Rice tungro disease (RTD) is a serious threat in rice production. RTD is caused by the interaction between Rice tungro spherical virus (RTSV) and Rice tungro bacilliform virus (RTBV). Natural RTSV resistance is a recessive trait controlled by the translation initiation factor 4 gamma gene (eIF4G). To develop new sources of resistance to RTD, the team of Anca Macovei of the International Rice Research Institute in the Philippines induced mutations in eIF4G using the CRISPR-Cas9system in the RTSV‐susceptible variety IR64.
The mutation rates ranged from 36.0 to 86.6% and the mutations were successfully transmitted to succeeding generations. Among the mutated eIF4G alleles examined, only those resulting in mutations in SVLFPNLAGKS residues conferred resistance. From these, the team developed lines with RTSV resistance and enhanced yield under greenhouse conditions. These developed lines no longer contain the Cas9 sequence.
These CRISPR-developed RTSV‐resistant plants with the novel eIF4G alleles represent a valuable material to develop more resistant rice varieties.
For more information, read the article in Plant Biotechnology Journal.