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 ABA and diniconazole on seed germination (a) and ABA contents (b). Rice seeds were imbibed at 28 °C in the presence of water, diniconazole, and ABA solutions. Seed samples were collected at different time intervals and stored at –80 °C for ABA content determination. ABA was detected by RIA as described in the Materials and methods. Values are means ±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

fig2: Effects of ABA and diniconazole on seed germination (a) and ABA contents (b). Rice seeds were imbibed at 28 °C in the presence of water, diniconazole, and ABA solutions. Seed samples were collected at different time intervals and stored at –80 °C for ABA content determination. ABA was detected by RIA as described in the Materials and methods. Values are means ±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: During the rice seed germination, ABA catabolism plays a key role by decreasing the ABA level in imbibed seeds (Zhu et al., 2009). Here an ABA catabolic inhibitor, diniconazole, which acts as a potent competitive inhibitor of ABA 8'-hydroxylase and is an effective ABA catabolic inhibitor (Kitahata et al., 2005), was used to demonstrate the suppressive effect of ABA on germination of rice caryopsis. As shown in Fig. 2a, seed germination is effectively suppressed by a low concentration of ABA (0.5 μM) and diniconazole. A high concentration (5 μM) of ABA totally arrested the seed germination. To reveal further ABA actions on seed germination, the ABA levels of imbibed seeds were determined using the RIA method. ABA contents decrease significantly within 6 h after the onset of imbibition. However, the ABA level in diniconazole-treated seeds is higher than that in control seeds, which results in inhibition of germination (Fig. 2b). These results indicate that a relatively high ABA level in Phase II is essential to suppress the germination of rice caryopsis.


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 ABA and diniconazole on seed germination (a) and ABA contents (b). Rice seeds were imbibed at 28 °C in the presence of water, diniconazole, and ABA solutions. Seed samples were collected at different time intervals and stored at –80 °C for ABA content determination. ABA was detected by RIA as described in the Materials and methods. Values are means ±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

fig2: Effects of ABA and diniconazole on seed germination (a) and ABA contents (b). Rice seeds were imbibed at 28 °C in the presence of water, diniconazole, and ABA solutions. Seed samples were collected at different time intervals and stored at –80 °C for ABA content determination. ABA was detected by RIA as described in the Materials and methods. Values are means ±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: During the rice seed germination, ABA catabolism plays a key role by decreasing the ABA level in imbibed seeds (Zhu et al., 2009). Here an ABA catabolic inhibitor, diniconazole, which acts as a potent competitive inhibitor of ABA 8'-hydroxylase and is an effective ABA catabolic inhibitor (Kitahata et al., 2005), was used to demonstrate the suppressive effect of ABA on germination of rice caryopsis. As shown in Fig. 2a, seed germination is effectively suppressed by a low concentration of ABA (0.5 μM) and diniconazole. A high concentration (5 μM) of ABA totally arrested the seed germination. To reveal further ABA actions on seed germination, the ABA levels of imbibed seeds were determined using the RIA method. ABA contents decrease significantly within 6 h after the onset of imbibition. However, the ABA level in diniconazole-treated seeds is higher than that in control seeds, which results in inhibition of germination (Fig. 2b). These results indicate that a relatively high ABA level in Phase II is essential to suppress the germination of rice caryopsis.

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