The Study Of The Key Transformation Period For Desiccation Ability Of Camptotheca Acuminata Of One Year Old Seedlings

Camptotheca acuminata is a tree unique to China. One special phase in September of one-year old C. acuminata seedlings was found in 973 programe research, there was obvious difference in up-regulated proteins before and after this phase under the same drought stress condition, so we describe this phenomena using the key transformation period for desiccation ability. One-year old C. acuminata seedlings were used as study object and small scales developmental phase division model based on differences of one-dimensional electrophoresis bands and height growth speed and biomass growth speed was established, and there was three developmental phases. The first developmental phase was before June 15^th, the second developmental phase was between June 15^th and September 15^th, and the third developmental phase was after September 15^th. There exists concordance between the developmental phase division and transformation of desiccation ability, thus two key transformation phases of desiccation ablity were determined. One was from the middle of June to the beginning of July, the other was from the middle of September to the beginning of October.Obvious differences at growth speed physiological level and molecular level exist in different developmental phases. In the first developmental phase, seedlings growed slowly, and net photosynthesis rate was higher with average 7. 5μmolm^-2s^-1, proteins expressed obviously, number 36 protein spot was special protein in this phase; In the second developmental phase, seedlings growed quickly, photosynthesis ablity was lower with average 5. 0μmolm^-2s^-1, number 9 and number 10 protein spots were special proteins, comparing to the first developmental phase, expression amount of 18 protein spots surpassed 50%; In the third developmental phase, seedlings growed very slowly even to stop, photosynthesis ability decreased furtherly with average 4. 0μmolm^-2s^-1, and there was few difference comparing to the first developmental phase, expression amount of 15 protein spots surpassed 50%.The elementary and secondary characteristics of seedlings under soil water deficit in different developmental phases were studied in this paper. The results indicate that there exists different anti-drought mechanism in different developmental phases. In the first developmental phase, sensitivity to drought stress of seedlings was weaker, RWC decreased most slowy, and it decreased 2.21% every day, keeping water ability was stronger, and this showed avoiding covariability; In the second developmental phase, net photosynthesis rate decreased more quikly, and it decreased 1. 12μmolm^-2s^-1 every day, keeping water ability was weaker, cell lipid membrane was destroyed strongly, drought resistance was weaker relatively; In the third developmental phase, cell lipid membrane was destroyed weakly, drouht resistance was improved by accumulation of osmoregulatory substances, pro line content increased 30 folds,...