Is oxidative stress involved in the loss of neem (Azadirachta indica) seed viability?

Neem (Azadirachta indica) is a valuable multipurpose tree of tropical arid and semi-arid regions. The use of its seeds is hindered by their short storage longevity. The possible causes of rapid loss of viability were investigated on different seed lots during exposure to 32% and 75% RH at 20°C. Within 6 months the seeds almost lost germinability at 75% RH, whereas at 32% RH viability decreased only slightly. On rehydration, the axis cells from nongerminable seeds had lost turgor, whereas those from viable seeds were turgescent as visualized by low temperature scanning electron microscopy images of fractured axes. Glutathione oxidation status was used to estimate oxidative stress during storage. Oxidative stress was much higher at 75% RH storage than at 32% RH, mainly caused by the rapid loss of reduced glutathione at 75% RH. Oligosaccharides and phospholipids decreased, and free fatty acids increased during storage at the high RH but remained at a constant level at the low RH. However, the degree of fatty acid unsaturation between viable and nonviable seed lots was similar. During the (slow) dehydration of fresh seeds, total glutathione, oligosaccharides and phospholipids accumulated, particularly in the initially more hydrated seeds. We interpret this accumulation as a post-maturation process associated with acquisition of the capability for long-term survival in the dry state. The mass ratio of oligosaccharides to sucrose was 0.19 on average in dehydrated neem seeds. The data suggest that the storage behaviour of neem seeds has features that characterize it as orthodox

Metabolomic variation of brassica rapa var. rapa (var. raapstelen) and raphanus sativus l. at different developmental stages

Brassica rapa (var. raapstelen) and Raphanus sativus (red radish) are being used as food and fodder while also known as model in recent plant research due to the diversity of metabolites as well as genetic resemblance to Arabidopsis. This study explains the change in metabolites (amino acids, organic acids, chlorophyll, carotenoids, tocopherols, ascorbic acid, sucrose, phenylpropanoids and glucosinolates) during plant development. In present study the metabolomic variation in relation to plant growth has been evaluated, for Brassica rapa (var. raapstelen) and red radish (Raphanus sativus) at three different developmental stages. A non-targeted and targeted metabolomic approach by NMR and HPLC in combination with Principal component analysis (PCA) of the data was used to identify phytochemicals being influenced by plant growth. The results lead to the better understanding of metabolic changes during plant development and show the importance of plant age with respect to the metabolomic profile of vegetables

Is oxidative stress involved in the loss of neem (Azadirachta indica) seed viability?

Neem (Azadirachta indica) is a valuable multipurpose tree of tropical arid and semi-arid regions. The use of its seeds is hindered by their short storage longevity. The possible causes of rapid loss of viability were investigated on different seed lots during exposure to 32% and 75% RH at 20°C. Within 6 months the seeds almost lost germinability at 75% RH, whereas at 32% RH viability decreased only slightly. On rehydration, the axis cells from nongerminable seeds had lost turgor, whereas those from viable seeds were turgescent as visualized by low temperature scanning electron microscopy images of fractured axes. Glutathione oxidation status was used to estimate oxidative stress during storage. Oxidative stress was much higher at 75% RH storage than at 32% RH, mainly caused by the rapid loss of reduced glutathione at 75% RH. Oligosaccharides and phospholipids decreased, and free fatty acids increased during storage at the high RH but remained at a constant level at the low RH. However, the degree of fatty acid unsaturation between viable and nonviable seed lots was similar. During the (slow) dehydration of fresh seeds, total glutathione, oligosaccharides and phospholipids accumulated, particularly in the initially more hydrated seeds. We interpret this accumulation as a post-maturation process associated with acquisition of the capability for long-term survival in the dry state. The mass ratio of oligosaccharides to sucrose was 0.19 on average in dehydrated neem seeds. The data suggest that the storage behaviour of neem seeds has features that characterize it as orthodox

Viability loss and oxidative stress in Lily bulbs during long-term cold storage.

The regeneration ability of bulb scales of the Asiatic hybrid lily (Lilium hybrids L.) ‘Enchantment’ was monitored for bulbs stored for 0 to 5 years at −2°C in moist peat. Regeneration ability decreased after more than 1 year of storage and was completely lost after 5 years. Possible involvement of oxidative stress in the loss of regeneration capacity was tested. In this study we used white (i.e. with no visual damage) scales to test whether breakdown of membranes by oxidative stress was an early event in this storage-induced viability loss of lily bulbs. The content of reduced glutathione, which was the main nonprotein thiol in the bulb scales, remained nearly constant, while that of oxidized glutathione was slightly increased after 3.3 years of storage. Significant changes in the content of phospholipids, neutral lipids and free fatty acids were not detected during storage. The degree of unsaturation of fatty acids in phospholipids increased during the first 3 years of storage. Ion leakage of bulb scales was not increased in bulbs that were stored for less than 4 years. No indication was found that oxidative stress is a major factor associated with the loss of regeneration capacity of lily bulbs during cold storage