December 2003, Volume 45 Issue 12

 

          Research Articles
A Novel Cotton Gene Encoding a New Class of Chitinase
Author: LI Ji, LIU Jin-Yuan
Journal of Integrative Plant Biology 2003 45(12): 1489-1496
      
    

A novel chitinase gene (GhChia7 ) was isolated from salicylic acid (SA)-treated cotton cotyledons and characterized by DNA sequence analysis of its cDNA and genomic DNA clone. The deduced amino acid sequence, designated as class Ⅶ chitinase, shares about 30% identity to class Ⅰ or Ⅱ chitinases, and does not correspond to any of the previously characterized classes Ⅰ-Ⅵ chitinases. Northern blotting analysis showed that the transcripts of GhChia7 were abundant both in cotton fibers and in the roots of the seedlings. The accumulation of GhChia7 mRNA in SA-treated cotyledons reached maximum at 7.5 mmol/L concentration after 18 h. Results indicate that GhChia7 might play an important role in cotton抯 active defense response.

 

Abstract (Browse 2072)  |  Full Text PDF       
Gene Expression Controlled by Heat-Inducible Site-Specific Recombination in Tobacco
Author: CHEN Ming, WANG Li-Xia, PENG Xiang-Lei, XU Hui-Jun, LIN Zhong-Ping
Journal of Integrative Plant Biology 2003 45(12): 1481-1488
      
    

Cre site-specific recombinase-mediated DNA excision system was driven by the heat shock promoter Gmhsp17.5C. In this system, the DNA fragment with CaMV35S-GUS franked by two identical orientation loxp sites could be excised from the transgenic tobacco (Nicotiana tabacum L. cv. W38) by Cre expression under control of heat shock promoter. This transgenic system has been determined by quantitative PCR and showed Cre/lox mediated recombination efficiency. Results showed that 41% of DNA fragment with CaMV35S-GUS in the transgenic tobacco could be excised after a two-hour heat shock treatment. Based on several advantages of heat shock-inducible site-specific recombination system such as easy manipulation, sensitivity to heat shock and no background expression, it can be potentially used for induc-ible DNA manipulation in transgenic plant.

利用热诱导的位点专一性重组系统在烟草中控制基因表达
陈 明 王立霞  彭向雷  徐惠君  林忠平

(1 . 北京大学生命科学学院蛋白质工程与植物基因工程国家重点实验室,北京 100871;
2.中国农业科学院作物育种与栽培研究所, 农业部作物遗传育种重点实验室,北京 100081)


摘要: 采用热激启动子Gmhsp17.5C 控制Cre 定位重组酶介导的DNA 删除系统。在这个系统中,在热激启动子控制下的Cre重组酶的表达导致两侧带有相同方向loxp位点的CaMV35S-GUS片段从转基因烟草(Nicotiana tabacum L.cv.W38)的基因组中删除。通过定量PCR的方法鉴定这个转基因系统,显示了这个系统的重组效率。结果显示在两个小时热激处理后转基因烟草中有41% 的CaMV35S-GUS 片段被删除。由于热激诱导的定点重组系统有容易操作、对热敏感和无背景表达等优点,因此有利于采用这个系统在转基因植物中进行可诱导的基因操作。
关键词: 烟草;Cre/lox; Cre 重组酶;热激;诱导

 通讯作者。 E-mail:<linzp@pku.edu.cn>。

Abstract (Browse 2113)  |  Full Text PDF       
Programmed Cell Death During Secondary Xylem Differentiation in Eucommia ulmoides
Author: CAO Jing, HE Xin-Qiang, WANG Ya-Qing, Sodmergen, CUI Ke-Ming
Journal of Integrative Plant Biology 2003 45(12): 1465-1474
      
    

Programmed cell death (PCD) during secondary xylem differentiation in Eucommia ulmoides Oliv. was examined using electron microscopy and by investigation of DNA fragmentation and degradation of caspase-like proteases (CLPs). DNA ladders were detected in developing secondary xylem by gel electrophoresis. DNA fragmentation was further confirmed by using the TdT-mediated dUTP nick-end labeling (TUNEL) method. Western blotting analysis showed that CLPs (caspase-8- and caspase-3-like proteases) and PARP (poly (ADP-ribose) polymerase) were degraded during secondary xylem differentiation. The results thus indicated that secondary xylem differentiation in E. ulmoides was a typical process of PCD and the degradation of CLPs might be a constitutive PCD event during secondary xylem differentiation.

