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The mycobiota of pine nuts was investigated. In total, 1832 fungi belonging to 31 species and 15 genera (Ascomycota, 2; Zygomycota, 3; mitosporic fungi, 10) could be isolated. Cladosporium spp. dominated the mycobiota with 685 isolations followed by Phoma macrostoma with 351 isolations. Overall, 16 potentially mycotoxigenic species were present on pine nuts.
The ascorbate and glutathione systems have been studied during the first stages of germination in orthodox seeds of the gymnosperm Pinus pinea L. (pine). The results indicate that remarkable changes in the content and redox balance of these metabolites occur in both the embryo and endosperm; even if with different patterns for the two redox pairs. Dry seeds are devoid of the ascorbate reduced form (ASC) and contain only dehydroascorbic acid (DHA). By contrast, glutathione is present both in the reduced (GSH) and in the oxidized (GSSG) forms. During imbibition the increase in ASC seems to be mainly caused by the reactivation of its biosynthesis. On the other hand, the GSH rise occurring during the first 24 h seems to be largely due to GSSG reduction, even if GSH biosynthesis is still active in the seeds. The enzymes of the ascorbate--glutathione cycle also change during germination, but in different ways. ASC peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) activities progressively rise both in the embryo and in endosperm. These changes are probably required for counteracting production of reactive oxygen species caused by recovery of oxidative metabolism. The two enzymes involved in the ascorbate recycling, ascorbate free radical (AFR) reductase (EC 1.6.5.4) and DHA reductase (EC 1.8.5.1), show different behaviour: the DHA reductase activity decreases, while that of AFR reductase remains unchanged. The relationship between ascorbate and glutathione metabolism and their relevance in the germination of orthodox seeds are also discussed.
New measurements of W-wave velocities in plants suggest that the previously observed velocity of 96 cm/s in plants is not unique but that there are several higher velocities, which appear to be integral multiples of 96 cm/s. The velocities apparently depend on the species, environment, and type of pulse when changed artificially. Measured vertical velocities are larger than horizontal velocities. This may provide a basis for gravitropism and may suggest a cosmic connection. Mean ratios of reciprocals of horizontal and vertical internodal spacings, in simple structure cases, give ratios like 1.25, 1.33, 1.50, 1.66, 3.0, and likely others. These ratios appear to confirm the velocity measurements since ratios of integral multiples of 96 cm/s give the same ratios. The versatility of plant growth is enhanced by the velocity variability.
It has not been possible to isolate a number of crucial enzymes involved in plant cell wall synthesis. Recent progress in identifying some of these steps has been overcome by the isolation of mutants defective in various aspects of cell wall synthesis and the use of these mutants to identify the corresponding genes. Secondary cell walls offer numerous advantages for genetic analysis of plant cell walls. It is possible to recover very severe mutants since the plants remain viable. In addition, although variation in secondary cell wall composition occurs between different species and between different cell types, the composition of the walls is relatively simple compared to primary cell walls. Despite these advantages, relatively few secondary cell wall mutations have been described to date. The only secondary cell wall mutations characterised to date, in which the basis of the abnormality is known, have defects in either the control of secondary cell wall deposition or secondary cell wall cellulose or lignin biosynthesis. These mutants have, however, provided essential information on secondary cell wall biosynthesis.
Loblolly pine (Pinus taeda L.) is the most widely planted tree species in the USA and an important tree in commercial forestry world-wide. The large genome size and long generation time of this species present obstacles to both breeding and molecular genetic analysis. Gene discovery by partial DNA sequence determination of cDNA clones is an effective means of building a knowledge base for molecular investigations of mechanisms governing aspects of pine growth and development, including the commercially relevant properties of secondary cell walls in wood. Microarray experiments utilizing pine cDNA clones can be used to gain additional information about the potential roles of expressed genes in wood formation. Different methods have been used to analyze data from first-generation pine microarrays, with differing degrees of success. Disparities in predictions of differential gene expression between cDNA sequencing experiments and microarray experiments arise from differences in the nature of the respective analyses, but both approaches provide lists of candidate genes which should be further investigated for potential roles in cell wall formation in differentiating pine secondary xylem. Some of these genes seem to be specific to pine, while others also occur in model plants such as Arabidopsis, where they could be more efficiently investigated.
