Junmin Li

Effect of hypersaline aniline-containing pharmaceutical wastewater on the structure of activated sludge-derived bacterial community.

In order to explore the effect of hypersaline aniline-containing pharmaceutical wastewater on the structure of activated sludge-derived bacterial community, RAPD-PCR and PCR-DGGE techniques were used to analyze the change of bacterial community diversity and structure during the acclimation to different concentrations of two types of wastewater. Different bacterial community structures and significant shift in the bacterial community diversity were observed during the acclimation of wastewater. The number of bacterial species and the abundance of bacteria acclimated to different concentration of wastewater decreased when the concentration increased. The trends of bacterial community diversity indices revealed by RAPD or DGGE profiles were different. The change of bacterial community diversity might be due to the adaptation and mutation under selection issues in the acclimation of wastewater. The relationship between diversity indices and the content of chemical oxygen demand (COD), chloride, salinity and aniline based on RAPD and DGGE data indicated that the change of the bacterial community diversity might not be due to a single factor but might be due to the integrated effects of all the contaminants in the wastewater. Phylogenic trees based on RAPD and DGGE fingerprints were different, indicating that the effect of wastewaters A and B on the bacterial community structure was different, which might be due to the characteristics of wastewater.

Interactive Effects of Arbuscular Mycorrhizal Fungi and Copper Stress on Flowering Phenology and Reproduction of Elsholtzia splendens

Plant responses to heavy metal contamination may depend on the presence of arbuscular mycorrhizal fungi (AMF). Elsholtzia splendens is an indicator species for the presence of copper (Cu) mines because both its flowering phenology and reproduction are tolerant to heavy metals. To test whether effects of Cu on the flowering phenology and reproduction of E. splendens depend on the presence of AMF, we conducted a factorial experiment with two Cu treatments (with or without Cu addition) crossed with two AMF treatments (with or without AMF inoculation). Without AMF, Cu addition significantly delayed the onset dates, ending dates and peak dates of flowering and decreased flowering duration. However, AMF inoculation reversed the effects of Cu stress, with recovered flowering onset and ending dates and increased the flowering duration. Cu addition significantly decreased inflorescence width and number, inflorescence biomass, vegetative biomass and total seed number, but significantly increased 1000-seed weight. AMF inoculation significantly increased vegetative biomass. Two-way ANOVA results showed that the interactive effects between Cu addition and AMF inoculation were significant on the inflorescence number, vegetative biomass and total seed number. These results indicate that AMF can alleviate the Cu stress on the flowering phenology and reproduction of E. splendens.

Effects of ploidy level and haplotype on variation of photosynthetic traits: Novel evidence from two Fragaria species.

To reveal the effects of ploidy level and haplotype on photosynthetic traits, we chose 175 genotypes of wild strawberries belonging to two haplotypes at two types of ploidy levels (diploidy and tetraploidy) and measured photosynthetic traits. Our results revealed that ploidy significantly affected the characteristics of light-response curves, CO2-response curves, and leaf gas exchange parameters, except intercellular CO2 concentration (Ci). Tetraploid species had a lower light saturation point (LSP) and CO2 saturation point (CSP), higher light compensation point (LCP), dark respiration (Rd), and CO2 compensation point (CCP) than diploid species. Furthermore, tetraploid species have lower photosynthetic capacity than diploid species, including net photosynthetic rate (Pn), stomatal conductivity (Gs), and transpiration rate (Tr). In addition, haplotype had a significant effect on LSP, CSP, Tr, and Ci as well as a significant interactive effect between ploidy and haplotype on the maximal photosynethic rate of the light-response curve and Rd. Most of the variance existed within haplotypes among individuals. These results suggest that polyploidization was the main driver for the evolution of photosynthesis with increasing ploidy level (i.e. from diploidy to tetraploidy in Fragaria species), while the origin of a chromosome could also affect the photosynthetic traits and the polyploidization effect on photosynthetic traits.