Study On Formation Of Resinous Substances By Hormone Induction In Aquilaria Sinensis Tree

Agarwood is known to produce fragrant resinous substances. Agarwood resins have beenused as a traditional Chinese medicine from ancient time in China. It takes long years for theagarwood to produce specific wood that include fragrant resins. It is also known that agarwoodresins are produced by physical wounding and fungal attack. We investigated an alternativemethod to induce agarwood resins and successfully induced the resinous substances in thephloem and xylem by applying two plant hormones (methyl jsmonate and ethephon) directly tothe living trees of Aquilaria sinensis. The following results were obtained:1. Three concentrations (1%,2%,5%) of Me-JA, Et and the mixture of Me-JA and Et (1:1) inlanolin were applied on the tree surface and left for110days.The resinous substances are induced by Me-JA(1%,2%,5%), area of them in1mm width is0.10㎜~2,0.12㎜~2,0.14㎜~2, resin content in phloem is8.70%,10.89%,12.33%. The resinoussubstances are induced by Et(1%,2%,5%), area of them in1mm width is0.00㎜~2,0.01㎜~2,0.02㎜~2, resin content in phloem is0.00%,0.53%,1.66%. The resinous substances are induced bymixture(1%,2%,5%), area of them in1mm width is0.38㎜~2,0.35㎜~2,0.31㎜,2resin content inphloem is20.10%,21.54%,17.35%.The resinous substances are induced by Me-JA, Et and mixture in A. sinensis. Me-JA, Ethave obvious synergistic on production of resinous substances in A. sinensis. The induction ofresinous substances increased with the increase of concentrations of Me-JA and Et, but not thecase in the mixture.2. The Me-JA, Et and their mixture of two concentrations (0.1%,1%) induced A. sinensis treeson surface of bark for180days.The resinous substances are induced by Me-JA(0.1%,1%), according to area in1mm width,control group is that:0.00㎜~2,0.02㎜~2, the experimental group is that:0.06㎜~2,0.16㎜~2; accordingto resin content in phloem, the control group is that:0.00%、0.87%, the experimental group isthat:4.18%、12.68%. The resinous substances are induced by Et(0.1%,1%), according to area in1mm width, control group is that:0.00㎜~2,0.01㎜~2, the experimental group is that:0.03㎜~2,0.07㎜~2; according to resin content in phloem, the control group is that:0.00%,0.75%, theexperimental group is that:2.26%,4.62%. The resinous substances are induced bymixture(0.1%,1%), according to area in1mm width, control group is that:0.22㎜~2,0.39㎜~2, theexperimental group is that:0.31㎜~2,0.61㎜~2; according to resin content in phloem, the controlgroup is that:11.78%,23.42%, the experimental group is that:20.26%,24.79%.The0.1%mixture can induce A. sinensis trees to product a little resinous substances, the production of resinous substances increase if concentration is1%or replace chemical every60days. The best program is that: use mixture as inducers and1%as concentration, replacechemical every60days.3. The Me-JA, Et and their mixture of two concentrations (0.1%,1%) induced A. sinensis treeson surface of bark for180days in different seasons.The resinous substances area induced by Me-JA(0.1%,1%)in three period within1mm isthat:0.02㎜~2,0.05㎜~2,0.01㎜~2and0.06㎜~2,0.17㎜~2,0.01㎜,2resin content of them in phloem isthat:1.23%,4.25%,0.54%and3.35%,10.13%,0.96%. The resinous substances area induced byEt(0.1%,1%)in three period within1mm is that:0.01㎜~2,0.00㎜~2,0.00㎜~2and0.002㎜~2、0.012㎜~2、0.000㎜~2resin content of them in phloem is that:0.69%,0.00%,0.00%and0.16%,1.25%,0.00%. The resinous substances area induced by mixture(0.1%,1%) in three periodwithin1mm is that:0.27㎜~2,0.24㎜~2,0.06㎜~2and0.46㎜~2,0.49㎜~2,0.49㎜,2resin content ofthem in phloem is that:12.76%,18.37%,4.01%and21.12%,30.43%,27.60%。The resinous substances inducted by1%mixture was no different in three period. Butinducted by other chemical, the resinous substances inducted from May1to October26and fromJune27to December20are more than them inducted from August20to the following February20.4. The resinous substances inducted by Et were observed in the phloem. The resinoussubstances inducted by Me-JA were observed in the phloem and cambium. The resinoussubstances inducted by the mixture of Me-JAand Et were observed in the phloem, cambium andxylem. Plant hormones were penetrated from the bark to xylem, gradually influenced cells fromoutside to inside. The cells generated resin in the order: cork layer cells, phloem-ray cells,phloem parenchyma cells，phloem parenchymal cells, cambial cells, wood ray cells, includedphloem cells and vessels.5. The application of Me-JA, Et and the mixture in lanolin paste induced resinous substancessimilar to the stimulation by physical wounding and fungus infection. The induction of resinoussubstances may be related to signaling pathways of Me-JA and Et. If the trees suffered fromartificial wounding, insect feeding or specific pathogen infection, Me-JA and Et signalingpathways will be activated inside the plants, resulting in the production of resinous substances toadapt to environmental stress. The external application of Me-JA and Et may follow thephenomenon similar to the wounding, insect attack or pathogen infection and directly activates toinduce resinous substances.