 

Abstract (Browse 2324)  |  Full Text PDF       
Control of In Vitro Regeneration of Individual Reproductive and Vegetative Organs in Dracaena fragrans cv. massangeana Hort.— Regularities of the Direct Regeneration of Individual Organs In Vitro
Author: LU Wen-Liang
Journal of Integrative Plant Biology 2003 45(12): 1453-1464
      
    

Various individual organs (tepal, flower bud, inflorescence branch, inflorescence, adult vegetative bud and juvenile vegetative bud) were directly regenerated respectively by callus in Dracaena fragrans cv. massangeana Hort. During the regeneration of these individual organs some regularity phenomena were observed. Firstly, the kind range of the individual organs, which are directly regenerated in vitro, is in close relationship to the differentiated stages of the organs used for explant excision during plant ontogeny. The explants excised from the epigeous organ that is differentiated at some stage (stage A) during plant ontogeny must be able to separately regenerate all of those individual epigeous organs: ones differentiated slightly later than the stage A, ones differentiated at the stage A and all ones differentiated earlier than the stage A. Secondly, within this range which kind of organ is regenerated depends on the exogenous auxin concentrations in medium. With the gradual increase of 2,4-D concentration from 0.005 mg/L to 0.5 mg/L, the kinds of regenerated organs will change by the order as follows: vegetative bud, inflorescence, inflorescence branch, flower bud, tepal. These regularities will be able to be used for inducing the direct regeneration of a given epigeous organ in angiosperms.

 

Abstract (Browse 2083)  |  Full Text PDF       
Effects of Acetylsalicylic Acid (ASA) and Ethylene Treatments on Ripening and Softening of Postharvest Kiwifruit
Author: ZHANG Yu, CHEN Kun-Song, CHEN Qing-Jun, ZHANG Shang-Long, REN Yi-Ping
Journal of Integrative Plant Biology 2003 45(12): 1447-1452
      
    

Kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson cv. Bruno) was used to investigate the effects of acetylsalicylic acid (ASA, 1.0 mmol/L, pH 3.5) and ethylene (100 mL/L) treatments on changes at endogenous salicylic acid (SA) levels and other senescence-related factors during fruit ripening and softening at 20 ℃. The level of endogenous SA in ripening fruits declined and a close relationship was observed between the change at endogenous SA level and the rate of fruit ripening and softening. ASA treatment elevated SA level in the fruit, slowed down the increases in lipoxygenase (LOX) and allene oxide synthase (AOS) activities, decreased the O22-. production in the preclimacteric phase and the early phase of ethylene climacteric rise, maintained the stability of cell membrane, inhibited ethylene biosynthesis, postponed the onset of the ethylene climacteric, and delayed the process of fruit ripening and softening. On the contrary, application of ethylene to ripening kiwifruit resulted at a lower SA level, an accelerated increases in the activities of LOX and AOS and the rate of O22-. production, an elevated relative electric conductivity and an advanced onset of ethylene climacteric, and a quicker fruit ripening and softening. It is suggested that the effects of ASA on ripening kiwifruit can be attributed to its ability to scavenge O22-. and/or to maintain stability of cell membrane.

 

Abstract (Browse 2232)  |  Full Text PDF       
Establishment of In Vitro Regeneration System of the Atrichum Mosses
Author: GANG Yong-Yun, DU Gui-Sen, SHI Ding-Ji, WANG Mei-Zhi, LI Xue-Dong, HUA Zhen-Ling
Journal of Integrative Plant Biology 2003 45(12): 1475-1480
      
    

In vitro regeneration systems of Atrichum mosses, Atrichum undulatum (Hedw.) P. Beauv. and A. undulatum var. minus (Hedw.) Par. were established. After one month, soft, friable and green calli were induced successfully from inoculated protonema of Atrichum mosses on MS medium containing glucose (4%) and 6-BA (0.2-2.0 mg/L). The suitable culture medium for the callus induction and regular subculture was MS medium with 1.0-2.0 mg/L 6-BA and 4% glucose. The calli of Atrichum mosses developed into protonema, when it was transferred to phytohormone-free MS medium with 4% glucose. Meanwhile, the calli developed into erect gametophytes through protonema phase on carbohydrate-free Benecke medium.

