This is an Open Access article distributed under the terms of the Creative Commons Attribution License.[Background]: Ovule lifespan is an important factor in determining the ability to set fruits and produce seeds. Once ovule senescence is established, fruit set capacity in response to gibberellins (GAs) is lost. We aimed to elucidate
whether ethylene plays a role in controlling ovule senescence and the fruit set response in Arabidopsis.
[Results]: Ethylene response inhibitors, silver thiosulphate (STS) and 1-methylcyclopropene (1-MCP), were able to delay the loss of pistil response to GA3. In addition, ethylene insensitive mutants ein2-5 and ein3-1 showed delayed loss of pistil response, as in plants treated with STS and 1-MCP, while constitutive mutant ctr1-1 displayed premature loss of response. The analysis of the expression of ethylene biosynthesis genes suggests that ethylene is synthesised in ovules at the onset of ovule senescence, while a transcriptional meta-analysis also supports an activated ethylene-dependent senescence upon the establishment of ovule senescence. Finally, a SAG12:GUS
reporter line proved useful to monitor ovule senescence and to directly demonstrate that ethylene specifically modulates ovule senescence.
[Conclusions]: We have shown that ethylene is involved in both the control of the ovule lifespan and the
determination of the pistil/fruit fate. Our data support a role of the ovule in modulating the GA response during
fruit set in Arabidopsis. A possible mechanism that links the ethylene modulation of the ovule senescence and the
GA3-induced fruit set response is discussed.This work has been supported by grants BIO2005-07156-C02-01 and BIO2008-01039
from the Spanish Ministry of Science and Innovation, Plan Nacional de I+D. PCB received a PhD fellowship from the Spanish Ministry of Science and Innovation.Peer reviewe