July 2009, Volume 51 Issue 7, Pages 626-713.


Cover Caption: Formation of Tension Wood
Tension wood (TW) is formed in leaning hardwood trees. One of the main characteristics of TW, which distinguishes it from normal wood, is the formation of fibers with a thick inner gelatinous cell wall layer. AVG and AgNO3 treatments do not inhibit the formation of gelatinous fibers on the adaxial side in horizontallypositioned Fraximus mandshurica seedlings. The cover picture shows gelatinous fibers formed in these seedling. See pages 707ĘC713 for details (cover design: Ying Wang).

 

          Metabolism and Biochemistry
Molecular and Biochemical Evidence for Phenypropanoid Synthesis and Presence of Wall-linked Phenolics in Cotton Fibers  
Author: Ling Fan, Wei-Jun Shi, Wen-Ran Hu, Xiao-Yan Hao, Dong-Mei Wang, Hui Yuan and Hong-Ying Yan
Journal of Integrative Plant Biology 2009 51(7): 626-637
Published Online: June 25, 2009
DOI: 10.1111/j.1744-7909.2009.00840.x
      
    

The mature cotton (Gossypium hirsutum L.) fiber is a single cell with a typically thickened secondary cell wall. The aim of this research was to use molecular, spectroscopic and chemical techniques to investigate the possible occurrence of previously overlooked accumulation of phenolics during secondary cell wall formation in cotton fibers. Relative quantitative reverse transcription-polymerase chain reaction analysis showed that GhCAD6 and GhCAD1 were predominantly expressed among seven gene homologs, only GhCAD6 was up regulated during secondary wall formation in cotton fibers. Phylogenic analysis revealed that GhCAD6 belonged to Class I and was proposed to have a major role in monolignol biosynthesis, and GhCAD1 belonged to Class III and was proposed to have a compensatory mechanism for monolignol biosynthesis. Amino acid sequence comparison showed that the cofactor binding sites of GhCADs were highly conserved with high similarity and identity to bona fide cinnamyl alcohol dehydrogenases. The substrate binding site of GhCAD1 is different from GhCAD6. This difference was confirmed by the different catalytic activities observed with the enzymes. Cell wall auto-fluorescence, Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and chemical analyses confirmed that phenolic compounds were bound to the cell walls of mature cotton fibers. Our findings may suggest a potential for genetic manipulation of cotton fiber properties, which are of central importance to agricultural, cotton processing and textile industries.
 

Fan L. Shi WJ, Hu WR, Hao XY, Wang DM, Yuan H, Yan HY (2009). Molecular and biochemical evidence for phenypropanoid synthesis and presence of wall-linked phenolics in cotton fibers. J. Integr. Plant Biol. 51(7), 626-637

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          Plant-environmental Interactions
Reactive Oxygen Species Scavenging Enzymes and Down-Adjustment of Metabolism Level in Mitochondria Associated with Desiccation-Tolerance Acquisition of Maize Embryo
Author: Jing-Hua Wu, Wei-Qing Wang, Song-Quan Song and Hong-Yan Cheng
Journal of Integrative Plant Biology 2009 51(7): 638-645
Published Online: June 25, 2009
DOI: 10.1111/j.1744-7909.2009.00841.x
      
    

It is a well-known fact that a mature seed can survive losing most of its water, yet how seeds acquire desiccation-tolerance is not well understood. Through sampling maize embryos of different developmental stages and comparatively studying the integrity, oxygen consumption rate and activities of antioxidant enzymes in the mitochondria, the main origin site of reactive oxygen species (ROS) production in seed cells, we found that before an embryo achieves desiccation-tolerance, its mitochondria shows a more active metabolism, and might produce more ROS and therefore need a more effective ROS scavenging system. However, embryo dehydration in this developmental stage declined the activities of most main antioxidant enzymes and accumulated thiobarbituric acid-reactive products in mitochondria, and then destroyed the structure and functional integrity of mitochondria. In physiologically-matured embryos (dehydration-tolerant), mitochondria showed lower metabolism levels, and no decline in ROS scavenging enzyme activities and less accumulation of thiobarbituric acid-reactive products after embryo dehydration. These data indicate that seed desiccation-tolerance acquisition might be associated with down-adjustment of the metabolism level in the late development stage, resulting in less ROS production, and ROS scavenging enzymes becoming desiccation-tolerant and then ensuring the structure and functional integrity of mitochondria.

