Variable Growth Responses of Water Thyme (Hydrilla verticillata) to Whole-Cell Extracts of Cylindrospermopsis raciborskii

Abstract

Static-renewal ecotoxicity trials monitored growth of Hydrilla verticillata in conjunction with exposure to Cylindrospermopsis raciborskii whole-cell extracts containing the cyanotoxin cylindrospermopsin (CYN). Maximum exposure concentrations were 400 microg L(-1) CYN over 14 days. The responses of Hydrilla to the treatments were variable according to the toxin concentrations and lengths of exposure. Plant deaths, chlorosis, and necrosis were not recorded from treated plants. However, Hydrilla experienced significant growth stimulation and redistribution of plant resources in conjunction with exposure to the whole-cell extracts. Root production was particularly impacted. The results of this study imply that root production could aid in reducing C. raciborskii cell concentrations and CYN toxicity. Results of chlorophyll analyses differed, indicating that CYN in whole-cell extracts might exert complex effects on photosynthesis. This is the first study to describe the responses of an aquatic macrophyte following exposure to C. raciborskii whole-cell extracts containing the cyanotoxin cylindrospermopsin.

Biochemical and growth performance of the aquatic macrophyte Azolla filiculoides to sub-chronic exposure to cylindrospermopsin

“…Chlorophyll a and b content and ratio a/b in S. oligorrhiza has showed small changes for a range of CYN concentrations between 7.5 and 120 lg L -1 (Kinnear et al 2007). On the other hand, chlorophylls a and b has decreased for all CYN concentrations (25-400 lg L -1 ) in H. verticillata, but the ratio a/b has increased (Kinnear et al 2008). Concerning antioxidative enzymes, the information also is scarce.…”

“…On the other hand, the aquatic plants S. oligorrhiza (Kinnear et al 2007) and H. verticillata (Kinnear et al 2008) has showed an increase in the relative growth rate even at a concentration of 113 and 400 lg L -1 respectively. In A. filiculoides also has occurred a growth increase with the two lower CYN concentrations (0.05 and 0.5 lg mL -1 ).…”

“…On the other hand, at concentrations of 0.57, 5.7 and 57 lg L -1 , root elongation in S. lycopersicum and P. sativum has decreased, but in L. sativa and P. vulgaris it increased (Silva and Vasconcelos 2010). Growth and biomass are also influenced with CYN: biomass of Oryza sativa has decreased after 9 days exposure to 2.5 lg CYN L -1 (Prieto et al 2011) but biomass of the aquatic macrophyte Spirodela oligorrhiza (Kinnear et al 2007) and growth of H. verticillata (Kinnear et al 2008) increased or decreased depending on concentration and exposure time.…”

“…Roots are one of the plants organs most affected by exposure to CYN. At a range of concentrations between 25-400 lg L -1 CYN has induced an increase in root growth in Hydrilla verticillata (Kinnear et al 2008), at 0.5-40 lg CYN mL -1 induced a decrease in root elongation and necrosis in root cortex of Phragmites australis (Beyer et al 2009) and at 0.01-20 lg CYN mL -1 has inhibited xylem differentiation and lateral roots in Sinapsis alba (Máthé et al 2013). On the other hand, at concentrations of 0.57, 5.7 and 57 lg L -1 , root elongation in S. lycopersicum and P. sativum has decreased, but in L. sativa and P. vulgaris it increased (Silva and Vasconcelos 2010).…”

The permeability effect of microcystin-RR on Escherichia coli and Bacillus subtilis

“…Recent reports showed that microcystins might induce apoptosis of hepatocyte in mice and lymphocyte in humans, chickens and carp [13−15]. It was also found that microcystins could inhibit plant growth [16,17] and induce the antioxidant system reaction of plants, in which oxidative stress may play an important role in the toxicity of microcystins on plants [18−20]. Currently, some reports focused on the effect of microcystins on algae.…”