ABA crosstalk with ethylene and nitric oxide in seed dormancy and germination

Abstract

Dormancy is an adaptive trait that enables seed germination to coincide with favorable environmental conditions. It has been clearly demonstrated that dormancy is induced by abscisic acid (ABA) during seed development on the mother plant. After seed dispersal, germination is preceded by a decline in ABA in imbibed seeds, which results from ABA catabolism through 8′-hydroxylation. The hormonal balance between ABA and gibberellins (GAs) has been shown to act as an integrator of environmental cues to maintain dormancy or activate germination. The interplay of ABA with other endogenous signals is however less documented. In numerous species, ethylene counteracts ABA signaling pathways and induces germination. In Brassicaceae seeds, ethylene prevents the inhibitory effects of ABA on endosperm cap weakening, thereby facilitating endosperm rupture and radicle emergence. Moreover, enhanced seed dormancy in Arabidopsis ethylene-insensitive mutants results from greater ABA sensitivity. Conversely, ABA limits ethylene action by down-regulating its biosynthesis. Nitric oxide (NO) has been proposed as a common actor in the ABA and ethylene crosstalk in seed. Indeed, convergent evidence indicates that NO is produced rapidly after seed imbibition and promotes germination by inducing the expression of the ABA 8′-hydroxylase gene, CYP707A2, and stimulating ethylene production. The role of NO and other nitrogen-containing compounds, such as nitrate, in seed dormancy breakage and germination stimulation has been reported in several species. This review will describe our current knowledge of ABA crosstalk with ethylene and NO, both volatile compounds that have been shown to counteract ABA action in seeds and to improve dormancy release and germination.

Do the seeds of Solidago gigantea Aiton have physiological determinants of invasiveness?

“…For this reason, the observed high resistance of S. gigantea seeds before dormancy could be attributed to their unique sensitivity to the major hormones regulating seed dormancy and germination. It has been demonstrated that the phytohormonal balance between abscisic acid and gibberellins integrates external cues for inducing or maintaining dormancy (abscisic acid) and for breaking dormancy or inducing germination (gibberellins) (Arc et al 2013). Dormant seeds treated with fluridone, an abscisic acid synthesis inhibitor, broke dormancy, which indicates that de novo biosynthesis of abscisic acid is required to maintain dormancy in imbibed seeds .…”

Participation of GA3, ethylene, NO and HCN in germination of Amaranthus retroflexus L. seeds with various dormancy levels

“…On the other hand, GA 3 enhanced ACC oxidase gene, ACC content and ethylene production. Recently, the cross talk between ABA with ethylene and nitric oxide has been considered for the control of seed dormancy and germination (Arc et al 2013). The interaction between exogenous ABA and ethylene in the case of non-dormant A. caudatus seeds was reported; exogenous ABA could decrease the effect of ethylene on germination of nondormant A. caudatus seeds (Kępczyński et al 2003a).…”

Ethylene Responses in Rice Roots and Coleoptiles Are Differentially Regulated by a Carotenoid Isomerase-Mediated Abscisic Acid Pathway

“…Endogenous ABA limits ethylene production (Tal, 1979;Rakitina et al, 1994;LeNoble et al, 2004) and ethylene can inhibit ABA biosynthesis (Hoffmann-Benning and Kende, 1992). Previous studies have suggested that both ethylene and ABA can inhibit root growth (Vandenbussche and Van Der Straeten, 2007;Arc et al, 2013). In Arabidopsis thaliana, the etr1-1 and ein2 roots are resistant to both ethylene and ABA, whereas the roots of the ABAresistant mutant abi1-1 and the ABA-deficient mutant aba2 have normal ethylene responses.…”