May 2005, Volume 47 Issue 5, Pages 513-636.


Cover Caption:
Cytokinin has been proposed to be transported in the nucleoside-conjugated forms, but the presumed transporters remain unidentified. In this issue, Sun et al. report that the Arabidopsis SOI33 protein displays a transporter activity specific to the nucleoside-type cytokinins. Mutations in SOI33 cause a reduced sensitivity and uptake to the nucleoside-type cytokinin isopentenyladenine riboside (iPR) but not to the free base-type cytokinin isopentenyladenine (iP). The images show wild type (left in both panels) and soi33 (right in both panels) seedlings germinated and grown in the presence of 1 mmol/L iPR (top left) or iP (bottom right) in the dark. See pages 588-603 for more detail.

 

          Research Articles
Phenylethanoid Glycosides from Picria felterrae Lour.
Author: Jie-Ming ZOU, Li-Sheng WANG, Xue-Mei NIU, Han-Dong SUNㄛYa-Jian GUO
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00082.x
      
    In our search for bioactive compounds from the whole plant of Picria felterrae Lour., three new phenylethanoid glycosides, picfeosides A每C (1每3), along with five known phenylethanoid glycosides, namely wiedemannioside (4), acteoside (5), acteoside isomer (6), cis-acteoside isomer (7), and cis-acteoside (8), were isolated using several chromatographic purification steps, including semipreparation HPLC on RP-18. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analysis.
Abstract (Browse 3350)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Spatio-Temporal Expression Pattern of Six Novel Candidate Genesin Ginsenoside Biosynthesis from Panax ginseng C. A. Meyer
Author: Zhi-Yong LUO, Shui-Ping LIU, Xiang-Hui CHEN, Ying RUAN, Jian-Qing LUO, Bin WEN, Chun-Lin LIU ㄛ Wei-Xin HU
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00064.x
      
    To explore the mode of the spatio-temporal expression of six newly discovered ginsenoside biosynthesis candidate gene transcripts, both Northern blotting and semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) were used to elucidate the mRNA expression levels of the transcripts in various tissues and organs of Panax ginseng C. A. Meyer during different growth development stages. The six gene transcripts were all differentially expressed in cultured callus, root, stem, leaf, and seed. The mRNA expression levels were significantly higher in four-year-old roots than in one-year-old roots, and results of semi-quantitative RT-PCR assays were in accordance with those of Northern blotting analyses. The results strongly suggest that all six genes were differentially expressed at root-specific developmental stages. In particular, when a quiescent early stage culture suspension of P. ginseng cells was exposed to the ginsenoside biosynthesis-promoting elicitor Aspergillus niger polysaccharide, the GBR6 gene transcript response showed time-dependent increments and was parallel with ginsenoside productivity (P < 0.01). Overexpression of the GBR6 gene is likely to play a critically important role in the biosynthesis of ginsenosides. The results of the present study provided a background for the further elucidation of the structure and physiological function of these six candidate genes.
Abstract (Browse 4054)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Expression in Escherichia coli of Three Different Soybean Late Embryogenesis Abundant (LEA) Genes to Investigate Enhanced Stress Tolerance
Author: Ying LAN, Dan CAIㄛYi-Zhi ZHENG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00025.x
      
    In order to identify the function of late embryogenesis abundant (LEA) genes, in vitro functional analyses were performed using an Escherichia coli heterologous expression system. Three soybean late embryogenesis abundant (LEA) genes, PM11 (GenBank accession No. AF004805; group 1), PM30 (AF117884; group 3), and ZLDE-2 (AY351918; group 2), were cloned and expressed in a pET-28a system. The gene products were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and identified by mass spectrometry. E. coli cells containing the recombinant plasmids or empty vector as controls were treated by salt and low temperature stress. Compared with control cells, the E. coli cells expressing either PM11 or PM30 showed a shorter lag period and improved growth when transferred to LB (Luria-Bertani) liquid media containing 800 mmol/L NaCl or 700 mmol/L KCl or after 4 ∼C treatment. E. coli cells expressing ZLDE-2 did not show obvious growth improvement both in either high KCl medium or after 4 ∼C treatment. The results indicate that the E. coli expression system is a simple, useful method to identify the functions of some stress-tolerant genes from plants.
Abstract (Browse 3166)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Identification and Characterization of Reverse Transcriptase Domain of Transcriptionally Active Retrotransposons in Wheat Genomes
Author: Yi-Miao TANG, You-Zhi MA, Lian-Cheng LI ㄛXing-Guo YE
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00055.x
      
