Physiological and molecular responses of the root system of indica–japonica intersubspecific tetraploid rice seedlings to ion beam stress

Abstract

Low-energy ion beam bombardment can induce various biological effects on plants, including stimulation, damage, and mutation. However, the physiological and molecular mechanisms of the stress effects of indica–japonica intersubspecific tetraploid rice seedlings roots in response to ion implantation are not fully understood. In this work, indica–japonica intersubspecific tetraploid rice seeds were implanted with different doses of ion beam to explore the responses of their seedling roots. The investigation found that that high-dose ion implantation significantly reduced the total root length, root surface area, total root volume and root tips number, significantly increased MDA content in roots, and interfered with the expression level of IAA biosynthesis and transport related genes. Under low-dose radiation, the antioxidant enzyme activity in the roots of intersubspecific tetraploid rice increased significantly compared with the control, and remained at a high level during 5–15 days of culture, without significant change. Meanwhile, the expression of IAA biosynthesis and transportation related genes were up-regulated, and the IAA content was significantly increased, which was 20.12% higher than that of the control, which finally made the root activity significantly higher than that of the parents. The aforementioned results will be useful for further research on the physiological and molecular mechanisms of indica–japonica intersubspecific tetraploid rice seedlings roots to ion beam stress.