Diversity and decomposition potential of endophytes in leaves of a Cinnamomum camphora plantation in China

This study was carried out to improve our understanding of the diversity and decomposition potential of endophytes in the leaves of Cinnamomum camphora trees grown in a subtropical region of China. We isolated and identified endophytic fungi from senescent leaves of C. camphora and tested their role in decomposition through pure-culture and pre-colonization. A total of 2,861 endophytic fungi isolated from 69 leaves of C. camphora were grouped into 39 taxa comprising 36 Ascomycetes and 3 Basidiomycetes based on sporulation and ITS sequence analysis. Of these, Colletotrichum gloeosporioides was the most common species (69% relative abundance and 96% colonization frequency), followed by Cladosporium sp.1, Colletotrichum sp. and Chaetomium sp. All 39 endophytes had the ability to decompose C. camphora leaf litter in pure culture, and a few exhibited >20% litter mass loss in 2 months. In most cases, single endopyhytic species showed lower mass loss than mixed microbial groups from active soil after 60 or 120 days. In pre-inoculation, endophytic fungi like Chaetomium sp., Cladosporium sp.1, C. gloeosporioides, Colletotrichum sp. and Guignardia sp. exhibited higher abundance and caused greater mass loss, indicating the potential of these groups to enter and significantly accelerate the process of decomposition. This study concludes that, after entering the decomposition process, selected endophytic fungi with high abundance could influence significantly the decomposition process and thus probably affect carbon and nutrient cycling in C. camphora plantations.     

Plant regeneration via direct somatic embryogenesis in Panax japonicus

Panax japonicus is one of the important medicinal plants. Here, we established the protocol for plant regeneration of P. japonicus via direct somatic embryogenesis. Somatic embryos were directly obtained from the segments of zygotic embryos on MS medium with 4.4 μM 2,4-D. Thereafter, somatic embryos were produced by repetitive secondary somatic embryogenesis. The secondary somatic embryo formation was enhanced by plasmolyzing pretreatment (1.0 M mannitol for 10 h). Frequency of secondary somatic embryo formation from cotyledon segments was lowered by plasmolyzing pretreatment, but the number of somatic embryos per explants was greatly increased. Plasmolyzing pretreatment resulted in retardation of embryo growth and required subculture to fresh medium for further growth of embryos into cotyledonary stage. Without plasmolyzing pretreatment, cotyledonary embryos were obtained after 8 weeks of culture. All the cotyledonary somatic embryos germinated by 5 μM GA₃ treatment, but only 15.3% were germinated on hormone-free medium. After 2 months of culture on 1/2 strength WPM medium, plantlets produced flowers spontaneously. In the anthers of in vitro flowers, microsporogenesis occurred normally with low number of pollen grains.     

Dynamic modeling for shear stress induced ATP release from vascular endothelial cells

A dynamic model is proposed for shear stress induced adenosine triphosphate (ATP) release from endothelial cells (ECs). The dynamic behavior of the ATP/ADP concentration at the endothelial surface by viscous shear flow is investigated through simulation studies based on the dynamic ATP release model. The numerical results demonstrate that the ATP/ADP concentration against time at endothelium-fluid interface predicted by the dynamic ATP release model is more consistent with the experimental observations than that predicted by previous static ATP release model.     

Protective effect of supplemental anthocyanins on Arabidopsis leaves under high light

Ten anthocyanin components have been detected in roots of purple sweet potato (Ipomoea batatas Lam.) by high‐performance liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry. All the anthocyanins were exclusively cyanidins or peonidin 3‐sophoroside‐5‐glucosides and their acylated derivatives. The total anthocyanin content in purple sweet potato powder obtained by solid‐phase extraction was 66 mg g^?1. A strong capacity of purple sweet potato anthocyanins (PSPA) to scavenge reactive oxygen species (superoxide, hydroxyl radical) and the stable 1,1‐diphenyl‐2‐picrylhydrazyl organic free radical was found in vitro using the electron spin resonance technique. To determine the functional roles of anthocyanins in leaves in vivo, for the first time, supplemental anthocyanins were infiltrated into leaves of Arabidopsis thaliana double mutant of the ecotype Landsberg erecta (tt3tt4) deficient in anthocyanin biosynthesis. Chlorophyll fluorescence imaging showed that anthocyanins significantly ameliorated the inactivation of photosystems II during prolonged high‐light (1300 µmol m^?2 s^?1) exposure. Comet assay of DNA revealed an obvious role of supplemental PSPA in alleviating DNA damage by high light in leaves. Our results suggest that anthocyanins could function in vitro and in vivo to alleviate the direct or indirect oxidative damage of the photosynthetic apparatus and DNA in plants caused by high‐light stress.     

Reactive oxygen species (ROS) generated by cyanobacteria act as an electron acceptor in the biocathode of a bio-electrochemical system

The enhanced electricity generation in a biocathode bio-electrochemical system (BES) with Microcystis aeruginosa IPP as the cathodic microorganism under illumination is investigated. The results show that this cyanobacterium is able to act as a potential cathodic microorganism under illumination. In addition, M. aeruginosa IPP is found to produce reactive oxygen species (ROS) in its growth in the BES. ROS, as more competitive electron acceptors than oxygen, are utilized prior to oxygen. The BES current is substantially reduced when the ROS production is inhibited by mannitol, indicating that the ROS secreted by the cyanobacterium play an important role in the electricity generation of such a biocathode BES. This work demonstrates that the ROS released by cyanobacteria benefit for an enhanced electricity generation of BES.     

Transfer of small chromosome fragments of<Emphasis Type="Italic">Agropyron elongatum</Emphasis> to wheat chromosome via asymmetric somatic hybridization

The chromosome constitution of hybrids and chromatin patterns of Agropyron elongatum (Host)Neviski in F₅ somatic hybrid lines -1–3 and I-1-9 between Triticum aestivum L. and A. elongatum were analyzed. Based on the statistic data of pollen mother cells, F₅ I-1-9 and-1-3 had 20–21 bivalents with a frequency of 84.66% and 85.28%, of which, 89.83% and 89.57% were ring bivalents. The result indicated that both hybrid lines were basically stable in the chromosome constitution and behavior. RAPD analysis showed that the two hybrids contained biparental and integrated DNA. GISH (Genome in situ hybridization) revealed that in the form of small chromosome segments, A. elongatum chromatin was scattered on 4–6 wheat chromosomes near by the region of centromere and telomere in the two hybrid lines. SSR analysis indicated that A. elongatum DNA segments were distributed on the 2A, 5B, 6B and 2D wheat chromosomes in the hybrids, which was in accordance with the GISH results that small-segments intercalated poly-site.