Study On Optimizing Of Cuttage Propagation And Mechanism Of Rooting In Tetraploid Robinia Pseudoacacia

Black locust (Robinia pseudoacacia L.) is a leguminous, deciduous, fast growing tree species native to the southeastern USA. It is a multi-purpose tree species suitable for production of timber, fuel wood, land reclamation, beekeeping and forage.Tetraploid Robinia pseudoacacia which was colchicine-induced from black locust in South Korea is considered to be a more promising forage tree than diploid R. pseudoacacia. But it is difficult to root,especially in cutting propagation. The objectives of the present study were to optimize techniques of hardwood cutting and softwood cutting for tetraploid R. pseudoacacia clones. Hardwood cutting after overwintering sand storage root promoting and wood-burying etiolation root promoting were used. Morphological structure, oxidase activity and endogenous hormone levels of wood-burying etiolation root promoting in softwood cutting process were researched. Functional proteomics was also studied by using two-dimensional electrophoresis, mass spectrometry and bioinformatics techniques to investigate mechanism of adventitious root formation on a protein level. These provided not only a theory to the improvement of black locust clone cuttage, but aslo references to proteomics studies on rooting mechanism of forest trees clones. The results were as follows:1. There were significant different survival rate between tetraploid R. pseudoacacia clones K1, K3, K4, YD and local seedlings in cutting positions, plant growth regulators and growth regulator concentrations in hardwood cutting. The difference of rooting ability between clones was also significant. The survival rate of clone YD was 87.8% whereas tetraploid R. pseudoacacia clone K4 was only 23.33%.2. Survival rate of hardwood cutting could be enhanced by combine of growth regulator treatment before sand storage and during cutting after overwintering sand storage. Combining with inverted storage root promoting the survival rate of tetraploid R. pseudoacacia clone K4 was increased to 71.11%.3. Soft wood cuttages of R. pseudoacacia picked from cutting orchard where planted with tissue cultured young seedlings were investigated on cutting positions, plant growth regulators treatment concentrations, treatment time, cutting time and cutting medium. Then the best combination was selected. The rooting rate of clone K4 was up to 77.78% from the best combination that using semi-lignified top cuttings with terminal buds in early June, and using vermiculite as medium and quick dipping for 30 seconds with ABT 2000 mg/L.4. Wood-burying etiolation root promoting was the process of covering hardwood cuttings with sand in spring and cutting with the bottom etiolated softwood. The survival rate of hardwood cutting of tetraploid R. pseudoacacia clone K4 was increased to 89.4% and its rooting time was shorter than the normal softwood cutting by using this method.5. The process of cutting rooting of etiolated softwood and non-etiolated softwood in wood-burying etiolation root promoting of clone K4 was investigated and 3 phases of adventitious root formation in morphological structure were found. These three phases were callus inducement stage, adventitious root primordium formation stage and adventitious root elongating stage. The results also showed that the activity of POD,IAAO and PPO and endogenous hormones IAA,ABA,GA3 and ZR were fluctuating with time during the period of adventitious root formation, and they were highly related to adventitious root formation.6. A system of 2-DE involving the preparation of protein sample, the electrophoresis and staining for the proteomic extracted from tetraploid R. pseudoacacia phloem was developed. And the proteomics of cutting rooting process of etiolated softwood and non-etiolated softwood in wood-burying etiolation root promoting were investigated. Then 148 differential protein spots were found, and 40 of them with high protein expression abundance were analyzed in PMF. Through MASCOT database searching, the identified proteins were involved in RNA proteins, signal transduction, metabolism proteins, lignin proteins and phyllo-proteins.Molecular regulation mechanism of cutting rooting on a protein expression level was discussed by analyzing the function of these proteins during the process of rooting.