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Rubber Trees (rubber + tree)

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Life Sciences100%

Selected Abstracts

Rubber tree (Hevea brasiliensis) trunk phloem necrosis: aetiological investigations failed to confirm any biotic causal agent

FOREST PATHOLOGY, Issue 1 2007
F. Pellegrin
Summary Trunk phloem necrosis (TPN) is currently a main constraint in rubber (Hevea brasiliensis) plantations. The apparent spread of the disease, from tree to tree along the planting line, strongly supported the implication of a pathogen that could be transmitted mechanically via the tapping knife. In order to detect a causal agent of the disease, studies focusing on characterization of the known mechanically transmitted pathogens (e.g. viroids, cryptic viruses or phytoplasma) were initiated. RNA strands of low molecular weight (200,400 and >500 bp) displaying structural similarities with viroids and viral dsRNAs were observed in various tested samples. However, attempts to show the potential role of these RNA molecules in the spread of the disease failed. First of all, there was no significant or reproducible correlation between the health status of the rubber trees sampled and these RNA molecules. Moreover, no sequence homology with known pathogens could be found when randomly amplified cDNA fragments isolated from trees presenting the disease symptoms were sequenced. In conclusion, the aetiological investigations, in order to show the presence of a pathogen responsible of the TPN disease, were non-conclusive, which tends to disprove the hypothesis of a biotic causal agent. [source]

Monoterpene emissions from rubber trees (Hevea brasiliensis) in a changing landscape and climate: chemical speciation and environmental control

GLOBAL CHANGE BIOLOGY, Issue 11 2007
YONG-FENG WANG
Abstract Emissions of biogenic volatile organic compounds (VOCs) have important roles in ecophysiology and atmospheric chemistry at a wide range of spatial and temporal scales. Tropical regions are a major global source of VOC emissions and magnitude and chemical speciation of VOC emissions are highly plant-species specific. Therefore it is important to study emissions from dominant species in tropical regions undergoing large-scale land-use change, for example, rubber plantations in South East Asia. Rubber trees (Hevea brasiliensis) are strong emitters of light-dependent monoterpenes. Measurements of emissions from leaves were made in the dry season in February 2003 and at the beginning of the wet season in May 2005. Major emitted compounds were sabinene, , -pinene and , -pinene, but , -ocimene and linalool also contributed significantly at low temperature and light. Cis -ocimene was emitted with a circadian course independent of photosynthetic active radiation (PAR) and temperature changes with a maximum in the middle of the day. Total isoprenoid VOC emission potential at the beginning of the wet season (94 ,g gdw,1 h,1) was almost two orders of magnitude higher than measured in the dry season (2 ,g g dw,1 h,1). Composition of total emissions changed with increasing temperature or PAR ramps imposed throughout a day. As well as light and temperature, there was evidence that assimilation rate was also a factor contributing to seasonal regulating emission potential of monoterpenes from rubber trees. Results presented here contribute to a better understanding of an important source of biogenic VOC associated with land-use change in tropical South East Asia. [source]

Defence Responses of Calli and Seeds of Hevea brasiliensis to Zoospores and the Elicitin of Phytophthora palmivora

JOURNAL OF PHYTOPATHOLOGY, Issue 11-12 2008
Nion Chirapongsatonkul
Abstract The defence responses of calli and seeds of two cultivars (resistant; BPM-24 and susceptible; RRIM600) of the rubber tree, Hevea brasiliensis, against zoospores and elicitin purified from its pathogen, Phytophthora palmivora, were investigated. Both zoospores and elicitin induced the biosynthesis of the phytoalexin, scopoletin (Scp), in Hevea calli ranging from 5 × 105 to 4.5 × 106 zoospores/ml and 0.5 to 2 ,g elicitin/g fresh weight of calli. At the highest concentration of zoospores (4.5 × 106 zoospores/ml) or elicitin (2 ,g/g fresh weight of calli), the rate of Scp production was fastest but then it rapidly decreased and produced lower peak value than detected at the optimum concentration. The decline of Scp level at the highest zoospore/elicitin concentration was correlated to the amount of cell death measured by Evans Blue method. Peroxidase (POD) activities in Hevea calli were also measured using the optimum level of zoospores or elicitin. Induction of Scp preceded the production of Scp POD and o -dianisidine POD then followed by the guaiacol POD. The Scp and POD accumulations were approximately two to three times higher in the resistance cultivar than those in the susceptible one. As the responses of the calli to elicitin were faster than those to the zoospores, it demonstrates that zoospores require more time to act on the host cells. The pattern of Scp and POD activities monitored in elicitin-treated Hevea seeds was similar to that of Hevea calli after treating with zoospores or elicitin. Therefore, the callus cultures could be used as a tool for studying other defence mechanisms in H. brasiliensis. The achieved knowledge will be applied to enhance resistance and led to the protection of Hevea young seedlings from the pathogen in the plantation. [source]