OBJECTIVE: To analyze the oil contents and fatty acid composition in the seeds of Torrreya in China. METHOD: The contents and composition were determined by gravimetric analysis and GC respectively. RESULT: The oil contents in the seeds were 42.67%-54.39%. Among the fatty acids, linoleic acid and oleic acid were dominant. The unsaturated fatty acids accounted for 76.1%-82.0% of the whole fatty acids, and the major saturated fatty acids were behenic acid and palmitic acid. CONCLUSION: The oil in the seeds of Torreya is of high-quality, and the higher contents of bdhenic acid are characteristic for the oil. The development and utilization values of the seed oil in Torreya are evaluated.
The formation of self-sustaining mechanism is one of the major objectives for the sustainable management of plantations. In this study, the incorporation of different proportions of native Michelia macclurei into Cunninghamia lanceolata plantation was practiced to restore the degraded C. lanceolata plantation, and the comparison of nutrient cycling characteristics and soil nutrient concentrations was made among four types of plantation stand with different mixed rate of native M. macclurei representing four different restoration stages of degraded C. lanceolata plantations. With the increase of the proportion of M. macclurei in the plantation, the litterfall and returned nutrients N, P, K, Ca and Mg increased. The nutrient cycling efficiency increased significantly, e.g., that of N and Mg increased from about 0.1 for the degraded pure C. lanceolata plantation to above 0.5 for the pure M. macclurei plantation. Soil organic matter and nutrients also elevated. It is suggested that the self-sustaining mechanism of the C. lanceolata plantation forest gradually reformed as the proportion of native M. macclurei mixed in the plantation increased. The criteria to determine the proportion of native broad-leaved tree species mixed in C. lanceolata plantations for the purpose of sustainable management should be based on whether the self-sustaining mechanism was reformed and whether the soil nutrient status was improved.
The mechanism of forest self-thinning is generally nonlinear and dynamic, and the artificial neural network has the characteristic of expressing arbitrary nonlinear mapping. In this paper, the feasibility and limitation of artificial neural network used to simulating forest self-thinning was expounded, and the principle and algorithms of the neural network model based on modified simplex method (BP-MSM mixed algorithms) for modeling forest self-thinning were described. Its applications in self-thinning of Populus tremula natural forest Cunninghamia lanceolata plantation were illustrated. The results of forest self-thinning examples show the BP-MSM mixed algorithms were satisfactory in simulating forest self-thinning, and its precision was higher, which develops the method and theory of artificial neural network, and enriches the simulating method of forest self-thinning.
The pine processionary caterpillar Thaumetopoea pityocampa (Lepidoptera: Notodontidae) is considered to be a serious pest of medical importance. The hair on the dorsum of the last instar larvae of the moth may cause urticarial reactions (erucism) as well as eye problems and temporary blindness. In Israel, the pest occurs in all pine plantations as well as on ornamental pine trees in urban areas. The biology, ecology and management of the moth population are discussed as well as the mechanism of action of the urticarial hairs and their medical significance. Awareness of the life cycle and ecology of the pest may reduce the contact of the population with the urticarial hairs and prevent the morbidity caused by it.
OBJECTIVE: To determine the preventive and regressive effects of total flavones of metasequosia (TFM) on left ventricular hypertrophy in rats. METHOD: Left ventricular hypertrophy was inducedin by partial ligation of abdominal aorta. The rats were given ig TFM(4, 40, 400 mg.kg-1.d-1) for six weeks. RESULT: TFM markedly reduced the HW/BW, LVW/BW, myofibril diameter and Ca2+ content in left ventricles but the systolic blood pressure (SBP) in rats wasn't obviously influenced. CONCLUSION: TFM can prevent and reverse the left ventricular hypertrophy due to pressure overload in rats. The mechanism may be related to its calcium antagonistic properties.
Dark coniferous forest is the predominant type of vegetation in the upper reaches of Yangtze River. Difference among different types of soil exists. The sand content of soil is higher and the soil texture is coarser in the early stage of forest succession. The sand content of soil decreases with the advancement of the forest succession while that of soil in Abies fabri over-mature forest is the lowest. In slope wash soil, the sand content of soil decreases with the increasing soil depth. The soil porosity and soil water-holding capacity increases and soil bulk density decreases with the advancement of forest succession and decrease of soil depth. The deeper soil depth or the smaller soil water content are, the smaller the unsaturated hydraulic conductivity of soil measured by CGA method. Moreover, the correlation of soil water content with unsaturated hydraulic conductivity of soil can be simulated by an exponential function. The saturated hydraulic conductivity of soil decreases exponentially with the increasing soil depth. The time to attain the stable infiltration rate is different among different soil depth, while the deeper the soil depth is, the longer the time needs. The variation in soil texture, soil physical properties and the high infiltration rate of soil there implicated that there are scarce surface runoff, but abundant in subsurface flow, return flow and seepage, which is the result of regulation by dark coniferous forest on hydrological processes.
