质壁分离处理刺五加合子胚促进了胼胝质合成酶基因的表达

在以前的研究中我们报道了经质壁分离预处理刺五加合子胚下胚轴,促进了体细胞胚形成。在本研究中,我们利用RT-PCR方法分析了刺五加合子胚经2,4-D,蔗糖,甘露醇处理后胼胝质合成酶基因的表达水平。结果显示:蔗糖和甘露醇处理明显促进了胼胝质合成酶基因的表达水平。而且我们观察到,体细胞胚发生过程中,外植体经质壁分离处理后细胞壁明显加厚。因此我们推测:胼胝质可能使表皮层细胞相互之间产生分离从而使其转变为具有胚性潜能的细胞。图2参20。     

Method to compute fiber directions in wood from computed tomography images

This paper describes a new method, called the CT-direction method, in which the fiber directions in wood in three-dimensional space are calculated from the pixel information on a series of two-dimensional computed tomography images. Local fiber directions are calculated from the principal directions of inertia of measurement spheres distributed throughout the body of the wood object. The calculated fiber directions are probably due to density streaks in the material, such as fiber bundles, which are directed in the fiber direction, and not the density of individual fibers, which are too small to be detected. The fiber directions vary locally, and density streaks from knots, growth rings, and compression wood influence the results, which adds spread to the results. The fiber directions are presented as spiral grain angles and conical angles and are compared with spiral grain angles measured with the tracheid-effect method. The comparisons show that the CT-direction method is a nondestructive way to measure fiber directions locally and in the interior of the body of a piece of wood.     

Nitrogen and fiber concentration in rumen contents and fecescontents of Mongolian gazelles

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Influence of planting date on the relationship between populations of Frankliniella flower thrips and predatory bug Orius niger in cotton

The influence of three planting dates [mid-March (early-planted), 15 April–15 May (normal-or timely planted) and mid-June (late-planted)] of cotton variety SG 125 on the relationship between populations of Frankliniella flower thrips (Thysanoptera: Thripidae) and the predatory bug, Orius niger (Wolff) (Hemiptera: Anthocoridae) were investigated in Adana province in the Eastern Mediterranean region of Turkey in 2003 and 2004. To facilitate emergences of cotton seedlings in early-plantings, cotton rows were mulched after sowing. Adult Frankliniella occidentalis (Pergande) dominated the thrips populations in flowers and colonized the flowers rapidly with high numbers in early-and normal-planted cotton, while adult F. intonsa (Trybom) were significantly more abundant on flowers in late-planted cotton (P ≤ 0.05). The significantly higher but short-lasted larval developments were detected only in late-planted cotton in both years (P ≤ 0.05). Although some scarring and silvering damage on leaves and bolls caused by larval feedings occurred in the late-planted cotton, Frankliniella flower thrips did not have any detrimental effect on plant developments and cotton yields in any of the plantings. Early- and mulch-planted cotton produced significantly higher numbers of fruiting parts and also cotton yield, followed by normal-planted cotton (P ≤ 0.05). We commented that the lower cotton yield in late-planted cotton were due to physiologically caused abscissions of the fruiting parts under unfavourable climatic conditions. O. niger was an effective predatory insect of Frankliniella thrips in the flowers especially in normal-planted cotton, as it was detected in significantly high numbers and thrips-to-predator ratios were lower. It is suggested that early planting of cotton in March could be a good cultural practice in the Mediterranean region.     

Production and harvest of fibers from Aphandra natalia (Palmae) in Ecuador

Aphandra natalia (Balslev & Henderson) Barfod is native to the western Amazon. It is exploited commercially for its leaf sheath and petiole fibers, which are used for brooms. Data from a 2 year study on production and harvest of fibers in the province of Morona-Santiago in Ecuador shows correlations to exist between the degree of the palm's exposure to light and leaf production, and between exposure to light and petiole length (maximum fiber length), while correlation is absent between exposure to light and fiber load per leaf. A linear relation was found between time and leaf production, with an overall average of 5.5 leaves produced per palm per year. No difference in leaf production of male and female palms was found among palms growing at low light intensities, while among palms in open, light-exposed areas, males were found to produce significantly more leaves than females. An average of 8.5 leaves are cut per palm per harvest, yielding 3.4 kg of fibers, while 6.9 leaves are left untouched. Average harvest time per palm is 33 min. Under optimal conditions (high densities of easy accessible palms), one harvester may harvest and clean about 20 kg of fibers in 1 day, selling at US$1.1 kg⁻¹. One hectare with high, but natural, densities of the palm may produce fibers worth US$460 per year, which can be harvested and prepared in 22 work days. Exploitation of the edible fruits may be combined with fiber extraction if female palms are left to produce fruits, while male palms are exploited for fibers, or if harvest frequency of fibers from female palms is lowered considerably below the average of once every 1.55 years. The exploitation practised in the study area appears sustainable.     