Rubber tree (Hevea brasiliensis) trunk phloem necrosis: aetiological investigations failed to confirm any biotic causal agent

FOREST PATHOLOGY, Issue 1 2007
F. Pellegrin
Summary Trunk phloem necrosis (TPN) is currently a main constraint in rubber (Hevea brasiliensis) plantations. The apparent spread of the disease, from tree to tree along the planting line, strongly supported the implication of a pathogen that could be transmitted mechanically via the tapping knife. In order to detect a causal agent of the disease, studies focusing on characterization of the known mechanically transmitted pathogens (e.g. viroids, cryptic viruses or phytoplasma) were initiated. RNA strands of low molecular weight (200,400 and >500 bp) displaying structural similarities with viroids and viral dsRNAs were observed in various tested samples. However, attempts to show the potential role of these RNA molecules in the spread of the disease failed. First of all, there was no significant or reproducible correlation between the health status of the rubber trees sampled and these RNA molecules. Moreover, no sequence homology with known pathogens could be found when randomly amplified cDNA fragments isolated from trees presenting the disease symptoms were sequenced. In conclusion, the aetiological investigations, in order to show the presence of a pathogen responsible of the TPN disease, were non-conclusive, which tends to disprove the hypothesis of a biotic causal agent. [source]

Monoterpene emissions from rubber trees (Hevea brasiliensis) in a changing landscape and climate: chemical speciation and environmental control

GLOBAL CHANGE BIOLOGY, Issue 11 2007
YONG-FENG WANG
Abstract Emissions of biogenic volatile organic compounds (VOCs) have important roles in ecophysiology and atmospheric chemistry at a wide range of spatial and temporal scales. Tropical regions are a major global source of VOC emissions and magnitude and chemical speciation of VOC emissions are highly plant-species specific. Therefore it is important to study emissions from dominant species in tropical regions undergoing large-scale land-use change, for example, rubber plantations in South East Asia. Rubber trees (Hevea brasiliensis) are strong emitters of light-dependent monoterpenes. Measurements of emissions from leaves were made in the dry season in February 2003 and at the beginning of the wet season in May 2005. Major emitted compounds were sabinene, , -pinene and , -pinene, but , -ocimene and linalool also contributed significantly at low temperature and light. Cis -ocimene was emitted with a circadian course independent of photosynthetic active radiation (PAR) and temperature changes with a maximum in the middle of the day. Total isoprenoid VOC emission potential at the beginning of the wet season (94 ,g gdw,1 h,1) was almost two orders of magnitude higher than measured in the dry season (2 ,g g dw,1 h,1). Composition of total emissions changed with increasing temperature or PAR ramps imposed throughout a day. As well as light and temperature, there was evidence that assimilation rate was also a factor contributing to seasonal regulating emission potential of monoterpenes from rubber trees. Results presented here contribute to a better understanding of an important source of biogenic VOC associated with land-use change in tropical South East Asia. [source]

In vitro Transient Expression System of Latex C-serum was used for Analysis of Hevein Promoter in Response to Abscisic Acid in Hevea brasiliensis

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2008
Xiao-Wen Fei
Abstract Hevein has been found to be an essential element in coagulation of rubber particles in latex of rubber trees. In a previous study, we cloned a 1 241-bp fragment of a 5, upstream region of the hevein gene by genome walking. This fragment was analyzed by a 5, end nested deletion method in the present study, fused with a uidA (gus) gene to produce a series of tested constructs, which were transferred into C-serum of latex and the Gus activities were detected. Results showed that the fragment from ,749 to ,292 was sufficient for expression of gus gene in latex, and the fragment from ,292 to ,168 was crucial in response to abscisic acid inducement. In a transient transgenic test of rubber leaf with particle bombardment, construct Hev749 conferred gus -specific expression in veins, in which the latex tubes mainly distributed. This implies that the fragment from ,749 to ,292 was laticiferous-specific. [source]