ABSTRACT
Cadmium (Cd) is one of the most toxic heavy metals and is difficult to be removed from contaminated soil and water. Italian ryegrass (Lolium multiflorum), as an energy crop, exhibits a valuable potential to develop Cd polluted sites due to its use as a biofuel rather than as food and forage. Previously, via a screening for Cd-tolerant ryegrass, the two most extreme cultivars (IdyII and Harukaze) with high and low Cd tolerance during seed germination, respectively, were selected. However, the underlying mechanism for Cd tolerance was not well investigated. In this study, we comparatively investigated the growth, physiological responses, and Cd uptake and translocation of IdyII and Harukaze when the seedlings were exposed to a Cd (0-100 µM) solution for 12 days. As expected, excess Cd inhibited seedling growth and was accompanied by an accumulation of malondialdehyde (MDA) and reduced photosynthetic pigments in both cultivars. The effects of Cd on the uptake and translocation of other nutrient elements (Zn, Fe, Mn and Mg) were dependent on Cd concentrations, cultivars, plant tissues and elements. Compared with Harukaze, IdyII exhibited better performance with less MDA and higher pigment content. Furthermore, IdyII was less efficient in Cd uptake and translocation compared to Harukaze, which might be explained by the higher non-protein thiols content in its roots. Taken together, our data indicate that IdyII is more tolerant than Harukaze, which partially resulted from the differences in Cd uptake and translocation.
ABSTRACT
Strigolactones (SLs) are classified into plant hormones, playing a key role as a mediator of plant growth in response to several abiotic stresses, including drought and salinity. However, the role of SLs in cadmium (Cd)-induced stress to plants is still unknown. The physiological responses of switchgrass (Panicum virgatum) stressed in 10 µmol L-1 Cd to exogenous synthetic SLs analog, GR24 were studied in hydroponics. The Cd stress significantly caused the adverse effects on plant growth and root morphology, inhibited photosynthesis, but boosted lipid peroxidation of Switchgrass seedlings. After treatment of 1 µmol L-1 GR24, the above adverse effects caused by Cd stress were significantly alleviated, mainly reflects in improvement of shoot biomass, relative water content, root development, chlorophyll contents, activities of typical antioxidant enzymes, nutrient uptake. The reason for exogenous GR24 alleviating cadmium toxicity might be owing to that exogenous GR24 promoted the content of endogenous SLs, increased some essential element Fe (iron), Zn (zinc), Mn (manganese) and Cu (copper) uptake and reduced cadmium uptake, accumulation and partition in shoot of switchgrass seedlings.
