Thunbergii Seedlings Research Articles

The effects of waterlogging duration on responses of above- and belowground organs of Pinus thunbergii seedlings after the release from waterlogging

ABSTRACT The tsunami in March 2011 heavily damaged the Pinus thunbergii Parlatore erosion-control coastal forests of northeastern Japan. The restoration is in process but has been challenged by waterlogging resulting from soil compaction of artificial growth bases. In this study, a pot experiment was conducted to elucidate the waterlogging responses of two-year-old P. thunbergii seedlings in terms of waterlogging duration. Three waterlogging durations were set (7 days, 17 days, and 32 days, water table at soil surface) during August, followed by a waterlogging-free recovery period (28 days) in September. In this experiment, the responses of both above- and belowground organs during waterlogging and after the release from waterlogging were elucidated, focusing on parameters, such as transpiration and photosynthesis rates, as well as fine root growth and morphology. As a result, we found that under the conditions of our experiment, if the waterlogging duration is within 17 days, P. thunbergii seedlings can recover physiological activity in about a week; however, if the waterlogging duration is over 32 days, recovery after the release from waterlogging largely varied among seedlings. For the seedlings that could recover, recovery took at least 2 weeks, which required new fine root growth. In cases where the damage was irreversible, seedlings showed an overall decline. These results suggest that it is important to manage the waterlogging conditions so that P. thunbergii seedlings can recover without prolonged negative effects.

Establishment of embryogenic Pinus thunbergii Parl. suspension cultures: growth parameters, dynamic analysis, and plant regenerative capacities

BackgroundPinus thunbergii is an economically important conifer species that plays a fundamental role in forest ecosystems. However, the population has declined dramatically in recent years as a result of the pine wilt disease outbreak. Thus, developing pine wilt-resistant P. thunbergii is an effective strategy for combating this epidemic.ResultsThe somatic embryogenesis of nematode-resistant P. thunbergii was previously reported by our group. The current study looked into the potential commercialization of suspension cultures as a means of large-scale production of nematode-resistant P. thunbergii seedlings. According to our findings, P. thunbergii suspension cultures were suitable for an initial inoculum of embryogenic tissue (2 g) and a subculture inoculum (6.7% (v/v)). Suspension cultures were cultivated for 8–10 days in a 30 mL liquid medium (Gupta and Durzan medium, DCR medium) to facilitate their maturation. The suspension cultures produced a large number of high-quality somatic embryos, which were then used to regenerate the plants and move them into the field. A more accurate assessment of the quality of suspension cultures for somatic embryogenesis could come from the suspension’s dynamics. The results showed that the medium’s phosphate, ammonium, nitrate, and carbohydrates were quickly eaten from day 0 to day 10. In terms of the absorption of nitrogen sources, the ammonium (NH4+) was absorbed prior to nitrate (NO3−). Additionally, the activity of mitochondrial succinate dehydrogenase and superoxide dismutase was directly related to cell growth.ConclusionsThis study presents an approach for selecting appropriate suspension cultures for efficient somatic maturation of P. thunbergii that can also be applied to other conifers. Furthermore, it is possible to commercialize nematode-resistant P. thunbergii seedlings using bioreactors, according to the suspension culture system we describe. To the best of our knowledge, this is the first work to describe a P. thunbergii suspension culture.

The Bursaphelenchus xylophilus Effector BxNMP1 Targets PtTLP-L2 to Mediate PtGLU Promoting Parasitism and Virulence in Pinus thunbergii.

Pinus is an important economic tree species, but pine wilt disease (PWD) seriously threatens the survival of pine trees. PWD caused by Bursaphelenchus xylophilus is a major quarantine disease worldwide that causes significant economic losses. However, more information about its molecular pathogenesis is needed, resulting in a lack of effective prevention and treatment measures. In recent years, effectors have become a hot topic in exploring the molecular pathogenic mechanism of pathogens. Here, we identified a specific effector, BxNMP1, from B. xylophilus. In situ hybridization experiments revealed that BxNMP1 was specifically expressed in dorsal gland cells and intestinal cells, and RT-qPCR experiments revealed that BxNMP1 was upregulated in the early stage of infection. The sequence of BxNMP1 was different in the avirulent strain, and when BxNMP1-silenced B. xylophilus was inoculated into P. thunbergii seedlings, the disease severity significantly decreased. We demonstrated that BxNMP1 interacted with the thaumatin-like protein PtTLP-L2 in P. thunbergii. Additionally, we found that the β-1,3-glucanase PtGLU interacted with PtTLP-L2. Therefore, we hypothesized that BxNMP1 might indirectly interact with PtGLU through PtTLP-L2 as an intermediate mediator. Both targets can respond to infection, and PtTLP-L2 can enhance the resistance of pine trees. Moreover, we detected increased salicylic acid contents in P. thunbergii seedlings inoculated with B. xylophilus when BxNMP1 was silenced or when the PtTLP-L2 recombinant protein was added. In summary, we identified a key virulence effector of PWNs, BxNMP1. It positively regulates the pathogenicity of B. xylophilus and interacts directly with PtTLP-L2 and indirectly with PtGLU. It also inhibits the expression of two targets and the host salicylic acid pathway. This study provides theoretical guidance and a practical basis for controlling PWD and breeding for disease resistance.

