Adaptation to ionizing radiation of higher plants: From environmental radioactivity to chernobyl disaster

Radiation environment in exploration-class space missions and plants’ responses relevant for cultivation in Bioregenerative Life Support Systems

“…Up to now, most of the research has been conducted in the medical field on animal models, where ionizing radiation has been increasingly used for both diagnostic and therapeutic purposes (Tinganelli and Durante, 2020). Regarding studies available in literature were often designed with different purposes and applications, ranging from topics related to the breeding industry up to radioecological issues at NORM (naturally occurring radioactive materials) sites or consequent to nuclear accidents (De Micco et al, 2011;Ludovici et al, 2020;Mrdakovic Popic and Skipperud, 2020). The effects of ionizing radiation on plants have also been studied because radiation is considered a tool to select cultivars with improved crop yield and quality in breeding programs and is a decontamination mean to sanitize seeds and food.…”

“…In the past decades, the studies on the effects of ionizing radiation on higher plants have been focused on several endpoints especially regarding genetic alterations (including chromosomal aberrations, formation of micronuclei and mechanisms for repair) and recent technological development has allowed highlighting more and more details of possible molecular and chromosomal damages compared to the first studies (De Micco et al, 2011;Ludovici et al, 2020). At morpho-functional level, investigations have been addressed to endpoints in growth and reproduction processes by analyzing germination, mortality, lethality, organ morphogenesis, photosynthesis, biomass partitioning, flowering and production of seeds for the next generation.…”

“…The first regards plant metabolism in which many processes, such as light reactions of photosynthesis normally produce reactive oxygen species (ROS) that plants are accustomed to block due to the large production of antioxidants. The second regards the growth mechanisms relying on meristems, reproductive processes based on the alternation of sporophytic and gametophytic generations, as well as the lack of a circulatory system which altogether make plants not suffering from the same stochastic and carcinogenic effects as animals (Ludovici et al, 2020). However, it has been recently highlighted that although stochastic effects arising from chronic low doses of ionizing radiation may be of little relevance in non-human biota, the issue is still under debate and stochastic effects in plants may be variable between individuals but also at intra-individual level due to different radiosensitivity of different organs (Esnault et al, 2010;Caplin and Willey, 2018).…”

“…'microtom'), with no alteration on morpho-anatomical and photosynthesis from 0.3 up to 100 Gy X-rays, delivered at the stage of dry seeds. areas in the periods immediately after the accidents), low acute doses (in areas at increasing distance in the periods immediately after the accidents) and long-term effects of chronic irradiations in the years subsequent to the accidents (Esnault et al, 2010;Ludovici et al, 2020). Some of the trends identified suggest that radiosensitivity declines with age, as well as chronic low dose irradiation is more harmful per unit dose than high-dose irradiation (Caplin and Willey, 2018;Ludovici et al, 2020).…”

“…areas in the periods immediately after the accidents), low acute doses (in areas at increasing distance in the periods immediately after the accidents) and long-term effects of chronic irradiations in the years subsequent to the accidents (Esnault et al, 2010;Ludovici et al, 2020). Some of the trends identified suggest that radiosensitivity declines with age, as well as chronic low dose irradiation is more harmful per unit dose than high-dose irradiation (Caplin and Willey, 2018;Ludovici et al, 2020). For instance, Zaka et al (2002) found that the chronic exposure of Stipa capillata seeds to g and b radiations led to a higher expression of scavenging enzymes, DNA-repair genes and antioxidants in plant tissues.…”