    To clarify activation characterization of wheat (Triticum aestivum L.) retrotransposons, transcriptionally active Ty1-copia retrotransposons were found in wheat by using RT-PCR to amplify the RT domain. Sequence analysis of random RT-PCR clones reveals that Ty1-copia retrotransposons are highly heterogeneous and can be divided into at least four groups, which are tentatively named TaRT-1 to TaRT-4. Dot blot hybridization indicates that TaRT-1 exists in the wheat genome as multiple copies (at 30 000 copies/a hexaploid genome (ABD)). Northern blot hybridization showed that TaRT-1 is only expressed at a low level under normal conditions in seedlings, but at a high level when induced by powdery mildew fungus, jasmonic acid (JA) and salicylic acid (SA). These results suggest that the TaRT-1 expression is highly sensitive to biotic and abiotic stresses.
Abstract (Browse 3091)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Arabidopsis SOI33/AtENT8 Gene Encodes a Putative Equilibrative Nucleoside Transporter That Is Involved in Cytokinin Transport In Planta  
Author: Jiaqiang SUN, Naoya HIROSE, Xingchun WANG, Pei WEN, Li XUE, Hitoshi SAKAKIBARAㄛJianru ZUO
Journal of Integrative Plant Biology 2005 47(5): 588-603
DOI: 10.1111/j.1744-7909.2005.00104.x
      
    The plant phytohormone cytokinin plays an important role in many facets of plant growth and development by regulating cell division and differentiation. Recent studies have shed significant light into the mechanisms of cytokinin metabolism and signaling. However, little is known about how the hormone is transported in planta, although it has been proposed that the hormone is presumably transported in nucleoside-conjugated forms. Here, we report the identification and characterization of cytokinin transporters in Arabidopsis. We previously reported that a gain-of-function mutation in the PGA22/AtIPT8 gene caused overproduction of cytokinins in planta. In an effort to screen for suppressor of pga22/atipt8 (soi) mutants, we identified a mutant soi33-1. Molecular and genetic analyses indicated that SOI33 encodes a putative equilibrative nucleoside transporter (ENT), previously designated as AtENT8. Members of this small gene family are presumed to be involved in the transport of nucleosides in eukaryotic cells. Under conditions of nitrogen starvation, loss-of-function mutations in SOI33/AtENT8 or in a related gene AtENT3 cause a reduced sensitivity to the nucleoside-type cytokinins isopentenyladenine riboside (iPR) and trans-zeatin riboside (tZR), but display a normal response to the free base-type cytokinins isopentenyladenine (iP) and trans-zeatin (tZ). Conversely, overexpression of SOI33/AtENT8 renders transgenic plants hypersensitive to iPR but not to iP. An in planta measurement experiment indicated that uptake efficiency of 3H-labeled iPR was reduced more than 40% in soi33 and atent3 mutants. However, a mutation in AtENT1 had no substantial effect on the cytokinin response and iPR uptake efficiency. Our results suggest that SOI33/AtENT8 and AtENT3 are involved in the transport of nucleoside-type cytokinins in Arabidopsis.
Abstract (Browse 3780)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Genetic Transformation of Tobacco with the Trehalose Synthase Gene from Grifola frondosa Fr. Enhances the Resistance to Drought and Salt in Tobacco
Author: Shu-Zhen ZHANG, Ben-Peng YANG, Cui-Lian FENGㄛHuo-Long TANG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00046.x
      
