Contrasting roles of fungal and oomycete pathogens in mediating nitrogen addition and winter grazing effects on biomass.

Both bottom-up and top-down processes modulate plant communities. Fungal and oomycete pathogens are most common in global grasslands, and due to differences in their physiology, function, host range, and life cycles, they may differentially affect plants (in both intensity and direction). However, how fungal and oomycete pathogens regulate bottom-up and top-down effects on plant community biomass remains unclear. To this end, we conducted a 3-year field experiment in an alpine meadow incorporating mammalian herbivore exclosure, fungicide/oomyceticide application, and nitrogen addition treatments. We arranged 12 blocks with half randomly assigned to be mammalian herbivore exclosures (fenced to exclude grazing sheep), and the other half were fenced most of the year but not in winter (winter grazing control). Six 2.5 × 2.5 m square plots were established in each block, with each of the six plots assigned as control, nitrogen addition, fungicide application, oomyceticide application, nitrogen addition + fungicide application, and nitrogen addition + oomyceticide application. We found that fungicide application significantly increased plant community biomass (mainly Poaceae species) under nitrogen addition and promoted the bottom-up effect of nitrogen addition on plant community biomass by altering the community-weighted mean of plant height (via species turnover). Meanwhile, oomyceticide application significantly increased plant community biomass (mainly Poaceae species) when mammalian herbivores were excluded and weakened the top-down effect of winter grazing on plant community biomass by driving intraspecific variation in plant height. Our results highlight that fungal and oomycete pathogens play important (but differing) roles in mediating the effects of nutrient availability and higher trophic levels on plant community biomass. Mechanistically, we demonstrated that plant pathogen-related modulation of plant community biomass is achieved by alterations to plant height. Overall, this study combines both community and disease ecology to reveal complex interactions among higher trophic levels and their potential impacts on terrestrial ecosystem functioning under human disturbance.

Complete chloroplast genome sequence of Scurrula notothixoides (Loranthaceae): a hemiparasitic shrub in South China.

Scurrula notothixoides (Loranthaceae) is a hemiparasitic shrub distributed in forest margins of Southeast Asian countries. Here, we report and characterize the complete plastid genome sequence of S. notothixoides in an effort to provide genomic resources useful for the phylogenetic studies for Santalales. The complete plastome is 123,810 bp in length and contains the typical structure and gene content of angiosperm plastomes, including two inverted repeat (IR) regions of 23,101 bp, a large single copy (LSC) region of 71,448 bp and a small single copy (SSC) region of 6160 bp. The plastome contains 88 genes, consisting of 61 unique protein-coding genes, 23 unique tRNA genes and four unique rRNA genes. The overall A/T content in the plastome of S. notothixoides is 62.7%. Phylogenetic analyses were performed using the entire plastome, including spacers, introns, etc. and we recovered that S. notothixoides and Taxillus sutchuenensis was closely related. The complete plastome sequence of S. notothixoides will provide a useful resource for the phylogenetic studies for Santalales.

Complete plastome sequence of Nepenthes mirabilis (Nepenthaceae): a "vulnerable" herb in China.

Nepenthes mirabilis (Nepenthaceae) is an erect or climbing (0.5-2 m tall) herb distributed in Africa (Madagascar), south and southeast Asia, North Australia and Pacific Islands (Caroline Islands). There is only one species in China. It grows in wet and sandy soils places throughout forests, grasslands, swamps, mountains, roadsides, wastelands having altitudes that sea level to 400 m. It has been ranked as a VU (Vulnerable) species in China. Here we report and characterize the complete plastid genome sequence of N. mirabilis in an effort to provide genomic resources useful for its conservation. The complete plastome is 155,755 bp in length and contains the typical structure and gene content of angiosperm plastomes, including two Inverted Repeat (IR) regions of 26,415 bp, a Large Single-Copy (LSC) region of 84,997 bp and a Small Single-Copy (SSC) region of 17,928 bp. The plastome contains 113 genes, consisting of 77 unique protein-coding genes, three pseudogenes, 29 unique tRNA genes, and four unique rRNA genes. The overall A/T content in the plastome of N. mirabilis is 62.8%. Phylogenetic analyses were performed using the entire plastome, including spacers, introns, etc., and we determined that N. mirabilis 32 and Dionaea muscipula were closely related. The complete plastome sequence of N. 33 mirabilis will provide a useful resource for the conservation genetics of this species as 34 well as for the phylogenetic studies in Caryophyllales.

