IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...

17 th International Congress on Nitrogen Fixation
Fremantle, Western Australia
27 November – 1 December 2011
Session Details: Thursday 1 December 2011
Concurrent Session 18 – P Nutrition & Symbioses
1100 - 1230
Authors: Neera Garg 1 and Harmanjit Kaur 2
Department of Botany, Panjab University, Chandigarh 160014, India
Presentation Title: Role of arbuscular mycorrhizal (am) fungi and zinc in enhancing nitrogen fixation in
pigeon pea under cadmium stress
Presentation Time: 1100 – 1120
AM fungi are known to alleviate heavy metal stress in plants (Hildebrandt et al 2007). Cadmium (Cd) is a toxic
non essential element, whereas Zinc (Zn) is an essential element but regarded toxic at high concentrations.
Cd and Zn compete for transport via common carrier at root plasma membrane and Zn interferes with Cd
uptake in plants (Hassan et al 2005). The intent of present work was to analyze accumulation of heavy metals
(Cd and Zn) in nodules of two Cajanus cajan (L.) Millsp. (pigeonpea) genotypes and their subsequent impact
on nitrogen fixation, oxidative stress and non protein thiols (glutathione and phytochelatins) with and without
AM fungus. Two levels of Cd (25 and 50 mg kg -1 dry soil) and two levels of Zn (500 and 1000 mg kg -1 dry soil)
were applied singly and in combinations to 15 day old seedlings. Accumulation of Cd and Zn resulted in sharp
reduction in nodule number (NN), nodule dry mass (NDM) as well as nitrogen fixation {leghemoglobin (LHb)
and nitrogenase (N2ase)} of pigeonpea plants, although Cd had more pronounced effects than Zn. Cd induced
ROS generation, lipid peroxidation and altered non protein thiols were largely reversed by Zn
supplementation, suggesting antagonistic behaviour of Zn. Remarkable genotypic variation was found, with
much more severe response of both the metals in P792 than Sel 85N. Glomus mosseae along with Zn further
attenuated the phytotoxic effects of metals in nodules by significantly decreasing metal uptake and oxidative
stress ultimately leading to better nitrogen-fixation in pigeonpea.
Hassan MJ, Zhang G, Wu F, Wei K & Chen Z (2005). Zinc alleviates growth inhibition and oxidative stress
caused by cadmium in rice J Plant Nutr Soil Sci 168: 255-261.
Hildebrandt U, Regvar M & Bothe H (2007). Arbuscular Mycorrhiza and Heavy Metal Tolerance.
Phytochemistry 68: 139-146.
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2011