The response of physiological and xylem anatomical traits under cadmium stress in Pinus thunbergii seedlings.

Studying the response of physiological and xylem anatomical traits under cadmium stress is helpful to understand plants' response to heavy metal stress. Here, seedlings of Pinus thunbergii Parl. were treated with 50, 100 and 150mg kg-1 Cd2+ for 28days. Cadmium and nonstructural carbohydrate content of leaves, stems and roots, root Cd2+ flux, cadmium distribution pattern in stem xylem and phloem, stem xylem hydraulic traits, cell wall component fractions of stems and roots, phytohormonal content such as abscisic acid, gibberellic acid 3, molecule -indole-3-acetic acid, and jasmonic acid from both leaves and roots, as well as xylem anatomical traits from both stems and roots were measured. Root Cd2+ flux increased from 50 to 100mmol L-1 Cd2+ stress, however it decreased at 150mmol L-1 Cd2+. Cellulose and hemicellulose in leaves, stems and roots did not change significantly under cadmium stress, while pectin decreased significantly. The nonstructural carbohydrate content of both leaves and stems showed significant changes under cadmium stress while the root nonstructural carbohydrate content was not affected. In both leaves and roots, the abscisic acid content significantly increased under cadmium stress, while the gibberellic acid 3, indole-3-acetic acid and jasmonic acid methylester content significantly decreased. Both xylem specific hydraulic conductivity and xylem water potential decreased with cadmium stress, however tracheid diameter and double wall thickness of the stems and roots were not affected. High cadmium intensity was found in both the stem xylem and phloem in all cadmium stressed treatments. Our study highlighted the in situ observation of cadmium distribution in both the xylem and phloem, and demonstrated the instant response of physiological traits such as xylem water potential, xylem specific hydraulic conductivity, root Cd2+ flux, nonstructural carbohydrate content, as well as phytohormonal content under cadmium stress, and the less affected traits such as xylem anatomical traits, cellulose and hemicellulose.

Effects of root-colonizing fungi on pioneer Pinus thunbergii seedlings in primary successional volcanic mudflow on Kuchinoerabu Island, Japan.

Root-colonizing fungi, such as mycorrhizal fungi and dark septate endophyte fungi, are often found on pioneer plant species during early primary succession. However, little is known about which fungal species are responsible for the establishment of pioneer plants when these symbionts colonize simultaneously. We investigated the root-colonizing fungal communities of Pinus thunbergii that established prior to lichens, bryophytes, and short-lived herbaceous plants in a primary successional volcanic mudflow site on Kuchinoerabu Island, Japan. We collected a total of 54 current-year and 1- to 2-year-old seedlings. The colonization of root fungi was evaluated by direct observation of key structures (e.g., mantle, arbuscule, microsclerotia, and hyphae) and molecular analysis. Of the 34 current-year seedlings collected, only 12 individuals were colonized by ectomycorrhizal (ECM) fungi. By contrast, all 1- to 2-year-old seedlings were colonized by ECM fungi. Seedlings colonized by pine-specific ECM fungi, specifically Rhizopogon roseolus and Suillus granulatus, showed higher nitrogen and phosphorus contents in their needles compared to non-ECM seedlings. Arbuscular mycorrhizal fungi and dark septate endophyte fungi were found in only two and three individuals, respectively. The high density of mycophagous deer on Kuchinoerabu-jima may contribute to the favored dispersal of ECM fungi over other root-colonizing fungi. In conclusion, the seedling establishment of P. thunbergii at the volcanic mudflow may be largely supported by ECM fungi, with negligible effects of arbuscular mycorrhizal fungi and dark septate endophytes.

