Reactive oxygen species, abscisic acid and ethylene interact to regulate sunflower seed germination

Abstract

Sunflower (Helianthus annuus L.) seed dormancy is regulated by reactive oxygen species (ROS) and can be alleviated by incubating dormant embryos in the presence of methylviologen (MV), a ROS-generating compound. Ethylene alleviates sunflower seed dormancy whereas abscisic acid (ABA) represses germination. The purposes of this study were to identify the molecular basis of ROS effect on seed germination and to investigate their possible relationship with hormone signalling pathways. Ethylene treatment provoked ROS generation in embryonic axis whereas ABA had no effect on their production. The beneficial effect of ethylene on germination was lowered in the presence of antioxidant compounds, and MV suppressed the inhibitory effect of ABA. MV treatment did not alter significantly ethylene nor ABA production during seed imbibition. Microarray analysis showed that MV treatment triggered differential expression of 120 probe sets (59 more abundant and 61 less abundant genes), and most of the identified transcripts were related to cell signalling components. Many transcripts less represented in MV-treated seeds were involved in ABA signalling, thus suggesting an interaction between ROS and ABA signalling pathways at the transcriptional level. Altogether, these results shed new light on the crosstalk between ROS and plant hormones in seed germination.

One Way to Achieve Germination: Common Molecular Mechanism Induced by Ethylene and After-Ripening in Sunflower Seeds

“…On the other hand, recent data emphasized the role of GPXs in redox signal transduction under stressful conditions [51]. Redox-responsive genes such as RD21 and Pap15, which are up-regulated in D/ET, have been associated with sunflower seed dormancy alleviation induced by methyl viologen (MV), a ROS generating compound [6]. Similarly, the ABA signaling elements were down-regulated by MV, suggesting a cross-talk between the ROS and hormones in sunflower seed germination [6].…”

“…Redox-responsive genes such as RD21 and Pap15, which are up-regulated in D/ET, have been associated with sunflower seed dormancy alleviation induced by methyl viologen (MV), a ROS generating compound [6]. Similarly, the ABA signaling elements were down-regulated by MV, suggesting a cross-talk between the ROS and hormones in sunflower seed germination [6]. The common underlying mechanism may be redox signaling, as several redox genes were altered in ND and D/ET (e.g., glutathione S-transferase, which represent an important component of the redox system) (Table S2).…”

“…In fact, ethylene overcomes the inhibitory action of ABA on germination in numerous species (for review [3]). In sunflowers, the ethylene supply breaks the dormancy and the endogenous ethylene is increased by dormancy alleviation treatments, with the addition of methylviologen, a reactive oxygen species (ROS)-generating compound, or cyanide (HCN) [4,5,6]. The after-ripening did not trigger an ethylene increase before the end of germination sensu stricto in sunflowers [6].…”

“…In sunflowers, the ethylene supply breaks the dormancy and the endogenous ethylene is increased by dormancy alleviation treatments, with the addition of methylviologen, a reactive oxygen species (ROS)-generating compound, or cyanide (HCN) [4,5,6]. The after-ripening did not trigger an ethylene increase before the end of germination sensu stricto in sunflowers [6]. It was shown that a peak of ethylene emission was concomitant with radicle protrusion through the seed coat in different species (reviewed in [3]).…”

Genomics: A Hallmark to Monitor Molecular and Biochemical Processes Leading Toward a Better Perceptive of Seed Aging and ex-situ Conservation

“…Gibberellic acid and abscisic acid are strongly correlated with the regulation of seed viability and inhibition of PCD, respectively (Fath et al, 2000;Chmielowska et al, 2015). Moreover, it is also assumed that ROS initiate the fundamental processes of PCD; as ROS threshold levels areattained, the PCD signal transduction pathway is triggered El-Maarouf-Bouteau et al, 2015). However, the mechanism by which ROS-initiated PCD contributes to reduced seed viability and vigor during aging is mostly unknown (Hossain et al, 2015).…”