 

Abstract (Browse 2218)  |  Full Text PDF       
Activation of Plasma Membrane NADPH Oxidase and Generation of H2O2 Mediate the Induction of PAL Activity and Saponin Synthesis by Endogenous Elicitor in Suspension-Cultured Cells of Panax ginseng
Author: HU Xiang-Yang, Steven J NEILL, CAI Wei-Ming, TANG Zhang-Cheng
Journal of Integrative Plant Biology 2003 45(12): 1434-1441
      
    

Endogenous elicitor, termed cellulase-degraded cell wall (CDW), was prepared from the cell wall of suspension-cultured ginseng (Panax ginseng C.A. Meyer) cells via cellulase degradation. CDW acti-vated the NADPH oxidase activity of isolated plasma membranes and stimulated in vivo H2O2 generation in ginseng cell suspensions. CDW also increased the activity of phenylalanine ammonia lyase (PAL), expres-sion of a P. ginseng squalene epoxidase (sqe) gene and saponin synthesis. NADPH oxidase inhibitors inhib-ited both in vitro NADPH oxidase activity and in vivo H2O2 generation. Induction of PAL activity, saponin synthesis and sqe gene expression were all inhibited by such inhibitor treatments and reduced by incuba-tion with catalase and H2O2 scavengers. These data indicate that activation of NADPH oxidase and genera-tion of H2O2 are essential signalling events mediating defence responses induced by the endogenous elicitor(s) present in CDW.

 

Abstract (Browse 2120)  |  Full Text PDF       
State Transition, Is It a Photochemical or Non-photochemical Process in Leaf in Response to Irradiance?
Author: JIA Hu-Sen, LI De-Quan
Journal of Integrative Plant Biology 2003 45(12): 1428-1433
      
    

The response of steady-state fluorescence (Fs) to irradiance in apple (Malus pumila Mill. cv. Tengmu No.1/Malus hupehensis Rehd.) leaf increased and decreased at light levels below and above 400 mmol.m-2.s-1 photosynthetic photon flux density (PPFD), respectively, while the light-adapted maximal fluorescence (Fm'') and minimal fluorescence (Fo'') decreased constantly with the increasing PPFD, and the closure of photosystem Ⅱ reaction center (PSⅡ RC) increased continuously, reflected by the chlorophyll fluorescence parameter of (Fs-Fo'')/(Fm''-Fo''). These facts indicated that decrease of Fs above 400 mmol.m-2.s-1 PPFD was not caused by closure of PSⅡ RC, but was mainly resulted from the process of light transfer from light-harvesting complexⅡ (LHCⅡ) to PSⅡ RC. In the presence of N-ethylmaleimide (NEM), an inhibitor of photosynthetic state transition, Fs kept on increasing in apple leaf at light levels from 400 to 700 mmol.m-2.s-1, which was the photosynthetic saturation irradiance of apple leaves. In addition, Fs still increased at light levels over 700 mmol.m-2.s-1 in apple leaf pre-treated with dithiothreitol (DTT), an inhibitor of xanthophyll cycle. These changes showed that state transition and xanthophyll cycle caused a decrease of Fs in apple leaf at light levels below and above the photosynthetic saturation irradiance, respectively. When apple leaf was pre-treated with NEM, the PSⅡ apparent rate of photochemical reaction (P-rate) and photochemical quenching (qP) decreased significantly in the light range of 600-800 mmol.m-2.s-1, but the non-photochemical quenching (qN) existed a small increase at 600-800 mmol.m-2.s-1 and a decrease above 800 mmol.m-2.s-1. These phenomena suggested that state transition was mainly a photochemical and a non-photochemical process in apple leaf responding to light lower and higher than photosynthetic saturation irradiance, respectively.

