December 2007, Volume 49 Issue 12, Pages 1665-1781.


Cover Caption:
The URO gene and lignin deposit
Deposition of legnin during the formation of the secondary cell wall gives rise to te rigidness of the wall, and the hardness of the wood. The content of lignin in the cell wall matters greatly to the paper and bioenergy industry. Yuan et al. (1754®C1762) reports in this issue the phenotypes of an Arabidopsis gain-of-function mutant called uro, which has dramatically reduced lignification in the stem, as compared with that in wild-type (as seen on the cover). The uro mutant provides a useful tool for characterizing secondary growth in plants.

 

          Invited Expert Reviews
Florigen (II): it is a mobile protein  
Author: Yuejun Yang, John Klejnot, Xuhong Yu, Xuanming Liu and Chentao Lin
Journal of Integrative Plant Biology 2007 49(12): 1665-1669
DOI: 10.1111/j.1744-7909.2007.00614.x
      
    The true identity of florigen ®C the molecule(s) that migrates from leaves to The true identity of florigen ®C the molecule(s) that migrates from leaves to apical meristem to initiate flowering ®C was notoriously elusive, having made it almost the "Bigfoot" of plant biology. There was never a lack of drama in the field of florigen study, and florigen researchers have once again experienced such a swing in the last two years. We wrote a minireview last year in this journal (Yu et al. 2006) to excitedly salute, among other discoveries, the notion that the flowering locus T (FT) mRNA might be the molecular form of a florigen. However, this hypothesis was challenged in a little less than two years after its initial proposition, and the original paper proposed that the FT mRNA hypothesis was retracted (Huang et al. 2005; Bohlenius et al. 2007). Interestingly enough, the FT gene previously proposed to encode a florigen was never challenged. Rather, the FT protein, instead of the FT mRNA, is now believed to migrate from leaves to the apical meristem to promote floral initiation. In this update, we will share with our readers some entertaining stories concerning the recent studies of florigen in five different plant species. In addition to the published reports referenced in this update, readers may also refer to our previous minireview and references therein for additional background information (Yu et al. 2006).
Abstract (Browse 2802)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Use of Random Amplified Polymorphic DNA Analysis for Economically Important Food Crops  
Author: Halima Hassan Salem, Bahy Ahmed Ali, Tian-Hua Huang, Da-Nian Qin, Xiao-Mei Wang and Qing-Dong Xie
Journal of Integrative Plant Biology 2007 49(12): 1670-1680
DOI: 10.1111/j.1744-7909.2007.00582.x
      
    The objective of this review is to summarize numerous studies on the use of the random amplified polymorphic DNA (RAPD) technique on rice, corn, wheat, sorghum, barley, rye, and oats to examine its feasibility and validity for assessment of genetic variation, population genetics, mapping, linkage and marker assisted selection, phylogenetic analysis, and the detection of somaclonal variation. Also we discuss the advantages and limitations of RAPD. Molecular markers have entered the scene of genetic improvement in different fields of agricultural research. The simplicity of the RAPD technique made it ideal for genetic mapping, plant and animal breeding programs, and DNA fingerprinting, with particular utility in the field of population genetics.
Abstract (Browse 2549)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Bioenergy Plants
Modeling Responses of Leafy Spurge Dispersal to Control Strategies
Author: Zewei Miao
Journal of Integrative Plant Biology 2007 49(12): 1681-1692
DOI: 10.1111/j.1744-7909.2007.00601.x
      
    Leafy spurge (Euphorbia esula L.) has substantial negative effects on grassland biodiversity, productivity, and economic benefit in North America. To predict these negative impacts, we need an appropriate plant-spread model which can simulate the response of an invading population to different control strategies. In this study, using a stochastic map lattice approach we generated a spatially explicitly stochastic process-based model to simulate dispersal trajectories of leafy spurge under various control scenarios. The model integrated dispersal curve, propagule pressure, and population growth of leafy spurge at local and short-temporal scales to capture spread features of leafy spurge at large spatial and long-temporal scales. Our results suggested that narrow-, medium-, and fat-tailed kernels did not differ in their ability to predict spread, in contrast to previous works. For all kernels, Allee effects were significantly present and could explain the lag phase (three decades) before leafy spurge spread accelerated. When simulating from the initial stage of introduction, Allee effects were critical in predicting spread rate of leafy spurge, because the prediction could be seriously affected by the low density period of leafy spurge community. No Allee effects models were not able to simulate spread rate well in this circumstance. When applying control strategies to the current distribution, Allee effects could stop the spread of leafy spurge; no Allee effects models, however, were able to slow but not stop the spread. The presence of Allee effects had significant ramifications on the efficiencies of control strategies. For both Allee and no Allee effects models, the later that control strategies were implemented, the more effort had to be input to achieve similar control results.
Abstract (Browse 1530)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Stress & Phytochemistry
Effects of Cadmium on Polar Lipid Composition and Unsaturation in Maize (Zea mays) in Hydroponic Culture
Author: Radhouane Chaffai, Tinni Nouhou Seybou, Brahim Marzouk and Ezzedine El Ferjani
Journal of Integrative Plant Biology 2007 49(12): 1693-1702
DOI: 10.1111/j.1744-7909.2007.00585.x
      
