Historical introgression among the species of Rodgersia (Saxifragaceae) in mountainous forests of southwest China

Therapeutic and immune-regulation effects of Scutellaria baicalensis Georgi polysaccharide on pseudorabies in piglets

Pseudorabies virus (PRV) can cause fatal encephalitis in newborn pigs and escape the immune system. While there is currently no effective treatment for PRV, Scutellaria baicalensis Georgi polysaccharides (SGP) and Rodgersia sambucifolia Hemsl flavonoids (RHF) are traditional Chinese herbal medicines with potential preventive and therapeutic effects against PRV infection. In order to explore which one is more effective in the prevention and treatment of PRV infection in piglets. We investigate the therapeutic effects of RHF and SGP in PRV-infected piglets using clinical symptom and pathological injury scoring systems. The immune regulatory effects of RHF and SGP on T lymphocyte transformation rate, cytokines, T cells, and Toll-like receptors were also measured to examine the molecular mechanisms of these effects. The results showed that SGP significantly reduced clinical symptoms and pathological damage in the lungs, liver, spleen, and kidneys in PRV-infected piglets and the T lymphocyte conversion rate in the SGP group was significantly higher than that in the other treatment groups, this potential dose-dependent effect of SGP on T lymphocyte conversation. Serum immunoglobulin and cytokine levels in the SGP group fluctuated during the treatment period, with SGP treatment showing better therapeutic and immunomodulatory effects in PRV-infected piglets than RHF or the combined SGP + RHF treatment. In conclusion, RHF and SGP treatments alleviate the clinical symptoms of PRV infection in piglets, and the immunomodulatory effect of SGP treatment was better than that of the RHF and a combination of both treatments. This study provides evidence for SGP in controlling PRV infection in piglets.

A clue to the evolutionary history of modern East Asian flora: insights from phylogeography and diterpenoid alkaloid distribution pattern of the Spiraea japonica complex

Each subkingdom of East Asian flora (EAF) has a unique evolutionary history, but which has rarely been described based on phylogeographic studies of EAF species. The Spiraea japonica L. complex, which is widespread in East Asia (EA), has received considerable attention because of the presence of diterpenoid alkaloids (DAs). It provides a proxy for understanding the genetic diversity and DA distribution patterns of species under various environmental conditions associated with the geological background in EA. In the present study, the plastome and chloroplast/nuclear DNA of 71 populations belonging to the S. japonica complex and its congeners were sequenced, combined with DA identification, environmental analyses, and ecological niche modelling, to investigate their phylogenetic relationships, genetic and DAs distribution patterns, biogeography, and demographic dynamics. An "ampliative" S. japonica complex was put forward, comprising all species of Sect. Calospira Ser. Japonicae, of which three evolutionary units carrying their respective unique types of DAs were identified and associated with the regionalization of EAF (referring to the Hengduan Mountains, central China, and east China). Moreover, a transition belt in central China with its biogeographic significance was revealed by genetic and DA distribution patterns from the perspective of ecological adaptation. The origin and onset differentiation of the "ampliative" S. japonica complex was estimated in the early Miocene (22.01/19.44 Ma). The formation of Japanese populations (6.75 Ma) was facilitated by the land bridge, which subsequently had a fairly stable demographic history. The populations in east China have undergone a founder effect after the Last Glacial Maximum, which may have been promoted by the expansion potential of polyploidization. Overall, the in-situ origin and diversification of the "ampliative" S. japonica complex since the early Miocene is a vertical section of the formation and development of modern EAF and was shaped by the geological history of each subkingdom.

Subspecies divergence and pronounced phylogenetic incongruence in the East-Asia-endemic shrub Magnolia sieboldii

BACKGROUND AND AIMS

The biogeographic patterns of the East-Asia-endemic shrub Magnolia sieboldii, in which the range of the subsp. sieboldii is interposed with the disjunct distribution of subsp. japonica, implies a complex evolutionary history, involving rapid speciation and hybridization. Here, we aim to reveal the evolutionary and phylogeographic histories of the species with a particular focus on the time of subspecies divergence, the hypothesis of secondary hybridization and the Pleistocene survival of each subspecies, using a combination of genetic analyses and ecological niche modelling.

METHODS

Genetic variation, genetic structures and phylogenetic relationships were elucidated based on nuclear low-copy genes, chloroplast DNA, and nuclear simple sequence repeats (SSRs). A scenario selection analysis and divergence time estimation were performed using coalescent simulation in DIYABC and *BEAST. Ecological niche modelling and a test of niche differentiation were performed using Maxent and ENMTools.

KEY RESULTS

All marker types showed deep, but pronouncedly incongruent, west-east genetic divergences, with the subspecies being delineated only by the nuclear low-copy genes. Phylogenetic tree topologies suggested that ancient hybridization and introgression were likely to have occurred; however, this scenario did not receive significant support in the DIYABC analysis. The subspecies differentiated their niches, but both showed a dependence on high humidity and were predicted to have persisted during the last glacial cycle by maintaining a stable latitudinal distribution via migration to lower altitudes.

CONCLUSIONS

We found a deep genetic divergence and a pronounced phylogenetic incongruence among the two subspecies of M. sieboldii, which may have been driven by major paleogeographic and paleoclimatic events that have occurred since the Neogene in East Asia, including global cooling, climate oscillations and the formation of land bridges. Both subspecies were, however, considered to persist in situ in stable climatic conditions during the late Pleistocene.