Thermal neutron as a potential mutagen for induced plant mutation breeding: radiosensitivity response on wheat and rice

Induced plant mutation breeding plays a pivotal role in crop improvement for several plant species. Induced mutagenesis using physical mutagens is widely carried out across the globe for improving different target traits. Gamma rays are the most common physical mutagen employed for mutagenesis programs, however, due to its inherent properties, the DNA damage and hence mutation spectrum achieved is limited. Other radiation sources such as neutrons, have much denser energy deposition mechanisms, and hence potentially can be used as a mutagen in plant mutation breeding to achieve desired mutations with minimal background mutations. Thermal neutrons have not been widely studied for plant mutation breeding due to technical constraints in its availability. In the current study, we used a dedicated thermal neutron facility with minimal contamination of fast neutron and gamma rays, to irradiate wheat (HI-1605) and rice (TCDM-1) varieties. Radiosensitivity analysis was carried out for both the varieties, HI-1605 had GR50 dose of 17.7 Gy while GR30 dose of 9.1 Gy, TCDM-1 had GR50 at 22.5 Gy and GR30 at 14.9 Gy. Wheat variety HI-1605 had LD50 dose of 17.4 Gy compared to 17.6 Gy of TCDM-1. Overall, the study demonstrates the potential of thermal neutron for plant mutagenesis in wheat and rice and in the future may be extended to other crops.