Ferrous iron-induced increases in capitate glandular trichome density and upregulation of CbHO-1 contributes to increases in blinin content in Conyza blinii.

MAIN CONCLUSION: Ferrous iron can promote the development of glandular trichomes and increase the content of blinin, which depends on CbHO-1 expression. Conyza blinii (C. blinii) is a unique Chinese herbal medicine that grows in Sichuan Province, China. Because the habitat of C. blinii is an iron ore mining area with abundant iron content, this species can be used as one of the best materials to study the mechanism of plant tolerance to iron. In this study, C. blinii was treated with ferrous-EDTA solutions at different concentrations, and it was found that the tolerance value of C. blinii to iron was 200 µM. Under this concentration, the plant height, root length, biomass, and iron content of C. blinii increased to the maximum values, and the effect was dependent on the upregulated expression of CbHO-1. At the same time, under ferrous iron, the photosynthetic capacity and capitate glandular trichome density of C. blinii also significantly increased, providing precursors and sites for the synthesis of blinin, thus significantly increasing the content of blinin. These processes were also dependent on the high expression of CbHO-1. Correlation analysis showed that there were strong positive correlations between iron content, capitate glandular trichome density, CbHO-1 gene expression, and blinin content. This study explored the effects of ferrous iron on the physiology and biochemistry of C. blinii, greatly improving our understanding of the mechanism of iron tolerance in C. blinii.

In vivo NMR investigations of glyphosate influences on plant metabolism.

Glyphosate is the world's most widely used herbicide; popular due to its relative low cost, low toxicity, and high efficacy in controlling most common weed species. Genetic engineering of crop seeds to be glyphosate-tolerant has facilitated the modern global agricultural practice whereby both weeds and crops are treated with herbicide, while only the crops survive. However, due to extreme selective pressure, glyphosate-resistant (GR) weed species are now found with increasing frequency in nature, threatening the dominant weed management system used in large-scale agriculture across much of the globe. In vivo NMR studies of plants have facilitated the discovery and understanding of the glyphosate-resistance mechanism of the multi-continent, highly invasive weed species, GR horseweed Conyza canadensis (L.) Cronq. and GR ryegrass (Lolium spp.). This study exemplifies how in vivo NMR spectroscopy can be used to better understandherbicide-associated metabolic alterations observed in living plants, which poses a significant threat to modern agriculture as it is currently practiced.

Physiological, morphological and biochemical studies of glyphosate tolerance in Mexican Cologania (Cologania broussonetii (Balb.) DC.).

In recent years, glyphosate-tolerant legumes have been used as cover crops for weed management in tropical areas of Mexico. Mexican cologania (Cologania broussonetii (Balb.) DC.) is an innate glyphosate-tolerant legume with a potential as a cover crop in temperate areas of the country. In this work, glyphosate tolerance was characterized in two Mexican cologania (a treated (T) and an untreated (UT)) populations as being representatives of the species, compared in turn to a glyphosate-susceptible hairy fleabane (S) (Conyza bonariensis (L.) Cronq.) population. Experiments revealed that T and UT Mexican cologania populations had a higher tolerance index (TI), and a lower shikimic acid accumulation and foliar retention than the hairy fleabane S population. Absorption and translocation, leaf morphology and metabolism studies were only carried out in the Mexican cologania T population and the hairy fleabane S population. The latter absorbed 37% more (14)C-glyphosate compared to the Mexican cologania T at 96 h after treatment (HAT). Mexican cologania T translocated less herbicide from the treated leaf to the remainder of the plant than hairy fleabane S. The Mexican cologania T presented a greater epicuticular wax coverage percentage than the hairy fleabane S. This morphological characteristic contributed to the low glyphosate absorption observed in the Mexican cologania. In addition, the Mexican cologania T metabolized glyphosate mainly into AMPA, formaldehyde and sarcosine. These results indicate that the high glyphosate tolerance observed in Mexican cologania is mainly due to the poor penetration and translocation of glyphosate into the active site, and the high glyphosate degradation into non-toxic substances.

Hyperaccumulative property comparison of 24 weed species to heavy metals using a pot culture experiment.

The screening of hyperaccumulators is still very much needed for phytoremediation. With properties such as strong tolerance to adverse environment, fast growing and highly reproductive rate, weed species may be an ideal plant for phytoremediation. The objectives of this study were to examine the tolerance and hyperaccumulative characteristics of 24 species in 9 families to Cd, Pb, Cu and Zn by using the outdoor pot-culture experiment. In the screening experiment, only Conyza canadensis and Rorippa globosa displayed Cd-hyperaccumulative characteristics. In a further concentration gradient experiment, C. canadensis was affirmed that it is not a Cd hyperaccumulator. Only R. globosa, indicated all Cd hyperaccumulative characteristics, especially Cd concentration in its stems and leaves were higher than 100 mg/kg, the minimum Cd concentration what a Cd-hyperaccumulator should accumulate. Thus, R. globosa was further validated as a Cd-hyperaccumulator.

Effects of the extract from Conyza canadensis on human blood platelet aggregation.

The effects of different parts of extract from medicinal plant Conyza canadensis, used to control bleeding, on human blood platelet aggregation in vitro were investigated. Aqueous extract of Conyza c. from young or old plants, glycoconjugate part, polysaccharide part and aglycon part at the concentrations above 0.75 mg/ml strongly inhibited platelet aggregation induced by collagen (2 microg/ml) in dose-dependent manner. Polysaccharide part isolated from plant extract had the strongest inhibitory effect on aggregation stimulated by collagen and seems to be responsible for antiaggregatory properties.