    This study aimed to evaluate the effect of Cd exposure (100 ¶Őmol/L) on polar lipid composition, and to examine the level of fatty acid unsaturation in maize (Zea mays L.). In roots, the level of 16:0 and monounsaturated fatty acids (16:1 + 18:1) decreased in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In contrast, the proportion of unsaturated 18-C fatty acid species showed an opposite response to Cd. The content, on the other hand, of PC, PE, digalactosyldiacylglycerol (DGDG), and steryl lipids increased in roots (2.9-, 1.6-, 5.3-, and 1.7-fold increase, respectively). These results suggest that a more unsaturated fatty acid composition than found in control plants with a concomitant increase in polar lipids may favor seedling growth during Cd exposure. However, the observed increase in the steryl lipid (SL) : phospholipid (PL) ratio (twofold), the decrease in monogalactosyldiacylglycerol (MGDG) : DGDG ratio, as well as the induction of lipid peroxidation in roots may represent symptoms of membrane injury. In shoots, the unsaturation level was markedly decreased in PC and phosphatidylglycerol (PG) after Cd exposure, but showed a significant increase in sulfoquinovosyldiacylglycerol (SQDG), MGDG and DGDG. The content of PG and MGDG was decreased by about 65%, while PC accumulated to higher levels (4.4-fold increase). Taken together, these changes in the polar lipid unsaturation and composition are likely to be due to alterations in the glycerolipid pathway. These results also support the idea that the increase in overall unsaturation plays some role in enabling the plant to withstand the metal exposure.
Abstract (Browse 1021)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Exogenous Hematin Alleviates Mercury-induced Oxidative Damage in the Roots of Medicago sativa
Author: Yi Han, Wei Xuan, Tian Yu, Wen-Bing Fang, Tian-Ling Lou, Yin Gao, Xiao-Yue Chen, Xiao Xiao and Wen-Biao Shen
Journal of Integrative Plant Biology 2007 49(12): 1703-1713
DOI: 10.1111/j.1744-7909.2007.00592.x
      
    In the present study, we evaluated the protective effect of exogenous heme oxygenase-1 (HO-1 EC 1.14.99.3) inducer hematin against mercury-induced oxidative damage in the roots of Alfalfa (Medicago sativa L.). Plants exposed to mercury (HgCl2) exhibited a significant increase of lipid peroxidation, as well as inhibition of root elongation. However, hematin (50 ¶ŐM) supplementation to HgCl2 (100 ¶Őmol/L) treated plants effectively reduced the lipid peroxidation and partially increased the root elongation. These responses were mimicked by the application of aqueous solution of carbon monoxide (CO) with 50% saturation. Also, treatment with hematin could result in the potent induction of HO-1 transcript in the root tissues, as detected 12 h following treatment. Moreover, the activation of anti-oxidant enzyme, including glutathione reductase, monodehydroascorbate reductase and superoxide dismutase activities, and the decrease of lipoxygenase activity, were induced by hematin at 12 h or 24 h, which was further confirmed by histochemical staining for the detection of lipid peroxidation and loss of membrane integrity. Whereas, ascorbate peroxidase and guaiacol peroxidase isozyme activities or their transcripts were reduced, respectively, indicating that hydrogen peroxide might act as a signal to mediate Hg-tolerance at the beginning of treatment. The ameliorating effects of hematin were specific, since the CO scavenger hemoglobin differentially reversed the above actions. Taken together, our results suggested that hematin exhibits a vital role in protecting the plant against Hg-induced oxidative damage.
Abstract (Browse 1571)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Volatile Compounds in the Flowers of Freesia Parental Species and Hybrids
Author: Yang Fu, Xiang Gao, Qun Yi Xue, Jun Yue Hui, Qing Feng Chen, Ping Quan Su, and Li Wang
Journal of Integrative Plant Biology 2007 49(12): 1714-1718
DOI: 10.1111/j.1744-7909.2007.00571.x
      
