Foliar application of lambda-cyhalothrin modulates root exudate profile and the rhizosphere bacteria community of dioecious Populus cathayana.

Dioecious plants show sexual differences in resistance traits to abiotic stresses. However, the effects of exogenous pesticide application on female and male plant growth and their associated adaptation mechanisms are unclear. Our study investigated the effects of the broad-spectrum pesticide lambda-cyhalothrin (λ-CY) on dioecious Populus cathayana growth and explored the factors through which λ-CY changed the rhizosphere bacterial community and physicochemical soil properties via sex-specific metabolomics. The sequential application of λ-CY significantly suppressed male shoot- and root biomass, with little effect on the growth of females. Females possessed a higher intrinsic chemo-diversity within their root exudates, and their levels of various metabolites (sugars, fatty acids, and small organic acids) increased after exposure to λ-CY with consequences on bacterial community composition. Maintaining high bacterial alpha diversity and recruiting specific bacterial groups slowed down the loss of rhizosphere nutrients in females. In contrast, the reduction in bacterial alpha diversity and network structure stability in males was associated with lower rhizosphere nutrient availability. Spearman's correlation analysis revealed that several bacterial groups were positively correlated with the root secretion of lipids and organic acids, suggesting that these metabolites can affect the soil bacterial groups actively involved in the nutrient pool. This study provided novel insights that root exudates and soil microbial interactions may mediate sex-specific differences in response to pesticide application.

One-pot quantitative hydrolysis of lignocelluloses mediated by black liquor.

Black liquor from the kraft process facilitates quantitative biomass hydrolysis converting cellulose and hemicellulose into organic acids such as lactic acid (~50%), and lignin into small molecular aromatics, without gasification and black tar formation. Oxygen transfer between lignin and carbohydrates may be the mechanism. With this method, three tons of lignocellulosic biomass can potentially produce up to one ton of lactic acid, and one ton of small molecular aromatics. This novel usage of black liquor is environmentally viable because it is accompanied by significant emission reduction of particulates, sulfur and nitrogen oxides, most organic sulfur compounds and sulfites of black liquor were converted into sulfates.