Rice is the important crop for more than half of the world population. However, drought can have a devastating impact on rice growth and reduce yield drastically. Understanding the response of rice to drought stress is especially important for crop breeding. Previously we found that rice enhanced its tolerance to drought stresses via stress memory mechanisms. Numerous memory genes were identified to play important roles in the process. DNA methylation was reported to mediate tolerance via regulating gene expression and enhances the survival rate of rice encountering drought stress. However, how DNA methylation involved in stress memory is still not clear. In this study, genome-wide bisulphite sequencing at a single base resolution methylome profiling level was performed and analyzed in rice cultivar under recurrent drought stresses and recovery treatments. We found that rice drought stress memory-related differentially methylated regions (DMRs) showed dynamic and distinct patterns. The drought-memory DMRs may regulate Transposable elements and gene expression to cope with short-term repeated drought stresses. Our findings of drought-memory DMRs can explain mechanisms of rice drought stress memory in a new perspective on global methylome details. Using epigenetic markers to breed drought-resistant rice would become a feasible way in the future research.

Traditional breeding strategies mainly focus on the evaluation of trait performance, but pay less attention to the changing genetic background. A comprehensive understanding of the genetic diversity of germplasms is crucial for the deliberate improvement of specific traits. A collection of 154 highland rice varieties were collected as the initial genetic resource in our breeding program to improve the pathogen resistance and eating and cooking qualities. These varieties were analyzed using a whole-genome SNP array and were clustered into three groups. Further analysis revealed that the favorable alleles of pathogen resistance genes are mostly absent in our collected varieties. However, it showed that most varieties possess favorable alleles of Waxy (Wx) and ALKALI DEGENERATION (ALK), which are able to enhance the eating and cooking qualities. Moreover, only about one fifth of all varieties harbors favorable the allele of fragrance gene Betainealdehyde dehydrogenase (BADH2). Together, these results give an overall view of the genetic constitution of the target traits, which provide useful information for future genetic improvement in breeding practices.

Climate change poses a threat to global rice production by increasing the frequency and intensity of extreme weather events. The widespread cultivation of genetically uniform modern varieties has narrowed the genetic base of rice, increasing its vulnerability to these increased pressures. Rice landraces are traditional rice varieties that have been cultivated by farming communities for centuries and are considered crucial resources of genetic diversity. These landraces are adapted to a wide range of agro-ecological environments and exhibit valuable traits that provide tolerance to various biotic stresses, including drought, salinity, nutrient-deficient soils, and the increasing severity of climate-related temperature extremes. In addition, many landraces possess diverse alleles associated with resistance to biotic stresses, including pests and diseases. In addition, rice landraces exhibit great grain quality characters including high levels of essential amino acids, antioxidants, flavonoids, vitamins, and micronutrients. Hence, their preservation is vital for maintaining agricultural biodiversity and enhancing nutritional security, especially in vulnerable and resource-limited regions. However, rice landraces are increasingly threatened by genetic erosion due to widespread adoption of modern high-yielding varieties, habitat loss, and changing farming practices. This review discusses the roles of rice landraces in developing resilient and climate-smart rice cultivars. Moreover, the Pantiange Heigu landrace, cultivated at one of the highest altitudes globally in Yunnan Province, China, has been used as a case study for integrated conservation by demonstrating the successful combination of in situ and ex situ strategies, community engagement, policy support, and value-added development to sustainably preserve genetic diversity under challenging environmental and socio-economic challenges. Finally, this study explores the importance of employing advanced genomic technologies with supportive policies and economic encouragements to enhance conservation and sustainable development of rice landraces as a strategic imperative for global food security. By preserving and enhancing the utilization of rice landraces, the agricultural community can strengthen the genetic base of rice, improve crop resilience, and contribute substantially to global food security and sustainable agricultural development in the face of environmental and socio-economic challenges.

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.

Hydrogen sulfide (H₂S) functions as a pivotal gaseous signaling molecule in plants, yet its role in promoting crop yield remains elusive. Here, we demonstrate that sodium hydrosulfide (NaHS) application, a donor of hydrogen sulfide (H₂S), significantly accelerates growth, promotes flowering, and enhances grain yield in rice (Oryza sativa L.). Optimal NaHS treatment increased plant height, root length, and biomass accumulation, concomitant with elevated sucrose, starch, chlorophyll contents, and nitrate reductase activity. Integrated transcriptomic and proteomic analyses revealed that NaHS reprograms key biological pathways, including photosynthesis, carbon metabolism, lipid metabolism, the hormone signal transduction pathway, and reactive oxygen species (ROS) homeostasis. NaHS also remodels fatty acid metabolism, significantly increasing unsaturated fatty acids, linoleic acid (C18:2n6c), and α-linolenic acid (C18:3n3)—the latter serving as the direct precursor for JA biosynthesis—thereby fueling jasmonic acid (JA) biosynthesis. NaHS treatment also induced ROS accumulation while simultaneously activating antioxidant enzymes, maintaining redox homeostasis, and promoting cell proliferation in root meristems. Transmission electron microscopy revealed that NaHS enlarges peroxisomes and increases chloroplast oil body number, linking organellar dynamics to enhanced JA synthesis and ROS signaling. Collectively, our findings establish NaHS as a novel chemical regulator that coordinates JA and ROS signaling to boost rice growth, flowering, and grain yield, offering a promising strategy to improve crop productivity.