Borneol Dehydrogenase from Pseudomonas sp. Strain TCU-HL1 Catalyzes the Oxidation of (+)-Borneol and Its Isomers to Camphor.

Most plant-produced monoterpenes can be degraded by soil microorganisms. Borneol is a plant terpene that is widely used in traditional Chinese medicine. Neither microbial borneol dehydrogenase (BDH) nor a microbial borneol degradation pathway has been reported previously. One borneol-degrading strain, Pseudomonas sp. strain TCU-HL1, was isolated by our group. Its genome was sequenced and annotated. The genome of TCU-HL1 consists of a 6.2-Mbp circular chromosome and one circular plasmid, pTHL1 (12.6 kbp). Our results suggest that borneol is first converted into camphor by BDH in TCU-HL1 and is further decomposed through a camphor degradation pathway. The recombinant BDH was produced in the form of inclusion bodies. The apparent Km values of refolded recombinant BDH for (+)-borneol and (-)-borneol were 0.20 ± 0.01 and 0.16 ± 0.01 mM, respectively, and the kcat values for (+)-borneol and (-)-borneol were 0.75 ± 0.01 and 0.53 ± 0.01 s-1, respectively. Two plant BDH genes have been reported previously. The kcat and kcat/Km values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. IMPORTANCE: The degradation of borneol in a soil microorganism through a camphor degradation pathway is reported in this study. We also report a microbial borneol dehydrogenase. The kcat and kcat/Km values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. The indigenous borneol- and camphor-degrading strain isolated, Pseudomonas sp. strain TCU-HL1, reminds us of the time 100 years ago when Taiwan was the major producer of natural camphor in the world.

Population Genetics of the Endemic Hawaiian Species Chrysodracon hawaiiensis and Chrysodracon auwahiensis (Asparagaceae): Insights from RAPD and ISSR Variation.

The genus Chrysodracon has six endemic species in the Hawaii Islands. Chrysodracon hawaiiensis is endemic to Hawaii Island and was described as a distinct species in 1980. It was listed as an endangered species on the International Union for the Conservation of Nature and Natural Resources (IUCN) Red List in 1997. This woody plant species was, at one time, common in exposed dry forests, but it became very rare due to grazing pressure and human development. The tree species Chrysodracon auwahiensis (C. auwahiensis), endemic to Maui and Molokai, still has large adult populations in dry lands of the islands, but unfortunately no regeneration from seed has been reported in those areas for many years. The two endemic species were examined using the molecular technique of random amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) to determine the genetic structure of the populations and the amount of variation. Both species possess similar genetic structure. Larger and smaller populations of both species contain similar levels of genetic diversity as determined by the number of polymorphic loci, estimated heterozygosity, and Shannon's index of genetic diversity. Although population diversity of Chrysodracon hawaiiensis (C. hawaiiensis) is thought to have remained near pre-disturbance levels, population size continues to decline as recruitment is either absent or does not keep pace with senescence of mature plants. Conservation recommendations for both species are suggested.

Amphidromous but endemic: Population connectivity of Rhinogobius gigas (Teleostei: Gobioidei).

Rhinogobius gigas is an amphidromous fish endemic to eastern Taiwan. Fishes with the diadromous behavior are expected to have a broader distribution range and higher genetic homogeneity despite that some amphidromous fishes with limited distribution are observed and R. gigas is an additional exception with a limited distribution range. Rhinogobius gigas has been documented to be retained inshore near the river plume with a short pelagic larval duration of 30-40 days, which may account for the endemism of this species. The short marine larval stage of R. gigas may imply a population genetic structure and the aim of the present study is to test whether the population genetic structure is present in R. gigas. To test the population genetic structure, fragments of mitochondrial displacement loop and cytochrome c oxidase subunit I were sequenced to provide molecular inference for genetic structure among populations. Sixty-nine haplotypes were identified among 191 R. gigas from 10 populations of eastern Taiwan and the mean haplotype and nucleotide diversities for all samples were 0.956 and 0.0024, respectively, implying a bottleneck followed by a recent population expansion further supported by Fu's Fs (-26.6; p < 0.001) and Tajima's D (-1.5; p = 0.037) values. The phylogenetic analysis revealed lack of genetic structure and the bush-like median joining network without commonly shared haplotypes supports the same scenario. The genetic homogeneity is probably due to the amphidromous life history providing the opportunity for passive larval transportation among the rivers through coastal currents in eastern Taiwan. The endemism to eastern Taiwan may be a consequence of complicated interactions among short pelagic larval duration, interspecific competition and coastal currents.

