| Henosepilachna vigintioctopunctata Fabricius is an important pest of various vegetables. Due to the increasing abuse of chemical pesticide universal, damage done by pests becomes more and more serious in the agricultural production. Therefore people pay more attention to biological control approaches which are highly effective and environmental friendly. We examined interactions between H. vigintioctopunctata and three isogenic tomato (Lycopersicon esculentum) genotypes which differed in the jasmonic acid (JA) pathway, were suppressor of prosystemin-mediated responses2(spr2) mutant plants,35.s::prosystemin (35s) plants, and wild type (Wt) plants. We studied the effect of tomato’s defense response induced by H. vigintioctopunctata on development of H. vigintioctopunctata. We also investigated defense signal pathway in tomato induced by H. vigintioctopunctata to explore the mechanism of action in defensing H. vigintioctopunctata. Major results as follows:(1) The larvae of H. vigintioctopunctata Fabricius feeding the foliage of excessive expression of JA type tomato (35s) had longer development duration than the group feeding the JA deletion type tomato (spr2). The body weight and feeding area of35s group were significantly lower than the spr2group. There was disadvantaged influence of35s tomato’s damaged by H. vigintioctopunctata on development of H. vigintioctopunctata(2) Feeding by H. vigintioctopunctata Fabricius could induce the increase of a variety of defense proteins, secondary substances significantly. The level of JA concentration in tomato foliage had a positive correlation with polyphenol oxidase (PPO), protease inhibitors (PI) and lipoxygenase (LOX) activity and relative gene expression, also with the concentration of tannin and flavone. The results showed that35s tomato had more defense protein content like PI and LOX during the same feeding stage than wt and spr2genotype. The spr2genotype was rarely induced defense protein and secondary substances after feeding. In the process of defense H. vigintioctopunctata, we found the content of nutrients had a negative correlation with the feeding time on all the three type tomatoes. (3) The exogenous JA which can constitutively activate the JA pathway in unwounded plants, result in stronger and quicker induced resistance, thus had a significantly effect on the relative gene expression of defense protein. Results showed that the exogenous JA could recover the expression of defense protein in spr2genotype and reduce the difference among the three genotypes.According to our results, we concluded that tomato could compound defense protein, secondary substance and reduce the content of nutrients to defense the stress by H. vigintioctopunctata Fabricius. In this process,35s genotype which was excessive expression of JA showed significantly higher resistance level than the other two genotypes and the defense measure of spr2genotype was hardly being induced by the feeding stress. After spraying exogenous JA, PI and LOX which are closely related to JA synthesis pathway were highly induced in spr2genotype and the differences in expression of PI and LOX’ mRNA were disappeared compared with35s and wt genotype. In conclusion the concentration of JA in tomato foliage had a prominently affect on the tomato resistance to H. vigintioctopunctata Fabricius. These results preliminarily reveal the defense response of tomato by stress by Henosepilachna vigintioctopunctata Fabricius and the important function of jasmonic acid in the plant resistance... |