    For centuries, freesia has been one of the most important crops in the floriculture industry. Here, aqua-space samples collected from entire flowers of diploid Freesia refracta, three tetraploid freesia cultivars, and interspecific hybrids of three tetraploid freesia cultivars were analyzed using gas chromatograph coupled with mass selective detector. In all, 75 different compounds were identified. The compounds were mainly terpenes, hydrocarbons, alcohols, fatty acid esters and aromatic class compounds. Among these, linalool was detected from all the sweet-scented flowers except for scentless white tetraploid F. hybrida. Stable inheritance of linalool between F. hybrida and their F1 progeny was observed. Based on the present analyses, the relationship between the aroma of freesia and linalool was discussed.
Abstract (Browse 1122)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Regulation of the High-Affinity Nitrate Transport System in Wheat Roots by Exogenous Abscisic Acid and Glutamine
Author: Chao Cai, Xue-Qiang Zhao, Yong-Guan Zhu, Bin Li, Yi-Ping Tong and Zhen-Sheng Li
Journal of Integrative Plant Biology 2007 49(12): 1714-1718
DOI: 10.1111/j.1744-7909.2007.00485.x
      
    Nitrate is a major nitrogen (N) source for most crops. Nitrate uptake by root cells is a key step of nitrogen metabolism and has been widely studied at the physiological and molecular levels. Understanding how nitrate uptake is regulated will help us engineer crops with improved nitrate uptake efficiency. The present study investigated the regulation of the high-affinity nitrate transport system (HATS) by exogenous abscisic acid (ABA) and glutamine (Gln) in wheat (Triticum aestivum L.) roots. Wheat seedlings grown in nutrient solution containing 2 mmol/L nitrate as the only nitrogen source for 2 weeks were deprived of N for 4 d and were then transferred to nutrient solution containing 50 ¶Őmol/L ABA, and 1 mmol/L Gln in the presence or absence of 2 mmol/L nitrate for 0, 0.5, 1, 2, 4, and 8 h. Treated wheat plants were then divided into two groups. One group of plants was used to investigate the mRNA levels of the HATS components NRT2 and NAR2 genes in roots through semi-quantitative RT-PCR approach, and the other set of plants were used to measure high-affinity nitrate influx rates in a nutrient solution containing 0.2 mmol/L 15N-labeled nitrate. The results showed that exogenous ABA induced the expression of the TaNRT2.1, TaNRT2.2, TaNRT2.3, TaNAR2.1, and TaNAR2.2 genes in roots when nitrate was not present in the nutrient solution, but did not further enhance the induction of these genes by nitrate. Glutamine, which has been shown to inhibit the expression of NRT2 genes when nitrate is present in the growth media, did not inhibit this induction. When Gln was supplied to a nitrate-free nutrient solution, the expression of these five genes in roots was induced. These results imply that the inhibition by Gln of NRT2 expression occurs only when nitrate is present in the growth media. Although exogenous ABA and Gln induced HATS genes in the roots of wheat, they did not induce nitrate influx.
Abstract (Browse 1422)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Omics & Epigenetics
Efficiency for Gene Silencing Induction in Nicotiana Species by a Viral Satellite DNA Vector
Author: You-Ping Xu, Lu-Ping Zheng, Qiu-Fang Xu, Chang-Chun Wang, Xue-Ping Zhou, Zu-Jian Wu and Xin-Zhong Cai
Journal of Integrative Plant Biology 2007 49(12): 1726-1733
DOI: 10.1111/j.1744-7909.2007.00569.x
      
