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1.
Pot‐grown and plantation‐grown Eucalyptus nitens trees (approximately 2 and 3 years old, respect‐ively) were experimentally wounded and inoculated with different fungi and in different seasons. Decay lesion development and defence zones were assessed. Two zones were described, a narrow brown decay interface (interface reaction zone, IRZ) and a diffuse zone beyond this being either pale brown or purple (reaction zone, RZ). The total phenol levels in the reaction zone were determined. Selected phenolics (pedunculagin, tellimagrandin 1, tetragalloylglucose, pentagalloylglucose and catechin) were quantified by liquid chromatography–mass spectrometry (LC–MS). A range of fungi (mainly decay‐causing) were used to inoculate wounds and the results indicated that more extensive decay lesions were generally associated with greater production of soluble phenols in response. Sterile inoculations and weakly aggressive fungi were associated with no or little xylem discoloration, whereas aggressive fungi elicited more discoloration and phenolic accumulation in advance of infection. This indicates that phenol accumulation is not a generalized response to wounding, but a variable response due to the interaction between microorganisms and sapwood. In plantation‐grown trees examined 6 months after wounding, purple reaction zones were commonly associated with large decay lesions. Seasonal differences in decay column area caused by Ganoderma applanatum were not significant 1 month after wounding and inoculation. 相似文献
2.
R. B. Pearce 《Forest Pathology》1990,20(5):275-289
Suberization responses to naturally-occurring fungal colonization of living xylem tissues were detected in 30 of 37 woody species examined. These responses comprised the suberization of traumatic parenchyma tissues in compartmentalization wall 4 barrier zones laid down in the vicinity of fungally infected wounds, or the suberization of parenchyma cells, tyloses and vessel linings in reaction zone decay margins in fully differentiated sapwood. Additionally, in a few species, suberization of xylem fibres and tracheids was observed where juvenile xylem tissues, apparently still incompletely differentiated, had been exposed by wounding. These xylem suberization responses are considered to increase the decay resistance of the altered cells, and may protect the hydraulic integrity of adjacent tissue, thus contributing to the antimicrobial defence of the living sapwood. 相似文献
3.
A study of lesion development in stems of Eucalyptus nitens following artificial inoculations with canker fungi was carried out on 16‐year‐old plantation trees. In a first trial cambium bark wounds on smooth‐ and rough‐barked trees were inoculated with the mycelium of nine species of canker fungi, including Endothia gyrosa. In a second trial spores or mycelium of E. gyrosa were applied directly onto undamaged or superficially wounded bark surfaces. Infection subsequent to artificial inoculation via wounding (whatever the wounding technique or type of inoculum) resulted in significantly larger external lesions (mean lesion area up to 35.6 cm2 20 months after inoculation) on smooth bark compared with those on rough bark (up to 19.0 cm2). Microscopic studies of infected rough and smooth bark suggest that, once smooth bark is compromised by wounding and artificial inoculation, the particular anatomical structure of smooth bark may offer less mechanical resistance to post‐penetration hyphal spread in comparison with rough bark. It is suggested that at a pre‐penetration stage under natural conditions spores of E. gyrosa more easily infect rough bark via cracks associated with this type of bark but not present in smooth bark. 相似文献
4.
To learn more about lignin formation in response to wounding in trees, we adopted two complementary approaches: (1) microscopic and histochemical studies of the wound response in 3.5‐month‐old Eucalyptus gunnii plantlets and (2) biochemical investigations of hydroxycinnamyl alcohol dehydrogenase activities in wounded 6‐year‐old, field‐grown E. gunnii trees. The first approach revealed that a barrier zone was formed in response to wounding in both ground tissues (cortex barrier and pith reaction zone) and vascular tissues. The barrier zone was barely detectable after 24 h but well‐developed 7 days after wounding. Microscopic analyses indicated that the barrier zone was formed by the reinforcement of cell walls with ‘lignin‐like material’ in both ground tissues and vascular tissue, and that, in addition, the lumen of certain xylem cells (vessels and fibres) were blocked by the deposition of polymeric phenolic material. Histochemical characterization revealed that the lignin‐like material (‘defence lignin’) deposited in ground tissue cell walls and xylem cell blockages was poor in syringyl (S‐type) lignin units and therefore differed from the usual mixed guaiacyl–syringyl (G–S) lignin unit composition of E. gunnii developmental lignin. In contrast, S‐type lignin appeared to be deposited in the cell walls of immature developing secondary xylem cells at a stage when the cell walls of comparable cells from unwounded control stems contained lignin poor in syringyl units. The second approach indicated that two different types of cinnamyl alcohol dehydrogenase activity are induced, and apparently regulated differentially, in response to wounding in E. gunnii trees. Coniferyl alcohol dehydrogenase activity was induced immediately and continued to increase throughout the first 15 days of the 17‐day experimental period, while sinapyl alcohol dehydrogenase activity was first detected at 8 days after wounding and continued to increase throughout the experimental period. The biological roles of the two alcohol dehydrogenase activities are discussed in relation to the formation of defence lignin versus developmental lignin in trees. 相似文献
5.
