Population Genetics of the Endangered and Wild Edible Plant Ottelia acuminata in Southwestern China Using Novel SSR Markers.

Ottelia acuminata is an edible aquatic plant species that is endemic to southwestern China. This plant has experienced habitat degradation resulting from environmental change and extensive human disturbance. Determining the genetic variation and genetic structure of O. acuminata populations could help develop strategies to collect, evaluate, utilize and conserve the species. To this end, we genotyped 183 individuals sampled throughout the species distribution using twelve novel nuclear microsatellite loci (nSSRs). Eight of these nSSRs exhibited low average levels of genetic diversity (HE = 0.351, Ho = 0.376) and showed evidence of significant inbreeding across several populations. A high degree of genetic differentiation was identified among populations (FST = 0.457), probably resulting from limited pollen and seed-mediated gene flow. Only 17.8% of variation existed between O. acuminata var. acuminata and other O. acuminata varieties. Bayesian analysis and a UPGMA dendrogram based on Nei's genetic distance also revealed notably low genetic differentiation among the varieties. This low genetic differentiation is possibly attributed to shared ancestral polymorphisms since their divergence. Additional taxonomic and phylogenetic studies with additional molecular markers are needed to determine the population genetic relationship between O. acuminata varieties. Conservation of this species depends on in situ and ex situ actions, such as controlling habitat water pollution and overexploitation and creating a germplasm bank based on the population genetic differences. To the best of our knowledge, this study represents the first attempt to understand the population genetics of O. acuminata in China using novel nSSR markers developed from transcriptome sequencing and could contribute to the conservation management of this economic plant.

[Experiment and model simulation of self-purification capacity of nitrogen and phosphorus in Lake Taihu].

A field experiment was carried out in Zhushanhu in September, 2011. On the basis of mass balance, nutrients flow in and out of Zhushanhu and their Digestion-absorption law was illustrated through water quantity-water quality observation of bay heart, bay mouth and rivers around Zhushanhu, which provides basic data for the further research on the self-purification capacity of Lake Taihu. The EcoTaihu model was adopted to simulate the nutrients flow and their self-purification capacity of Lake Taihu. The simulated annual self-purification capacity of total nitrogen and total phosphorus of Zhushanhu was 1 911 t and 116 t, respectively, whereas the observed annual self-purification capacity of total nitrogen and total phosphorus of Zhushanhu was 1 979 t and 119 t, respectively. The model was validated by the observation data. The simulated result showed that the self-purification capacity of total nitrogen of Lake Taihu in year 2006, 2008 and 2010 was 4. 00 x 10(4) t, 4. 27 x 10(4) t and 4. 11 x 10(4) t, respectively, whereas the self-purification capacity of total phosphorus of Lake Taihu in year 2006, 2008 and 2010 was 1.56 x 10(3) t, 1.80 x 10(3) t and 1.71 x 10(3) t, respectively.

[Spatial distribution characteristics and ecological significance of alkaline phosphatase in water column of Taihu Lake].

Based on different ecological zone of Taihu Lake, alkaline phosphatase activity (APA), the kinetic parameters and the chemical parameters in water column from different zone of Taihu Lake were monitored, and the spatial distribution characteristics and the effects of environmental factors on the values of APA, Vmax and Km were studied. The results showed that the values of APA, Vmax and Km in water column from Taihu Lake had a spatial heterogeneous distribution. The spatial distribution characteristic of APA values was the same as that of Vmax, ones in water from different zones of Taihu Lake, namely, the maximal values of APA (9.43 +/- 5.30) nmol x (L x min)(-1) and Vmax (13.70 +/- 7.42) nmol x (L x min)(-1) occurred in water from estuary zone in western bank of Taihu Lake. The value distribution of APA and Vmax in other zone of Taihu Lake followed as: the central zone of Taihu Lake > the grass type zone of Taihu Lake > the Meiliang Bay zone of Taihu Lake > the Zhushan Bay zone of Taihu Lake > the Gonghu Bay zone of Taihu Lake. The value of Km from the grass type zone of Taihu Lake was the highest (20.50 +/- 11.30) micromol x L(-1) , and the one from estuary zone in western bank of Taihu Lake was the lowest (9.17 +/- 3.46) micromol x L(-1) The value of kinetic parameter Vmax was significantly positively correlated with the values of pH, total phosphorus (TP) and the chlorophyll a (Chla), with r(pH) = 0.6512** (p < 0.01), r(TP) = 0.4885** (p < 0.01) and r(Chla) = 0.7656** (p < 0.01), respectively. However, the effects of hydro-temperature, dissolved total phosphorus (DTP) and orthophosphorus (PO4(3-) -P) on Vmax values were negligible. There was no significant influence of the hydro-temperature, pH, DTP, PO4(3-)-P and Chla concentrations on the Km values, nevertheless significant negative relationship between the Km value and TP content was found with r = -0.3834* (p = 0.048).