Wu JH, Wang WQ, Song SQ, Cheng HY (2009).Reactive oxygen species scavenging enzymes and down-adjustment of metabolism level in mitochondria associated with desiccation-tolerance acquisition of maize embryo. J. Integr. Plant Biol. 51(7), 638-645.

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The Response Difference of Mitochondria in Recalcitrant Antiaris toxicaria Axes and Orthodox Zea mays Embryos to Dehydration Injury
Author: Song-Quan Song, Mei-Hua Tian, Jing Kan and Hong-Yan Cheng
Journal of Integrative Plant Biology 2009 51(7): 646-653
Published Online: May 21, 2009
DOI: 10.1111/j.1744-7909.2009.00836.x
      
    

Long-term preservation of recalcitrant seeds is very difficult because the physiological basis on their desiccation sensitivity is poorly understood. Survival of Antiaris toxicaria axes rapidly decreased and that of immature maize embryos very slowly decreased with dehydration. To understand their different responses to dehydration, we examined the changes in mitochondria activity during dehydration. Although activities of cytochrome (Cyt) c oxidase and malate dehydrogenase of the A. toxicaria axis and maize embryo mitochondria decreased with dehydration, the parameters of maize embryo mitochondria were much higher than those of A. toxicaria, showing that the damage was more severe for the A. toxicaria axis mitochondria than for those of maize embryo. The state I and III respiration of the A. toxicaria axis mitochondria were higher than those of maize embryo, the former rapidly decreased, and the latter slowly decreased with dehydration. The proportion of Cyt c pathway to state III respiration for the A. toxicaria axis mitochondria was low and rapidly decreased with dehydration, and the proportion of alternative oxidase pathway was high and slightly increased with dehydration. In contrast, the proportion of Cyt c pathway for maize embryo mitochondria was high, and that of alternative oxidase pathway was low. Both pathways decreased slowly with dehydration.
 

Song SQ, Tian MH, Kan J, cheng HY (2009). The Response difference of mitochondria in recalcitrant Antiaris toxicaria axes and orthodox Zea mays embryos to dehydration injury. J. Integr. Plant Biol. 51(7), 646-653.

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Involvement of Protein Phosphorylation in Water Stress-induced Antioxidant Defense in Maize Leaves
Author: Shucheng Xu, Haidong Ding, Fengxia Su, Aying Zhang and Mingyi Jiang
Journal of Integrative Plant Biology 2009 51(7): 654-662
Published Online: June 25, 2009
DOI: 10.1111/j.1744-7909.2009.00844.x
      
    

Using pharmacological and biochemical approaches, the role of protein phosphorylation and the interrelationship between water stress-enhanced kinase activity, antioxidant enzyme activity, hydrogen peroxide(H2O2) accumulation and endogenous abscisic acid in maize (Zea mays L.) leaves were investigated. Water-stress upregulated the activities of total protein phosphorylation and Ca2+-dependent protein kinase, and the upregulation was blocked in abscisic acid-deficient vp5 mutant. Furthermore, pretreatments with a nicotinamide adenine dinucleotide phosphate oxidase inhibitor and a scavenger of H2O2 significantly reduced the increased activities of total protein kinase and Ca2+-dependent protein kinase in maize leaves exposed to water stress. Pretreatments with different protein kinase inhibitors also reduced the water stress-induced H2O2 production and the water stress-enhanced activities of antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase. The data suggest that protein phosphorylation and H2O2 generation are required for water stress-induced antioxidant defense in maize leaves and that crosstalk between protein phosphorylation and H2O2 generation may occur.
 

Xu S, Ding H, Su F, Zhang A, Jiang M (2009).Involvement of protein phosphorylation in water stress-induced antioxidant defense in maize leaves. J. Integr. Plant Biol. 51(7), 654-662

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Regulation of OsSPX1 and OsSPX3 on Expressions of OsSPX domain Genes and Pi-starvation Signaling in Rice  
Author: Zhiye Wang, Han Hu, Hongjie Huang, Ke Duan, Zhongchang Wu and Ping Wu
Journal of Integrative Plant Biology 2009 51(7): 663-674
Published Online: May 14, 2009
DOI: 10.1111/j.1744-7909.2009.00834.x
      
    