The responses of juvenile leaves of two Eucalyptus species, with contrasting susceptibility to infection by Mycosphaerella leaf disease, were compared. The anatomical changes, accumulation of phenolics, suberin, lignin and anthocyanin and the retention of chlorophyll were studied in leaf lesions of varying developmental stages caused by species of Mycosphaerella. Enhanced resistance of Eucalyptus nitens in southern Australia was attributed to the formation of an effective lignified and suberized necrophylactic periderm, to restrict pathogen spread. Leaves of E. nitens contained isobilateral palisade which resulted in both abaxial and adaxial cell division and the initiation of a strong reinforced cellular zone from an early lesion stage. Eucalyptus globulus formed a slower, distorted necrophylactic periderm through hypertrophic changes to existing mesophyll and limited cell divisions of the single adaxial palisade layer. Deposits of lignin and suberin did not occur until later in lesion development, which were not effective in preventing further disease development. From this study it is hypothesized that tolerance of eucalypts to Mycosphaerella pathogens may be associated with constitutive mesophyll density. 相似文献
6.
Species of Botryosphaeriaceae are associated with canker and dieback of Eucalyptus spp. worldwide, but little is known about their effect on the host physiology. The aim of this study was to evaluate the impact of Botryosphaeriaceae isolates from nine species in three genera (Botryosphaeria, Diplodia and Neofusicoccum), previously isolated from eucalypts, on three different Eucalyptus hosts (seedlings of E. nitens, cuttings of E. globulusand of E. globulus× E. cypellocarpa). An approach combining standard pathogenicity trials with evaluation of plant morpho‐physiological parameters was used. The size of the lesions produced revealed differences in fungal aggressiveness and host susceptibility. Isolates of Neofusicoccum kwambonambienseand Diplodia corticolawere the most aggressive, while Botryosphaeria dothidea and Diplodia seriataisolates were the least aggressive. In general, hybrid E. globulus× E. cypellocarpa plants developed smaller lesions, followed by E. nitens and E. globulus. Eucalyptus nitensplants showed minimal modifications on the morpho‐physiological profile when infected, although more severe symptoms and mortality were observed. This is probably due to a more variable genetic background of the plants. However, in general, no direct association between putative fungal aggressiveness and plant physiological disorders could be found. Results suggested that under optimal growth conditions plants manage to cope with pathogen attack and maintain their physiological performance. 相似文献
7.
The genus Mycosphaerella Johanson contains many pathogens capable of causing a severe impact on the growth of susceptible eucalypt species. The lack of knowledge about which species are present in Tasmania and their potential risk to the plantation industry prompted this study into the Mycosphaerella species occurring on Eucalyptus globulus and Eucalyptus nitens plantations in Tasmania. A total of 36 plantation and five road verge sites of E. globulus and E. nitens were sampled. Five Mycosphaerella species and three species from associated anamorph genera were isolated and identified in Tasmania; Mycosphaerella nubilosa, Mycosphaerella cryptica, Mycosphaerella tasmaniensis, Mycosphaerella grandis, Mycosphaerella vespa, Coniothyrium ovatum, Sonderhenia eucalypticola and Sonderhenia eucalyptorum. The most frequently isolated species with the highest incidence and severity of infection were M. cryptica and M. nubilosa. These two species appear to have the greatest potential to damage juvenile eucalypt plantations in Tasmania. A link between Mycosphaerella vespa and Coniothyrium ovatum is described for the first time. 相似文献
8.
接种苗木在生长量和生物量上均表现出极其显著的生长优势,ＥＣＭ真菌蜡蘑菌单接种及其与４种ＶＡ菌根菌剂混合接种,对苗木生长的促进作用尤为显著。在接种后１６周时,与对照苗相比,蓝桉和尾叶桉接种苗木的高生长量最大增幅分别为２８．８６％（ＬＳ）和８６．６５％（ＬＧ）;两种桉树地上部分平均干质量最大增幅分别为１２９．９３％（ＬＳ）和１３３．３４％（Ｌ）,地下部分分别为１１９．９３％（ＬＦ）和１７４．８３％（Ｌ 相似文献
9.
