April 2007, Volume 49 Issue 4, Pages 409-567.


Cover Caption:
Vectors for plant transformation
Regenerated rice plantlets transformed with a construct based on pCB2006 of a series of high-throughput binary cloning vectors constructed to facilitate gene function analysis in higher plants. This series includes high-throughput binary vectors for plant expression, promoter analysis, gene silencing and GFP fusions for protein localization. See pages 556-567 for more details.

 

          Bioenergy Plants
Studies on Temporal and Spatial Variations of Phytoplankton in Lake Chaohu
Author: Dao-Gui Deng, Ping Xie, Qiong Zhou, Hua Yang and Long-Gen Guo
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00390.x
      
    Temporal and spatial variations of the phytoplankton assemblage in Lake Chaohu, a large shallow eutrophic lake in China, were studied from September 2002 to August 2003. A total of 191 phytoplankton species was identified, among which Chlorophytes (101) ranked the first, followed by Cyanophytes (46) and Bacillariophytes (28). On average over the entire lake, the maximum total algal biomass appeared in June (19.70 mg/L) with a minimum (5.05 mg/L) in November. In terms of annual mean biomass, cyanobacteria contributed 45.43% to total algal biomass, followed by Chlorophytes (27.14%), and Bacillariophytes (20.6%). When nitrate (NO3-N) and ammonium (NH4-N) concentrations dropped in spring, fixing-nitrogen cyanobacterium (Anabaena) developed quickly and ranked the first in terms of biomass in summer. It is likely that dominance of zooplanktivorous fish and small crustacean zooplankton favored the development of the inedible filamentous or colony forming cyanobacteria. The persistent dominance of cyanobacteria throughout all seasons may indicate a new tendency of the response of phytoplankton to eutrophication in Lake Chaohu.
Abstract (Browse 2288)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Leaflet Movement of Robinia pseudoacacia in Response to a Changing Light Environment
Author: Cheng-Cheng Liu, Clive V. J. Welham, Xian-Qiang Zhang and Ren-Qing Wang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00392.x
      
    Diurnal and nocturnal leaflet movement of black locust (Robinia pseudoacacia L.) was investigated under three light schemes: 100% natural irradiance, 50% shading, and 90% shading. Changes in leaf mid-vein angle were described by measurements of two planes: (i) b, the angle formed by the bottom of the petiolule and its relation to the horizontal plane; and (ii) q, the angle between the petiolule and the main leaflet vein. The two highest light regimens had a significant effect on b. Variation in b tends to make the leaflet more erect, thereby minimizing any negative impact of high irradiance on leaf lamina. Light-dark rhythms induced variation in q (termed nyctinastic movement). Nyctinastic movement is important during the low light levels experienced by leaflets in early morning and late afternoon. At low light levels, the leaflet stopped nyctinastic movement and q was fixed at an angle that may have enabled the leaf lamina to maximize light interception. After the light-dark cycle was reestablished, nyctinastic movement was restored. Taken together, our results suggest that irradiance induces variation in b leading to diurnal leaflet movement (diaheliotropism), whereas the light-dark cycle influences q, which results in nocturnal leaflet movement. Both angles are important for describing patterns of leaf movement in R. pseudocacia.
Abstract (Browse 2094)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Sap Flow of Populus euphratica in a Desert Riparian Forest in an Extreme Arid Region During the Growing Season
Author: Jian-Hua Si, Qi Feng, Xiao-You Zhang, Zong-Qiang Chang, Yong-Hong Su and Hai-Yang Xi
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00388.x
      
