Journal of Environmental Biology

Heat stress tolerance in relation to oxidative stress

and antioxidants in Brassica juncea

Robin A. Wilson^1,2,3, M.K. Sangha^{1, 2}*, S.S. Banga¹, A. K. Atwal¹ and Shilpa Gupta¹

¹Department of Plant Breeding and Genetics, Punjab Agricultural University, P.O. PAU, Ludhiana-141 004, India

²Department of Biochemistry, Punjab Agricultural University, Ludhiana-141 004, India

³Central Institute of Post Harvest Engineering and Technology, Ludhiana-141 004, India

*Corresponding Author E-mail: manjeet_kaursangha@yahoo.com

Publication Data

Paper received:

16 October 2012

Revised received:

29 May 2013

Accepted:

31 July 2013

Abstract

In the present study fifty genotypes of Brassica juncea were evaluated for heat stress tolerance in terms of biochemical components, in four day old seedlings. Heat shock was given at 45^?C for 4.5 hr and thereafter survival percentage, electrolyte leakage and chlorophyll content were estimated. Tolerant genotypes (10) registered survival greater than 65%, moderately tolerant (20) between 35-65% and susceptible (20) less than 35%. Electrolyte leakage was significantly (p<0.001) higher in susceptible genotypes than in tolerant ones with respect to control seedlings. Chlorophyll content showed no significant variation among the tolerant, moderately tolerant and susceptible genotypes, although it registered a decline in response to heat stress. Lipid peroxidation, assessed by malondialdehyde (MDA) in stressed conditions was 4.66 (MDA g^-1 f. wt. of tissue) in tolerant genotypes, 7.44 (MDA g^-1 f. wt. of tissue) in susceptible genotypes and correlated significantly (r=0.563) with electrolyte leakage. Increase in POD activity under heat stress was maximum in tolerant class with respect to control. CAT activity showed decrease after heat shock treatment in all the three classes but the decrease was 1.3 fold in tolerant genotypes as compared to 1.6 fold in susceptible genotypes. The non-enzymatic antioxidants glutathione and proline registered a significantly (<0.01) high value in tolerant genotypes on heat shock treatment in comparison to susceptible genotypes corroborating the role of antioxidants in mitigating the effect of heat stress in B juncea. The antioxidants and proline seemed to play role in mitigating the effect of heat stress.

 Key words

Antioxidant relationship, Brassica juncea, Heat stress, Oxidative stress

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