In Eucalyptus regnans and E. obliqua a rapid increase in the spread of defects (discolouration and decay) was observed more than 14 years after wounding. This increase was due to a breakdown of the barrier zone and the subsequent spread of defects into wood formed after wounding. Satisfactory relationships predicting defect extent using time since wounding could not be derived. 相似文献
10.
Within-tree variation in fibre length and coarseness was studied in fifty trees of E. globulus and E. nitens to develop a non-destructive sampling strategy. Trees, aged 5 to 9 years, were sampled across a range of sites in southern
Australia. Simulated core samples were removed at six fixed heights easily accessible from the ground (0.5, 0.7, ... 1.5 m)
and at eight percentage heights (0, 10, 20, ... 70%). Whole-tree values, calculated from percentage height data, were correlated
with the core data to determine the optimal sampling height. Core samples were found to be reliable predictors of whole-tree
fibre length, but results were variable for fibre coarseness. Simulated cores taken from the recommended sampling heights
explained 87% and 71% of variation in whole-tree fibre length for E. globulus and E. nitens respectively and 54% and 45% of the variation in whole-tree fibre coarseness. Fibre length at all fixed heights showed good
correlations with whole-tree values at all sites for E. globulus. For E. nitens the correlations were slightly lower and variable across sites. Results for fibre coarseness varied across sampling heights
and sites for both species. The recommended sampling height for fibre length is 1.5 m for both species, whilst for fibre coarseness,
the recommended sampling heights are 0.9 and 1.1 m for E. globulus, and 0.9 and 1.3 m for E. nitens. Radial orientation of cores was not important and neither fibre length nor coarseness were related to tree size or basic
density. To estimate stand mean fibre length to an accuracy of ±5% would require sampling 9 whole trees or taking cores from
13 trees for E. globulus and 4 whole trees or cores from 8 trees for E. nitens. For estimating stand mean fibre coarseness, 10 whole trees of E. globulus and 7 whole trees are needed for E. nitens. Core sampling for stand mean coarseness would require more trees: 13 to 21 for E. globulus and 11 to 16 trees for E. nitens.
Received 17 September 1998 相似文献
11.
Summary Decay columns resulting from naturally infected pruning wounds in 5‐ to 8‐year‐old plantation‐grown Eucalyptus nitens in Tasmania are interfaced by a reaction zone in the sapwood. The reaction zone is blue‐purple in colour and occasionally associated with a white zone at the reaction zone/healthy sapwood interface. A log incubation experiment has shown that the reaction zone is particularly durable against decay. The reaction zone is significantly drier than healthy sapwood, with lower levels of potassium, and a lower pH than both sapwood and heartwood. The increased total phenols levels and abundant tyloses in the reaction zone may be particularly important in defence. 相似文献
12.
Lesions of variable size, associated with the hymenomycete Inocutis jamaicensis, a white‐rot fungus, have been observed on the stems of Eucalyptus globulus trees in Uruguay. The aim of this study was to evaluate some ecophysiological characteristics of I. jamaicensis and assess its ability to colonize E. globulus trees of two different seed origins (Geeveston and Jeeralang) and the clone, 334‐1‐AR, obtained by micropropagation (ENCE, Spain). The growth of an I. jamaicensis isolate (MVHC11379) was evaluated at 25°C in a medium with a water potential of 0 (Ψ = 0). The growth rate did not vary significantly with a growth medium pH of between 4 and 7. I. jamaicensis showed no growth at either 5 or 37°C at any pH or Ψ tested. Weight loss of heartwood and sapwood of different plant provenances inoculated with I. jamaicensis under laboratory conditions was evaluated, and significant differences observed. Lignin‐modifying enzyme activity was evaluated in culture medium with or without E. globulus sawdust as substrate or inducer. Laccase activity was observed with sawdust and manganese peroxidase activity with and without sawdust. Only slight activity of aryl‐alcohol oxidase and lignin peroxidase was detected without sawdust. Experimental inoculation with I. jamaicensis of 3‐year‐old Geeveston and Jeeralang, and of 4‐year‐old 334‐1‐AR stems, resulted in successful fungal colonization of 56% of the 334‐1‐AR, 50% of Geeveston and 25% of Jeeralang trees. Only the heartwood was decayed. In 334‐1‐AR, the rotted wood was delimited by a reaction zone. Wood characteristics and the ability of I. jamaicensis to overcome the chemical reactions in the tree could partially explain differences in susceptibility to the fungus among provenances observed under natural and laboratory conditions. 相似文献
13.