    In the present study, the heat pulse technique was applied to investigate the stem sap flow of Populus euphratica in a desert riparian forest in an extreme arid region from April to October 2003 and from May to October 2004. The experimental sites were in Qidaoqiao (101?0'' E, 41?9'' N) and Bayantaolai farm (101?4'' E, 42?1'' N) in Ejina county, in the low reaches of the Heihe River, China. The results indicated that the diurnal change in the velocity of sap flow showed minor fluctuations. At night, the rising of sap flow could be observed in the main tree species because of root pressure. During the growing season, the maximum average velocity was observed in July, followed by August, and the same velocity was observed in September and May; the minimum velocity was observed in October. The transpiration from June to August during the growing season accounted for approximately 70% of the annual total transpiration. The sap flow velocity of P. euphratica trees of different ages could be arranged in the order: 15 yr > 25 yr > 50 yr. Sap flow velocity was closely related to changes in micrometeorological factors, with average sap flow velocity showing a significant linear correlation with net radiation, air temperature and relative humidity.
Abstract (Browse 2020)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Contaminant Removal of Domestic Wastewater by Constructed Wetlands: Effects of Plant Species
Author: Qiong Yang, Zhang-He Chen, Jian-Gang Zhao and Bin-He Gu
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00389.x
      
    A comparative study of the efficiency of contaminant removal between five emergent plant species and between vegetated and unvegetated wetlands was conducted in small-scale (2.0 m?.0 m?.7 m, length×width×depth) constructed wetlands for domestic wastewater treatment in order to evaluate the decontaminated effects of different wetland plants. There was generally a significant difference in the removal of total nitrogen (TN) and total phosphorus (TP), but no significant difference in the removal of organic matter between vegetated and unvegetated wetlands. Wetlands planted with Canna indica Linn., Pennisetum purpureum Schum., and Phragmites communis Trin. had generally higher removal rates for TN and TP than wetlands planted with other species. Plant growth and fine root (root diameter 3 mm) biomass were related to removal efficiency. Fine root biomass rather than the mass of the entire root system played an important role in wastewater treatment. Removal efficiency varied with season and plant growth. Wetlands vegetated by P. purpureum significantly outperformed wetlands with other plants in May and June, whereas wetlands vegetated by P. communis and C. indica demonstrated higher removal efficiency from August to December. These findings suggest that abundance of fine roots is an important factor to consider in selecting for highly effective wetland plants. It also suggested that a plant community consisting of multiple plant species with different seasonal growth patterns and root characteristics may be able to enhance wetland performance.
Abstract (Browse 2094)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Stress & Phytochemistry
Astaxanthin Accumulation in the Green Alga Haematococcus pluvialis: Effects of Cultivation Parameters
Author: Ping He, James Duncan and James Barber
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00468.x
      
    The green alga, Haematococcus pluvialis Flotow is used as a source of the ketocarotenoid astaxanthin for application in fish aquaculture, pharmaceutical and cosmetic industries. Cells of the green alga were induced by the application of different light and starvation conditions to evaluate the effect in astaxanthin accumulate. The conditions used for the induction were high light intensity (170 mmol.m?.s?), iron starvation, sulfur starvation and phosphate starvation. The results show that stresses applied in culture, which interfere with cell division, trigger the accumulation of astaxanthin. Notably, sulfur starvation results in a massive accumulation of this commercially important carotenoid.
Abstract (Browse 1975)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Diphenyl Ether Glycoside from the Stems of Ilex litseaefolia Hu et Tang
Author: Yan-Hua Xiao, Ai-Lian Zhang and Guo-Lin Zhang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00399.x
      
    New diphenyl ether glycoside, ilexfoliaoside, was isolated from the stems of Ilex litseaefolia Hu et Tang, along with esculetin and 3,4-dimethoxybenzylacetic acid. The structure of ilexfoliaoside was determined as 6,2''-dihydroxy-4,4''-di-vanilloyloxymethyl-1,1''-diphenyl ether 2-O-b-D-glucopyranoside on the basis of chemical and spectroscopic evidence.
Abstract (Browse 1597)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Growth and Major Nutrient Concentrations in Brassica campestris Supplied with Different NH4+/NO3- Ratios
Author: Fu-Cang Zhang, Shao-Zhong Kang, Fu-Sheng Li and Jian-Hua Zhang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00373.x
      