Molecular Cloning of a Cellulose Synthase Gene PtoCesA1 from Populus tomentosa and Its Genetic Transformation in Tobacco

A 3 125 bp cellulose synthase gene, PtoCesA1, which has a 98% identity to PtrCesA1 from Populus tremuloides, was cloned from cDNA prepared from secondary xylem of P tomentosa. Four anti-expression vectors with different fragments of PtoCesAl, named as pBIPF, pBICC1, pBIPR and pBIBR, were constructed. Some traits of transformed tobacco of pBICC1, pBIPR and pBIBR differed from wild types, such as small leaves, ＂dwarf＂ phenotype and thinner xylem and fiber cell walls than wild plants consistent with a loss of cellulose. It indicated that the growth of transgenic tobacco was restrained by the expression of anti-PtoCesA1. Transgenic tobacco was obtained and the contents of cellulose and lignin were analyzed as well as the width and length of fiber cells, and xylem thickness for both transgenic and control plants. Transformed tobacco showed a different phenotype from control plants and it implied that PtoCesA1 was essential for the cellulose biosynthesis in poplar stems.     

Contribution of cultivated crops,vegetables, weeds and ornamental plants in harboring of <Emphasis Type="Italic">Bemisia tabaci </Emphasis>(Homoptera: Aleyrodidae) and associated parasitoids (Hymenoptera: Aphelinidae) in cotton agroecosystem in Pakistan

The population dynamics of Bemisia tabaci and its parasitoids was studied on Gossypium hirsutum, Cucumis melo, Helianthus annus, Glycine max, Solanum melangena, Cucurbita pepo melopopo, Bauhinia pupurea, Morus alba, Albizzia lebbek, Lantana camara, Achyranthus aspera, and Convolvulus arvensis in cotton growing areas of Punjab, Pakistan during 2004 and 2005. Whitefly infested leaves having maximum number of second to third instar were collected and kept in glass petri dishes with lid on at 28 ± 2°C and 65 ± 3% RH. Mean population of whitefly adults that emerged per 200 cm² leaf area per sampling period recorded was maximum on G. hirsutum (43.2), followed by C. melo (31.5), L. camara (23.0), H. annus (20.5), G. max (19.3), C. pepo melopopo (18.1), S. melangena (16.9), A. aspera (11.2), C. arvensis (9.2), B. pupurea (5.4), M. alba (5.3) and A. lebbek (5.0). Percentage parasitism was higher on G. hirsutum (44.3%), followed by C. melo (38.9%), A. aspera (38.3%), L. camara (38.1%), A. lebbek (35.3%), G. max (33.5%), C. arvensis (33.0%), M. alba (31.1%), B. pupurea (27.0%), S. melangena (24.8%), C. pepo melopopo (16.1%) and H. annus (15.2%). Overall the population of whitefly remained low during winter (November–February) and high during summer (May–August) whereas, the percentage parasitism was higher during June–September and lower during December–February. The study revealed that the availability of parasitoids could be enhanced by planting L. camara, B. pupurea, A. lebbek and M. alba in the cotton growing area.     

Damage assessment of the leafhopper complex [<Emphasis Type="Italic">Asymmetrasca decedens</Emphasis> (Paoli) and <Emphasis Type="Italic">Empoasca decipiens</Emphasis> Paoli] (Homoptera: Cicadellidae) in cotton

The leafhoppers [Asymmetrasca decedens (Paoli) and Empoasca decipiens Paoli] have only recently become significant pests of cotton in Turkey. Action threshold level (ATL) of this pest complex is uncertain. The effect of leafhoppers on fruit set and development and yields of glabrous varieties, Caroline Queen, Çukurova 1518 and SG 125 was compared under sprayed (at the ATL of ten leafhoppers per leaf) or unsprayed conditions in 2002–2003. Comparisons of sprayed and unsprayed cotton showed that leafhoppers significantly reduced numbers of fruit and yield. Total losses of the fruiting parts (square plus boll) were similar, ranging from 35 to 55% as well as cotton losses varied from 35 to 50%. Numbers of sucking insects (cotton aphid, whitefly and thrips) and also lepidopterian pests (pink bollworm and bollworm) were very low in both years, and they did not affect cotton development. The current regional ATL for the cotton leafhoppers appears to be too high, and it appears that even five leafhoppers per leaf may be sufficient to significantly reduce yields. It is concluded that ATL of the cotton leafhoppers needs to be re-evaluated in cotton fields in Turkey and also other geographic regions which share similar ecological conditions and same leafhopper species.     

