Improved cadmium uptake and accumulation in the hyperaccumulator Sedum alfredii:the impact of citric acid and tartaric acid

The elucidation of a natural strategy for metal hyperaccumulation enables the rational design of technologies for the clean-up of metal-contaminated soils.Organic acid has been suggested to be involved in toxic metallic element tolerance,translocation,and accumulation in plants.The impact of exogenous organic acids on cadmium(Cd) uptake and translocation in the zinc(Zn)/Cd co-hyperaccumulator Sedum alfredii was investigated in the present study.By the addition of organic acids,short-term(2 h) root uptake of 109 Cd increased significantly,and higher 109 Cd contents in roots and shoots were noted 24 h after uptake,when compared to controls.About 85% of the 109 Cd taken up was distributed to the shoots in plants with citric acid(CA) treatments,as compared with 75% within controls.No such effect was observed for tartaric acid(TA).Reduced growth under Cd stress was significantly alleviated by low CA.Long-term application of the two organic acids both resulted in elevated Cd in plants,but the effects varied with exposure time and levels.The results imply that CA may be involved in the processes of Cd uptake,translocation and tolerance in S.alfredii,whereas the impact of TA is mainly on the root uptake of Cd.

Purified isolation of vacuoles from Sedum alfredii leaf-derived protoplasts

This study aims to develop a method for isolating and purifying protoplasts/vacuoles from fresh leaves of the Cd hyperaccumulator plant species, Sedum alfredii. The results revealed that preheating cellulase and macerozyme at 50 ℃ for 5 rain significantly accel- erated the cell wall degradation. For the most optimal conditions for mesophyll protoplast isolation, the mixture of fresh leaves and cell lysates was followed by a 2-h-long vibration. The protoplast lysate for vacu- ole isolation was diluted, and 0.675 mmol/L was identi- fied as the most appropriate 3-[（3-cholamidopropyl） dimethylammonio]- 1 -propanesulfonic acid （CHAPS） level, in which S. alfredii large vacuoles are charac- terized by a high metal and malic acid content.

Improved yield and Zn accumulation for rice grain by Zn fertilization and optimized water management

Zinc（Zn） deficiency and water scarcity are major challenges in rice（Oryza sativa L.） under an intensive rice production system.This study aims to investigate the impact of water-saving management and different Zn fertilization source（ZnSO4 and Zn-EDTA） regimes on grain yield and Zn accumulation in rice grain.Different water managements,continuous flooding（CF）,and alternate wetting and drying（AWD） were applied during the rice growing season.Compared with CF,the AWD regime significantly increased grain yield and Zn concentrations in both brown rice and polished rice.Grain yield of genotypes（Nipponbare and Jiaxing27）,on the average,was increased by 11.4%,and grain Zn concentration by 3.9% when compared with those under a CF regime.Zn fertilization significantly increased Zn density in polished rice,with a more pronounced effect of ZnSO4 being observed as compared with Zn-EDTA,especially under an AWD regime.Decreased phytic acid content and molar ratio of phytic acid to Zn were also noted in rice grains with Zn fertilization.The above results demonstrated that water management of AWD combined with ZnSO4 fertilization was an effective agricultural practice to elevate grain yield and increase Zn accumulation and bioavailability in rice grains.