Photosynthetic Physiology and Molecular Response Mechanisms of Indica–Japonica Intersubspecific Tetraploid Rice Seedlings to Ion Beams

Abstract

Indica–japonica intersubspecific tetraploid rice is a useful germplasm that has greater biological and yield potentials than diploid rice. However, the physiological and molecular mechanisms of the stress effects of indica–japonica intersubspecific tetraploid rice 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 seedlings. The investigation found that the growth and development of seedlings was inhibited, the leaf area and chlorophyll content was reduced, and photosynthesis and the expression levels of related genes were disturbed by ion beam irradiation. The decrease rate of chlorophyll content in tetraploid rice under medium-dose irradiation was lower than those of indica/japonica diploid parents may be due to the upregulated expression of HEMD, and the decrease rate of photosynthetic gas exchange parameters and chlorophyll fluorescence parameters in tetraploid rice under low-dose irradiation were lower than those of indica/japonica diploid parents may be due to the upregulated expression of PetB. The aforementioned results will be useful for further research on the physiological and molecular mechanisms of indica–japonica intersubspecific tetraploid rice to ion beam stress.