Two communities of the natural evergreen forest in Luoba Nature Reserve, North Guangdong, each represented by a 2500 m2 plot, were surveyed with Tree-layer-frequency method. Based on these data, the niche characteristics of 12 dominant populations, i.e., Castanopsis fargesii, Pinus massoniana, Schima superba, Liquidambar formosana, Diospyros morrisiana, Myrica rubra, Castanopsis lamontii, Adinandra milletii, Castanopsis eyrei, Elaeocarpus silvestris, Daphniphyllum calycinum, Neolitsea chuii, were described and analyzed, with stand layer as the resource state and tree abundance as the resource state descriptor of niche. The results indicate that most of the shade-tolerant tree species have higher niche breadth values, while the intolerant tree species have the lower ones, with zero value for Pinus massoniana and Liquidambar fomosana, which is in accordance with the declining status of the two species in the community. All the dominant populations, both shade-tolerant and intolerant, showed some adaptation to the community environment. 54.5% of the population-links had a niche similarity over 0.5, and 51.5% of them had a niche overlap over 0.2 in community 1. Niche characterization combined with conventional Tree-layer-frequency method could better determine the status and regenerating potential of tree species in the community. On the other hand, measuring tree abundance in different stand layers as the resource niche could demonstrate tree's requirement for the habitat. Variations in tree composition result in varied niche breadth, which lead to the variations of niche similarity and niche overlap values.
In higher plants the primary and the secondary structures of 5S ribosomal RNA gene are considered highly conservative. Little is known about the 5S rRNA gene structure, organization and variation in gyimnosperms. In this study we analyzed sequence and structure variation of 5S rRNA gene in Pinus through cloning and sequencing multiple copies of 5S rDNA repeats from individual trees of five pines, P. bungeana, P. tabulaeformis, P. yunnanensis, P. massoniana and P. densata. Pinus bungeana is from the subgenus Strobus while the other four are from the subgenus Pinus (diploxylon pines). Our results revealed variations in both primary and secondary structure among copies of 5S rDNA within individual genomes and between species. 5S rRNA gene in Pinus is 120 bp long in most of the 122 clones we sequenced except for one or two deletions in three clones. Among these clones 50 unique sequences were identified and they were shared by different pine species. Our sequences were compared to 13 sequences each representing a different gymnosperm species, and to six sequences representing both angiosperm monocots and dicots. Average sequence similarity was 97.1% among Pinus species and 94.3% between Pinus and other gymnosperms. Between gymnosperms and angiosperms the sequence similarity decreased to 88.1%. Similar to other molecular data, significant sequence divergence was found between the two Pinus subgenera. The 5S gene tree (neighbor-joining tree) grouped the four diploxylon pines together and separated them distinctly from P. bungeana. Comparison of sequence divergence within individuals and between species suggested that concerted evolution has been very weak especially after the divergence of the four diploxylon pines. The phylogenetic information contained in the 5S rRNA gene is limited due to its shorter length and the difficulties in identifying orthologous and paralogous copies of rDNA multigene family further complicate its phylogenetic application. Pinus densata is a diploid hybrid between P. tabulaeformis and P. yunnanensis. Its 5S rDNA composition is consistent with its hybrid origin. 5S rRNA of all gymnosperms published so far could be folded into a general secondary structure. Variation in this secondary structure was detected among species. About 55% of the 120 bp nucleotide positions was variable, in which 68% was on stem regions. Nevertheless, the positions at the end of the stems and those adjacent to loops are conserved. Their stability directly determines the size of the loops. Some mutations such as compensatory base-pair substitutions, and G-U pairing could be regarded as mechanisms for maintaining a stable secondary structure. The loops of the secondary structure are also relatively conserved. It seems that stable helices are necessary for the function of the gene. The conserved nucleotides in the loops are probably involved in the interaction with proteins and/or RNAs or with other nucleotide in the formation of the tertiary structure. However, unlike other reports, Loop E was found quite mutable among pines. These variations together with those on stems might be caused by the presence of pseudogenes among our clones. A preliminary evaluation indicates that only seven of 50 unique sequences are potentially functional genes.
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