The rice (Oryza sativa L.) genome contains at least six genes exclusively with an SPX (SYG1/PHO81/XPR1) domain at the N-terminal, designated as OsSPX1-6. Here we report the diverse expression patterns of the OsSPX genes in different tissues and their responses to Pi-starvation. Among them, five genes, OsSPX1, 2, 3, 5 and 6 are responsive to Pi-starvation in shoots and/or in roots. The subcellular localization analysis indicates that OsSPX1 and OsSPX2 is exclusively located in nucleus, OsSPX3 in the cytoplasm, and OsSPX4 is a membrane localization protein. OsSPX1 regulates OsSPX2, 3 and 5 at the transcription level and is positively involved in the responses of the genes to Pi-starvation. Overexpression of OsSPX3 downregulates OsSPX5 in shoots under Pi-sufficiency. OsSPX3 negatively regulates the PSI (Pi starvation induced) gene, OsIPS1 and is involved in the responses of miR399 and OsPHO2 to Pi-starvation. Our results suggest that OsSPX1 may be a regulator involved in the transcriptions of OsSPX2, 3 and 5. OsSPX3 plays a role in OsIPS1/miR399 mediated long distance regulation on OsPHO2. Our results also indicate that OsSPX3 is involved in plant tolerance to Pi-starvation stress.
 

Wang Z, Hu H, Huang H, Duan K,Wu Z,Wu P (2009). Regulation of OsSPX1 and OsSPX3 on expression of OsSPX domain genes and Pi-starvation signaling in rice. J. Integr. Plant Biol. 51(7), 663-674.

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          Molecular Physiology
Oxygation Enhances Growth, Gas Exchange and Salt Tolerance of Vegetable Soybean and Cotton in a Saline Vertisol
Author: Surya P. Bhattarai and David J. Midmore
Journal of Integrative Plant Biology 2009 51(7): 675-688
Published Online: June 25, 2009
DOI: 10.1111/j.1744-7909.2009.00837.x
      
    

Impacts of salinity become severe when the soil is deficient in oxygen. Oxygation (using aerated water for subsurface drip irrigation of crop) could minimize the impact of salinity on plants under oxygen-limiting soil environments. Pot experiments were conducted to evaluate the effects of oxygation (12% air volume/volume of water) on vegetable soybean (moderately salt tolerant) and cotton (salt tolerant) in a salinized vertisol at 2, 8, 14, 20 dS/m ECe. In vegetable soybean, oxygation increased above ground biomass yield and water use efficiency (WUE) by 13% and 22%, respectively, compared with the control. Higher yield with oxygation was accompanied by greater plant height and stem diameter and reduced specific leaf area and leaf Na+ and Cl concentrations. In cotton, oxygation increased lint yield and WUE by 18% and 16%, respectively, compared with the control, and was accompanied by greater canopy light interception, plant height and stem diameter. Oxygation also led to a greater rate of photosynthesis, higher relative water content in the leaf, reduced crop water stress index and lower leaf water potential. It did not, however, affect leaf Na+ or Cl concentration. Oxygation invariably increased, whereas salinity reduced the K+ : Na+ ratio in the leaves of both species. Oxygation improved yield and WUE performance of salt tolerant and moderately tolerant crops under saline soil environments, and this may have a significant impact for irrigated agriculture where saline soils pose constraints to crop production.
 

Bhattarai SP, Midmore DJ (2009).Oxygation enhances growth, gas exchange and salt tolerance of vegetable soybean and cotton in a saline vertisol. J. Integr. Plant Biol. 51(7), 675-688.

Abstract (Browse 1255)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Ecology and Evolution
Growth, and Nitrogen Uptake and Flow in Maize Plants Affected by Root Growth Restriction
Author: Liangzheng Xu, Junfang Niu, Chunjian Li and Fusuo Zhang
Journal of Integrative Plant Biology 2009 51(7): 689-697
Published Online: June 25, 2009
DOI: 10.1111/j.1744-7909.2009.00843.x
      
    

The objective of the present study was to investigate the influence of a reduced maize root-system size on root growth and nitrogen (N) uptake and flow within plants. Restriction of shoot-borne root growth caused a strong decrease in the absorption of root: shoot dry weight ratio and a reduction in shoot growth. On the other hand, compensatory growth and an increased N uptake rate in the remaining roots were observed. Despite the limited long-distance transport pathway in the mesocotyl with restriction of shoot-borne root growth, N cycling within these plants was higher than those in control plants, implying that xylem and phloem flow velocities via the mesocotyl were considerably higher than in plants with an intact root system. The removal of the seminal roots in addition to restricting shoot-borne root development did not affect whole plant growth and N uptake, except for the stronger compensatory growth of the primary roots. Our results suggest that an adequate N supply to maize plant is maintained by compensatory growth of the remaining roots, increased N uptake rate and flow velocities within the xylem and phloem via the mesocotyl, and reduction in the shoot growth rate.

