Effect of Pb toxicity on root morphology, physiology and ultrastructure in the two ecotypes of Elsholtzia argyi.
Seed germination and hydroponics experiments were conducted to underpin the effects of Pb on mined ecotype (ME) and non-mined ecotype (NME) of Elsholtzia argyi from Pb/Cu mining areas and the non-contaminated agricultural areas, respectively. In both experiments, ME exhibited higher tolerance to excessive levels of Pb in the growth medium. Various Pb treatments caused a stimulatory effect on seed germination of both the ecotypes. Concentrations of Pb in the leaves and the stem of the ME were 2.6 and 4.5 times respectively higher than those of the NME when plants were supplied with Pb level of 200microM. Pb posed adverse effects on root morphological organization and root activity of both the ecotypes but decrease was not sharp and root activity was recovered in ME plants. Root ultrastructural studies revealed that in ME, Pb was detected as fine particles dispersed throughout the cell membrane and cell wall fraction, whereas most of the Pb was found as large aggregates deposited in the cell walls of NME plants. Comparatively better growth, higher tolerance and accumulation of Pb expressed by ME plants is mainly attributed to the maintenance of its root growth and activity as well as integrity of cell organelles.
Islam
Ejazul
E
MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Natural Resources and Environmental Science, Zhejiang University, Huajiachi Campus, Hangzhou 310029, China. ejazulislam75@yahoo.com
Yang
Xiaoe
X
Li
Tingqiang
T
Liu
Dan
D
Jin
Xiaofen
X
Meng
Fanhua
F
D004305:Dose-Response Relationship, Drug; D004787:Environmental Pollution; D018525:Germination; D019686:Lamiaceae / Q000145:classification / Q000187:drug effects* / Q000378:metabolism; D007854:Lead / Q000633:toxicity*; D046529:Microscopy, Electron, Transmission; D018517:Plant Roots / Q000187:drug effects* / Q000254:growth & development / Q000648:ultrastructure; D012989:Soil Pollutants / Q000633:toxicity*; D013045:Species Specificity
D012989:Soil Pollutants; D007854:Lead