    Trehalose is a non-reducing disaccharide of glucose that functions as a protectant in the stabilization of biological structures and enhances the tolerance of organisms to abiotic stress. In the present study, we report on the expression of the Grifola frondosa Fr. trehalose synthase (TSase) gene for manipulating abiotic stress tolerance in tobacco (Nicotiana tabaccum L.). The expression of the transgene was under the control of two tandem copies of the CaMV35S promoter and was transferred into tobacco by Agrobacterium tumefaciens EHA105. Compared with non-transgenic plants, transgenic plants were able to accumulate high levels of products of trehalose, which were increased up to 2.126每2.556 mg/g FW, although levels were undetectable in non-transgenic plants. This level of trehalose in transgenic plants was 400-fold higher than that of transgenic tobacco plants cotransformed with Escherichia coli TPS and TPP on independent expression cassettes, twofold higher than that of transgenic rice plants transformed with a bifunctional fusion gene (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) of E. coli, and 12-fold higher than that of transgenic tobacco plants transformed the yeast TPS1 gene. It has been reported that transgenic plants with E. coli TPS and/or TPP were severely stunted and had morphological alterations of their roots. Interestingly, our transgenic plants have obvious morphological changes, including thick and deep-coloured leaves, but show no growth inhibition; moreover, these morphological changes can restore to normal type in T2 progenies. Trehalose accumulation in 35S-35S:TSase plants resulted in increased tolerance to drought and salt, as shown by the results of tests on drought, salt tolerance, and drought physiological indices, such as water content in excised leaves, malondialdehyde content, chlorophyll a and b contents, and the activity of superoxide dismutase and peroxidase in excised leaves. These results suggest that transgenic plants transformed with the TSase gene can accumulate high levels of trehalose and have enhanced tolerance to drought and salt.
Abstract (Browse 3733)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Where is the Site of the ※Oxygen Burst§ Located During Light Induction in Dark-Adapted Leaves? A Study Using Photoacoustic Techniques
Author: Da-Yong FANㄛ Rong-Fu GAO
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00075.x
      
    The ※oxygen burst§ phenomenon that appeared during the light-induction period of intact leaves could be monitored using a photoacoustic technique high time resolution. The relationship between oxygen bursts and dark-adapted time, far-red light pretreatment, photothermal signal, and chlorophyll a (Chl a) fluorescence kinetics were investigated in the present study. Using extraneous inhibitors or cofactors of electron transport, a modified vacuum-infiltration method was undertaken to locate directly the site at which oxygen bursts of intact leaves occurred. We found that the photothermal signal showed little evidence of oscillation during the light-induction period. The oxygen burst was resolved into two components if dark-adapted time lasted longer than 20 min. Methyl viologen (MV) or far-red light could not eliminate the first component, whereas formate-Na (pH 7.0, 20 mmol/L) eliminated the first component but had no effect on the second one. Furthermore, the photochemical quenching, the electron transport rate of Chl a fluorescence, and the first component of the oxygen bursts approached lowest values simultaneously. This evidence indicates that the site at which the first component of oxygen bursts occurred was located between photosystem (PS)I and PSII (i.e. the PQ pool). The formate-Na experiment also showed a linkage between the first component and the S state of oxygen evolution at the donor side of PSII. Furthermore, elimination of the second component by far-red light and absorption of the second component by MV indicated that the site at which the second component of oxygen bursts may be located at the acceptor side of PSII.
Abstract (Browse 3157)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Characteristics of Gas Exchange, Chlorophyll Fluorescence and Expression of Key Enzymes in Photosynthesis During Leaf Senescence in Rice Plants
Author: Xiao-Yan WENG, Hong-Xia XUㄛDe-An JIANG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00098.x
      
    Gas exchange, chlorophyll (Chl) fluorescence, photosynthetic pigments, and the expression of Rubisco and Rubisco activase in flag leaves of rice (Oryza sativa L.) from the heading to mature grain stage were investigated. The results showed that the photosynthetic capacity declined after full expansion of flag leaves. The decline of photosynthetic rate (Pn) in two cultivars during natural senescence was accompanied by a decrease in Chl content, as well as in the Rubisco and Rubisco activase contents. The Rubisco and Rubisco activase contents in Zhenong 966 decreased faster than that in Zhenong 952. The Pn diminished without a decrease in intercellular CO2 concentration during the early senescence of flag leaves, indicating that lower photosynthetic capacity is not caused by stomatal limitation but by reduced carboxylation efficiency. During the senescence of flag leaves, the correlation between the change in photosynthetic capacity and the variation in the abundance of Rubisco and Rubisco activase suggested that the decline in Pn of flag leaves could be attributed to the lower level of rbcS and rca transcripts. The PSII and the electron transport rate appeared in the same rate as Pn. However, excitation pressure (1每qP) showed a different pattern and there was an inverse linear correlation between increased excitation pressure and the reduced Rubisco. Therefore, it is likely that the increased excitation pressure resulted from saturation of the electron transport chain, owing to a limitation of the reductant used by the Calvin cycle; in addition, the change in excitation pressure could further mediate the expression of the rbcS and rca genes, resulting in a fast reduction in Rubisco content.
Abstract (Browse 3284)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Phosphorus and Nitrogen Interactions in Field-Grown Soybean as Related to Genetic Attributes of Root Morphological and Nodular Traits
Author: Rui-Bin KUANG, Hong LIAO, Xiao-Long YANㄛYing-Shan DONG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00072.x
      