T. Ona T. Sonoda K. Ito M. Shibata Y. Tamai Y. Kojima J. Ohshima S. Yokota N. Yoshizawa 《Wood Science and Technology》2001,35(3):229-243
Relationships between cell and pulp properties were investigated by examining the within-tree property variations in Eucalyptus camaldulensis and Eucalyptus globulus. Properties investigated included proportions of ray and axial parenchyma, thickness of cell walls and cell wall percentages.
The characteristics of the ray and axial parenchyma (their proportions and wall thickness) were found to have a significant
influence on all measured pulp properties, including paper strength properties. Multiple regression of pulp properties in
relation to cell properties revealed that nearly all measured pulp properties were explained by cell properties at the 1%
significance level. It was concluded, therefore, that all cell types are important for predicting pulp properties, and it
is strongly recommended that tree breeding programs for Eucalyptus include the measurement of all cell types.
Received 6 July 1999 相似文献
14.
Shy seed production in orchards of Eucalyptus nitens is a major barrier to the deployment of genetic gain in South African plantations. A machine learning method was used to identify optimal sites for the establishment of E. nitens seed orchards within the plantation forestry landscape of the summer rainfall region of South Africa. The ensemble classifier random forests (RF) was used to identify the environmental factors conducive to E. nitens floral bud production, and, based on these, build a predictive model deployable to the plantation forestry landscape for identifying suitable areas for E. nitens seed orchards. The RF model predicted site suitability likelihood for floral bud production with a high level of accuracy (area under the receiver operating characteristic curve = 0.83). Within the climatically optimal range for growing E. nitens, flower bud production was more abundant and consistent on cold slopes, i.e. sites experiencing lower minimum air temperatures during spring and autumn. The model was applied to the commercial plantation forestry landscape for the purpose of indicating sites climatically optimal for floral bud production in E. nitens and the establishment of breeding and seed production orchards of the same species. 相似文献
15.
16.
Gene flow between introduced and native Eucalyptus species 总被引：2，自引：0，他引：2
Barbour Robert C. Potts Brad M. Vaillancourt René E. Tibbits Wayne N. Wiltshire Robert J.E. 《New Forests》2002,23(3):177-191
The first evidence of in situ F1 hybridisation between an introduced eucalypt plantation species, Eucalyptus nitens, and a native eucalypt species is presented. Open-pollinated seed was collected from a mature E. nitens trial and from the adjacent native species, E. ovata and E. viminalis on the island of Tasmania. Nearly 70 000 seedlings were grown to a size at which hybrids could be clearly distinguished from pure species seedlings on the basis of morphology and a nearly species-specific isozyme allele. Hybridisation was observed between E. nitens and E. ovata, but no hybrids involving E. viminalis were found. This pattern of hybridisation was consistent with the flowering time overlap between the E. ovata and E. nitens. Eucalyptus nitens progenies displayed a low and relatively homogeneous level of hybridisation, averaging 0.15% per tree. In comparison, the proportion of hybrids obtained from the adjacent E. ovata trees varied from 0.04 to 16% per tree. Whether progeny arising from such hybridisation will survive and grow in nature to allow for backcrossing and introgression of the exotic genes into the native population is not yet known. 相似文献
17.
A non-destructive sampling strategy for basic density, based on removing 12 mm bark-to-bark cores, was developed in E. globulus and E. nitens. Fifty trees of each species, aged 5 to 9 years, were sampled across a range of sites. Core samples were removed on both
a north-south and an east-west axis from 6 fixed heights in the base of the tree (0.5 m, 0.7 m, …, 1.5 m). Whole-tree values
were calculated from disc samples removed at eight percentage heights (0, 10, 20, …, 70%) and correlations between the cores
and whole-tree values were used to determine the optimal sampling height. Core samples were found to be reliable predictors
of whole-tree density, explaining between 84% and 89% of the variation between trees. Core sampling of E. globulus and E. nitens to estimate basic density of whole-trees and stands is feasible; cores from trees at all E. globulus sites gave high correlations with whole-tree values. For E. nitens, site differences were apparent, and it is recommended that a small destructive sampling program should be undertaken prior
to commencing a major sampling program. Recommended optimal sampling heights are 1.1 m for E. globulus and 0.7 m for E. nitens. Core orientation was not important and density was not related to tree size. Six whole-tree samples or eight core samples
are required for estimating the mean density of a stand at a specific site to an accuracy of ±20 kg m−3 with a 95% confidence interval.
