Polyploids have elevated stress tolerance, but the underlying mechanisms remain largely elusive. In this study, we showed that naturally occurring tetraploid plants of trifoliate orange (Poncirus trifoliata (L.) Raf.) exhibited enhanced cold tolerance relative to their diploid progenitors. Transcriptome analysis revealed that whole‐genome duplication was associated with higher expression levels of a range of well‐characterized cold stress‐responsive genes. Global DNA methylation profiling demonstrated that the tetraploids underwent more extensive DNA demethylation in comparison with the diploids under cold stress. CHH methylation in the promoters was associated with up‐regulation of related genes, whereas CG, CHG, and CHH methylation in the 3'‐regions was relevant to gene down‐regulation. Of note, genes involved in unsaturated fatty acids (UFAs) and jasmonate (JA) biosynthesis in the tetraploids displayed different CHH methylation in the gene flanking regions and were prominently up‐regulated, consistent with greater accumulation of UFAs and JA when exposed to the cold stress. Collectively, our findings explored the difference in cold stress response between diploids and tetraploids at both transcriptional and epigenetic levels, and gained new insight into the molecular mechanisms underlying enhanced cold tolerance of the tetraploid. These results contribute to uncovering a novel regulatory role of DNA methylation in better cold tolerance of polyploids.

Lithium-based batteries are the most potential state-of-the-art energy storage device for flexible electronics. The flexible lithium batteries have the advantages of high energy density, robust mechanical durability, and stable power output even under dynamic deformation. Among them, the synergies of flexible free-standing electrodes, solid electrolytes, and electrode-electrolyte interfaces are crucial to achieving the goal of high energy density and safety performance for flexible lithium batteries.Therefore, a thorough understanding of the interface formation mechanism and influencing factors is crucial for the design of flexible electrodes and solid electrolytes. In this review, the interface challenges in flexible lithium-based batteries including interface formation, electrodeselectrolyte interface, and interparticle interface characteristics are presented. Then, strategies of interface optimization are summarized and discussed. Following this, the interface of flexible lithium-based batteries with novel architecture is introduced, including the interface between each component and unit of the battery. Finally, the perspectives for the future development of flexible lithium-based batteries are also given.

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