    In the present study, we investigated whether growth and main nutrient ion concentrations of cabbage (Brassica campestris L.) could be increased when plants were subjected to different NH4+/NO3?ratios. Cabbage seedlings were grown in a greenhouse in nutrient solutions with five NH4+/NO3- ratios (1:0; 0.75:0.25; 0.5:0.5; 0.25:0.75; and 0:1). The results showed that cabbage growth was reduced by 87% when the proportion of NH4+-N in the nutrient solution was more than 75% compared with a ratio NH4+/NO3- of 0.5:0.5 35 d after transplanting, suggesting a possible toxicity due to the accumulation of a large amount of free ammonia in the leaves. When the NH4+/NO3?ratio was 0.5:0.5, fresh seedling weight, root length, and H2PO4?(P), K+, Ca2+, and Mg2+ concentrations were all higher than those in plants grown under other NH4+/NO3-ratios. The nitrate concentration in the leaves was the lowest in plants grown at 0.5:0.5 NH4+/NO3- The present results indicate that an appropriate NH4+/NO3-ratio improves the absorption of other nutrients and maintains a suitable proportion of N assimilation and storage that should benefit plant growth and the quality of cabbage as a vegetable.
Abstract (Browse 2018)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Changes in Unsaturated Levels of Fatty Acids in Thylakoid PSII Membrane Lipids During Chilling-induced Resistance in Rice  
Author: Su-Qin Zhu, Chun-Mei Yu, Xin-Yan Liu, Ben-Hua Ji and De-Mao Jiao
Journal of Integrative Plant Biology 2007 49(4): 463-471
DOI: 10.1111/j.1744-7909.2007.00438.x
      
    Temperature is one of the abiotic factors limiting growth and productivity of plants. In the present work, the effect of low non-freezing temperature, as an inducer of “chilling resistance? was studied in three cultivars of rice (Oryza sativa L.), japonica cv. 9516 (j-9516), the two parental lines of superhigh-yield hybrid rice between subspecies, Peiai/E32 (ji-PE), and the traditional indica hybrid rice Shanyou 63 (i-SY63). Leaves of chill-treated rice showed chilling-induced resistance, as an increase of their low-temperature tolerance was measured using chlorophyll fluorescence measurements, revealing a change in photosystem II (PSII) efficiency. After 5 d of exposure to 11 ºC under low light (100 mmol.m-2.s-1), levels of unsaturated fatty acids in PSII thylakoid membrane lipids decreased during the initial 1? d, then increased slowly and reached 99.2%, 95.3% and 90.1% of the initial value (0 d) in j-9516, ji-PE and i-SY63, respectively, on the fifth day. However, under medium light (600 mmol.m-2.s-1), all cultivars experienced similar substantial photoinhibition, which approached steady state levels after a decline in levels of unsaturated fatty acids in PSII thylakoid membrane lipids to about 57.1%, 53.8% and 44.5% of the initial values (0 d) in j-9516, ji-PE and I-SY63 on the fifth day. Under either chilling-induced resistance (the former) or low temperature photoinhibition (the latter) conditions, the changes of other physiological parameters such as D1 protein contents, electron transport activities of PSII (ETA), Fv/Fm, xanthophyl cycle activities expressed by DES (deepoxide state) were consistent with that of levels of unsaturated fatty acids in PSII thylakoid membrane lipids. So there were negative correlations between saturated levels of fatty acids (16:1(3t), 16:0, 18:0), especially the 16:1(3t) fatty acid on thylakoid membrane and other physiological parameters, such as D1 protein contents, ETA and (A+Z)/(A+V+Z). A specific role of desaturation of fatty acids and the photoprotective pigments of the xanthophyl cycle, leading to an acclimation response in thylakoid membrane lipids may be involved. We conclude that chilling-induced resistance is accelerated by the unsaturation of thylakoid membranes, and the ability of rice plants to cold-harden can be enhanced by genetic engineering.
Abstract (Browse 3057)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Local Nitrogen Supply on Water Uptake of Bean Plants in a Split Root System
Author: Shiwei Guo, Qirong Shen and Holger Brueck
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00436.x
      
