Induced Resistance Of Mongol Almond, Amygdalus Mongolica, To Exogenous Methyl Jasmonate And Effect On Tent Caterpillar, Malacosoma Neustria Testacca

Mongol almond, Amygdalus mongolica, is an endemic and relic species in desert ofthe Mongolian Plateau in central Asia. Tent caterpillar, Malacosoma neustria testacca,is one of the main pests of mongol almond and could lead to huge amount of death ofmongol almond when it happened seriously. In this research, MeJA、mongol almond andtent caterpillar were selected as a research object, and from the changes of nutrition,protective enzymes, defensive proteins and secondary metabolites, in order to study theeffect of MeJA on physical and chemical resistance and temporal variation ofmongol almond by biochemical measurement and raising observation, as well as theimpact of induced resistance on the growth and food utilization of tent caterpillar.The study was expected to provide theory for resistance genes screening and resistantvarieties selection of mongol almond and sustainable forest insect control. The main resultswere as follows:1Induced physical defense of mongol almond by MeJAExogenous MeJA could induce the changes of leaf water potential, chlorophyll,waxy content, crystal cells of mongol almond, whose level was connected with the densityof MeJA and the time of induction. Leaf water potential was significantly lower than thatof the control on the1stday after MeJA treatment. The decreasing degree induced by0.1mmol/L MeJA was the highest among the three concentrations, which was55.39、35.47and32.84%on the1st、3rdand5thday respectively after induced. Chlorophyll contentincreased comparing with the control. There was a positive correlation between increasingdegree and MeJA concentration. Chlorophyll content increased along with concentrationsand treatment during the time prolonged. Waxy content increased comparing with thecontrol. The result was12.46%、12.54%and14.21%after0.1mmol/L MeJA induced onthe1st、3rd、5thday. The density of the stomata became smaller and there was a positivecorrelation between decreased range and MeJA concentration. The number of Crystal cellswas obviously more than that under the control, however, no obvious difference was foundamong the concentration treatments.2Change of the chemical substance induced by MeJAPrimary metabolism material reduced: the content of protein and soluble sugar induced by MeJA was significantly lower than that under the control, the decreasing rangerelated to MeJA concentration and treatment time. Protein content decreasing degreeinduced by1.0mmol/L MeJA was the biggest among the three concentrations on the1stday induction. It decreased to8.76mg/g. Soluble sugar content decreasing range inducedby0.01mmol/L MeJA was the biggest on the3rdday, which decreased from61.44mg/g to41.46mg/g.Protective, defensive enzymes and defensive proteins activities increased: PODactivity increased induced by MeJA and was influenced by the MeJA concentration. ThePOD activity induced by0.1mmol/L increased much more than the others, which rankedas0.1mmol/L＞0.01mmol/L＞1.0mmol/L. POD activity reached to the maximum on the3rdday after induction no matter which concentration was.LOX, PPO, PAL, involving in secondary metabolites synthesis, were induced byMeJA treatment. LOX activity with0.1mmol/L treatment was higher than that with0.01and1.0mmol/L treatment. Compared with the object under the control, LOX activity wassignificantly higher and enhanced when treatment time prolonged. The performanceranked as5d＞3d＞1d. PPO activity with0.1mmol/L treatment was higher than that with0.01and1.0mmol/L treatments. PPO activity reached to the maximum on the3rdday afterMeJA treatment. PAL activity increased by MeJA induced but was not statistically obviousthan the0.1mmol/L concentration and on the3rdday after the MeJA treatment.TI activity was significantly increased after MeJA treatment, which reached to themaximum on the3rdday after the treatment. The induced effect related to treatmentconcentrations. The effects ranked as0.1＞1.0＞0.01mmol/L.Secondary metabolism material increased. Flavonoids, tannic acid and lignin contentsignificantly increased after MeJA treatment and also had relation with the MeJAconcentrations and treatment time. The induced effect of0.1mmol/L treatment was themost obvious, inducing all the three substances to the maximum on the3rdand5thafter thetreatment.3The induced effect of MeJA on the growth and food utilization of tent caterpillarTent caterpillar fed on the MeJA treated leaves of mongol almond, it showedinhibited growth, reduced ECI and increased death rate.0.1mmol/L treatment had themost obvious inhibiting effect on growth of tent caterpillar. RGR of larvae fed on leavespicked on the5thday after0.1mmol/L MeJA treatment was only0.19, which decreased52.63%compared with the control. AD of larvae fed on leaves picked on the5thday after0.1mmol/L MeJA treatment was29.74%, which decreased35.67%compared with the control. ECI and ECD of tent caterpillar fed on leaves picked on the5th day after0.1mmol/L MeJA treatment significantly affected too, which decreased9.21%and20.22%respectively. Death rate of tent caterpillar fed on leaves treated by0.01,0.1and1.0mmol/L MeJA and picked on the3rd day after the treatment increased3.3,23.54and13.68%respectively.