 

Abstract (Browse 2042)  |  Full Text PDF       
Effect of Polar Auxin Transport on Rice Root Development
Author: ZHOU Da-Xi, YIN Ke, XU Zhi-Hong, XUE Hong-Wei
Journal of Integrative Plant Biology 2003 45(12): 1421-1427
      
    

Polar auxin transport (PAT) is critical in plant growth and development, especially polar differentiation and pattern formation. Lots of studies have been performed in dicots while relative less in monocots. Using two kinds of PAT inhibitors, 2, 3, 5-triiodobenzoic acid (TIBA) and 9-hydroxyfluorene-9-carboxylic acid (HFCA), it was shown that PAT is important for rice (Oryza sativa L. cv. Zhonghua 11) root development, including elongation of the primary roots, initiation and elongation of lateral roots, and formation of adventitious roots. Inhibition of PAT resulted in the shortened primary roots, less and short-ened lateral and adventitious roots. Exogenously supplemented NAA can partially rescue the formation of adventitious roots but not lateral roots, while low concentration of NAA (0.1 mmol/L) could not rescue either of them, suggesting the possible different mechanisms of lateral and adventitious root initiations. Treatment of 30 mmol/L TIBA did not completely inhibit the initiation of lateral roots, and survival capaci-ties of which were demonstrated through cross section experiments revealing the presence of primordial of lateral roots at different stages. Further studies through localized application of PAT inhibitors indicated that auxin flow, transported from coleoptiles to the base, is not only responsible for the auxin contents in stem nodes but also critical for initiation and elongation of adventitious roots.

 

Abstract (Browse 2275)  |  Full Text PDF       
Properties of Picosecond Fluorescence of Super High-Yield Hybrid Rice
Author: REN Zhao-Yu, XU Xiao-Ming, WANG Shui-Cai, XIN Yue-Yong, HE Jun-Fang, KUANG Ting-Yun
Journal of Integrative Plant Biology 2003 45(12): 1442-1446
      
    

Thylakoid membrane preparations of super high-yield hybrid rice (Oryza sativa L.), Liangyoupeijiu (P9) and Shanyou 63 (SH 63) were used for investigating its spectral and time properties by using picosecond time-resolved fluorescence spectrum measuring system. The thylakoid membrane preparations of P9 and SH 63 were excited by an Ar+ laser with a pulse width of 120 ps, repetition rate of 4 MHz and wavelength of 514 nm. The time constants of the excited energy transfer in these two varieties at flowering stage and grain filling stage were calculated from the experimental data. Based on the comparative studies of the time and spectral properties of the excited fluorescence in these ultrafast dynamic experiments the following was found: at both the flowering stage and grain filling stage, the speed of the excitation energy transfer, in photosystem Ⅰ was faster than that in photosystem Ⅱ in P9 variety; and the speed of the excitation energy transfer at grain filling stage was faster than those at flowering stage for both rice varieties; the experiments also implied that the components and assembly of pigments in SH 63, but not in P9, changed during the process from flowering stage to grain filling stage for in these two rice varieties.

 

Abstract (Browse 1910)  |  Full Text PDF       
Behavior of Carbon and Nutrients Within Two Types of Leaf Litter During 3.5-year Decomposition
Author: TIAN Xing-Jun, SUN Shu-Cun, MA Ke-Ping, AN Shu-Qing
Journal of Integrative Plant Biology 2003 45(12): 1413-1420
      
    

A litter bag study of needle (Abies veitchii Lindl. and A. mariesi Mast.) and leaf litter (Betula ermanii Cham. and B. corylifolia Regal. et Maxim.) conducted in a coniferous forest of Mt. Ontake, Japan showed the similar qualities of two type litters in later stages (after the 30th month). Although the difference in remaining mass between the two litters was larger in later stage of decomposition and initial concentration of nutrients was different. The concentrations of carbon (C) fraction and nutrients between the two types of litter tended to similar in the later stages. The similar concentration trend of nutrients was due to different mechanisms. Nitrogen (N) was due to immobilization of fungi and binding with lignin. K and Mg were leaching elements. They were very easily affected in leaching process. In the later stage, they reached a similar concentration because of a balance with the soil concentration. Ca is a construction element, so its behavior has closely related to that of C fractions. Moreover, C fractions were lignified or humuified and remained similar in later stage, Ca was also became similar in concentration in the later stage.

