Physiological responses and detoxific mechanisms to Pb, Zn, Cu and Cdin young seedlings of Paulownia fortunei
Jiang Wang , Weihua Li , Chongbang Zhang , Shisheng Ke
DOI:
Received December 02, 2009,Revised March 05, 2010, Accepted , Available online
Volume 22,2010,Pages 1916-1922
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Paulownia fortunei has been successfully used in the phytoremediation of many Pb/Zn mine tailings. However, seed germination
and young seedlings of P. fortunei rarely occurred in these mine tailings. The physiological responses and detoxific mechanisms of
P. fortunei young seedling to Pb, Zn, Cu and Cd stress were investigated. The germinated rate, shoot length, chlorophyll and carotenoid
contents in leaves of young seedlings had a great reduction under Zn and Cu treatments, but had little decrease under Pb and Cd
treatments. The production rate of O2
.??, H2O2 and malondialdehyde (MDA) contents significantly increased in response to added Zn
and Cu indicating great oxidative stress for young seedlings, but they had no significant change to added Pb and Cd. Young seedlings
had e ective detoxific mechanism to Pb and Cd, as antioxidant enzymes activities, phytochelatins (PCs-SH) and proline contents
increased with increasing rates of added Pb and Cd. However, young seedlings had un-e ective detoxific mechanisms to Zn and Cu
stress. Results revealed the heavy metals (such as Cu) that present at low concentrations in mine tailings may be major constraint for
the survival of young seedlings.
