Effects of Acute and Chronic Gamma Irradiation on the Cell Biology and Physiology of Rice Plants

Abstract

The response to gamma irradiation varies among plant species and is affected by the total irradiation dose and dose rate. In this study, we examined the immediate and ensuing responses to acute and chronic gamma irradiation in rice (Oryza sativa L.). Rice plants at the tillering stage were exposed to gamma rays for 8 h (acute irradiation) or 10 days (chronic irradiation), with a total irradiation dose of 100, 200, or 300 Gy. Plants exposed to gamma irradiation were then analyzed for DNA damage, oxidative stress indicators including free radical content and lipid peroxidation, radical scavenging, and antioxidant activity. The results showed that all stress indices increased immediately after exposure to both acute and chronic irradiation in a dose-dependent manner, and acute irradiation had a greater effect on plants than chronic irradiation. The photosynthetic efficiency and growth of plants measured at 10, 20, and 30 days post-irradiation decreased in irradiated plants, i.e., these two parameters were more severely affected by acute irradiation than by chronic irradiation. In contrast, acutely irradiated plants produced seeds with dramatically decreased fertility rate, and chronically irradiated plants failed to produce fertile seeds, i.e., reproduction was more severely affected by chronic irradiation than by acute irradiation. Overall, our findings suggest that acute gamma irradiation causes instantaneous and greater damage to plant physiology, whereas chronic gamma irradiation causes long-term damage, leading to reproductive failure.

Gamma rays induced morphological, flowering and palynological modifications in horse gram (Macrotyloma uniflorum)

“…A positive correlation between pollen fertility with pollen germination and seed set was witnessed (Table 1). Similar trend was reported by Priyanka et al (2020) and Choi et al (2021). Further, Lasa and Bosemark (1993) opined that pollen sterility-based male sterility is the most successful, stable, and proven method in tapping the potential of heterosis in many crops including self-pollinated species.…”

Chronic Gamma Irradiation Changes Phenotype and Gene Expression Partially Transmitted to Next-Generation Tomato Seedlings

“…This understanding is necessary for predicting plant development and inheritance in radiation-exposed terrestrial areas or non-terrestrial space environments where cosmic radiation exists, and for the application of chronic irradiation to mutation breeding [47]. Although physiological characteristics or gene expression patterns in response to chronic irradiation have been analyzed [3,7,11], integrative studies combining both research areas are limited. Additionally, there has been limited research on the analysis of inheritance of characteristics under uncontrolled irradiation conditions [48,49].…”

“…In addition to DNA mutations, irradiation has been shown to affect epigenetic modifications by increasing the expression of epigenetic regulators (MET1, CMT3, and SUVH5) in Arabidopsis subjected to irradiation with X-rays [77]; furthermore, modifications pertaining to hypermethylated DNA sequences in Pinus sylvestris trees exposed to radiation after the Chernobyl accident [78] and hypomethylated DNA sequences in rice subjection to irradiation with gamma rays [3] have also been observed. Sidler et al [75] hypothesized that epigenetic changes (hypermethylation in this case) following radiation exposure might constitute an adaptive response of plants to prevent genome instability and reshuffling.…”

“…Irradiation of plant tissues causes various biological effects at both morphological and physiological levels of plant organisms and cellular levels [1]. At the morphological and physiological levels of plant organisms, the irradiation of rice with carbon beams or gamma rays results in morphological and functional defects, including reduction in fertility [2] and plant height [3]. Gamma irradiation also causes other developmental changes, such as increased trichome density in Arabidopsis [4] and elongation of internode diameter in Brachypodium [5].…”

“…Several mutants with novel traits have been obtained through chronic irradiation, including a black spot disease-resistant pear variety ('Gold Nijisseiki') [25] and 10 chrysanthemum cultivars with variation in flower color and shape [26]. A few studies have shown that chronic irradiation subsequently induces physiological responses or inflicts damage, such as reduction in the fertility in rice [3], alterations in the expression patterns of diverse genes in Arabidopsis and wheat [7,11], and degradation of lignocellulose in Brachypodium [5]. Whole-genome sequencing of Arabidopsis lines that were chronically or acutely subjected to irradiation with gamma rays for five generations showed that chronic irradiation could generate a higher frequency of heritable DNA mutations than those observed with acute irradiation [17].…”