Transcriptome Sequencing and Analysis of Genes Related to Disease Resistance in Pinus thunbergii

Pinus thunbergii (P. thunbergii) is a gymnosperm with important economic and ecological value. In order to investigate the diagnosis and defense mechanism of P. thunbergii against Bursaphelenchus xylophilus (the pinewood nematode, PWN), the needles of P. thunbergii seedlings on the fifth day after being infected by PWN were taken as samples for transcriptome sequencing analysis. Compared with the control group, 647 genes were differentially expressed in the treatment group, of which 277 genes were upregulated and 370 genes were downregulated. Enrichment analysis showed that most of these differentially expressed genes were abundant in the biosynthesis of secondary metabolites, pathogen interaction and hormone signal transduction. In addition, among the differential genes, NBS-LRR genes, thiamine-metabolizing enzymes, phenylalanine ammonia lyase and acetaldehyde dehydrogenase were screened and analyzed. The analysis of the response of P. thunbergii to PWN stress and its disease resistance genes lays a foundation for the breeding of disease-resistant P. thunbergii in the future.

The effects of ectomycorrhizal inoculation on survival and growth of Pinus thunbergii seedlings planted in saline soil

The effects of ectomycorrhizal inoculation on survival and growth of Pinus thunbergii seedlings planted in saline soil

An ectomycorrhizal fungus, Cenococcum geophilum, in a coastal pine forest has a high tolerance for an insecticide used to control pine wilt disease

Cenococcum geophilum Fr., one of several ectomycorrhizal species associated with black pine (Pinus thunbergii Parl.), is dominant in the coastal forests of Japan, even under adverse abiotic environmental conditions. In these forests, many tonnes of Sumipine® (fenitrothion) are applied every year to protect P. thunbergii from pine wilt disease, which is transmitted by a beetle. Here, we examined the effect of this insecticide on the species of fungi found as ectomycorrhizae on naturally regenerated P. thunbergii seedlings collected from coastal forest sites that had or had not been sprayed with fenitrothion. The proportion of C. geophilum ectomycorrhizae on black pine root tips was significantly higher in areas where fenitrothion had been applied than in areas where it had not. We measured the in vitro mycelial growth of C. geophilum as well as other ectomycorrhizal fungi of coastal black pine, Rhizopogon roseolus (Corda) Th. Fr. and Pisolithus arhizus (Scop.) Rauschert, at three levels of fenitrothion (density: 1.32 g/cm3), i.e., 0, 0.1 and 0.2 mL L−1. The growth of all three species decreased significantly as the fenitrothion dosage increased. However, the reduction of mycelial growth in response to fenitrothion was lower in C. geophilum than in the other two species. These results suggest that C. geophilum has a high tolerance for fenitrothion, which may explain its dominance over other ectomycorrhizal species in coastal forests in Japan where fenitrothion is routinely sprayed.

증가한 온도와 CO₂ 농도가 소나무와 곰솔 유묘의 바이오매스 및 생리적 변화에 미치는 영향

본 연구는 증가한 온도와 CO₂ 농도 환경에서 소나무(Pinus densiflora)와 곰솔(P. thunbergii) 유묘의 바이오매스 생장 변화와 생리적 반응을 분석하기 위하여 실시하였다. 기후변화시나리오에 따라, 온도는 현재 대기 온도(24℃)와 50년 후 예측 온도(27℃)로 처리하였고, CO₂ 농도는 현재 대기 평균 농도(400ppm)와 100년 후 예측 농도(750ppm)를 적용하였다. 온도와 CO₂ 농도 증가는 소나무 유묘의 줄기와 뿌리 바이오매스 변화에는 영향을 주지 않았으나, 곰솔 유묘의 줄기와 뿌리 바이오매스를 증가시켰다. 특히, 높은 온도는 곰솔 줄기의 바이오매스에 더 큰 영향을 주었고, 증가한 CO₂ 농도는 곰솔의 줄기와 뿌리 바이오매스 모두에 영향을 주었다. 또한, 증가한 온도와 CO₂ 농도는 소나무 침엽 내 광색소 함량에는 영향을 주지 않았으나, 곰솔 침엽에서는 광색소 함량을 감소시켰다. 두 수종 모두에서 온도와 CO₂ 농도 증가 시 엽록소 a/b의 비율과 총 엽록소 및 카로테노이드 함량 비율이 감소하였다. 온도와 CO₂ 농도 증가에 따른 항산화효소의 활성은 두 수종 간, 효소 간에 차이가 컸다. 증가한 온도와 CO₂ 농도 환경에서, 소나무 침엽 내 SOD와 GR 활성은 증가하였으나, 곰솔에서는 SOD, APX, GR 활성이 모두 감소하였다. 결론적으로, 증가한 온도와 CO₂ 농도가 소나무에는 스트레스로 작용하여 생장을 억제하였으나, 곰솔에는 생장 촉진 효과를 준 것으로 판단된다.

