Limits...
Ascorbic acid and reactive oxygen species are involved in the inhibition of seed germination by abscisic acid in rice seeds.

Ye N, Zhu G, Liu Y, Zhang A, Li Y, Liu R, Shi L, Jia L, Zhang J - J. Exp. Bot. (2011)

Bottom Line: Such reduced ROS also led to an inhibition of ASC production.GA accumulation was also suppressed by a reduced ROS and ASC level, which was indicated by the inhibited expression of GA biosynthesis genes, amylase genes, and enzyme activity.Production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.

ABSTRACT
The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination, but the mechanism of antagonism during this process is not known. The possible links among ABA, reactive oxygen species (ROS), ascorbic acid (ASC), and GA during rice seed germination were investigated. Unlike in non-seed tissues where ROS production is increased by ABA, ABA reduced ROS production in imbibed rice seeds, especially in the embryo region. Such reduced ROS also led to an inhibition of ASC production. GA accumulation was also suppressed by a reduced ROS and ASC level, which was indicated by the inhibited expression of GA biosynthesis genes, amylase genes, and enzyme activity. Application of exogenous ASC can partially rescue seed germination from ABA treatment. Production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. It can be concluded that ABA regulates seed germination in multiple dimensions. ROS and ASC are involved in its inhibition of GA biosynthesis.

Show MeSH
Effects of ASC on germination of rice seeds in water and ABA. (a) Inhibition of seed germination by different concentrations of ASC. (b) Endogenous ASC level in seeds treated with different concentrations of ASC. (c) Effect of ASC on ABA during seed germination. Seeds were sown on filter paper with solutions of ABA at 5 μM plus different concentrations of ASC for imbibition. Seeds imbibed for 36 h were used for the ASC measurement. Error bars here show ±SD (n=5). Means denoted by the same letter did not differ significantly at P < 0.05 according to Duncan’s multiple range test.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC3295380&req=5

fig8: Effects of ASC on germination of rice seeds in water and ABA. (a) Inhibition of seed germination by different concentrations of ASC. (b) Endogenous ASC level in seeds treated with different concentrations of ASC. (c) Effect of ASC on ABA during seed germination. Seeds were sown on filter paper with solutions of ABA at 5 μM plus different concentrations of ASC for imbibition. Seeds imbibed for 36 h were used for the ASC measurement. Error bars here show ±SD (n=5). Means denoted by the same letter did not differ significantly at P < 0.05 according to Duncan’s multiple range test.

Mentions: Many investigations have shown that ASC is induced during seed germination (De Gara et al., 1991, 2000; De Tullio and Arrigoni, 2003). However, its functions in this process have not been investigated. In the present study, it was found that an ASC concentration higher than 4 mM would inhibit seed germination (Fig. 8a). Consistent with this, the ASC content in seeds treated with >4 mM ASC showed a significant increase, which was not seen with those treated with concentrations <4 mM when compared with the control (Fig. 8b). A similar result has also been reported in wheat (Takemura et al., 2010). These results indicate that the ASC level in imbibing seeds in normal conditions is sufficient and under fine control. To find out whether exogenous ASC can compensate for the inhibitory effect of ABA on seed germination, seeds were treated with ABA and various concentrations of ASC, together. As shown in Fig. 8c, application of ASC at 1 mM and 2 mM can only rescue a small part of the seed, whereas ASC concentrations >4 mM have aggravated the suppression of seed germination. This result indicates that ABA-inhibited seed germination is partially mediated by ASC.


Ascorbic acid and reactive oxygen species are involved in the inhibition of seed germination by abscisic acid in rice seeds.

Ye N, Zhu G, Liu Y, Zhang A, Li Y, Liu R, Shi L, Jia L, Zhang J - J. Exp. Bot. (2011)

Effects of ASC on germination of rice seeds in water and ABA. (a) Inhibition of seed germination by different concentrations of ASC. (b) Endogenous ASC level in seeds treated with different concentrations of ASC. (c) Effect of ASC on ABA during seed germination. Seeds were sown on filter paper with solutions of ABA at 5 μM plus different concentrations of ASC for imbibition. Seeds imbibed for 36 h were used for the ASC measurement. Error bars here show ±SD (n=5). Means denoted by the same letter did not differ significantly at P < 0.05 according to Duncan’s multiple range test.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3295380&req=5

fig8: Effects of ASC on germination of rice seeds in water and ABA. (a) Inhibition of seed germination by different concentrations of ASC. (b) Endogenous ASC level in seeds treated with different concentrations of ASC. (c) Effect of ASC on ABA during seed germination. Seeds were sown on filter paper with solutions of ABA at 5 μM plus different concentrations of ASC for imbibition. Seeds imbibed for 36 h were used for the ASC measurement. Error bars here show ±SD (n=5). Means denoted by the same letter did not differ significantly at P < 0.05 according to Duncan’s multiple range test.
Mentions: Many investigations have shown that ASC is induced during seed germination (De Gara et al., 1991, 2000; De Tullio and Arrigoni, 2003). However, its functions in this process have not been investigated. In the present study, it was found that an ASC concentration higher than 4 mM would inhibit seed germination (Fig. 8a). Consistent with this, the ASC content in seeds treated with >4 mM ASC showed a significant increase, which was not seen with those treated with concentrations <4 mM when compared with the control (Fig. 8b). A similar result has also been reported in wheat (Takemura et al., 2010). These results indicate that the ASC level in imbibing seeds in normal conditions is sufficient and under fine control. To find out whether exogenous ASC can compensate for the inhibitory effect of ABA on seed germination, seeds were treated with ABA and various concentrations of ASC, together. As shown in Fig. 8c, application of ASC at 1 mM and 2 mM can only rescue a small part of the seed, whereas ASC concentrations >4 mM have aggravated the suppression of seed germination. This result indicates that ABA-inhibited seed germination is partially mediated by ASC.

Bottom Line: Such reduced ROS also led to an inhibition of ASC production.GA accumulation was also suppressed by a reduced ROS and ASC level, which was indicated by the inhibited expression of GA biosynthesis genes, amylase genes, and enzyme activity.Production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.

ABSTRACT
The antagonism between abscisic acid (ABA) and gibberellin (GA) plays a key role in controlling seed germination, but the mechanism of antagonism during this process is not known. The possible links among ABA, reactive oxygen species (ROS), ascorbic acid (ASC), and GA during rice seed germination were investigated. Unlike in non-seed tissues where ROS production is increased by ABA, ABA reduced ROS production in imbibed rice seeds, especially in the embryo region. Such reduced ROS also led to an inhibition of ASC production. GA accumulation was also suppressed by a reduced ROS and ASC level, which was indicated by the inhibited expression of GA biosynthesis genes, amylase genes, and enzyme activity. Application of exogenous ASC can partially rescue seed germination from ABA treatment. Production of ASC, which acts as a substrate in GA biosynthesis, was significantly inhibited by lycorine which thus suppressed the accumulation of GA. Consequently, expression of GA biosynthesis genes was suppressed by the low levels of ROS and ASC in ABA-treated seeds. It can be concluded that ABA regulates seed germination in multiple dimensions. ROS and ASC are involved in its inhibition of GA biosynthesis.

Show MeSH