Pine wilt disease(PWD)is one of the most devastating diseases of Pinu s spp.and is caused by the pine wood nematode(PWN),Bursaphelenchus xylophilus(Steiner&Buhrer)Nickle.To study adaptation of PWN to survive in ho...Pine wilt disease(PWD)is one of the most devastating diseases of Pinu s spp.and is caused by the pine wood nematode(PWN),Bursaphelenchus xylophilus(Steiner&Buhrer)Nickle.To study adaptation of PWN to survive in hosts that differ in resistance,we examined the self-regulatory characteristics of PWN at the biological and molecular levels early in the interaction.Two-year-old susceptible Pinus thunbergii and resistant Pinus taeda were selected for this experiment,and changes in PWNs after inoculation were assessed.q RT-PCR was used to detect changes in genes related to PWN pathogenicity and detoxification.The results showed that the migration and reproductive abilities of PWNs in P.thunbergii were stronger than those of PWNs in P.taeda.After 7 d,the number of nematodes in P.thunbergii was approximately 3.2-fold higher than in P.taeda.After 15 d,the number of nematodes in P.thunbergii was approximately twofold higher than that in P.taeda.Because PWN can adjust its sex ratio after infection,we compared the sex ratio of uninoculated PWNs,to that in the two pine species.In P.thunbergii,the female to male ratio first decreased and then stabilized over time;in P.taeda first decreased and then increased.Relative fat accumulation in PWNs increased significantly after the PWNs entered the tree body;the accumulation rate in P.thunbergii was higher than in P.taeda at 7 d,but lower after 15 d.Scanning electron microscopy(SEM)showed significantly more bacteria on the surface of PWNs in P.taeda compared with PWNs in susceptible P.thunbergii.At 12 h after inoculation,the expression of genes related to cell-wall degradation(Bx Beta1-4 and Bxpel1),effectors(Bx CDP1,Bx Sap B1),and active oxygen metabolism(Bxy-ctl-1 and Bx GST3)was 2–6×higher in the resistant pine than in the susceptible one.In contrast,in PWNs,the expression of autophagy-related genes Bx ATG1 and Bx ATG16 was 1.5–2 times higher in P.thunbergii than in P.taeda.These results indicate that the interaction between PWNs and pine trees with different resistance levels elicits a series of physiological and molecular adaptations that affect nematode reproduction and virulence.This study will help elucidate the adaptive mechanisms of PWN in different pine trees.展开更多
Background： Different types of growth and yield models provide essential information for making informed decisions on how to manage forests. Whole-stand models often provide well-behaved outputs at the stand level, b...Background： Different types of growth and yield models provide essential information for making informed decisions on how to manage forests. Whole-stand models often provide well-behaved outputs at the stand level, but lack information on stand structures. Detailed information from individual-tree models and size-class models typically suffers from accumulation of errors. The disaggregation method, in assuming that predictions from a whole-stand model are reliable, partitions these outputs to individual trees. On the other hand, the combination method seeks to improve stand-level predictions from both whole-stand and individual-tree models by combining them. Methods： Data from 100 plots randomly selected from the Southwicte Seed Source Study of Ioblolly pine （Pinus taedo L） were used to evaluate the unadjusted individual-tree model against the disaggregation and combination methods. Results： Compared to the whole-stand model, the combination method did not show improvements in predicting stand attributes in this study. The combination method also did not perform as well as the disaggregation method in tree-level predictions. The disaggregation method provided the best predictions of tree- and stand-level survival and growth. Conclusions： The disaggregation approach provides a link between individual-tree models and whole-stand models, and should be considered as a better alternative to the unadjusted tree model.展开更多
基金supported by the major emergency project in science and technology of National Forestry and Grassland Administration(ZD202001)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Pine wilt disease(PWD)is one of the most devastating diseases of Pinu s spp.and is caused by the pine wood nematode(PWN),Bursaphelenchus xylophilus(Steiner&Buhrer)Nickle.To study adaptation of PWN to survive in hosts that differ in resistance,we examined the self-regulatory characteristics of PWN at the biological and molecular levels early in the interaction.Two-year-old susceptible Pinus thunbergii and resistant Pinus taeda were selected for this experiment,and changes in PWNs after inoculation were assessed.q RT-PCR was used to detect changes in genes related to PWN pathogenicity and detoxification.The results showed that the migration and reproductive abilities of PWNs in P.thunbergii were stronger than those of PWNs in P.taeda.After 7 d,the number of nematodes in P.thunbergii was approximately 3.2-fold higher than in P.taeda.After 15 d,the number of nematodes in P.thunbergii was approximately twofold higher than that in P.taeda.Because PWN can adjust its sex ratio after infection,we compared the sex ratio of uninoculated PWNs,to that in the two pine species.In P.thunbergii,the female to male ratio first decreased and then stabilized over time;in P.taeda first decreased and then increased.Relative fat accumulation in PWNs increased significantly after the PWNs entered the tree body;the accumulation rate in P.thunbergii was higher than in P.taeda at 7 d,but lower after 15 d.Scanning electron microscopy(SEM)showed significantly more bacteria on the surface of PWNs in P.taeda compared with PWNs in susceptible P.thunbergii.At 12 h after inoculation,the expression of genes related to cell-wall degradation(Bx Beta1-4 and Bxpel1),effectors(Bx CDP1,Bx Sap B1),and active oxygen metabolism(Bxy-ctl-1 and Bx GST3)was 2–6×higher in the resistant pine than in the susceptible one.In contrast,in PWNs,the expression of autophagy-related genes Bx ATG1 and Bx ATG16 was 1.5–2 times higher in P.thunbergii than in P.taeda.These results indicate that the interaction between PWNs and pine trees with different resistance levels elicits a series of physiological and molecular adaptations that affect nematode reproduction and virulence.This study will help elucidate the adaptive mechanisms of PWN in different pine trees.
基金Funding for this project was provided in part by the Mclntire-Stennis funds
文摘Background： Different types of growth and yield models provide essential information for making informed decisions on how to manage forests. Whole-stand models often provide well-behaved outputs at the stand level, but lack information on stand structures. Detailed information from individual-tree models and size-class models typically suffers from accumulation of errors. The disaggregation method, in assuming that predictions from a whole-stand model are reliable, partitions these outputs to individual trees. On the other hand, the combination method seeks to improve stand-level predictions from both whole-stand and individual-tree models by combining them. Methods： Data from 100 plots randomly selected from the Southwicte Seed Source Study of Ioblolly pine （Pinus taedo L） were used to evaluate the unadjusted individual-tree model against the disaggregation and combination methods. Results： Compared to the whole-stand model, the combination method did not show improvements in predicting stand attributes in this study. The combination method also did not perform as well as the disaggregation method in tree-level predictions. The disaggregation method provided the best predictions of tree- and stand-level survival and growth. Conclusions： The disaggregation approach provides a link between individual-tree models and whole-stand models, and should be considered as a better alternative to the unadjusted tree model.
