R2R3-MYB genes (R2R3-MYBs) form one of the largest transcription factor gene families in the plant kingdom, with substantial structural and functional diversity. However, the evolutionary processes leading to this amazing functional diversity have not yet been clearly established. Recently developed genomic and classical molecular technologies have provided detailed insights into the evolutionary relationships and functions of plant R2R3-MYBs. Here, we review recent genome-level and functional analyses of plant R2R3-MYBs, with an emphasis on their evolution and functional diversification. In land plants, this gene family underwent a large expansion by whole genome duplications and small-scale duplications. Along with this population explosion, a series of functionally conserved or lineage-specific subfamilies/groups arose with roles in three major plant-specific biological processes: development and cell differentiation, specialized metabolism, and biotic and abiotic stresses. The rapid expansion and functional diversification of plant R2R3-MYBs are highly consistent with the increasing complexity of angiosperms. In particular, recently derived R2R3-MYBs with three highly homologous intron patterns (a, b, and c) are disproportionately related to specialized metabolism and have become the predominant subfamilies in land plant genomes. The evolution of plant R2R3-MYBs is an active area of research, and further studies are expected to improve our understanding of the evolution and functional diversification of this gene family.

Flowering plants, or angiosperms, consist of more than 300,000 species, far more than any other land plant lineages. The accumulated evidence indicates that multiple ancient polyploidy events occurred around 100 to 120 million years ago during the Cretaceous and drove the early diversification of four major clades of angiosperms: gamma whole-genome triplication in the common ancestor of core eudicots, tau whole-genome duplication during the early diversification of monocots, lambda whole-genome duplication during the early diversification of magnoliids, and pi whole-genome duplication in the Nymphaeales lineage. These four polyploidy events have played essential roles in the adaptive evolution and diversification of major clades of flowering plants. Here, we specifically review the current understanding of this wave of ancient whole-genome duplications and their evolutionary significance. Notably, although these ancient whole-genome duplications occurred independently, they have contributed to the expansion of many stress-related genes (e.g., heat shock transcription factors and Arabidopsis response regulators)，and these genes could have been selected for by global environmental changes in the Cretaceous. Therefore, this ancient wave of paleopolyploidy events could have significantly contributed to the adaptation of angiosperms to environmental changes, and potentially promoted the wide diversification of flowering plants.

The recent rise of disinformation and propaganda on social media has attracted strong interest from social scientists. Research on the topic has repeatedly observed ideological asymmetries in disinformation content and reception, wherein conservatives are more likely to view, redistribute, and believe such content. However, preliminary evidence has suggested that race may also play a substantial role in determining the targeting and consumption of disinformation content. Such racial asymmetries may exist alongside, or even instead of, ideological ones. Our computational analysis of 5.2 million tweets by the Russian government-funded “troll farm” known as the Internet Research Agency sheds light on these possibilities. We find stark differences in the numbers of unique accounts and tweets originating from ostensibly liberal, conservative, and Black left-leaning individuals. But diverging from prior empirical accounts, we find racial presentation—specifically, presenting as a Black activist—to be the most effective predictor of disinformation engagement by far. Importantly, these results could only be detected once we disaggregated Black-presenting accounts from non-Black liberal accounts. In addition to its contributions to the study of ideological asymmetry in disinformation content and reception, this study also underscores the general relevance of race to disinformation studies.

Summary Azalea belongs to Rhododendron, which is one of the largest genera of flowering plants and is well known for the diversity and beauty in its more than 1000 woody species. Rhododendron contains two distinct groups: the most high‐altitude and a few low‐altitude species; however, the former group is difficult to be domesticated for urban landscaping, and their evolution and adaptation are little known. Rhododendron ovatum has broad adaptation in low‐altitude regions but possesses evergreen characteristics like high‐altitude species, and it has floral fragrance that is deficient in most cultivars. Here we report the chromosome‐level genome assembly of R. ovatum, which has a total length of 549 Mb with scaffold N50 of 41 Mb and contains 41 264 predicted genes. Genomic micro‐evolutionary analysis of R. ovatum in comparison with two high‐altitude Rhododendron species indicated that the expansion genes in R. ovatum were significantly enriched in defence responses, which may account for its adaptability in low altitudes. The R. ovatum genome contains much more terpene synthase genes (TPSs) compared with the species that lost floral fragrance. The subfamily b members of TPS are involved in the synthesis of sesquiterpenes as well as monoterpenes and play a major role in flora scent biosynthesis and defence responses. Tandem duplication is the primary force driving expansion of defence‐responsive genes for extensive adaptability to the low‐altitude environments. The R. ovatum genome provides insights into low‐altitude adaptation and gain or loss of floral fragrance for Rhododendron species, which are valuable for alpine plant domestication and floral scent breeding.

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