M_1TDS Technology and Creation of Low-cadmium Accumulation Parents for Hybrid Rice Breeding

SHAO Ye;PENG Yan;MAO Bi-gang;YU Li-xia;TANG Li;LI Yao-kui;HU Yuan-yi;ZHANG Dan;YUAN Zhi-cheng;LUO Wu-zhong;PENG Xuan-ming;LI Wen-jian;ZHOU Li-bin;BAI Lian-yang;ZHAO Bing-ran;State Key Laboratory of Hybrid Rice,Hunan Hybrid Rice Research Center;National Laboratory of Heavy Ion Accelerator of Lanzhou, Institute of Modern Physics, Chinese Academy of Science;Hunan Academy of Agricultural Sciences;

M_1TDS;;OsNramp5;;chimeric;;hybrid rice;;Lianliangyou 1;;low-cadmium accumulation

The problem of "cadmium-contaminated rice" is an urgent issue for the development of rice industry in south China. Breeding rice cultivars with low-cadmium accumulation in grains is the most direct and economical way to solve this problem. Here, we developed a technology of high-throughput screening for chimeric mutants in M1 generation based on targeted deep sequencing, so-called as M1 generation targeted deep sequencing(M1 TDS) technology. Using this technology, chimeric rice plants with mutations of cadmium transporter gene OsNramp5 were screened out from the heavy ion mutagenized plants in M1 generation, and the sterile line Lian 1 S and restorer line R001 carrying homozygous osnramp5 gene were obtained in M2 generation. Furthermore, in the fields contaminated with an effective soil cadmium content of 0.443 mg/kg at pH 4.93, the grain cadmium content of the hybrid rice Lianliangyou 1 derived from Lian 1 S and R001 was stable below 0.03 mg/kg, much lower than that of control hybrid rice Zhenliangyou 8612(0.38 mg/kg) and the national limit standard of 0.20 mg/kg. This study not only provides important new germplasms for solving the problem of "cadmium-contaminated rice", but breaks the technical bottleneck of high-throughput identification of chimeric mutants in the M1 generation of physicochemical mutagenesis, so as to provide a generic technology for targeted improvement of germplasms in physicochemical mutagenesis for rice and other crops.