Leaf Photosynthesis and Antioxidant Defense in Male and Hermaphrodite Tree of A Critically Endangered Legume, Gymnocladus assamicus Kanjilal ex P.C. Kanjilal 
,
Dibyendu Talukdar2 
2. Plant Cell and Stress Biology Lab, Department of Botany, R.P.M. College (University of Calcutta), Uttarpara, Hooghly 712258, West Bengal, India
Author Correspondence author
Plant Gene and Trait, 2014, Vol. 5, No. 1 doi: 10.5376/pgt.2014.05.0001
Received: 22 Jul., 2013 Accepted: 03 Dec., 2013 Published: 02 Jan., 2014
Talukdar, 2014, Leaf Photosynthesis and Antioxidant Defense in Male and Hermaphrodite Tree of A Critically Endangered Legume, Gymnocladus assamicus Kanjilal ex P.C. Kanjilal, Plant Gene and Trait, Vol.5, No.1 1-10 (doi: 10.5376/pgt.2014.05.0001)
Photosynthetic pigment content, photosynthesis rate and antioxidant defense components were studied in leaves of male and hermaphrodite trees of an endemic and critically endangered leguminous tree Gymnocladus assamicus Kanjilal ex P.C. Kanjilal in Indian Himalayas to ascertain the differential physiological behavior between two different breeding types. Significant differences were noticed between male and hermaphrodite trees during leaf flushing stage and between leaf flushing and seed setting stage in hermaphrodite trees. During flushing period, pigment content and photosynthetic rates were significantly higher in hermaphrodite tree compared with its male. Similarly, reduced ascorbate (AsA) and glutathione (GSH), and their redox states were substantially higher in hermaphrodites than those in male tree undergoing flushing stage. By contrast, low levels of ascorbate peroxidase, dehydroascorbate reductase and glutathione reductase jeopardized scavenging of H2O2 and regeneration of AsA and GSH in male plant, consequently resulting in over-accumulation of H2O2 and high level of lipid peroxidation in leaves of male tress, marking the onset of oxidative stress, despite the high level of superoxide dismutase, catalase and guaiacol-peroxidase in male. No such situation was encountered in hermaphrodite trees during leaf flushing, although a significant decline of physiological fitness was observed after its entry into seed setting stage. Concomitant with reduction in photosynthetic capacity, there was a marked decrease in radical-scavenging capacity, leading to rise in H2O2 level in leaves. Accumulation of malondealdehyde suggested oxidative damage in hermaphrodites, which may be instrumental for low photosynthetic capacity, high pollen sterility and reduction in number of healthy reproductive population of G. assamicus.