Complete plastome sequence of Hydnocarpus hainanensis Merr (Achariaceae): an endemic 'vulnerable' tree in South China.

Hydnocarpus hainanensis Merr. is an evergreen tree with a height of 6-12 m and a diameter at breast height of 50 cm. It is distributed in Guangxi, Guizhou, Hainan, South of Yunnan Province of China. Here, we report and characterize the complete plastid genome sequence of H. hainanensis in an effort to provide genomic resources useful for promoting its conservation and systematics research. The plastome of H. hainanensis is found to possess a total length 163,330 bp with the typical quadripartite structure of angiosperms, containing two inverted repeats (IRs) of 26,870 bp, a large single copy (LSC) region of 91,510 bp and a small single copy (SSC) region of 18,080 bp. The plastome contains 111 genes, consisting of 78 unique protein-coding genes (seven of which are duplicated in the IR: rps 12, rps7, ndhB, ycf2, rpl23, rpl2, and rps 19), 29 unique tRNA genes (seven of which are duplicated in the IR, i.e. trnNGUU , trnRACG, trnAUGC, trnlGAU, trnVGAC, trnLCAA , and trnlCAU ) and four unique rRNA genes (5S rRNA, 4.55S rRNA, 23S rRNA, and 16S rRNA). The overall A/T content in the plastome of H. hainanensis is 63.70%. The phylogenetic analysis indicated that H. hainanensis is close to Salix rorida within Malpighiales. The complete plastome sequence of H. hainanensis will provide a useful resource for the conservation genetics of the one species as well as for the phylogenetic studies of Achariaceae.

Preparation of highly pure zeaxanthin particles from sea water-cultivated microalgae using supercritical anti-solvent recrystallization.

Xanthophylls, including zeaxanthin, are considered dietary supplements with a potentially positive impact on age-related macular degeneration. Using pilot-scale column fractionation coupled with supercritical anti-solvent (SAS) recrystallization, highly pure zeaxanthin particulates were prepared from ultrasonic extracts of the microalgae, Nannochloropsis oculata, grown in sea water. Column partition chromatography increased the concentration of zeaxanthin from 36.2 mg/g of the ultrasonic extracts to 425.6 mg/g of the collected column fractions. A response surface methodology was systematically designed for the SAS process by changing feed concentration, CO(2) flow rate and anti-solvent pressure. Zeaxanthin-rich particles with a purity of 84.2% and a recovery of 85.3% were produced using supercritical anti-solvent recrystallization from the column eluate at a feed concentration of 1.5 mg/mL, CO(2) flow rate of 48.6 g/min and pressure of 135 bar.

Designing supercritical carbon dioxide extraction of rice bran oil that contain oryzanols using response surface methodology.

This study examines the supercritical carbon dioxide (SC-CO(2)) extraction of oryzanols contained rice bran oil from powdered rice bran. The extraction efficiencies and concentration factors of oryzanols, free fatty acids and triglycerides in the SC-CO(2) extracts were determined. With top-flow type SC-CO(2) extraction the total oil yield was 18.1% and the extraction efficiencies of oryzanols and triglycerides were 88.5 and 91.3% respectively, when 2750 g CO(2 )was consumed during the extraction of 35 g rice bran powder. The concentration factors of oryzanols and triglycerides in SC-CO(2)-extracted oil were higher than in the Soxhlet n-hexane extracted oil. SC-CO(2) extractions indicated that pressure can be used more effectively than temperature to enhance the extraction efficiency and concentration factor of oryzanols. A two-factor central composite scheme of response surface methodology was employed to determine the optimal pressure (300 bar) and temperature (313 K) for increasing the concentration of oryzanols in the SC-CO(2) extracted oil.