Search

Since the inception of genetic investigations into the origin of Dryopteris species belonging to D. subg. Erythrovariae in East Asia, around 20 taxa with hybrid ancestry have been identified. Among these species, some have arisen from distant interspecific hybridization events. In this study, we describe and illustrate two newly discovered hybrids from China: Dryopteris parabissetiana sp. nov., a triploid species, and D. ×tiantangzhaiensis nothosp. nov., a diploid hybrid within Dryopteridaceae. Morphologically, D. parabissetiana exhibits similarities to D. bissetiana but can be distinguished by its ovate scales, while D. ×tiantangzhaiensis clearly displays intermediate characteristics between D. gymnophylla and D. tsoongii. Phylogenetic analyses indicate that D. tsoongii serves as their maternal parent, while D. bissetiana and D. gymnophylla are their paternal parents, respectively. Furthermore, we propose a section‐level classification for such hybrids of mixed parental sections. [ABSTRACT FROM AUTHOR]

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 (γ event). 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. [ABSTRACT FROM AUTHOR]

Multiple shortening took place during the Mesozoic in the periphery of the North China block (NCB), a major tectonic grain of East Asia, but no consensus exists as to the timing, intensity, and causes of individual events. This work focuses on the first phase shortening in Jurassic, which represents the initiation of Yanshanian orogeny, by investigating the structural evolution of the Yanshan belt in the middle segment of the northern NCB. The first-phase shortening used to be regarded as a weak compressive event for it is recorded by parallel or low-angle unconformities between Middle and Upper Jurassic strata in some places. Our recent field investigations, however, identified some pronounced angular unconformities separating the Upper Jurassic strata from the underlying highly folded units in the northern Yanshan belt. The new observations demonstrate that the first-phase shortening was actually a strong contractional event. The co-existence of parallel and angular unconformities in the southern and northern Yanshan belt can be explained by different thrusting processes. It is argued that lateral variations of initial basement dips must have played a crucial role in controlling structural evolution of the overlying pre-Middle Jurassic sedimentary succession. It is shown that the first-phase thrusting and folding system was thin-skinned and predominantly verge northwestward. Deformational intensity also weakened toward the north and northwest. The first-phase shortening is constrained to occur in a short time span from 170 to 165 Ma based on new radiometric ages of strata above and below the unconformity, and presumably took place simultaneously in the northern NCB. The first-phase shortening was likely driven by horizontal tectonic push from the southeast. It is suggested that low-angle subduction of the paleo-Pacific plate might be responsible for the Middle Jurassic orogeny in the northern NCB and other parts of East Asia. • Middle Jurassic orogeny was a strong shortening event in the northern North China block. • Shortening occurred in a short timespan from ~170 to 165 Ma. • Thrusting and folding are thin-skinned and verge predominantly northwestward. • Flat subduction of the paleo-Pacific plate might trigger the Middle Jurassic orogeny. [ABSTRACT FROM AUTHOR]