Resin flow, symptom development, and lignin biosynthesis in response to wounding and fungal inoculation were investigated in Pinus rigida and Pinus densiflora. The two-year-old seedling stems were subjected to three types of treatments: (i) wounding without inoculation, (ii) wound-inoculation with a...
Resin flow, symptom development, and lignin biosynthesis in response to wounding and fungal inoculation were investigated in Pinus rigida and Pinus densiflora. The two-year-old seedling stems were subjected to three types of treatments: (i) wounding without inoculation, (ii) wound-inoculation with a conidial suspension of Fusarium circinatum, and (iii) pre-wounding woundinoculation with the fungus 20 days after the initial wounding. Resin flow from wounding sites was more evident in P. rigida than P. densiflora in all treatments. The wound-inoculation with the fungus induced almost two-fold higher levels of resin flow than the other treatments in both species. The pre-wounding woundinoculation appeared to result in a decrease in pitch canker development in the two pine species. Some reductions in disease severity were observed in the prewounding wound-inoculated P. rigida, showing a mean disease severity of less than 85%, compared with approximately 100% in the wound-inoculated stems. Disease severity was approximately 50% in the woundinoculated P. densiflora, whereas 10% in the pre-wounding wound-inoculated stems. Higher amounts of lignin were found from bark (ca. 40%) than from xylem (ca. 30%). The wound-inoculated bark and the pre-wounding wound-inoculated bark exhibited higher amounts of lignin among the other treatments. These results suggest that the wound-inoculation apparently prompt the increase in resin flow and lignin biosynthesis from the two pine species, and the prior wounding may be involved in decreased disease severity against the further invasion of F. circinatum.
Resin flow, symptom development, and lignin biosynthesis in response to wounding and fungal inoculation were investigated in Pinus rigida and Pinus densiflora. The two-year-old seedling stems were subjected to three types of treatments: (i) wounding without inoculation, (ii) wound-inoculation with a conidial suspension of Fusarium circinatum, and (iii) pre-wounding woundinoculation with the fungus 20 days after the initial wounding. Resin flow from wounding sites was more evident in P. rigida than P. densiflora in all treatments. The wound-inoculation with the fungus induced almost two-fold higher levels of resin flow than the other treatments in both species. The pre-wounding woundinoculation appeared to result in a decrease in pitch canker development in the two pine species. Some reductions in disease severity were observed in the prewounding wound-inoculated P. rigida, showing a mean disease severity of less than 85%, compared with approximately 100% in the wound-inoculated stems. Disease severity was approximately 50% in the woundinoculated P. densiflora, whereas 10% in the pre-wounding wound-inoculated stems. Higher amounts of lignin were found from bark (ca. 40%) than from xylem (ca. 30%). The wound-inoculated bark and the pre-wounding wound-inoculated bark exhibited higher amounts of lignin among the other treatments. These results suggest that the wound-inoculation apparently prompt the increase in resin flow and lignin biosynthesis from the two pine species, and the prior wounding may be involved in decreased disease severity against the further invasion of F. circinatum.
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가설 설정
, 2005) focused specifically on the roles of pathogens in decreased disease severity of trees, the wounding/inoculation treatments in this study could allow the assessment of wounding effects on decreased disease severity in pines. It is hypothesized that the pine seedlings become less vulnerable to subsequent inoculations after an initial wounding than unwounded seedlings. Both salicylic and jasmonic acids have been suggested as inducers of decreased disease development in conifers, as verified when applied exogenously in high concentrations (Davis et al.
제안 방법
circinatum. In this study, responses of P. rigida and P. densiflora to wounding and pathogen inoculation were investigated, and different levels of disease severity by prior wounding were examined in the pine-F. circinatum interaction.
One seedling was allocated for each wounding/inoculation treatment. The experiment was arranged as a completely randomized design with three replications, and it was repeated twice. Data from two experiments were pooled to compare mean areas covered with resin and mean disease severity among the treatments by Fisher’s protected least significant difference (FLSD) test using a statistical software (SAS; SAS Institute, Cary, NC, USA).
This study demonstrated the resin flow, symptom development, and lignin biosynthesis of P. rigida and P. densiflora seedling stems in response to wounding and inoculation with F. circinatum. Different levels of resin flow and disease severity were evident in the two pine species.
대상 데이터
Unwounded stems of both species were also included as a control. The air dried specimens were divided into bark and xylem, and finely ground with a laboratory ball miller (Pulverisette 6; Fritsch, Idar-Oberstein, Germany). Lignin content in the specimens was determined as reported previously (Sluiter et al.
데이터처리
Data from two experiments were pooled to compare mean areas covered with resin and mean disease severity among the treatments by Fisher’s protected least significant difference (FLSD) test using a statistical software (SAS; SAS Institute, Cary, NC, USA).
성능/효과
circinatum. An intriguing finding in this study was the almost twofold higher levels of resin-covered areas from the wound inoculated stems than other treatments regardless of pine species. A similar instance was noted in loblolly pine (P.
It was apparent that P. densiflora stems produced less amount of resin than P. rigida stems from initially wounding sites in all treatments throughout the experiment (Fig. 2B). Wound-inoculated stems exhibited a great increase in resin flow, reaching to over 80% of resin-covered areas 45 days after inoculation.
rigida stems showed approximately 60% resin flow 25 days after inoculation, resulting in 100% 30 days after inoculation. Significantly less amount of resin flow was observed from the stems of P. densiflora than those of P. rigida throughout the experiment, ranging from around 40% to 80% of resin-covered areas (P=0.01).
후속연구
Given the insignificant changes of lignin content in xylem after the wounding/inoculation treatments, the biosynthesis of lignin through the wounding/inoculation appears to be mostly localized to bark, reinforcing lignocellulosic architecture around wounding sites. The identification of triggering factors governing the increases in resin flow and lignin content, e.g., live pathogens, (nonpathogenic) microbes, etc., needs to be addressed in further studies. To our knowledge, this is the first report on the quantitative analysis of lignin content in the bark and xylem of P.
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