Influence of temperature on pine wilt disease progression in Pinus thunbergii seedlings

Pine wilt disease (PWD) affects forests globally and is caused by the pinewood nematode (PWN) Bursaphelenchus xylophilus. It has been proposed that PWD development has a strong association with air temperature. Because symptom development is related to the number of PWNs and they are poikilothermic animals whose development and multiplication are affected by temperature; it appears that temperature conditions affect the PWN multiplication rate, which leads to difference in disease progression. However, limited information is available about the temperatures inside pine trees, and the understanding of how temperature affects PWN multiplication and PWD progression remains incomplete. Therefore, in the present study, we evaluated the temperature, number of PWNs, and external symptoms of PWD in Pinus thunbergii seedlings infected with PWNs at air temperatures of 20 °C, 25 °C, and 30 °C over time. We found that the seedling temperatures were slightly higher than the air temperature under each temperature condition and that the effective accumulated temperature calculated using a base temperature of 10 °C was related to the number of PWNs and symptom development in all temperature test groups. However, at 20 °C, there were very few PWNs in some seedlings and none of the seedlings showed partial or full wilting. These findings suggest that PWD progression is greatly affected by ambient temperature and facilitated by increase in PWN populations with effective accumulated temperature especially in the range of 25 °C–30 °C.

Spatial and temporal distribution of Bursaphelenchus xylophilus inoculated in grafts of a resistant clone of Pinus thunbergii

ABSTRACTPreventive plantation of resistant Pinus thunbergii seedlings is anticipated in non-epidemic areas of pine wilt disease (PWD) in Japan. The scions of resistant clones, which are required to establish a seed orchard for the production of resistant seedlings, might harbor Bursaphelenchus xylophilus (a pathogen of PWD), as they are grown in epidemic areas and artificially inoculated with B. xylophilus to verify their resistance. In this study, we analyzed within-tree distribution of B. xylophilus in inoculated grafts of a resistant P. thunbergii clone, Yuza-155, at two different times, 7 and 19 months after inoculation. Experimental evidence using both direct extraction of nematodes and a DNA-based detection technique demonstrated that the migration and propagation of inoculated nematodes were restricted mostly within the scion stems and rootstocks. In branch samples, nematodes were detected less frequently by the DNA-based method and no live nematodes were extracted at 7 months after inoculation, whereas at 19 months after inoculation, neither of the methods detected any nematodes. Thus, the probability that the current-year shoots of this resistant clone, Yuza-155, which initiated plant growth in the season following inoculation, are infected with B. xylophilus is quite low. Therefore, they may serve as pathogen-free scions for propagation of ramets of resistant P. thunbergii clones and construction of seed orchards in PWD non-epidemic locations.

The Control of Fusarium Root Rot and Development of Coastal Pine (Pinus thunbergii Parl.) Seedlings in a Container Nursery by Use of Bacillus licheniformis MH48

This study investigated the control of Fusarium root rot and development of coastal pine (Pinus thunbergii) seedlings in a container nursery by using Bacillus licheniformis MH48. High-quality seedlings without infectious diseases cause vigorous growth. Fusarium root rot caused by Fusarium oxysporum is responsible for serious damage to coastal pine seedlings in nurseries. B. licheniformis MH48 produced enzymes that degraded the fungal cell walls, such as chitinase and β-1,3-glucanase. These lytic enzymes exhibited destructive activity toward F. oxysporum hyphae, which were found to play key roles in the suppression of root rot. In addition, B. licheniformis MH48 increased the nitrogen and phosphorus in soils via fixed atmospheric nitrogen and solubilized inorganic phosphate. B. licheniformis MH48 produced the phytohormone auxin, which stimulated seedling root development, resulting in increased nutrient uptake in seedlings. Both the bacterial inoculation and the chemical fertilizer treatments significantly increased seedling growth and biomass, and the bacterial inoculation had a greater effect on seedling development. Based on the results from this study, B. licheniformis MH48 showed potential as a biological agent against Fusarium root rot and as a promoter of growth and development of Pinus thunbergii seedlings.

