Desiccation-induced changes in lipid peroxidation, superoxide level and antioxidant enzymes activity in neem (Azadirachta indica A. Juss) seeds

Abstract

The freshly harvested mature neem seeds (42.2 % seed moisture content) with 100 % viability deteriorate when naturally desiccated to below 10.9 %. The desiccation-induced loss of viability was closely associated with over accumulation of superoxide anion and lipid peroxidation products both in the embryonic axes and cotyledons. The levels of superoxide anion and lipid peroxidation products were higher in axes compared to cotyledons. Superoxide dismutase activity was not much affected, both in the axes and cotyledons of 100 % viable seeds during desiccation from 42.2 % to 10.9 % seed moisture content. Steep rise in its activity was observed during drying below lowest safe moisture content (LSMC). Activities of catalase and peroxidase exhibited substantially higher levels in the 100 % viable seeds dehydrated up to LSMC. Their activities declined sharply in seeds with water content below LSMC. Impairment of catalase and peroxidase activities possibly lead to enhanced accumulation of reactive oxygen species. The accumulation of superoxide anion, lipid peroxidation and differential expression of superoxide dismutase and catalse/peroxidse activities in response to desiccation (below LSMC) is discussed to explain the intermediate storage physiology of neem seeds.List of abbreviations: L S M C : least safe moisture content; M D A : malondialdehyde; ROS : reactive oxygen species; SOD : superoxide dismutase;

Changes in Seed Germination Ability, Lipid Peroxidation and Antioxidant Enzyme Activities of Ginkgo biloba Seed during Desiccation

“…Thus, the desiccation of G. biloba seeds accompanied by a deepening degree of membrane lipid oxidation led to the severe damage of the membrane system, causing a large accumulation of MDA. This was consistent with seeds of Azadirachta indica [50] and Pachira macrocarpa [51]. However, it is important to mention that a decline from 30% to 25% MC was observed in Figure 7, where with respect to SOD and POD, the peak values were found at 25% and 30% MC, respectively ( Figures 5 and 6), and the germination percentage kept constant.…”

Oxidative metabolism-related changes in cryogenically stored neem (Azadirachta indica A. Juss) seeds

“…In the third week of June, mature ripe yellow fruits of Azadirachta indica A. Juss (neem) 12 weeks after flowering (Varghese and Naithani, 2002) were harvested manually from trees growing in Pt. Ravishankar Shukla University campus, Raipur, and brought to the laboratory immediately.…”

“…A few seeds from the lot were immediately depulped mechanically to determine the seed water content, which is hereafter referred to as the initial water content. Seeds were extracted from the fruit tissue by soaking them in 20% H 2 SO 4 (Merck, India) for 30 min after depulping by rubbing with hands over a wire mesh and washing repeatedly under tap water as described elsewhere (Varghese and Naithani, 2002).…”

“…The activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) change markedly during seed germination in embryonic axes of soybean in response to cytoplasmic increase in O 2 À and H 2 O 2 (Puntarulo et al, 1991). AOS metabolism is the characteristic feature of fresh mature non-orthodox seeds of Shorea robusta Naithani, 1994, 1998), Azadirachta indica (Sacande et al, 2000b;Varghese and Naithani, 2002), and was also suggested for Avicienia marina (Greggains et al, 2001) seeds. Decreasing antioxidant enzyme activity is closely associated with the loss of germinability in recalcitrant seeds like Shorea robusta Naithani, 1994, 1998) and Avicennia marina (Greggains et al, 2001).…”

Ageing increases the sensitivity of neem (Azadirachta indica) seeds to imbibitional stress

“…They have also been reported to display orthodox behaviour (Roederer and Bellefontaine, 1989;Bellefontaine and Audinet, 1993;Tompsett and Kemp, 1996;Sacandé et al, 2000b). Other studies concluded that neem seeds belong to the intermediate category of storage behaviour (Gaméné et al, 1996;Sacandé et al, 1996;Hong and Ellis, 1998;Varghese and Naithani, 2002). Many factors, such as seed provenance, maturity at harvest and conditions of storage and sensitivity to imbibition, have been suggested to explain these apparent controversies.…”