    Two field experiments with different soybean (Glycine max L.) materials were conducted to investigate the interactions between phosphorus (P) and nitrogen (N) as related to the genetic attributes of root morphological and nodular traits. In experiment one, 13 cultivated soybean varieties were grown in a field with relatively low soil P and N availability. P application with 160 kg P/hm2 as triple superphosphate produced a significant simultaneous increase in the content of both P and N in shoot, demonstrating positive P and N interactions. The addition of P also increased root dry weight, root nodule number, nodule mass, nodule size, and nodulation index, but decreased root length and root surface area, indicating that P may affect N nutrition in soybean through a number of root morphological and nodular traits. Interestingly, like P content, N content appeared to be more correlated with root morphological traits (root weight, root length, and root surface area) than with root nodular traits (nodule number, nodule size, nodule mass, and nodulation index) at both P levels, implying that N taken up by the roots may contribute more to the plant N status than biological N2 fixation under the present experimental conditions. In experiment two, 57 soybean lines of a recombinant inbred line (RIL) population derived from a cross between a cultivated variety and a wild genotype were grown on another field site with moderately sufficient P and N levels to further characterize the genetic attributes of root morphological and nodular traits and their relationships with P and N interactions. The results indicated that all morphological and nodular traits measured continually segregated in the RIL population with a normal distribution of the phenotypic values, indicating that these traits are possibly controlled by quantitative trait loci (QTLs). Genetic analysis revealed that all these root traits had relatively low heritabilities (h2b=74.12, 70.65, 73.76, 56.34, 52.59, and 52.24 for root weight, root length, root surface area, nodule number, nodule mass, and nodule size, respectively), suggesting that root morphology and nodule formation are influenced greatly by environmental factors. Correlation analysis of the RILs showed that shoot N content was significantly correlated with P content, confirming positive P℅N interactions. Similar to experiment one, shoot N content was only significantly correlated with root morphological traits, but not with root nodular traits, again denoting the fact that the N status in soybean could be attributed more to N uptake from the soil than to biological N2 fixation under the present experimental conditions.
Abstract (Browse 3135)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effect of Nitrogen Supply on the Nitrogen Use Efficiency of an Annual Herb, Helianthus annuus L.  
Author: Zhi-You YUAN, Ling-Hao LI, Jian-Hui HUANG, Xing-Guo HANㄛShi-Qiang WAN
Journal of Integrative Plant Biology 2005 47(5): 539-548
DOI: 10.1111/j.1744-7909.2005.00006.x
      
    Nitrogen use efficiency (NUE) is the product of nitrogen productivity (NP) and the mean residence time of nitrogen (MRT). Theory suggests that there should be a trade-off between both components, but direct experimental evidence is still scarce. To test this hypothesis, we analyzed the effect of varying nitrogen supply levels on NUE and its two components (NP, MRT) in Helianthus annuus L., an annual herb. The plants investigated were subjected to six nitrogen levels (0, 2, 4, 8, 16, and 32 g N/m2). Total plant production increased substantially with increasing nitrogen supply. Nitrogen uptake and loss also increased with nitrogen supply. Nitrogen influx (rin) and outflux (rout) were defined as the rates of nitrogen uptake and loss per unit aboveground nitrogen, respectively. Both rin and rout increased with increasing nitrogen supply. In addition, rin was far higher than rout. Consequently, the relative rate of nitrogen increment (rin 每 rout) also increased with nitrogen supply. There were marked differences between treatments with respect to parameters related to the stress resistance syndrome: nitrogen pool size, leaf nitrogen concentration, and net aboveground productivity increased with nitrogen supply. Plants at high nitrogen levels showed a higher NP (the growth rate per unit aboveground nitrogen) and a shorter MRT (the inverse of rout), whereas plants at low nitrogen levels displayed the reverse pattern. Shorter MRT for plants at high nitrogen levels was caused by the abscission of leaves that contained relatively large fractions of total plant nitrogen. We found a negative relationship between NP and MRT, the components of NUE, along the gradient of nitrogen availability, suggesting that there was a trade-off between NP and MRT. The NUE increased with increasing nitrogen availability, up to a certain level, and then decreased. These results offer support for the hypothesis that adaptation to infertile habitats involves a low nitrogen loss (long MRT in the plant) rather than a high NUE per se. The higher NUE at the plant level was a result, in part, of greater nitrogen resorption during senescence. We suggest that a long MRT (an index of nitrogen conservation) is a potentially successful strategy in nitrogen-poor environments.
Abstract (Browse 3653)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Community Characteristics of Early Recovery Vegetation on Abandoned Lands of Shifting Cultivation in Bawangling of Hainan Island, South China
Author: Yi DINGㄛRun-Guo ZANG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00026.x
      
