Molecular Breeding for Improving Ozone Tolerance in Rice: Recent Progress and Future Perspectives

Rising tropospheric ozone concentrations are challenging global rice production as they affect rice yields and interfere with grain and straw quality. As farmers have almost no management options to control the atmospheric conditions to which their crops are exposed, the breeding of adapted rice varieties constitutes a promising approach to enhance global food security. Intraspecific variability in ozone adaptation in rice has been genetically dissected by mapping quantitative trait loci using bi-parental populations or genome-wide association studies. Marker-assisted breeding, in addition to transgenic approaches targeting ozone tolerance mechanisms can be effective strategies to enhance rice yield and production. Ozone-tolerance breeding requires field-based evaluation of plant materials, which can be technically challenging and expensive when using ozone fumigation facilities, or may not be feasible in highly ozone-affected areas in Asia. In the absence of simple diagnostic tools, ozone-related yield reductions are under-estimated by farmers and agronomists. Therefore, we discuss the potential of molecular-breeding strategies to cope with ozone stress, and simple diagnostic tools to assess ozone response and tolerance, for the breeding of tolerant rice.