The Phoebe genome sheds light on the evolution of magnoliids

Lauraceae includes the genus Phoebe,and the family is linked to the evolution of magnoliids.We sequenced the genome of Phoebe bournei Nanmu.The assembled genome size was 989.19 Mb,with a contig N50 value of 2.05 Mb.A total of 28,198 protein-coding genes were annotated in P.bournei.Whole-genome duplication(WGD)analysis showed that Lauraceae has experienced two WGD events;the older WGD event occurred just before the divergence of Lauraceae and Magnoliales,and the more recent WGD was shared by all lineages of Lauraceae.The phylogenetic tree showed that magnoliids form a sister clade to monocots and eudicots.We also identified 63 MADS-box genes,including AGL12-like genes that may be related to the regulation of P.bournei roots and FIN219-like genes encoding GH3 proteins,which are involved in photomorphogenesis.SAUR50-like genes involved in light signal-mediated pedicel or stem development were also identified.Four ATMYB46-and three PtrEPSP-homologous genes related to lignin biosynthesis were identified.These genes may be associated with the formation of straight trunks in P.bournei.Overall,the P.bournei reference genome provides insight into the origin,evolution,and diversification of Phoebe and other magnoliids.

Chromosome-scale assembly of the Kandelia obovata genome

The mangrove Kandelia obovata(Rhizophoraceae)is an important coastal shelterbelt and landscape tree distributed in tropical and subtropical areas across East Asia and Southeast Asia.Herein,a chromosome-level reference genome of K.obovata based on PacBio,Illumina,and Hi-C data is reported.The high-quality assembled genome size is 177.99 Mb,with a contig N50 value of 5.74 Mb.A large number of contracted gene families and a small number of expanded gene families,as well as a small number of repeated sequences,may account for the small K.obovata genome.We found that K.obovata experienced two whole-genome polyploidization events:one whole-genome duplication shared with other Rhizophoreae and one shared with most eudicots(γevent).We confidently annotated 19,138 protein-coding genes in K.obovata and identified the MADS-box gene class and the RPW8 gene class,which might be related to flowering and resistance to powdery mildew in K.obovata and Rhizophora apiculata,respectively.The reference K.obovata genome described here will be very useful for further molecular elucidation of various traits,the breeding of this coastal shelterbelt species,and evolutionary studies with related taxa.