    Virus-induced gene silencing (VIGS) is a useful technique for rapid plant gene function analysis. We recently reported a new VIGS vector modified from Tomato yellow leaf curl China virus (TYLCCNV) DNA¶¬ (DNAm¶¬). In this study we compared in detail DNAm¶¬-induced gene silencing in four Nicotiana species including N. benthamiana, N. glutinosa, N. tabacum and N. paniculata. We found that DNAm¶¬-induced gene silencing in the four species was distinct in developing dynamics, tissue specificity, efficiency, and constancy in the plant life span. It was most efficient in N. benthamiana, where development of VIGS was most rapid, without tissue specificity and nearly 100% efficient. DNAm¶¬-induced gene silencing in N. glutinosa was also efficient despite being slightly less than in N. benthamiana. It initially occurred in veins, later was scattered to mesophyll, finally led to complete silencing in whole leaves. In both species, VIGS constantly expressed until the plants died. However, DNAm¶¬-mediated VIGS in the other two Nicotiana species, N. tabacum and N. paniculata, was significantly less efficient. It was strictly limited within the veins of the silenced leaves, and constantly occurred only over 3®C4 weeks. The upper leaves that emerged later stopped showing the silencing phenotype. DNAm¶¬-induced gene silencing in N. benthamiana and N. glutinosa was not significantly influenced by the growth stage when the plants were agro-inoculated, and was not sensitive to high growth temperature up to 32 °„C. Our results indicate that this system has great potential as a versatile VIGS system for routine functional analysis of genes in some Nicotiana species.
Abstract (Browse 1565)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Development & Photosynthesis
Structures, Components and Functions of Secretory Tissues in Houttuynia cordata
Author: Xi-Lu Ni, Li Peng and Wen-Zhe Liu
Journal of Integrative Plant Biology 2007 49(12): 1734-1745
DOI: 10.1111/j.1744-7909.2007.00481.x
      
    Houttuynia cordata Thunb., traditionally used as a therapeutic plant in folk medicine, has shown antioxidant and anticancer activities. The species, as a core component of paleoherbs, is normally characterized based on the presence of different types of secretory tissue: oil cells, three types of secretory cells and glandular hairs. The aim of this work was to study the structural, componential, and the functional characteristics of the secretory tissues in both the floral and vegetative parts. The results indicate that oil cells and secretory cells are distributed in all organs of the plant, while glandular hairs are situated on the aerial stems and leaves. Both oil cells and glandular hairs initiate from the protoderm, but their developmental processes are different. Although three types of secretory cells initiate from different primary meristems, the developmental patterns of different secretory cells are the same. Also, although the origins of secretory cells are different from oil cells, their early developmental processes are the same. Histochemical results show that oil cells, secretory cells and glandular hairs produce flavonoids, phenolic compounds, tannins, lipids, aldehyde and ketone-compounds. In addition, there are terpenoids and pectic-like substances in oil cells, alkaloids in secretory cells of aerial stems, and terpenoids and alkaloids in glandular hairs. These compounds play very important roles in protecting plants from being eaten by herbivores (herbivory) and infected by microbial pathogens. The oil cell and secretory cell, as unicellular secretory tissues, are intermediates between the primitive surface glandular and secretory cavity and canal during the evolution of secretory structures.
Abstract (Browse 2496)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Genetic Analysis and Molecular Mapping of a Rolling Leaf Mutation Gene in Rice
Author: Ji-Cai Yi, Chu-Xiong Zhuang, Xu-Jie Wang, You-Pei Cao, Yao-Guang Liu and Man-Tong Mei
Journal of Integrative Plant Biology 2007 49(12): 1746-1753
DOI: 10.1111/j.1744-7909.2007.00572.x
      
    A rice mutant with rolling leaf, namely ¶√-rl, was obtained from M2 progenies of a native indica rice stable strain Qinghuazhan (QHZ) from mutagenesis of dry seeds by ¶√-rays. Genetic analysis using the F2 population from a cross between this mutant and QHZ indicated the mutation was controlled by a single recessive gene. In order to map the locus for this mutation, another F2 population with 601 rolling leaf plants was constructed from a cross between ¶√-rl and a japonica cultivar 02428. After primary mapping with SSR (simple sequence repeats) markers, the mutated locus was located at the short arm of chromosome 3, flanked by RM6829 and RM3126. A number of SSR, InDel (insertion/deletion) and SNP (single nucleotide polymorphism) markers within this region were further developed for fine mapping. Finally, two markers, SNP121679 and InDel422395, were identified to be flanked to this locus with genetic distances of 0.08 cM and 0.17 cM respectively, and two SNP markers, SNP75346 and SNP110263, were found to be co-segregated with this locus. These results suggested that this locus was distinguished from all loci for the rolling leaf mutation in rice reported so far, and thus renamed rl10(t). By searching the rice genome database with closely linked markers using BLAST programs, an e-physical map covering rl10(t) locus spanning about a 50 kb region was constructed. Expression analysis of the genes predicted in this region showed that a gene encoding putative flavin-containing monooxygenase (FMO) was silenced in ¶√-rl, thus this is the most likely candidate responsible for the rolling leaf mutation.
Abstract (Browse 1830)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Genome-wide Expression Profiling in Seedlings of the Arabidopsis Mutant uro that is Defective in the Secondary Cell Wall Formation
Author: Zheng Yuan, Xuan Yao, Dabing Zhang, Yue Sun and Hai Huang
Journal of Integrative Plant Biology 2007 49(12): 1754-1762
DOI: 10.1111/j.1744-7909.2007.00586.x
      