    To study the effects of local nitrogen supply on water and nutrient absorption, French bean (Phaseolus vulgaris L.) plants were grown in a split root system. Five treatments supplied with different nitrogen forms were compared: homogeneous nitrate (NN) and homogenous ammonium (AA) supply, spatially separated supply of nitrate and ammonium (NA), half of the root system supplied with N-free nutrient solution, the other half with either nitrate (N0) or ammonium (A0). The results showed that 10 d after onset of treatments, root dry matter (DM) in the nitrate-supplied vessels treated with NA was more than two times higher than that in the ammonium-supplied vessels. Water uptake from the nitrate-supplied vessels treated with NA was 281% higher than under ammonium supply. In treatments N0 and A0, the local supply of N resulted in clearly higher root DM, and water uptake from the nitrate-supplied vessels was 82% higher than in the –N vessels. However, in A0 plants, water uptake from the –N nutrient solution was 129% higher than from the ammonium-supplied vessels. This indicates a compensatory effect, which resulted in almost identical rates of total water uptake of treatments AA and A0, which had comparable shoot DM and leaf area. Ammonium supply reduced potassium and magnesium absorption. Water uptake was positively correlated with N, Mg and K uptake.
Abstract (Browse 1819)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Salt Stress-induced Programmed Cell Death in Rice Root Tip Cells
Author: Jian-You Li, Ai-Liang Jiang and Wei Zhang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00445.x
      
    Salt stressed rice root tips were used to investigate the changes of reactive oxygen species (ROS) and antioxidant enzymes at the early stages of programmed cell death (PCD). The results indicated that 500 mmol/L NaCl treatment could lead to specific features of PCD in root tips, such as DNA ladder, nuclear condense and deformation, and transferase mediated dUTP nick end labeling positive reaction, which were initiated at 4 h of treatment and progressed thereafter. Cytochrome c release from mitochondria into cytoplasm was also observed, which occurred at 2 h and was earlier than the above nuclear events. In the very early phase of PCD, an immediate burst in hydrogen peroxide and superoxide anion production rate was accompanied by two-phase changes of superoxide dismutases and ascorbate peroxidase. A short period of increase in the activity was followed by prolonged impairment. Thus, we conclude that salt can induce PCD in rice root tip cells, and propose that in the early phase of rice root tip cell PCD, salt stress-induced oxidative burst increased the antioxidant enzyme activity, which, in turn, scavenged the ROS and abrogated PCD. Also, when the stress is prolonged, the antioxidant system is damaged and accumulated ROS induces the PCD process, which leads to cytochrome c release and nuclear change.
Abstract (Browse 2517)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Development & Photosynthesis
Proteomics Associated with Virulence Differentiation of Curvularia lunata in Maize in China
Author: Shufa Xu, Jie Chen, Lixing Liu, Xiaofei Wang, Xiuli Huang and Yuhong Zhai
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00469.x
      
    One-dimensional electrophoresis (1-DE) of proteins, two-dimensional electrophoresis (2-DE) of proteins and cloning of cDNA sequence were used to study the virulence differentiation of Curvularia lunata (Wakker) Boed. isolated from maize (Zea maydis L.) in China. From 1-DE gel profiles of proteins, 110 reproducible bands were separated from six isolates of C. lunata CX-3, SD-6, C-152, C107-1, DD-60 and W-18. Sixty-eight bands (61.82%) were polymorphic, suggesting huge biodiversities among the isolates. All isolates for the experiment were clustered into three groups consisting of different virulent types by coefficient value of 0.605. Group 1, consisting of CX-3, SD-6 and C-152 with high virulence displayed more protein bands than Groups 2 and 3, consisting of C107-1 and DD-60 with low virulence. Proteomics approaches based on 2-DE techniques were applied to identify specific proteins associated with the virulence differentiation in CX-3 and DD-60. A total of 423 protein spots were separated. Out of them 75 specific protein spots were displayed in 2-DE gels. Among them 28 protein spots were unique in CX-3 and eight in DD-60, and 39 protein spots were shown on both 2-DE gels but expressed differently in intensity. Twenty protein spots including three unique protein spots and 17 differentially expressed protein spots (more than two-fold DD-60) in CX-3 were further identified with MALDI-TOF MS/MS. Results indicated that most of the identified proteins were found to be associated with virulence differentiation, metabolisms, stress response and signal transduction. One of them was identified as Brn1 protein, which had been reported to be related to melanin biosynthesis and the virulence differentiation in fungi. Combined with our previous findings, we assumed that Brn1 protein and its regulating products might be involved in the virulence differentiation of C. lunata. Consequently, we cloned a Brn1 cDNA fragment and aligned it with the fragments in other fungi. Results indicated that the 633-bp sequence of Brn1 cloned in C. lunata was highly homological with the compared fungi. Further work for the exact gene roles of Brn1 in our case is underway.
Abstract (Browse 1686)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Prasinoxanthin-constaining Prasinophyceae Discovered in Jiaozhou Bay, China
Author: Zhi-Gang Yu, Chun-Mei Deng, Peng Yao, Yu Zhen and Shu-Ben Qian
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00424.x
      