 

Abstract (Browse 2084)  |  Full Text PDF       
Acid Buffering Capacity of Forest Litter from Some Important Plantation and Natural Forests in South China
Author: LI Zhi-An, CAO Yu-Song, ZOU Bi, DING Yong-Zhen, REN Hai
Journal of Integrative Plant Biology 2003 45(12): 1398-1407
      
    

The role of forest litter as an acid-base buffering system was assessed by litter from plantation and natural forests in South China. Samples were either extracted with acid solutions or titrated with acid or base solutions. Litter was found to be a strong acid-base buffering system. Two legume species, Acacia mangium Willd and A. auriculaiformis A. Cunn, had very high litter pH values of around 6, which was 2 pH units higher than that of the soil where they grew. Litter of all other plantation species had litter pH of around 4, similar to that of the soil. Both legume species have high potential to neutralize soil acidity and the litter layer could act to shield soil against acid rain. The current stand of two legume species was estimated to be able to raise rain acidity by 0.1 to 0.4 pH units. Inorganic ions did not fully explain the pH pattern of different litter extracts, but high sodium and low nitrate partly accounted for the high pH of the two legume species. Some natural forest species had extremely low pH. As a whole, the litter of the natural climax forest was the driving force of soil acidification. Although plant residues are strong acid-base buffering system and able to adjust acidity of environment, only a few species can be expected to make soil more acid or alkaline through this mechanism since most species have litter pH values similar to those of soil where they grow.

 

Abstract (Browse 2035)  |  Full Text PDF       
Stem Respiration of a Larch (Larix gmelini) Plantation in Northeast China
Author: WANG Wen-Jie, YANG Feng-Jian, ZU Yuan-Gang, WANG Hui-Mei, TAKAGI Kentaro, SASA Kaichiro, KOIKE Takayoshi
Journal of Integrative Plant Biology 2003 45(12): 1387-1397
      
    

Stem respiration is an important part of the activity of a tree and is an important source of CO2 evolution from a forest ecosystem. Presently, no standard methods are available for the accurate estimation of total stem CO2 efflux from a forest. In the current study, a 33-year-old (by the year 2001) larch (Larix gmelini Rupr.) plantation was measured throughout 2001-2002 to analyze its monthly and seasonal patterns of stem respiration. Stem respiration rate was also measured at different heights, at different daily intervals and any variation in the larch plantation was recorded. The relationship between stem temperature, growth status and respiration rate was analyzed. Higher respiration rates were recorded in upper reaches of the larch tree throughout the season and these were affected partially by temperature difference. Midday depression was found in the diurnal changes in stem respiration. In the morning, but not in the afternoon, stem respiration was positively correlated with stem temperature. The reason for this variation may be attributed to water deficit, which was stronger in the afternoon. In the larch plantation, a maximum 7-fold variation in stem respiration was found. The growth status (such as mean growth rate of stem and canopy projection area) instead of stem temperature difference was positively correlated with this large variation. An S-model (sigmoid curve) or Power model shows the greatest regression of the field data. In the courses of seasonal and annual changes of stem respiration, peak values were observed in July of both years, but substantial interannual differences in magnitude were observed. An exponential model can clearly show this regression of the temperature-respiration relationship. In our results, Q10 values ranged from 2.22 in 2001 to 3.53 in 2002. Therefore, estimation of total stem CO2 efflux only by a constant Q10 value may give biased results. More parameters of growth status and water status should be considered for more accurate estimation.

 

Abstract (Browse 2492)  |  Full Text PDF       
Daily Ambrosia Pollen Concentration in the Air of Ankara, Turkey (1990-1999)
Author: Ay�e KAPLAN, Nazmiye �AKIYAN, N Münevver PINAR
Journal of Integrative Plant Biology 2003 45(12): 1408-1412
      
    

The airborne ragweed pollen spectrum was investigated in the air of Ankara, Turkey for a period of ten years (1990-1999) using a Burkard seven-day volumetric recording trap. In our study period, long distance transported Ambrosia pollen has been registered. Daily pollen levels varied from low to high in Burge抯 system. In last three years, the pollen concentration of Ambrosia showed a clear increasing tendency. Our results prove that ragweed pollen may be an important threat for ragweed sensitive patients in Ankara city in near future.

Abstract (Browse 3730)  |  Full Text PDF       
 

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