Xu L, Niu J, Li C, Zhang F (2009). Growth, and nitrogen uptake and flow in maize plants affected by root growth restriction. J.Integr.Plant Biol. 51(7),689-697.

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Repeated Range Expansion and Glacial Endurance of Potentilla glabra (Rosaceae) in the Qinghai-Tibetan Plateau
Author: Liu-Yang Wang, Hiroshi Ikeda, Teng-Liang Liu, Yu-Jin Wang and Jian-Quan Liu
Journal of Integrative Plant Biology 2009 51(7): 698-706
Published Online: May 21, 2009
DOI: 10.1111/j.1744-7909.2009.00818.x
      
    

To date, little is still known about how alpine species occurring in the Qinghai-Tibetan Plateau (QTP) responded to past climatic oscillations. Here, by using variations of the chloroplast trnT-L, we examined the genetic distribution pattern of 101 individuals of Potentilla glabra, comprising both the interior QTP and the plateau edge. Phylogenetic and network analyses of 31 recovered haplotypes identified three tentative clades (A, B and C). Analysis of molecular variance (AMOVA) revealed that most of the genetic variability was found within populations (0.693), while differentiations between populations were obviously distinct (Fst = 0.307). Two independent range expansions within clades A and B occurring at approximately 316 and 201 thousand years ago (kya) were recovered from the hierarchical mismatch analysis, and these two expansions were also confirmed by Fu’s FS values and ‘g’ tests. However, distant distributions of clade C and private haplotypes from clades A and B suggest that they had survived the Last Glacial Maximum (LGM) and previous glaciers in situ since their origins. Our findings based on available limited samples support that multiple refugia of a few cold-enduring species had been maintained in the QTP platform during LGM and/or previous glacial stages.

Wang LY, Ikeda H, Liu TL, Wang YJ, Liu JQ (2009). Repeated range expansion and glacial endurance of Potentilla glabra (Rosaceae) in the Qinghai-Tibetan Plateau. J. Integr. Plant Biol. 51(7), 698-706.

Abstract (Browse 1842)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Ethylene Evolution Changes in Tilted Fraxinus mandshurica Rupr. var. japonica Maxim. Seedlings in Relation to Tension Wood Formation
Author: Sha Jiang, Ke Xu, Na Zhao, Shu-Xin Zheng, Yan-Ping Ren, Yu-Bao Gao and Song Gu
Journal of Integrative Plant Biology 2009 51(7): 707-713
Published Online: May 14, 2009
DOI: 10.1111/j.1744-7909.2009.00835.x
      
    

The effects of ethylene on tension wood formation were studied in 3-year-old Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings in two separate experiments. In experiment 1, ethylene evolution of buds and stems was measured using gas chromatography after 0, 2, 4, 7, 14, and 21 d of treatment; in experiment 2, both aminoethoxyvinylglycine (AVG) and AgNO3 were applied to the horizontally-placed stems, and the cell numbers on sites of applications were measured after 40 d. Ethylene evolution from buds was found to be much greater in tilted seedlings than in upright ones. The cell numbers of wood fibers in shoots and 1-year-old stems were reduced in treatments with 12.5 × 10−7 μmol/L AVG, 12.5 × 10−8 μmol/L AVG, and 11.8 × 10−8 μmol/L AgNO3; whereas the horizontal and vertical diameters were reduced by treatment of 12.5 × 10−7 μmol/L AVG. Ethylene evolutions of shoots and 1-year-old stems were inhibited greatly in comparison with the control by applying 12.5 × 10−7 μmol/L AVG. The formation of a gelatinous layer of wood fibers was affected by neither AVG nor AgNO3 application. These results suggest that ethylene regulates the quantity of wood production, but does not affect G-layer formation in F. mandshurica Rupr. var. japonica Maxim. seedlings.

Jiang S, Xu K, Zhao N, Zheng SX, Ren YP, Gu S (2009). Ethylene evolution changes in tilted Fraxinus mandshurica Rupr. var. japonica maxim. seedlings in relation to tension wood formation. J. Integr. Plant Biol. doi: 51(7), 707-713.

Abstract (Browse 1885)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
 

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