Ethylene perception is involved in female cucumber flower development

Abstract

SUMMARYIt is well established that ethylene promotes female flower development in cucumber. However, little is known about how the gaseous hormone selectively affects female flowers, and what mechanism it uses. Previously, we found organ-specific DNA damage in the primordial anther of female cucumber flowers. This finding led to a hypothesis that ethylene might promote female flower development via the organ-specific induction of DNA damage in primordial anthers. In this study, we tested this hypothesis first by demonstrating ethylene induction of DNA damage via the ethylene signaling pathway using cucumber protoplasts. Then, using representative component genes of the ethylene signaling pathway as probes, we found that one of the ethylene receptors, CsETR1, was temporally and spatially downregulated in the stamens of stage-6 female cucumber flowers, especially along with the increase of the nodes. Furthermore, by constructing transgenic Arabidopsis plants with organ-specific expression of antisense CsETR1 under the control of an AP3 promoter to downregulate ETR1 expression in the stamens, we generated Arabidopsis 'female flowers', in which the abnormal stamens mimic those of female cucumber flowers. Our data suggest that ethylene perception is involved in the arrest of stamen development in female cucumber flowers through the induction of DNA damage. This opens up a novel perspective and approach to solve the half-century-long puzzle of how gaseous ethylene selectively promotes female flowers in the monoecious cucumber plant.

Roles of Ethylene Production and Ethylene Receptor Expression in Regulating Apple Fruitlet Abscission

“…This may be due to the lower sensitivity to ethylene achieved in seeds of central fruitlets by up-regulating the expression of its receptor genes. A similar mechanism was found to be involved in female cucumber (Cucumis sativus) flower development (Wang et al, 2010). In that case, the down-regulation of ETR1 and the concurrent enhancement of ethylene sensitivity were shown to promote DNA damage specifically in primordial anthers, resulting in female flowers whose development was paralleled by a reduced sensitivity to the hormone caused by higher levels of its receptors.…”

Comparative Transcriptome Analysis between Gynoecious and Monoecious Plants Identifies Regulatory Networks Controlling Sex Determination in Jatropha curcas

“…The M locus encodes the CsACS2 gene, in which a conserved residue conversion (Gly33Cys) causes bisexual flower production (Li et al, 2009). The ETH receptor ETR1 is suppressed, causing female flower generation in Arabidopsis , suggesting that ETH perception is involved in stamen abortion (Wang et al, 2010). Sex determination in melon is controlled by two loci, andromonoecious ( a) and gynoecious ( g) (Poole and Grimball, 1939), and their interaction results in a range of sexual types (Kenigsbuch and Cohen, 1990).…”

A GAMYB homologue CsGAMYB1 regulates sex expression of cucumber via an ethylene-independent pathway

“…In this process, ethylene treatment can produce increased numbers of female flowers in cucumber (Iwahori et al , 1969; MacMurray and Miller, 1968), and the mechanism has been widely understood. Two major genes encoding ACC synthase (a key enzyme of ethylene biosynthesis), F ( CsACS1G ), and M ( CsACS2 ) control female sex expression in cucumber; the F gene governs the development of female flowers (Knopf and Trebitsh, 2006; Mibus and Tatlioglu, 2004; Trebitsh et al , 1997), whereas the M gene inhibits stamen development in flower buds (Bie et al , 2013; Li et al , 2012; Saito et al , 2007; Wang et al , 2010; Yamasaki et al , 2001; Yamazaki et al , 2003). In addition, GA application can promote the male tendency (Pike and Peterson, 1969), but the molecular regulation remains elusive.…”