    Shifting cultivation is a major form of agricultural practice in most parts of tropical regions worldwide. In places where the bush fallow period is excessively shortened or the period of cultivation is extended for too long, the rate of vegetation recovery and biodiversity on abandoned lands of shifting cultivation would decline. The recovery of the secondary plant communities could even be inhibited for a prolonged period because of grass occupancy. Because of the vital significance of the early recovery communities to secondary succession, we studied the community characteristics of early recovery vegetation on abandoned lands of shifting cultivation in Bawangling of Hainan Island. Measurements were made of the community composition and structure of early recovery vegetation. The sprouting abilities of different functional groups and different species in the same functional group, and the effect of the grass functional group on the composition and quantitative characteristics of tree and shrub functional groups were analyzed. Results indicated that only a few families, genera, or species apparently dominated in the early recovery vegetation on the abandoned lands of shifting cultivation and that deciduous species occurred with a rather high percentage in this early recovery community compared with the natural secondary or old growth forests. Small-sized individuals dominated the woody community. The abundance and basal area of sprouting stems for species in the tree functional group were greater than those of seeder stems, whereas the abundance and basal area of resprouters and seeders for species in the shrub functional group did not differ. The total abundance of stems for the community, stem abundances for species in tree or shrub functional groups, and for seeder or resprouter stems were all negatively correlated with coverage of the grass functional group. The mean sprouting ability in the tree functional group was greater than in the shrub functional group. The sprouting ability for different species in the same functional group was also significantly different.
Abstract (Browse 3304)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Bolboschoenus (Ascherson) Palla (Cyperaceae) from Pliocene of China
Author: Xiu-Qun LIU, Cheng-Sen LIㄛYu-Fei WANG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00079.x
      
    Tubers, culms, rhizomes, and leaves of Bolboschoenus cf. yagara (Ohwi) YC Yang et M Zhan were reported from the sediments of Zhangcun Formation, Late Pliocene in Shanxi Province, China. The fossil species possesses trigonous culms. And tubers are cordiform, spindle shaped, or round, and are covered by roots in internodes and often connected by rhizomes. This is the first convincing fossil record of Cyperaceae in China.
Abstract (Browse 3121)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Supplemental Cytogeographical Studies on the Scilla sinensis (Louriro) Merrill Complex in China
Author: Kai-Yu DING, Wei WANG, Quan LONG, Biao LI Bing-Yi WANG
Journal of Integrative Plant Biology 2005 47(5)
DOI: 10.1111/j.1744-7909.2005.00076.x
      
    Seven hundred and fourteen individuals of the Scilla sinensis (Louriro) Merrill complex were sampled from 21 populations at 19 localities in 10 provinces and two cities of China and investigated cytologically in order to test its cytotype composition and cytogeographical variation still further. Five cytotypes were found (i.e. AA (2n = 16), BB (2n = 18), AABB (2n = 34), AAA (2n = 24), and AABB+9 (2n = 43)). Until now, nine of the 12 cytotypes have been identified on the continent, which indicates that it is an important place for the cytotypic differentiation of the complex. The cytotype AABB+9 is a new record on the continent. AAA was recorded for the second time in this complex. The majority of populations are composed of only one cytotype (AA, BB, or AABB), whereas another four populations consist of more than two cytotypes involving AA, BB, AAA, AABB, and AABB+9. The distribution of BB covers the entire region south to Huai River, whereas AA populations are distributed in Taiwan, Fujian, Hong Kong, and Guangdong and are isolated from its major distribution. The appearance of AABB+9 is possibly evidence for the degeneration of the subglobular bulb type of AABB and the fact that AAA and AAAA exist in the interior border regions of the range of this complex probably suggests that drought is a major factor promoting plant polyploidization. In addition, the mean numbers of B chromosomes per individual, the percentage of individuals with the B chromosome in each population, and the correlation coefficients between the latter and their latitude/longitude were calculated. Generally speaking, the B chromosome number is higher in BB populations compared with AA populations and there is a prominent tendency that the B chromosome content in either AA or BB populations correlates with the latitude and longitude of the populations.
Abstract (Browse 3323)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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