Harnessing climate-adaptive breeding to accelerate tolerance to extreme temperatures in rice

Rice is a crucial staple crop for global food security; however, its production is adversely affected by climate change-induced extreme temperatures. High and low extreme temperatures significantly impair rice development, growth, yield, and grain quality. These adverse effects are due to disruption of physiological processes at different growth stages. Rice germplasm provides great genetic diversification from wild relatives, traditional landraces, and modern cultivars. The subspecies indica and japonica include valuable alleles that can be employed for breeding rice varieties adapted to extreme temperatures. The classical methods of hybridization and phenotypic selection are the basis of breeding programs. However, developing an improved rice variety using classical breeding methods requires 8-12 years, which is inconsistent with the rapid and extreme fluctuations in climate conditions currently threatening rice production. The potential of molecular genetics and gene editing technologies, such as quantitative trait loci (QTL), marker-assisted selection (MAS), genome-wide association studies (GWAS), genomic selection (GS), transcriptomics, and genome editing (CRISPR-Cas9) can support classical methods in breeding precision, understanding transcription factors, and enables rapid modification to accelerate the development of climate-resilient cultivars. Furthermore, speed breeding combined with high-throughput phenotyping can shorten the breeding cycle by controlling environmental factors to implement multiple generations within a single year. This review discusses climate-adaptive breeding pipeline by integrating the discovery of favorable alleles from diverse germplasm, precision trait integration using genomic selection and CRISPR-Cas9 editing, and accelerated line development through speed breeding. This framework could effectively advance rice improvement to extreme temperatures and contribute to sustained rice production for ensuring global food security under climate change.