space radiation, which is recognized as a powerful mutagen for photosynthetic organisms thus being responsible for morphostructural, physiological and genetic alterations. Until now, many studies have shown evidence as to how the response to ionizing radiation is influenced by several factors associated both with plant characteristics (e.g. cultivar, species, developmental stage, tissue structure) and/or radiation features (e.g. dose, quality and exposure time). The photosynthetic machinery is particularly sensitive to ionizing radiation. The severity of the damage induced by ionizing radiation on plant cell and tissues may depend on the capability of plants to adopt protective mechanisms and/or repair strategies. In this paper, a selection of results from studies on the effects of ionizing radiation on plants at the anatomical and eco-physiological level is reported and some aspects related to radioresistance are explored.