Background: The three-dimensional spatial organization of the genome plays important roles in chromatin accessibility and gene expression in multiple biological processes and has been reported to be altered in response to environmental stress. However, the functional changes in spatial genome organization during environmental changes in crop plants are poorly understood. Results: Here we perform Hi-C, ATAC-seq, and RNA-seq in two agronomically important rice cultivars, Nipponbare (Nip; Japonica) and 93-11 (Indica), to report a comprehensive profile of nuclear dynamics during heat stress (HS). We show that heat stress affects different levels of chromosome organization, including A/B compartment transition, increase in the size of topologically associated domains, and loss of short-range interactions. The chromatin architectural changes were associated with chromatin accessibility and gene expression changes. Comparative analysis revealed that 93-11 exhibited more dynamic gene expression and chromatin accessibility changes, including HS-related genes, consistent with observed higher HS tolerance in this cultivar. Conclusions: Our data uncovered higher-order chromatin architecture as a new layer in understanding transcriptional regulation in response to heat stress in rice.

The tetraploid genome and clonal propagation of the cultivated potato (Solanum tuberosum L.)^1,2 dictate a slow, non-accumulative breeding mode of the most important tuber crop. Transitioning potato breeding to a seed-propagated hybrid system based on diploid inbred lines has the potential to greatly accelerate its improvement³. Crucially, the development of inbred lines is impeded by manifold deleterious variants; explaining their nature and finding ways to eliminate them is the current focus of hybrid potato research^{4,5,6,7,8,9,10}. However, most published diploid potato genomes are unphased, concealing crucial information on haplotype diversity and heterozygosity^11,12,13. Here we develop a phased potato pangenome graph of 60 haplotypes from cultivated diploids and the ancestral wild species, and find evidence for the prevalence of transposable elements in generating structural variants. Compared with the linear reference, the graph pangenome represents a broader diversity (3,076 Mb versus 742 Mb). Notably, we observe enhanced heterozygosity in cultivated diploids compared with wild ones (14.0% versus 9.5%), indicating extensive hybridization during potato domestication. Using conservative criteria, we identify 19,625 putatively deleterious structural variants (dSVs) and reveal a biased accumulation of deleterious single nucleotide polymorphisms (dSNPs) around dSVs in coupling phase. Based on the graph pangenome, we computationally design ideal potato haplotypes with minimal dSNPs and dSVs. These advances provide critical insights into the genomic basis of clonal propagation and will guide breeders to develop a suite of promising inbred lines.

The Streptophyta include unicellular and multicellular charophyte green algae and land plants. Colonization of the terrestrial habitat by land plants is a major evolutionary event that has transformed the planet. So far, lack of genome information on unicellular charophyte algae hinders the understanding of the origin and the evolution from unicellular to multicellular life in Streptophyta. This work reports the high‐quality reference genome and transcriptome of Mesostigma viride, a single‐celled charophyte alga with a position at the base of Streptophyta. There are abundant segmental duplications and transposable elements in M. viride, which contribute to a relatively large genome with high gene content compared to other algae and early diverging land plants. This work identifies the origin of genetic tools that multicellular Streptophyta have inherited and key genetic innovations required for the evolution of land plants from unicellular aquatic ancestors. The findings shed light on the age‐old questions of the evolution of multicellularity and the origin of land plants.

Global warming poses a significant threat to plant ecosystems and agricultural productivity, primarily through heat stress (HS), which disrupts photosynthesis, respiration, and overall plant metabolism. Epigenetic modifications, including DNA methylation, histone modifications, and RNA modifications, enable plants to dynamically and heritably adjust gene expression in response to environmental stressors. These mechanisms not only help plants survive immediate stress but also confer stress memory, enhancing their resilience to future HS events. This review explores the mechanisms underlying plant thermotolerance, emphasizing the critical role of epigenetic regulation in adapting to HS. It also highlights how DNA methylation modulates stress-responsive genes, histone modifications facilitate transcriptional memory, and RNA modifications influence mRNA stability and translation. Recent advancements in genome editing technologies, such as CRISPR-Cas9, have enabled precise modifications of epigenetic traits, offering new avenues for breeding climate-resilient crops. The integration of these modern tools with traditional breeding methods holds significant promise for developing crops with enhanced thermotolerance. Despite the potential, challenges such as the stability and heritability of epigenetic marks and the complex interplay between different epigenetic modifications need to be addressed. Future research should focus on elucidating these interactions and identifying reliable epigenetic markers for selection. By leveraging the insights gained from epigenetic studies, we can develop innovative breeding strategies to improve crop resilience and ensure sustainable agricultural productivity in the face of global warming. This review underscores the importance of epigenetic regulation in plant adaptation to heat stress and its potential to revolutionize crop breeding, offering a pathway to secure food production and sustainability under changing climatic conditions.