Ectomycorrhizal fungi may not act as a barrier inhibiting host plant absorption of heavy metals

Whether the huge external hyphal system of ectomycorrhizae that promotes host plants' acquisition of water and nutrients can selectively inhibit their transport of heavy metals at the same time remains unclear. In this experiment, we designed and conducted two types of soil-pot test to clarify the effects of EMF on the absorption and transport of copper (Cu) and cadmium (Cd) by host Pinus thunbergii seedlings. In the root-bag test, external hyphae took the initiative into the Cu/Cd-contaminated bulk soil, absorb and transport Cu and Cd to the rhizosphere soils and further transport it to the shoots of the host plants. Inoculation with EMF also promoted the uptake of nutrients by host plants, thereby increasing their biomass and improving Cu/Cd tolerance compared with non-inoculated plants. Inoculation with EMF species with higher Cu or Cd tolerance generated more phytostabilization and phytoextraction of Cu or Cd by host plants. In a short-term exposure test, inoculation with EMF accelerated the absorption of Cu and Cd by P. thunbergii within 12 h of Cu or Cd irrigation. Therefore, we concluded that EMF do not act as a barrier inhibiting the absorption of heavy metals by host plants, but rather promote this absorption. Improving the plant's nutritional status and promoting growth, diluting heavy metal concentrations, thereby reducing the toxic effects of heavy metals on host plants. These results provide the theoretical basis for the application of EMF in plant–microbial combinations for the phytostabilization and phytoextraction of heavy metal–contaminated soils.

Ectomycorrhizal fungi reduce the light compensation point and promote carbon fixation of Pinus thunbergii seedlings to adapt to shade environments

We examined the effects of three ectomycorrhizal (ECM) symbionts on the growth and photosynthesis capacity of Japanese black pine (Pinus thunbergii) seedlings and estimated physiological and photosynthetic parameters such as the light compensation point (LCP), biomass, and phosphorus (Pi) concentration of P. thunbergii seedlings. Through this investigation, we documented a new role of ectomycorrhizal (ECM) fungi: enhancement of the survival and competitiveness of P. thunbergii seedlings under low-light condition by reducing the LCP of seedlings. At a CO2 concentration of 400 ppm, the LCP of seedlings with ECM inoculations was 40–70 μmol photons m−2 s−1, significantly lower than that of non-mycorrhizal (NM) seedlings (200 μmol photons m−2 s−1). In addition, photosynthetic carbon fixation (Pn) increased with light intensity and CO2 level, and the Pn of ECM seedlings was significantly higher than that of NM seedlings; Pisolithus sp. (Pt)- and Laccaria amethystea (La)-mycorrhizal seedlings had significantly lower Pn than Cenococcum geophilum (Cg)-mycorrhizal seedlings. However, La-mycorrhizal seedlings exhibited the highest fresh weight, relative water content (RWC), and the lowest LCP in the mycorrhizal group. Concomitantly, ECM seedlings showed significantly increased chlorophyll content of needles and higher Pi concentrations compared to NM seedlings. Overall, ECM symbionts promoted growth and photosynthesis while reducing the LCP of P. thunbergii seedlings. These findings indicate that ECM fungi can enhance the survival and competitiveness of host seedlings under low light.

Pathway and sink activity for translocation of 14C absorbed as amino acids in the Pisolithus extraradical mycelium of ectomycorrhizal Pinus thunbergii seedlings

To characterize the pathway and sink activity for the translocation of amino acids and their metabolites in the extraradical mycelium (ERM) of ectomycorrhizal (ECM) symbiosis, we locally labeled a part of the ERM of Pinus thunbergii seedlings colonized by a Pisolithus isolate with [14C(U)]-l-alanine (14C-Ala) or [14C(U)]-l-glutamine (14C-Gln) and followed the 14C distribution in the ERM by autoradiography. After 14C-Ala or 14C-Gln labeling, 14C was mainly distributed in a bundle of rhizomorphs extending from the labeled part towards ECM root tips of the host, but not in thick roots or the aboveground part of the seedling. When 14C-Ala was added after seedling removal, no 14C bundle appeared in the remaining ERM. These results indicate that 14C amino acids and their metabolites are translocated unidirectionally towards the ECM root tips, where strong sink activity for amino acids is localised. 14C was also distributed diffusely over a broad region in ERM surrounding the labeled part. This result suggests that 14C amino acids and their metabolites are also translocated multidirectionally in the ERM by sink activity distributed diffusely all over the whole ERM.

