The Role Of Arabidopsis ACS7 In Regulation Of Flowering Time

Flowering is the process by which higher plants change from vegetative phase to reproductive phase.Blooming at the appropriate time,have a positive effect on the sustainable development of the next generation.Flowering time relates to various endogenous genetic factors and environmental cues.The signal pathways composed of endogenous genetic factors mainly include light,vernalization,autonomous,gibberellin,age,and temperature.These pathways cross each other.The flowering activator FLOWERING LOCUS T(FT)is the key integration factors.FT protein generates in leaves,and transport to the stem top meristem,where promoted the flowering initiation.It is known that plant hormone ethylene in involved in the regulation of flowering time.1-aminocyclopropane-l-carboxylic acid(ACC)is a precursor of ethylene ACC synthase(ACS)is the rate-limiting enzyme for ACC or ethylene biosynthesis.Model plant Arabidopsis genome contains 12 ACS genes(ACS1-12).Levels of ethylene in the single A CS gene mutants are different.This study focuses on ACS7's involvement in flowering time regulationThe relationship between ACS7 expression activity and flowering time was studied firstly.The T-DNA insertion acs7-1 mutant seeds gained from Arabidopsis biological resource center stocks.The acs7-1 complementary plants(ACS7/acs7-1),as well as A CS7-overexpression transgenic lines(A CS7-OE1)were created.Growth phenotype observation showed that,under the conditions of long-time light,the flowering time of acs7-1 was significantly advanced,and the number of rosette leaves decreased,in comparison with that in WT;under the conditions of ACC and GA treatment,the flowering time of acs7-1 was still ahead of WT.ACS7/acs7-1 restore the early flower phenotype of acs7-1,suggesting that ACS7 could play an role in flowering time regulation.Physiological phenotype studies show there was no significant change in levels of ethylene and ACC in acs7-1,in comparison with that in WT.It implied that the early flowering of acs7-1 did not rely on ACC or ethylene accumulation.Further studies show that the ACS7 expression activity was abundant in WT leaves,while the expression of FT in acs7-1 leaves increased.Using ACS7 protein as the bait the interaction proteins were screened from the yeast library.A total of 53 candidate proteins appeared.It is interested that these candidates included FT protein.By yeast two hybrid system,bimolecular fluorescence,pull down to detect the relationship between ACS7 and FT,and results indicated that ACS7 and FT interacted.The above results indicate that the ACS7 expression activity may be involved in the regulation of flowering time.ACS7 was expressed in leaves,which was consistent with FT biosynthesis site.Therefore,it was speculated that ACS7 and FT interacted in leaves,hindering FT's transportation to stem tip tissue and thus hindering flowering initiation.We continue to observe the accumulation of FT protein in leaves and stems,and subsequent experiments are ongoing.