| Aquilaria sinensis（Lour.） Gilg, an evergreen tree of Thymelaeaceae, is one of most important tree resources for producing agarwood and listed as category Ⅱ endangered plant in China. Under natural conditions, agarwood can only be produced by natural wounding such as injury by lightning or wounding by animals, typically around wounded or rotting parts of the trunk, but that is a very time-consuming process. With the exhausted wildlife resource and sharply increasing market demand, it is an urgent to research an efficiency technology for stimulating high grade agarwood. We studied the effect of wound-induced,plant growth regulator, inorganic salts and fungal on xylem structure, defense response,stem respiration and volatie oil of A. sinensis tree.The results shown the agarwood-stimulated technique and agarwood formation mechanism. The main results were as follows:（1） Different wound-induced methods promoted the formation of high-density and small vessel. The distributions of fat-like substance included phloem and ray parenchyma cell significantly increased. Treatments did not significantly affect the DBH, height and crown width growth of the tree. The discoloration width of burning and red-hot iron drill bit（BCD）treatment was the maximum, up to 0.7cm at the end of treatment. BCD treatment integrated the strongest defense response, and principal component score was 3.09. Stem respiration was extremely relevant with air temperature durning different treatment. Dynamic of stem respiration was "bimodal" trend, and seasonal variation had a single peak. The annual stem respiration rate of BCD treatment was highest(up to 5.29μmol ? m-2? s-1),temperature-sensitivity coefficient（Q10）（2.02） higher than the control（1.32）. The volatile oil content of BCD tratment（6.95%） was 2.04 times of the control（3.25%）. The sum of relative amount of sesquiterpenes and aromatic compounds in the different volatile oil was 5.55- 6.07 times that of control, and 0.55 to 0.56 times that of wild agarwood. There were significantly correlation within discoloration width,defense response strength, stem respiration rate andvolatile oil content. BCD treatment was the best heartwood formation of A. sinensis tree among the all physical wounded treatments.（2） Different plant growth regulator treatments significantly affected the formation of the vessel and fat-like substance distribution of A. sinensis xylem. Treatments did not significantly affect the DBH, height and crown width growth of the tree. The discoloration area of Me JA（0.05%）, ABA（0.1%）, 6-BA（0.005%） and ETH（0.1%）（ME treatment） mix solution was the maximum, up to 140.75 cm2. ME treatment had the strongest defense response, and principal component score was 2.26. There were significantly relevant between stem respiration and temperature of at different treatment. The annual stem respiration rate of ME treatment was highest,up to 5.61μmol ? m-2 ? s-1, Q10 was 2.11. The volatile oil content of the highest treatment（ME treatment） was 9.12%. The sum of relative amount of sesquiterpenes and aromatic compounds in the ME treatment volatile oil was the highest among treatments,was6.69 and 0.61 times that of control and wild agarwood, respectively. Me JA（0.1%） and ETH（0.1%） was proposed to induce most effectively the agarwood formation.（3） Cell death, fat-like substance accumulation,starch grains disappearence in the parenchyma cell of A. sinensis xylem were demonstrated at different inorganic salt treatments.The fourth treatment（Na HSO3（0.3%）, Na Cl（1%）, Fe Cl2（2%））caused lower vessel diameter and higher vessel density than that of control in A. Sinensis, also had the lowest DBH, height and crown width growth of the tree. The discoloration area of treatment 4 mix solution was the maximum, up to 145.22 cm2. Treatment 4 had the strongest defense response, and principal component score was 2.26. Stem respiration and temperature of different treatment were extremely relevant. The average stem respiration rate of treatment 4 was highest,up to 5.22μmol ? m-2 ? s-1, Q10 was 1.82. The volatile oil content of the highest treatment（treatment 4）was 11.11%.The sum of relative amount of sesquiterpenes and aromatic compounds in the treatment 4 volatile oil was the highest among the treatments,was 5.53 and 0.51 times that of control and wild agarwood, respectively. The mix solution of Na HSO3（0.22%）, Na Cl（0.25%）and Fe Cl2（2.00%） was proposed to induce most effectively the agarwood formation.（4） The effective fungi to induce agarwood formation were L. theobromae, Pen.meleagrinum, T. atroviride, T. koningiopsis, Pen. italicum, F. solani and B. rhodina.After the ten month period induction, ethanol extract contents of A. sinensis tree were up to pharmacopoeia standards under the seven fungi stimulation.（5） There was a commom phenomennon that cell death in the vessl with different fungi treatments, which caused by starch consumption and fat-like substance accumulation in parenchymal cell. DBH, height and crown width growth of the tree in all the treatments did not have a significant difference. The discoloration area of T. atroviride treatment was the maximum. T. atroviride treatment had the strongest defense response, and principal component score was 0.87. The annual stem respiration rate of T. atroviride treatment was the highest among the treatments,up to 6.06 μmol ? m-2 ? s-1, Q10 was 2.02. 2-（2-Phenylethyl）chromone, a specific component in the volatile oil content was found in all the fungi treatments. The highest volatile oil content from T. atroviride treatment was 13.65%.The sum of relative amount of sesquiterpenes and aromatic compounds in the T. atroviride treatment volatile oil were 7.13 and 0.65 times that of control and wild agarwood, respectively. Stem respiration had a certain correlationship with discoloration area, defense response strength and volatile oil content,Morever, T. atroviride suspension mixed Na HSO3 treatment was the best method which induced heartwood formation of A. sinensis tree.（6） The treatment of fungi solution added acidic salt was efficiently induced agar wood. Agarwood formation was an inductive stimulus, resulting in defense response, an d produce secondary metabolism during the dynamic process. Artificial wound, plant gr owth regulators, inorganic salt and fungi were effective methods of the agarwood forma tion.The stem defense reponse and respiration would have the certain indexfor predictin g the agarwood formation. |
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