    The class Prasinophyceae (Chlorophyta) contains some photosynthetic eukaryotic ultraplankton species characterized by containing prasinoxanthin. The existence and abundance of these organisms can be estimated by the diagnostic pigment. We detected the unique pigments of prasinoxanthin-containing Prasinophyceae in Jiaozhou Bay, China using high performance liquid chromatography (HPLC). This was the first finding of this kind in Chinese seas. Using the ratio of prasinoxanthin to chlorophyll a, the abundance of prasinoxanthin-containing Prasinophyceae has been calculated. The average contribution of prasinoxanthin-containing Prasinophyceae to the chlorophyll a pool was 8.5% and 17.0% in May and August 2004 in Jiaozhou Bay, and the maximums were 25.9% and 36.3%. Size fractionated pigment analysis suggested that more than 80% of prasinoxanthin were in the fraction of 2?0 mm. According to the results of pigment and morphological analysis, the possible genera of prasinoxanthin-containing Prasinophyceae and the reasons for causing this high abundant phytoplankton in Jiaozhou Bay were discussed. This kind of phytoplankton can not be discovered in traditional biological investigation, but its contribution to the coastal ecosystem is significant enough to be studied further.
Abstract (Browse 1614)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Endopeptidase Isoenzyme Characteristics in Cucumis sativus Leaves During Dark-induced Senescence
Author: Peng Zhang, Fei Wang, Lie-Feng Zhang, Qi Rui and Lang-Lai Xu
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00432.x
      
    The changes and characteristics of endopeptidase (EP) isoenzymes in cucumber (Cucumis sativus L.) leaves during dark-induced senescence were investigated by activity staining after gradient-polyacrylamide gel electrophoresis (G-PAGE) containing co-polymerized gelatin as substrate. The results showed that both the chlorophyll and the protein contents of leaves were decreased, and the protein degradation was correlated with the increase of proteolytic activity during the course of leaf senescence. Meanwhile, nine cucumber endopeptidases isoenzymes (CEP) with 140, 120, 106, 94, 76, 55, 46, 39 and 35 kDa molecular weights were detected. Four of these, CEP2, 3, 4 and CEP9 appeared all the time, but the changes of the activity were different during incubation. Another four CEPs (CEP5, 6, 7 and CEP8) whose activities increased with dark-induced time were only detected in senescent leaves. Furthermore, the biochemical properties of these nine CEP were also characterized. All the CEPs had high activities from 35 °C to 45 °C, and the optimum temperature was found to be 40 °C. However, the activities of CEPs were not detected below 25 °C or over 60 °C. The activity bands appeared at a wide range of pH from 5.0 to 9.0, but the optimum pH was found at 7.0. No CEPs were detected at pH 4 or pH 10. By inhibition analysis we concluded that CEP2, 3, 4 and CEP9 were serine endopeptidases and CEP6 was a kind of cysteine protease. It is suggested that serine endopeptidases might play a major role in cucumber leaf senescence, and for the first time, six senescence-related endopeptidases (CEP1, 5, 6, 7, 8 and 9) were found in cucumber leaves.
Abstract (Browse 2010)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Changes in Thermostability of Photosystem II and Leaf Lipid Composition of Rice Mutant with Deficiency of Light-harvesting Chlorophyll a/b Protein Complexes
Author: Yunlai Tang, Mei Chen, Yinong Xu and Tingyun Kuang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00433.x
      
