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Xia F.S.,China Agricultural University | Xia F.S.,Beijing Key Laboratory of Grassland Science | Xia F.S.,Shanxi Agricultural University | Chen L.L.,China Agricultural University | And 9 more authors.
Seed Science and Technology | Year: 2016

This experiment was designed to measure the changes in ultrastructure, antioxidant enzymatic activities and lipid peroxidation in ultra-dried (4% moisture content) and artificially aged (48 days at 45°C) oat (Avena sativa L.) seeds. The seeds were also primed with polyethylene glycol (PEG) solutions (0, -0.3, -0.6, -0.9 and -1.2 MPa) for 12 hours at 20°C. The results showed that seed vigour, antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR), and the ultrastructure of the embryo cells were improved at lower water potential, whilst the malondialdehyde (MDA) contents decreased significantly (P < 0.05). This indicated that the effect of PEG-priming on seed vigour was positively related to antioxidant enzymes and ultrastructure of embryo cells, but was negatively related to MDA content. In terms of ultrastructure, the mitochondria were the most sensitive organelles to PEG-priming. PEG- priming at 0, -0.3 and -0.6 MPa aggravated the damage of seed ageing, but priming at -0.9 and -1.2 MPa was beneficial. It is therefore recommended that the water potential used for priming with PEG should be less than -0.9 MPa for ultra-dried aged seeds.

Kong L.,China Agricultural University | Kong L.,Beijing Key Laboratory of Grassland Science | Kong L.,University of California at Davis | Huo H.,China Agricultural University | And 3 more authors.
Frontiers in Plant Science | Year: 2015

To evaluate deterioration of oat seeds during storage, we analyzed oxygen radicals, antioxidant enzyme activity, proline content, and gene transcript levels in oat seeds with different moisture contents (MCs; 4, 16, and 28% w/w) during storage for 0, 6, and 12. months (CK, LT-6, and LT-12. treatments, respectively) at 4°C. The germination percentage decreased significantly with higher seed MCs and longer storage duration. The concentrations of superoxide radical and hydrogen peroxide increased with seed MC increasing. The activities of catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) may have had a complementary or interacting role to scavenge reactive oxygen species. As the storage duration extended, the proline content decreased in seeds with 4. and 16% MC and increased in 28%. These findings suggest that proline played the main role in adaptation to oxidative stress in seeds with higher MC (28%), while antioxidant enzymes played the main role in seeds with lower MCs (4%, 16%). In the gene transcript analyses, SOD1. transcript levels were not consistent with total SOD activity. The transcript levels of APX1. and CAT1. showed similar trends to those of APX and CAT activity. The transcript levels of P5CS1, which encodes a proline biosynthetic enzyme, increased with seed MC increasing in CK. Compared with changing of proline content in seeds stored 12. months, PDH1. transcript levels showed the opposite trend and maintained the lower levels in seeds of 16. and 28% MCs. The transcript level of P5CS1. was significantly affected by MC, and PDH1. could improve stress resistance for seed aging and maintain seed vigor during long-term storage. © 2015. Kong, Huo and Mao.

Xia F.,China Agricultural University | Xia F.,Beijing Key Laboratory of Grassland Science | Chen L.,China Agricultural University | Chen L.,Beijing Key Laboratory of Grassland Science | And 4 more authors.
Acta Physiologiae Plantarum | Year: 2015

This experiment was designed to determine the relationship between the ultrastructure of the embryo cells and the changes in antioxidant enzymatic activities and lipid peroxidation in oat (Avena sativa L.) seeds with different moisture contents (4, 10 and 16 %) that were aged for 0, 8, 16, 24, 32 and 40 days in 45 °C. The results showed that the declining in the germination percentage and integrity of cell ultrastructure in oat aged seeds were presented during the aged process, and these changes would be enhanced by the higher moisture content. There were consequent changes for biochemical reactions and lipid peroxidation exhibited. For oat seeds with 4 and 10 % moisture content, SOD and CAT were much more sensitive than APX at the early stages of imbibition after mild ageing, the activities of SOD, CAT, APX and MDHAR at 4 h of imbibition decreased significantly (P < 0.05) after being aged from 32 to 40 days. On the contrary, MDA and H2O2 contents both did not increase further. Upon imbibition the activities of DHAR and GR increased after mild ageing, declined after further ageing and maintained a stable level after ageing from 24 to 40 days at those moisture levels. Both activities were higher after ageing at 4 % moisture content than at 10 %. The decline in integrity of ultrastructural cells was related with accumulation of H2O2 during seed ageing, and favoured by the decrease of SOD, CAT, APX and MDHAR activities after imbibition. The activities of antioxidant enzymes and contents of MDA and H2O2 in oat seeds with 16 % moisture content all gradually decreased after ageing from 8 to 40 days, also the ultrastructure of embryo cells was severely damaged. Its ultrastructure was destroyed much more quickly in the seeds with higher moisture content. The level of moisture content could accelerate the seed deterioration, and mitochondrial damages were probably the main reason for oat seed ageing. However, the activities of antioxidant enzymes were the key factor to repair the damage from lipid peroxidation and to maintain the integrity of cell ultrastructure for oat aged seeds during imbibition. © 2015, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

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