Dataset Information

The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination.

ABSTRACT: Seed dormancy is one of the adaptive responses in the plant life cycle and an important agronomic trait. Reactive oxygen species (ROS) release seed dormancy and promote seed germination in several cereal crops; however, the key regulatory mechanism of ROS-mediated seed dormancy and germination remains controversial. Here, we focused on the relationship between hydrogen peroxide (a ROS) and abscisic acid (ABA) in dormant and non-dormant barley seeds. The hydrogen peroxide (H₂O₂) level produced in barley seed embryos after imbibition was higher in non-dormant seeds than in dormant seeds. H₂O₂ regulated the ABA content in the embryos through ABA-8'-hydroxylase, an ABA catabolic enzyme. Moreover, compared with non-dormant seeds, in dormant seeds the activity of NADPH oxidase, which produces ROS, was lower, whereas the activity of catalase, which is a H₂O₂ scavenging enzyme, was higher, as was the expression of HvCAT2. Furthermore, precocious germination of isolated immature embryos was suppressed by the transient introduction of HvCAT2 driven by the maize (Zea mays) ubiquitin promoter. HvCAT2 expression was regulated through an ABA-responsive transcription factor (HvABI5) induced by ABA. These results suggest that the changing of balance between ABA and ROS is active in barley seed embryos after imbibition and regulates barley seed dormancy and germination.

SUBMITTER: Ishibashi Y

PROVIDER: S-EPMC5359625 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination.

Ishibashi Yushi Y Aoki Nozomi N Kasa Shinsuke S Sakamoto Masatsugu M Kai Kyohei K Tomokiyo Reisa R Watabe Gaku G Yuasa Takashi T Iwaya-Inoue Mari M

Frontiers in plant science 20170321

Seed dormancy is one of the adaptive responses in the plant life cycle and an important agronomic trait. Reactive oxygen species (ROS) release seed dormancy and promote seed germination in several cereal crops; however, the key regulatory mechanism of ROS-mediated seed dormancy and germination remains controversial. Here, we focused on the relationship between hydrogen peroxide (a ROS) and abscisic acid (ABA) in dormant and non-dormant barley seeds. The hydrogen peroxide (H<sub>2</sub>O<sub>2</s ...[more]

PMID: 28377774

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Project description:DELAY OF GERMINATION-1 (DOG1), is a master regulator of primary dormancy (PD) that acts in concert with ABA to delay germination. The ABA and DOG1 signaling pathways converge since DOG1 requires protein phosphatase 2C (PP2C) to control PD. DOG1 enhances ABA signaling through its binding to PP2C ABA HYPERSENSITIVE GERMINATION (AHG1/AHG3). DOG1 suppresses the AHG1 action to enhance ABA sensitivity and impose PD. To carry out this suppression, the formation of DOG1-heme complex is essential. The binding of DOG1-AHG1 to DOG1-Heme is an independent processes but essential for DOG1 function. The quantity of active DOG1 in mature and viable seeds is correlated with the extent of PD. Thus, dog1 mutant seeds, which have scarce endogenous ABA and high gibberellin (GAs) content, exhibit a non-dormancy phenotype. Despite being studied extensively in recent years, little is known about the molecular mechanism underlying the transcriptional regulation of DOG1. However, it is well-known that the physiological function of DOG1 is tightly regulated by a complex array of transformations that include alternative splicing, alternative polyadenylation, histone modifications, and a cis-acting antisense non-coding transcript (asDOG1). The DOG1 becomes modified (i.e., inactivated) during seed after-ripening (AR), and its levels in viable seeds do not correlate with germination potential. Interestingly, it was recently found that the transcription factor (TF) bZIP67 binds to the DOG1 promoter. This is required to activate DOG1 expression leading to enhanced seed dormancy. On the other hand, seed development under low-temperature conditions triggers DOG1 expression by increasing the expression and abundance of bZIP67. Together, current data indicate that DOG1 function is not strictly limited to PD process, but that it is also required for other facets of seed maturation, in part by also interfering with the ethylene signaling components. Otherwise, since DOG1 also affects other processes such us flowering and drought tolerance, the approaches to understanding its mechanism of action and control are, at this time, still inconclusive.

Project description:Abscisic acid (ABA) is a crucial phytohormone for the regulation of seed germination. The ABA content of seeds is regulated by synthesis and catabolic pathways. Coumarin, an important plant allelochemical, can inhibit seed germination effectively, although whether it is involved in the regulation of ABA content during seed germination has not been elucidated. For the study reported herein, we show that coumarin effectively inhibits rice seed germination and vivipary. We found that the ABA content gradually decreased in water-imbibed rice seeds and that the content and activity of the Oryza sativa 9-cis epoxycarotenoid dioxygenases (OsNCEDs), which are ABA synthases, decreased during seed germination. At the transcription level, the expression of OsNCED1-3 appeared to decrease, whereas the expression of the ABA 8'-hydroxylase 2 and 3 genes (OsABA8'ox2/3) first appeared to increase and then decrease. Samples of rice seeds were also imbibed in water containing coumarin, which increased their ABA content but did not significantly increase the activity or content of their OsNCEDs or OsNCED1-3 transcription. Interestingly, coumarin imbibition remarkably reduced OsABA8'ox2/3 expression in rice embryos, which partially explained how coumarin increased the ABA content of germinating rice embryos. Coumarin also inhibited the accumulation of reactive oxygen species (ROS) in rice embryos and increased the activity of superoxide dismutase and catalase, which are indispensable for seed germination. These results indicate that coumarin delays seed germination by inhibiting ABA catabolism, particularly by decreasing the expression of OsABA8'ox2/3 rather than by increasing ABA synthesis. Moreover, coumarin increases the ABA content while decreasing the ROS content in rice embryos. Our results enhance our understanding of the regulation of ABA and ROS during seed germination and provide theoretical support for application of coumarin to prevent sprouting before crop harvesting.

Dataset Information

The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination.

Publications

The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination.

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