| The peony with its extraordinary beauty,has enormous potentiality to be used as cut flowers. The gaseous plant hormone ethylene plays a crucial role in the process of tree peony cut flowers postharvest opening and senescence,but the mechanism of its function has been unclear.And current studies show that the flowers at different opening stage show different sensitivity to ethylene.So it is of great theoretical value to study the mechanism of ethylene effect by analyzing the different sensitivity of the 'Luo Yang Hong' tree peony cut flowers at different opening stages.To investigate the responses of Paeonia suffruticosa 'Luo Yang Hong'cut flowers at different opening stages to exogenous ethylene and 1-methycyclopropene(1-MCP),the flowering process,the vase life,as well as the endogenous ethylene production,the ACC content and the activity of ACC synthase,ACC oxidase were measured.Also,the expression of PsACS in flowers at stage 1 were studied.The main experimental results are indicated as follows:1.10.0μl·L-1 ethylene treatment for 6h accelerated the opening and senescence process,shortened the vase life;while 1.0μl·L-1 1-MCP treatment alleviated the opening process,prolonged the during of the best display season.2.Luo Yang Hong' tree peony cut flowers are climacteric flowers.The flowers at different opening stage showed different sensitivity to ethylene,among which the flowers at stage 3 have the highest sensitivity to ethylene,and the flowers at stage 1 and 2 showed no different sensitivity to ethylene.We also found that the increase in ethylene production was associated with a parallel increase in ACC synthase activity of the flowers at different opening stages.The ethylene induced the activity of ACS,and especially the peak of the activity of ACS appeared 1 stage in advance after the flowers at stage 1 were treated by ethylene.The ACC content was roughly concomitant with the ethylene production,but the application of the ethylene retarded the accumulation of the ACC.However the activity of the ACO in control flowers werecomplicated,and the response of the ACC oxidase activity to the exogenous ethylene was complicated.3.1.0μl·L-1-MCP application suppressed the ACC synthase activity and the accumulation of the ACC which was concomitant with a lower ethylene production of the flowers at different opening stage. But no significant difference were found in different opening stage flowers to 1-MCP,so the responses of the tree peony cut flowers to the higher concentration 1-MCP need further study.4.The expression of PsACS is associated with flower opening and senescence process.The application of the ethylene on the flowers at stage 1 induced the expression of PsACS,which induced the accumulation of the mRNA of flowers at stage 3 and 4.Compared with the control,PsACS was suppressed by 1-MCP,and the peak of its expression appeared when flowers were at stage 5.PsACS was involved in the regulation of tree peony cut flower ethylene teaction at the transcriptional level. |