    We studied the difference in thermostability of photosystem II (PSII) and leaf lipid composition between a T-DNA insertion mutant rice (Oryza sativa L.) VG28 and its wild type Zhonghua11. Native green gel and SDS-PAGE electrophoreses revealed that the mutant VG28 lacked all light-harvesting chlorophyll a/b protein complexes. Both the mutant and wild type were sensitive to high temperatures, and the maximal efficiency of PSII photochemistry (Fv/Fm) and oxygen-evolving activity of PSII in leaves significantly decreased with increasing temperature. However, the PSII activity of the mutant was markedly more sensitive to high temperatures than that of the wild type. Lipid composition analysis showed that the mutant had less phosphatidylglycerol and sulfoquinovosyl diacylglycerol compared with the wild type. Fatty acid analysis revealed that the mutant had an obvious decrease in the content of 16:1t and a marked increase in the content of 18:3 compared with the wild type. The effects of lipid composition and unsaturation of membrane lipids on the thermostability of PSII are discussed.
Abstract (Browse 1566)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Novel Evidence for a Reversible Dissociation of Light-harvesting Complex II from Photosystem II Reaction Center Complex Induced by Saturating Light Illumination in Soybean Leaves
Author: Yi Liao and Da-Quan Xu
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00435.x
      
    After saturating light illumination for 3 h the potential photochemical efficiency of photosystem II (PSII) (Fv/Fm, the ratio of variable to maximal fluorescence) decreased markedly and recovered basically to the level before saturating light illumination after dark recovery for 3 h in both soybean and wheat leaves, indicating that the decline in Fv/Fm is a reversible down-regulation. Also, the saturating light illumination led to significant decreases in the low temperature (77 K) chlorophyll fluorescence parameters F685 (chlorophyll a fluorescence peaked at 685 nm ) and F685/F735 (F735, chlorophyll a fluorescence peaked at 735 nm) in soybean leaves but not in wheat leaves. Moreover, trypsin (a protease) treatment resulted in a remarkable decrease in the amounts of PsbS protein (a nuclear gene psbS-encoded 22 kDa protein) in the thylakoids from saturating light-illuminated (SI), but not in those from dark-adapted (DT) and dark-recovered (DRT) soybean leaves. However, the treatment did not cause such a decrease in amounts of the PsbS protein in the thylakoids from saturating light-illuminated wheat leaves. These results support the conclusion that saturating light illumination induces a reversible dissociation of some light-harvesting complex II (LHCII) from PSII reaction center complex in soybean leaf but not in wheat leaf.
Abstract (Browse 1528)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
AtCLH2, a Typical but Possibly Distinctive Chlorophyllase Gene in Arabidopsis
Author: Yang Liao, Kun An, Xiao Zhou, Wen-Jun Chen and Ben-Ke Kuai
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00444.x
      
    Chlorophyllase (EC 3.1.1.14) is involved in the first step of chlorophyll degradation. Isolation of chlorophyllase genes greatly facilitates characterization of chlorophyllase properties and elucidation of molecular regulation of their in vivo activities. There are two chlorophyllase genes, AtCLH1 and AtCLH2, in Arabidopsis thaliana. The in vivo roles of AtCLH1 have been reported previously. However, few studies have been carried out on AtCLH2. Here, we show that purified recombinant Chlase2, encoded by AtCLH2, exhibits in vitro chlorophyllase activity. Interestingly, “activation?of in vitro activity of the recombinant Chlase2 required higher concentrations of a detergent or a polar solvent. To determine its activity in vivo, the expression of AtCLH2 was inhibited by RNA interference. RNAi plants showed decreased contents of chlorophyllide without a substantial change in the total amount of the extractable chlorophyll and consequently presented lower chlorophyllide to chlorophyll ratios in their leaves. In addition, the two AtCLHs exhibited differential expression patterns. Our results suggest that AtCLH2 might play a distinctive role in chlorophyll catabolism in vivo.
Abstract (Browse 2281)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Signal Transduction
Integrin-like Protein Is Involved in the Osmotic Stress-induced Abscisic Acid Biosynthesis in Arabidopsis thaliana
Author: Bing Lu, Feng Chen, Zhong-Hua Gong, Hong Xie and Jian-Sheng Liang
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00439.x
      