Biological efficiency and nutritional value of the culinary-medicinal mushroom Auricularia cultivated on a sawdust basal substrate supplement with different proportions of grass plants.

Auricularia polytricha was cultivated on a sawdust basal substrate supplemented with different proportions (30%, 45%, and 60%, respectively) of stalks of three grass plants, i.e., Panicum repens (PRS), Pennisetum purpureum (PPS), and Zea mays (ZMS), to determine the most effective substrate. The mycelial growth rate, total colonization time, days to primordial formation, biological efficiency and chemical composition of fruiting bodies were evaluated. The results indicated that 30PPS was the best substrate for mycelial growth of A. polytricha, with a corresponding total colonization period of 32.0 days. With the exception of 30PPS, the total biological efficiency of all of the substrates containing P. repens stalk, P. purpureum stalk and Z. mays stalk was higher (P < 0.05) than that of the control. The most suitable substrate with a high biological efficiency was 60PRS (148.12%), followed by 30ZMS (145.05%), 45ZMS (144.15%) and 30PRS (136.68%). The nutrient values of fruiting bodies were affected by different substrates. The ash contents of A. polytricha cultivated on a substrate containing Z. mays stalk were higher than that of the control; meanwhile, the protein contents of mushroom cultivated on a substrate containing P. repens stalk (except substrate 45PRS) were higher than that of the control. The biological efficiency of the substrates was tested, and according to the results, it is feasible to use the stalks of P. repens and Z. mays on partially replaced sawdust to cultivate A. polytricha.

Evolutionary origin of a periodical mass-flowering plant.

The evolutionary origin of periodical mass-flowering plants (shortly periodical plants), exhibiting periodical mass flowering and death immediately after flowering, has not been demonstrated. Within the genus Strobilanthes (Acanthaceae), which includes more than 50 periodical species, Strobilanthes flexicaulis on Okinawa Island, Japan, flowers gregariously every 6 years. We investigated the life history of S. flexicaulis in other regions and that of closely related species together with their molecular phylogeny to reveal the evolutionary origin of periodical mass flowering. S. flexicaulis on Taiwan Island was found to be a polycarpic perennial with no mass flowering and, in the Yaeyama Islands, Japan, a monocarpic perennial with no mass flowering. Molecular phylogenetic analyses indicated that a polycarpic perennial was the ancestral state in this whole group including S. flexicaulis and the closely related species. No distinctive genetic differentiation was found in S. flexicaulis among all three life histories (polycarpic perennial, monocarpic perennial, and periodical plant). These results suggest that among S. flexicaulis, the periodical mass flowering on Okinawa Island had evolved from the polycarpic perennial on Taiwan Island via the monocarpic perennial in the Yaeyama Islands. Thus, the evolution of life histories could have taken at the level of local populations within a species.

Vegetation and fire in lowland dry forest at Wa'ahila Ridge on O'ahu, Hawai'i.

Long-term ecological studies are critical for providing key insights in ecology, environmental change, natural resource management and biodiversity conservation. However, island fire ecology is poorly understood. No previous studies are available that analyze vegetative changes in burned and unburned dry forest remnants on Wa'ahila Ridge, Hawai'i. This study investigates vegetation succession from 2008 to 2015, following a fire in 2007 which caused significant differences in species richness, plant density, and the frequency of woody, herb, grass, and lichens between burned and unburned sites. These findings infer that introduced plants have better competitive ability to occupy open canopy lands than native plants after fire. This study also illustrates the essential management need to prevent alien plant invasion, and to restore the native vegetation in lowland areas of the Hawaiian Islands by removing invasive species out-planting native plants after fire.