Spatio-temporal Expression Analysis Of ACO And ETR Gene Families In Vitis Vinifera

Grape is an important economic tree species in the world.More than 80% of them are table grapes.Table grapes are stored and sold in bunches,and dry,browning rachis and berry drop are unfavorable for storage,transportation and sale.Grape berrys are the climacteric organ while grape rachis are non-climacteric.Ethylene plays an important role in pre-harvest ripening.ACC oxidase(ACO)is one of the key enzymes of ethylene biosynthesis in higher plants and ethylene receptor(ETR)is the first protein in signal transduction.Inthis study,we measured release rate of ethylene from berries and the non-fruit rachis of ‘Thompson seedless' and ‘Ruby seedless' during development and at veraison,and analyzed the temporal and spatial expression of two cultivars.It will be used to lay the theoretical foundation of improving the quality of storage and extending storage time.Since grapes develop in a cluster that comprises both the fruit berry and the non-fruit rachis,we measured the release of ethylene from both tissues.Detached berries from V.vinifera ‘Ruby seedless' and ‘Thompson seedless' showed ethylene release peaks at the beginning of berry development and at veraison.Ethylene production in the rachis was higher than that in the berry and had an obvious peak before harvest in ‘Thompson seedless'.In both varieties,ethephon treatment induced ethylene production in the rachis but not in the berry.Expression of 1-aminocyclopropane-1-carboxylase oxidase(ACO)genes and ethylene receptor(ETR)genes showed diverse temporal and spatial patterns in ‘Thompson seedless' and ‘Ruby seedless'.Expression levels of most of the ACO and ETR genes did not correlate with ethylene released in the same organ.In berries of ‘Thompson seedless' and ‘Ruby seedless',the transcriptional levels of Vv ACO1 coincided with ethylene production,indicating possible roles in berry development.ETR genes are negative regulators of ethylene signaling.In berries and the non-fruit rachis of ‘Thompson seedless' and ‘Ruby seedless',the transcriptional levels of Vv ERS2 negatively correlatedwith ethylene production.So Vv ERS2 may play an important role in berry and rachis development.Expression of Vv ACO1-3 and ETR genes was not consistent with ethylene production during storage or in response to ethephon treatment,which suggests that expression of ACO was affected by other stress factors after harvest.