    We studied the perception of plant cells to osmotic stress that leads to the accumulation of abscisic acid (ABA) in stressed Arabidopsis thaliana L. cells. A significant difference was found between protoplasts and cells in terms of their responses to osmotic stress and ABA biosynthesis, implying that cell wall and/or cell wall-plasma membrane interaction are essential in identifying osmotic stress. Western blotting and immunofluorescence localization experiments, using polyclonal antibody against human integrin b1, revealed the existence of a protein similar to the integrin protein of animals in the suspension-cultured cells located in the plasma membrane fraction. Treatment with a synthetic pentapeptide, Gly-Arg-Gly-Asp-Ser (GRGDS), which contains an RGD domain and interacts specifically with integrin protein and thus blocks the cell wall-plasma membrane interaction, significantly inhibited osmotic stress-induced ABA biosynthesis in cells, but not in protoplasts. These results demonstrate that cell wall and/or cell wall-plasma membrane interaction mediated by integrin-like proteins played important roles in osmotic stress-induced ABA biosynthesis in Arabidopsis thaliana.
Abstract (Browse 2622)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Effects of Acetylcholine, Cytochalasin B and Amiprophos-methyl on Phloem Transport in Radish (Raphanus sativas)
Author: Chong-Jun Yang, Zhi-Xi Zhai, Yu-Hai Guo and Peng Gao
Journal of Integrative Plant Biology 2007 49(4)
DOI: 10.1111/j.1744-7909.2007.00434.x
      
    We investigated the role of the “sieve tube-companion cell complex?lining the tube periphery, particularly the microfilament and microtubule, in assisting the pushing of phloem sap flow. We made a simple phloem transport system with a living radish plant, in which the conducting channel was exposed for local treatment with chemicals that are effective in modulating protoplasmic movement (acetylcholine, (ACh) a neurotransmitter in animals and insects; cytochalasin B, (CB) a specific inhibitor of many cellular responses that are mediated by microfilament systems and amiprophos-methyl, (APM) a specific inhibitor of many cellular responses that are mediated by microtubule systems). Their effects on phloem transport were estimated by two experimental devices: (i) a comparison of changes in the amount of assimilates in terms of carbohydrates and 14C-labeled photosynthetic production that is left in the leaf blade of treated plants; and (ii) distribution patterns of 14C-labeled leaf assimilates in the phloem transport system. The results indicate that CB and APM markedly inhibited the transfer of photosynthetic product from leaf to root via the leaf vein, while ACh enhanced the transfer of photosynthetic product in low concentrations (5.0?0-4 mol/L) but inhibited it in higher concentrations (2.0?0-3 mol/L) from leaf to root via the leaf vein. Autoradiograph imaging clearly reveals that ACh treatment is more effective than the control, and both CB and APM treatments effectively inhibit the passage of radioactive assimilates. All of the results support the postulation that the peripheral protoplasm in the sieve tube serves not only as a passive semi-permeable membrane, but is also directly involved in phloem transport.
Abstract (Browse 2337)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          New Technology
High-throughput Binary Vectors for Plant Gene Function Analysis  
Author: Zhi-Yong Lei, Ping Zhao, Min-Jie Cao, Rong Cui, Xi Chen, Li-Zhong Xiong, Qi-Fa Zhang, David J. Oliver and Cheng-Bin Xiang
Journal of Integrative Plant Biology 2007 49(4): 556-567
DOI: 10.1111/j.1744-7909.2007.00442.x
      
    A series of high-throughput binary cloning vectors were constructed to facilitate gene function analysis in higher plants. This vector series consists of plasmids designed for plant expression, promoter analysis, gene silencing, and green fluorescent protein fusions for protein localization. These vectors provide for high-throughput and efficient cloning utilizing sites for l phage integrase/excisionase. In addition, unique restriction sites are incorporated in a multiple cloning site and enable promoter replacement. The entire vector series are available with complete sequence information and detailed annotations and are freely distributed to the scientific community for non-commercial uses.
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