Difference in Tissue Structure and Pine Resin Components of Pine Trees with Different Resistances

Resistances to pine wood nematode disease are significantly different, and the research on the disease resistance mechanism of different pine trees is still in the exploratory stage. In this study, four pine species with different resistances, namely Pinus massoniana, P. thunbergii, P. elliottii, and P. taeda, were selected as research objects, whose hanatomical structures and resin component contents were observed and determined, analyzing the relationship between resistance and tissue structure and resin component contents. The results showed that there were significant differences in the resin ducts characteristics of the tissue structures among the four pine species, the resin ducts in the tissues of P. elliottii and P. taeda presenting the characteristics of large area and numerous numbers. According to the variance analysis, the contents of monoterpenes and sesquiterpenes in the resin components were significantly different among the four pine species with different resistances, that of sesquiterpenes was extremely low in P. taeda and P. elliottii. Correlation analysis indicated that resistance of pine trees was significantly or very significantly positively correlated with the contents of β-pinene and limonene, and was negatively correlated with the contents of long leaf pinene, cyclo-long leaf pinene and long leaf pinene. The result above lays a foundation for resistance breeding and the preparation of resistance biological agents of pine trees.