The genus Liriodendron belongs to the family Magnoliaceae, which resides within the magnoliids, an early diverging lineage of the Mesangiospermae. However, the phylogenetic relationship of magnoliids with eudicots and monocots has not been conclusively resolved and thus remains to be determined1–6. Liriodendron is a relict lineage from the Tertiary with two distinct species—one East Asian (L. chinense (Hemsley) Sargent) and one eastern North American (L. tulipifera Linn)—identified as a vicariad species pair. However, the genetic divergence and evolutionary trajectories of these species remain to be elucidated at the whole-genome level7. Here, we report the first de novo genome assembly of a plant in the Magnoliaceae, L. chinense. Phylogenetic analyses suggest that magnoliids are sister to the clade consisting of eudicots and monocots, with rapid diversification occurring in the common ancestor of these three lineages. Analyses of population genetic structure indicate that L. chinense has diverged into two lineages—the eastern and western groups—in China. While L. tulipifera in North America is genetically positioned between the two L. chinense groups, it is closer to the eastern group. This result is consistent with phenotypic observations that suggest that the eastern and western groups of China may have diverged long ago, possibly before the intercontinental differentiation between L. chinense and L. tulipifera. Genetic diversity analyses show that L. chinense has tenfold higher genetic diversity than L. tulipifera, suggesting that the complicated regions comprising east–west-orientated mountains and the Yangtze river basin (especially near 30° N latitude) in East Asia offered more successful refugia than the south–north-orientated mountain valleys in eastern North America during the Quaternary glacial period.

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Oplegnathus fasciatus and O. punctatus (Teleostei: Centrarchiformes: Oplegnathidae), are commercially important rocky reef fishes, endemic to East Asia. Both species present an X1X2Y sex chromosome system. Here, we investigated the evolutionary forces behind the origin and differentiation of these sex chromosomes, with the aim to elucidate whether they had a single or convergent origin. To achieve this, conventional and molecular cytogenetic protocols, involving the mapping of repetitive DNA markers, comparative genomic hybridization (CGH), and whole chromosome painting (WCP) were applied. Both species presented similar 2n, karyotype structure and hybridization patterns of repetitive DNA classes. 5S rDNA loci, besides being placed on the autosomal pair 22, resided in the terminal region of the long arms of both X1 chromosomes in females, and on the X1 and Y chromosomes in males. Furthermore, WCP experiments with a probe derived from the Y chromosome of O. fasciatus (OFAS-Y) entirely painted the X1 and X2 chromosomes in females and the X1, X2, and Y chromosomes in males of both species. CGH failed to reveal any sign of sequence differentiation on the Y chromosome in both species, thereby suggesting the shared early stage of neo-Y chromosome differentiation. Altogether, the present findings confirmed the origin of the X1X2Y sex chromosomes via Y-autosome centric fusion and strongly suggested their common origin.

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Investigations have demonstrated a strong and positive association between dietary intact phospholipid (PL) inclusion and aquatic larval growth, nevertheless, the precise molecular mechanism underlying PL inclusion on growth performance has not been well elucidated. This study aimed to investigate the effects of dietary soybean lecithin (SL) inclusion on growth performance, liver metabolism, resistance to hypoxia stress, and potential molecular mechanisms in rock bream (Oplegnathus fasciatus) larvae. Four types of equal-protein and equal-lipid content microdiets (MDs) were formulated with graded levels of SL to achieve phospholipid levels of (PLs, dry matter) 3.84% (SL0), 6.71% (SL4), 9.38% (SL8), and 12.21% (SL12). Rock bream larvae (25 days post-hatching) were fed the respective MDs for 30 days with three replicates. We found that dietary SL inclusion promoted growth performance, survival rate, and stress resistance to hypoxia stress. The increased dietary SL inclusion improved intestinal structure, as shown by the increased perimeter ratio, muscular thickness, and mucosal fold height of the mid-intestinal tissue. Moreover, a high SL inclusion diet (SL12) increased the activity of the key lipolysis-related enzyme (lipase [LP]) in liver tissue but decreased the activity of amino acid catabolism-related enzymes (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]). RNA sequencing results in liver tissue revealed that the SL12 diet increased the transcriptional level of fatty acid activation-related genes (acsl6 and acsbg2), phospholipid catabolism-related genes (acat2, lpin2, and crls), and amino acid synthesis-related genes (gs, csb, aldh18a1, and oct), but decreased the expression of amino acid catabolism-related gene gprt2. Notably, the SL12 diet significantly increased the expression of ribosome biogenesis-related genes (pes1, nop56, nop58, and rpf2) in liver tissue. The ribosome protein-related pathways were the most enriched pathways mapped in the GO database. Collectively, this study demonstrated the necessity of dietary SL for survival, growth performance, promotion of mid-intestinal morphology, and hypoxia stress during the rock bream larval stage. The SL-induced growth performance promotion was likely attributed to increasing nutrient acquisition by intestinal morphology improvement and to increasing SL catabolism and thereby sparing amino acids for protein synthesis.