Received 17 September 1998 相似文献
18.
Anatomical and cellular responses of Pinus monticola stem tissues to invasion by Cronartium ribicola
J. W. Hudgins G. I. McDonald P. J. Zambino N. B. Klopfenstein V. R. Franceschi 《Forest Pathology》2005,35(6):423-443
White pine blister rust (Cronartium ribicola) causes extensive damage to white pines and their associated ecosystems across North America. The anatomical and cellular characteristics of C. ribicola colonization in Pinus monticola branch and stem tissues were studied as a basis for understanding host tree reactions that may be related to resistance. Samples examined showed typical fusiform swelling and some had produced aecia. The reaction of phloem and xylem tissues was compared with non-infected tissue using light and electron microscopy. Cortical parenchyma and phloem polyphenolic parenchyma cells underwent mitotic division, cell swelling, and ca sixfold greater accumulation of phenolic compounds in colonized vs. control stems. In the cortex and secondary phloem, haustoria were common in parenchymatous cells, and hyphae were abundant in the intercellular spaces, but cell death was rare, unless aecia had ruptured the stem cortex. Hyphae were also common in xylem rays, tracheids and between tracheids. Disease-induced changes in the cambial zone included development of cambium-derived xylem traumatic resin ducts. Results demonstrate that diverse host defence responses were activated in the bark of apparently susceptible trees, but lack of mechanical damage by C. ribicola to the phenol-containing host cells and the resin duct system allowed extensive colonization and development of aecia despite elicitation of these stem defences. Interactions between P. monticola and C. ribicola are discussed and compared with other conifer–fungus pathosystems. 相似文献
19.
Haustorial morphology of the cone-rust pathogen, C. conigenum, was investigated among naturally infected female strobili of three Guatemalan pines, P. maximinoi, P. pseudostrobus, and P. oocarpa. Among the three pine species, haustorial shapes and sizes were more variable in P. maximinoi and P. oocarpa than in P. pseudostrobus. The haustorial shapes and sizes were more variable in parenchyma cells of the cortex, xylem, and pith than in the cells in the phloem, xylem rays, and tracheids. The haustoria were also present in larger numbers in the parenchyma cells of the cortex, xylem, and pith than in phloem parenchyma cells and tracheids. In living cells, the tips of some haustoria were appressed to the host nuclei. 相似文献
20.
C. A. Raymond L. R. Schimleck A. Muneri A. J. Michell 《Wood Science and Technology》2001,35(3):203-215
Within-tree variation in kraft pulp yield, predicted using near infrared reflectance analysis, was studied in thirty trees
of E. globulus and fifty trees of E. nitens to develop a non-destructive sampling strategy. Trees, aged 5 to 9 years, were sampled across a range of sites in southern
Australia. Simulated core samples were removed at six fixed heights easily accessible from the ground (0.5, 0.7, ... 1.5 m)
and at seven percentage heights (0, 20, 30, ... 70%). Whole-tree values, calculated from percentage height data, were correlated
with the core data to determine the optimal sampling height. Core samples were found to be good predictors of whole-tree pulp
yield for E. globulus, with simulated cores taken from the recommended sampling height (1.1 m) explaining more than 50% of variation in whole-tree
pulp yield. Results for E. nitens were variable with large site differences apparent. On high quality sites, core samples from the recommended sampling height
(0.9 m) were good predictors of whole-tree pulp yield, explaining around 60% of the variation. On poor quality sites, cores
were poor predictors of whole-tree pulp yield. Radial orientation of cores was not important and predicted pulp yield was
not related to tree size, basic density or fibre length. To estimate stand mean pulp yield to an accuracy of ±1% would require
sampling 6 trees of E. globulus and 4 trees for E. nitens using either multiple discs or core samples. A single sampling height (1.1 m) is recommended for sampling for basic density,
fibre length, fibre coarseness and predicted pulp yield in E. globulus. For E. nitens the recommended sampling height for basic density and fibre length is 0.7 m and 0.9 m is recommended for predicted pulp yield
on good quality sites.
Received 17 September 1998 相似文献