PdSABP2A involved in jasmonic acid biosynthesis regulates Anoplophora glabripennis resistance of Populus deltoides ‘Shalinyang’

Abstract

Populus deltoids ‘Shalinyang’ (PdS) is a new poplar variety with insect resistance cultivated in the western region of China. Anoplophora glabripennis (ALB) is an important forestry pest that causes great harm to poplar trees. However, the research on the insect resistance mechanism of PdS is still unclear, so exploring its defense response mechanism against ALB can provide theoretical and technical support for the subsequent cultivation of new varieties of poplar suitable for extensive planting and resistant to biotic stress. This study primarily aims to elucidate the molecular mechanisms underlying PdS's inducible resistance by jasmonic acid (JA). Here, 50 μM JA was applied to 1-year-old PdS plants to verify its anti-insect effect in PdS. It was found that superoxide dismutase (SOD) activity and hydrogen peroxide (H₂O₂) content increased, malondialdehyde (MDA) content decreased, and the feeding area of ALB leaves and the number of stem bite marks decreased by 56.92 % and 49.33 % respectively compared to the control group. The results indicated that JA treatment had a positive regulatory effect on insect resistance in PdS. Based on the transcriptome data, the key gene PdSABP2A was screened from the methylesterase (MES) gene family that played an important role in plant defense response. The expression level of PdSABP2A gene also significantly increased in the external JA treatment experiment. The virus-induced gene silencing (VIGS) experiment was used for gene function validation, and it was found that the expression level of PdSABP2A gene decreased by 73.72 %, and the JA content also significantly decreased. In addition, PdS subjected to the VIGS silencing treatment were more severely nibbled by ALB. The larvae inside PdS plants grew faster, had higher activity of digestive and defense enzymes, and lower mortality rates, all of which indicated a decrease in PdS insect resistance. These findings indicated that the PdSABP2A gene is involved in regulating the synthesis of JA and inducing the defense response of PdS against ALB.