The Effect On Flowering Time Of T1N6₂2Gene Mutation In Arabidopsis Thaliana

In our previous research, t1n6₂2, a susceptible mutant to Botrytis cinerea, had beenidentified by screening from the Arabidopsis thaliana T-DNA insertion mutant library.T1N6₂2gene had been isolated and identified as a resistant-related gene of A. thalianaagainst B. cinerea by further analyses of T1N6₂2complementing plants. We had foundthat t1n6₂2mutants delayed the transition of flowering under long-day conditions, andthat the T1N6₂2gene showed no homology with any known flowering-related genes.On this basis, we observed flowering time of the t1n6₂2mutant under differenttreatments （photoperiod, gibberellin and vernalization） conditions and expression levelsof genes related to flowering. The mainly results were as follows:1. The t1n6₂2mutant was later flowering than the wild type Col-0under long-dayor short-day conditions. The flowering time of t1n6₂2/T1N6₂2mutant was similar tothat of the Col-0. The results showed that the T1N6₂2gene was a flowering-time geneof A. thaliana.2. Under long-day conditions or short-day conditions, we found that GA3orvernalization treatment significantly promoted the flowering of t1n6₂2. This indicatedthat t1n6₂2retained responsiveness to gibberellin or vernalization. This feature of thet1n6₂2mutant was similar with phenotype of the autonomous pathway mutants. It wassuggested that the T1N6₂2gene might be regulated flowering time in A. thalianathrough autonomous pathway.3. RT-PCR was used to analyze the expression levels of genes related to floweringregulatory pathways in the Col-0, t1n6₂2and t1n6₂2/T1N6₂2plants. It was foundthat the expression levels of autonomous pathway genes LD, FVE and FLC wereup-regulated. Under LD condition the expression levels of gibberellin pathway genesSPY1and SPY2were down-regulated, but under SD condition there was no significantchange in the expression levels of SPY1and SPY2. The expression levels of vernalizationpathway genes VRN1, VRN2and FLC had no significant effect. It was further suggested that T1N6₂2gene might be regulated flowering time through autonomous pathway.4. RT-PCR was used to analyze the expression level of T1N6₂2gene in thedifferent tissues of A. thaliana. The results showed that the T1N6₂2gene might be aconstitutive expression in the different tissues such as rosette leaf, stem, cauline leaf andflower. It had a highest expression in the flower, rosette leaf was second.