    Plant secondary growth is of tremendous importance, not only for plant growth and development but also for economic usefulness. Secondary tissues such as xylem and phloem are the conducting tissues in plant vascular systems, essentially for water and nutrient transport, respectively. On the other hand, products of plant secondary growth are important raw materials and renewable sources of energy. Although advances have been recently made towards describing molecular mechanisms that regulate secondary growth, the genetic control for this process is not yet fully understood. Secondary cell wall formation in plants shares some common mechanisms with other plant secondary growth processes. Thus, studies on the secondary cell wall formation using Arabidopsis may help to understand the regulatory mechanisms for plant secondary growth. We previously reported phenotypic characterizations of an Arabidopsis semi-dominant mutant, upright rosette (uro), which is defective in secondary cell wall growth and has an unusually soft stem. Here, we show that lignification in the secondary cell wall in uro is aberrant by analyzing hypocotyl and stem. We also show genome-wide expression profiles of uro seedlings, using the Affymetrix GeneChip that contains approximately 24 000 Arabidopsis genes. Genes identified with altered expression levels include those that function in plant hormone biosynthesis and signaling, cell division and plant secondary tissue growth. These results provide useful information for further characterizations of the regulatory network in plant secondary cell wall formation.
Abstract (Browse 1686)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Evolution
Traits of Masson Pine Affecting Attack of Pine Wood Nematode
Author: Juan Shi, You-Qing Luo, Ji-Ying Song, Hai-Wei Wu, Lei Wang and Gary Z. Wang
Journal of Integrative Plant Biology 2007 49(12): 1763-1771
DOI: 10.1111/j.1744-7909.2007.00613.x
      
    Masson pine characteristics were analyzed in five sample plots in Zhejiang Province, China. Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (pine wood nematode, PWN) carried by Monochamus alternatus predominately attacked Masson pines in the lower diameter classes. Among the 10 tree characteristics examined, mean crown width, percentage of bole with crown, 5-year cumulative diameter growth, and resin amount showed significant variation between successfully attacked and unattacked trees. The attacked trees had a lower percentage of the bole covered with tree crown, lower crown width, lower radial growth in the last 5 years, and produced less induced resinosis than unattacked trees. Results allowed for effective ranking of the pine forest based on individual tree resistance to PWN. This index of resistance should be considered throughout the development of an "Evaluation Criterion and Indicator System". The preceding ranking can be used to evaluate the resistance and resiliency of the pine forest ecosystem to PWN's invasion, which is similar to Pest Risk Analysis (PRA).
Abstract (Browse 1102)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Genotypes of Heading Date of Middle Indica Rice in the Mid-lower Region of the Yangtze River
Author: Jun-Feng Xu, Ling Jiang, Xiang-Jin Wei, Wen-Wei Zhang, Shi-Jia Liu, Liang-Ming Chen, Lin-Guang Luo and Jian-Min Wan
Journal of Integrative Plant Biology 2007 49(12): 1772-1781
DOI: 10.1111/j.1744-7909.2007.00580.x
      
    Middle indica cultivars are planted in the middle to lower regions of the Yangtze River. Hybrid combinations with these cultivars have a high yield potential but the presence of late-transgressive-segregants limits the further exploitation of heterosis. To understand the genetic basis of the heading date in these middle maturing cultivars, we carried out a genetic analysis of 10 typical middle-season cultivars using a number of heading date isogenic lines under both long and short day conditions. The results showed that Teqing, 752, CDR22, Bo B, 9311 and II-32B carry two photoperiod sensitive genes E1 or Se-1 and E3, and Teqing, 752 and CDR22 carry a dominant early-heading gene Ef-1 while Bo B, 9311 and II-32B carry a recessive late-heading gene ef-1. Based on the findings of the present and previous works on Guichao 2, Minghui 63, Nanjing 11 and Pei'ai64S, it was concluded that all of these middle indica cultivars carried the recessive allele hd2, which could inhibit the expression of E1 or Se-1, and they formed rational combinations of genotype for heading date during a long period of evolution. The effects of the different combinations of genotype for heading date on rice cultivation and extension were discussed, and genetic basis of broad adaptability of hybrid middle indica cultivars was analyzed.
Abstract (Browse 1531)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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