Promotive effect of the hot water-soluble fraction from corn fiber on vegetative mycelial growth in edible mushrooms

Corn fiber (CNF) is an abundant by-product of the wet corn milling process used to produce corn starch. In light of the need to recycle organic wastes, the effects of adding a hot water-soluble fraction (HWSF) from CNF to a medium on the vegetative mycelial growth of nine edible mushrooms such as Lentinula edodes and Pholiota nameko were investigated. The results showed that the mycelial growth of these fungi was markedly increased (1.4–9.5 times that of the control) by adding 5%–20% CNF-HWSF to the medium. These promotive effects were also apparent on mycorrhizal mushrooms, such as Tricholoma matsutake (3.3-fold) and Lyophyllium shimeji (3.7-fold). The promotive effects on mycelial growth were shown in the low-molecular-weight fractions (molecular weight <500 daltons) prepared from CNF-HWSF. The promotive actions were more effective on slow-growing mushrooms (L. edodes and P. nameko) than on rapidly growing mushrooms (Pleurotus ostreatus and Flammulina velutipes). The results obtained in this experiment suggest that CNF-HWSF can be used as a promotive substance for cultivating edible mushrooms.Part of this work was presented at the 4th meeting of the Japanese Society of Mushroom Science and Biotechnology, Hiroshima, 2000; and at the 2nd meeting of the Far East Asia for Collaboration on Edible Fungi Research, Tottori, 2002     

Effects of the lateral growth rate on wood quality parameters of Eucalyptus grandis from different latitudes in Brazil and Argentina

Climate change resulting from increased atmospheric carbon dioxide (CO₂) and shortages of fossil fuels such as petroleum are major problems worldwide. Under these conditions, demand for woody biomass resources is increasing. We investigated the feasibility of using fast-growing Eucalyptus grandis for material production. Samples of E. grandis were collected from four plantations in different latitude divisions, including tropical and subtropical Brazil and subtropical Argentina. Various xylem qualities were measured and related to the lateral growth rate. Lateral growth rate did not significantly affect the longitudinal released strain of the surface growth stresses or the xylem density at any of the sampling sites. Higher lateral growth rate, higher values of xylem density, and lower absolute values of the released strain were observed in plantations closer to the equator. Higher growth rates in tropical climate promote longer fiber length. In subtropical plantations, smaller diameter trees will produce tension wood with smaller microfibril angles. Planting E. grandis closer to the equator thus produces higher quality wood than in plantations at lower latitudes.     

Molecular cloning of a cellulose synthase gene PtoCesA1 from Populus tomentosa and its genetic transformation in tobacco

A 3 125 bp cellulose synthase gene, PtoCesA1, which has a 98% identity to PtrCesA1 from Populus tremuloides, was cloned from cDNA prepared from secondary xylem of P. tomentosa. Four anti-expression vectors with different fragments of PtoCesA1, named as pBIPF, pBICC1, pBIPR and pBIBR, were constructed. Some traits of transformed tobacco of pBICC1, pBIPR and pBIBR differed from wild types, such as small leaves, “dwarf” phenotype and thinner xylem and fiber cell walls than wild plants consistent with a loss of cellulose. It indicated that the growth of transgenic tobacco was restrained by the expression of anti-PtoCesA1. Transgenic tobacco was obtained and the contents of cellulose and lignin were analyzed as well as the width and length of fiber cells, and xylem thickness for both transgenic and control plants. Transformed tobacco showed a different phenotype from control plants and it implied that PtoCesA1 was essential for the cellulose biosynthesis in poplar stems. [Supported by the Hi-Tech Research and Development Program of China (863) (2001AA244060 and 2003AA244020) and National Basic Research Program of China (973) (J1999016003)]     

The Formation of Tidal Creeks in a Salt Marsh: New Evidence from the Loyola Bay Salt Marsh,Rio Gallegos Estuary,Argentina

A mechanism is proposed for the Formation of tidal creeks in salt marshes which is exemplified by the marshes of the Rio Gallegos estuary, Argentina. It has been observed that salt pans are elongated in the mean wind direction and are likely to extend by wave erosion of the surrounding marshes. Interconnection between the pans leads to growth and interaction with existing creeks and channels. Tidal exchange of the waters then promotes further erosion, or subsequently to filling in by the introduced suspended sediment. This mechanism contrasts with headward erosion by existing creeks.     

Inheritance and cross-resistance of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> insecticidal crystal protein Cry1Ac resistance in cotton bollworm <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> Hubner population from Tamil Nadu,India

Cotton bollworm, Helicoverpa armigera Hubner selected for five generations with Bacillus thuringiensis insecticidal crystal protein Cry1Ac in the laboratory developed 12.98-fold resistance. Resistance and susceptible populations were mass crossed to study the dominance of resistance. The Cry1Ac—selected (BCR) population showed 5.8-fold resistance to Cry1Aa and 5.04-fold resistance to Cry1Ab. The degree of dominance (D) was 0.34 and 0.40 for the R × S and S × R hybrids, respectively, which indicates incomplete recessive character of Cry1Ac resistance in the population. The estimated realized heritability (h ²) and response quotient (Q) of resistance for Cry1Ac were 0.52 and 0.15, respectively. This indicated the lower phenotypic variation in the selected population. The resistance risk assessment based on h ² indicated that the resistance would increased tenfold after <9 generations for Cry1Ac in the resistant population. The results show the ability of H. armigera to develop resistance against Cry1Ac and cross-resistance to Cry1Aa and Cry1Ab.