Pathway and sink activity for photosynthate translocation in Pisolithus extraradical mycelium of ectomycorrhizal Pinus thunbergii seedlings.

The purpose of this study was to identify the pathway and sink activity of photosynthate translocation in the extraradical mycelium (ERM) of a Pisolithus isolate. We labelled ectomycorrhizal (ECM) Pinus thunbergii seedlings with (14)CO2 and followed (14)C distribution within the ERM by autoradiography. (14)C photosynthate translocation in the ERM resulted in (14)C distribution in rhizomorphs throughout the ERM, with (14)C accumulation at the front. When most radial mycelial connections between ECM root tips and the ERM front were cut, the whole allocation of (14)C photosynthates to the ERM was reduced. However, the overall pattern of (14)C distribution in the ERM was maintained even in regions immediately above and below the cut, with no local (14)C depletion or accumulation. We inferred from this result that every portion in the ERM has a significant sink activity and a definite sink capacity for photosynthates and that photosynthates detour the cut and reach throughout the ERM by translocation in every direction. Next, we prepared paired ECM seedlings, ERMs of which had been connected with each other by hyphal fusion, alongside, labelled the left seedling with (14)CO2, and shaded none, one or both of them. (14)C photosynthates were acropetally and basipetally translocated from the left ERM to ECM root tips of the right seedling through rhizomorphs in the left and right ERMs, respectively. With the left seedling illuminated, (14)C translocation from the left to the right ERM increased by shading the right seedling. This result suggests that reduced photosynthate transfer from the host to its ERM increased sink activity of the ERM.

Observations on the embolism and survival of Pinus thunbergii seedlings inoculated with Bursaphelenchus xylophilus

To elucidate the relationship between seedling survival and the distribution of xylem embolisms after infection with pinewood nematode (PWN), Bursaphelenchus xylophilus, we examined embolised xylem areas using acid fuchsin dye solution in five groups of 3-year-old Pinus thunbergii seedlings which included a susceptible group and four groups with varying degrees of resistance. We confirmed that embolised areas caused by infection with PWN could be delineated accurately using a dye uptake method with appropriate procedures. In all groups, the additional embolisms were visible 1 cm above or below the inoculation wound 45 days after inoculation (DAI). In all stained seedlings, the distribution of embolisms was associated with axial resin canals and not with ray tissues. The difference in survival rates among the resistant groups depended on the distribution of embolisms in the current-year xylem. A susceptible group and two groups with varying degrees of resistance that showed higher percentage loss of water-conducting area at 45 DAI exhibited low survival rate at 5 months after inoculation. In many surviving seedlings, water movement was generally observed in newer tracheids, while embolisms extended to near the cambium in some seedlings of the three groups. Retention of the water-conducting pathway of newer tracheids is thought to be necessary for survival after infection with PWN.

「抵抗性マツと樹幹注入剤を併用した場合のマツ材線虫病に対する防除効果－２」３年生苗木への接種線虫数が防除効果に及ぼす影響

「抵抗性マツと樹幹注入剤を併用した場合のマツ材線虫病に対する防除効果－２」３年生苗木への接種線虫数が防除効果に及ぼす影響

Effect of ectomycorrhizal composition on survival and growth of Pinus thunbergii seedlings varying in resistance to the pine wilt nematode

Ectomycorrhizal composition and associated fungi affect the intra-specific ability of resistant black pines for physiological adaptation. Since Japanese black pine (Pinus thunbergii Parl.) forests have been widely devastated by pine wilt disease, several kinds of resistant black pines have been developed. Although all of the resistant black pines are the same species, these resistant trees show different physiological characteristics. We investigated the survival rates and growth rates, as well as ectomycorrhizal composition and associated fungi, on four kinds of Japanese black pine seedlings (three pine wilt-resistant and one non-resistant), and elucidated the factors affecting the various physiological characteristics. We found that the abundance of ectomycorrhizal types differed even though seedlings were grown sympatrically in the same areas for about 2 years. The seedlings that had plentiful white ectomycorrhizae showed the highest survival and growth rates regardless of the variety of black pine. Sequence similarities of the white ectomycorrhizae in the rDNA ITS region were best matched with members of Astraeus sp., Atheliaceae, Boletaceae and Thelephoraceae. Our findings indicate that intra-specific physiological adaptation might be affected by ectomycorrhizal composition or by the specific ectomycorrhizal species.

海岸防災林の復旧に向けたクロマツの増殖

海岸防災林の復旧に向けたクロマツの増殖