July 2010, Volume 52 Issue 7, Pages 602C691.

Cover Caption: GAMYB-regulated Anther Development
Anther development in plants is a complex biological process, which requires the cooperative interaction of sporophytic and gametophytic genes. The study of Liu et al. (pp 670C678) identified a new allele of GAMYB and analyzed its functions in rice anther development. The cover picture shows the yellow anthers from the wildtype plants and the white and smaller anthers in the male sterile gamyb-4 mutant. Subsequent expression analysis revealed an elaborate gene regulatory network in rice anther development.


          Cell and Developmental Biology
Starch Synthesis and Programmed Cell Death during Endosperm Development in Triticale (Triticosecale Wittmack)
Author: Chun-Yan Li, Wei-Hua Li, Cheng Li, Denis A. Gaudet, André Laroche, Lian-Pu Cao and Zhen-Xiang Lu
Journal of Integrative Plant Biology 2010 52(7): 602-615
Published Online: May 21, 2010
DOI: 10.1111/j.1744-7909.2010.00961.x

Triticale (×Triticosecale Wittmack) grains synthesize and accumulate starch as their main energy source. Starch accumulation rate and synthesis activities of ADP-glucose pyrophosphorylase, soluble starch synthases, granule-bound starch synthase and starch-branching enzyme showed similar pattern of unimodal curves during endosperm development. There was no significant difference in activity of the starch granule-bound protein isolated from total and separated starch granules at different developmental stages after anthesis in triticale. Evans Blue staining and analysis of DNA fragmentation indicated that cells of triticale endosperm undergo programmed cell death during its development. Dead cells within the endosperm were detected at 6 d post anthesis (DPA), and evidence of DNA fragmentation was first observed at 21 DPA. The period between initial detection of PCD to its rapid increase overlapped with the key stages of rapid starch accumulation during endosperm development. Cell death occurred stochastically throughout the whole endosperm, meanwhile, the activities of starch biosynthetic enzymes and the starch accumulation rate decreased in the late stages of grain filling. These results suggested that the timing and progression of PCD in triticale endosperm may interfere with starch synthesis and accumulation.

Li CY, Li WH, Li C, Gaudet DA, Laroche A, Cao LP, Lu ZX (2010) Starch synthesis and programmed cell death during endosperm development in triticale (× Triticosecale Wittmack). J. Integr. Plant Biol. 52(7), 602–615.

Abstract (Browse 2988)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Coronatine Alleviates Water Deficiency Stress on Winter Wheat Seedlings
Author: Xiangwen Li, Xuefeng Shen, Jianmin Li, Anthony Egrinya Eneji, Zhaohu Li, Xiaoli Tian and Liusheng Duan
Journal of Integrative Plant Biology 2010 52(7): 616-625
Published Online: May 24, 2010
DOI: 10.1111/j.1744-7909.2010.00958.x

With the aim to determine whether coronatine (COR) alleviates drought stress on wheat, two winter wheat (Triticum aestivum L.) cultivars, ChangWu134 (drought-tolerant) and Shan253 (drought-sensitive) were studied under hydroponic conditions. Seedlings at the three-leaf stage were cultured in a Hoagland solution containing COR at 0.1 μM for 24 h, and then exposed to 20% polyethylene glycol 6000 (PEG-6000). Under simulated drought (SD), COR increased the dry weight of shoots and roots of the two cultivars significantly; the root/shoot ratio also increased by 30% for Shan253 and 40% for ChangWu134. Both cultivars treated with COR under SD (0.1COR+PEG) maintained significantly higher relative water content, photosynthesis, transpiration, intercellular concentration of CO2 and stomatal conductance in leaves than those not treated with PEG. Under drought, COR significantly decreased the relative conductivity and malondialdehyde production, and the loss of 1,1-diphenyl-2-picrylhydrazyl scavenging activity in leaves was significantly alleviated in COR-treated plants. The activity of peroxidase, catalase, glutathione reductase and ascorbate peroxidase were adversely affected by drought. Leaves of plants treated with COR under drought produced less abscisic acid (ABA) than those not treated. Thus, COR might alleviate drought effects on wheat by reducing active oxygen species production, activating antioxidant enzymes and changing the ABA level.

Li X, Shen X, Li J, Eneji AE, Li Z, Tian X, Duan L (2010) Coronatine alleviates water deficiency stress on winter wheat seedlings. J. Integr. Plant Biol. 52(7), 616–625.

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The Interactions among DWARF10, Auxin and Cytokinin underlie Lateral Bud Outgrowth in Rice  
Author: Shuying Zhang, Gang Li, Jun Fang, Weiqi Chen, Haipai Jiang,Junhuang Zou, Xue Liu, Xianfeng Zhao, Xiaobing Li, Chengcai Chu, Qi Xie, Xiangning Jiang and Lihuang Zhu
Journal of Integrative Plant Biology 2010 52(7): 626-638
Published Online: May 27, 2010
DOI: 10.1111/j.1744-7909.2010.00960.x

Previous studies have shown that DWARF10 (D10) is a rice ortholog of MAX4/RMS1/DAD1, encoding a carotenoid cleavage dioxygenase and functioning in strigolactones/strigolactone-derivatives (SL) biosynthesis. Here we use D10- RNA interference (RNAi) transgenic plants similar to d10 mutant in phenotypes to investigate the interactions among D10, auxin and cytokinin in regulating rice shoot branching. Auxin levels in node 1 of both decapitated D10-RNAi and wild type plants decreased significantly, showing that decapitation does reduce endogenous auxin concentration, but decapitation has no clear effects on auxin levels in node 2 of the same plants. This implies that node 1 may be the location where a possible interaction between auxin and D10 gene would be detected. D10 expression in node 1 is inhibited by decapitation, and this inhibition can be restored by exogenous auxin application, indicating that D10 may play an important role in auxin regulation of SL. The decreased expression of most OsPINs in shoot nodes of D10-RNAi plants may cause a reduced auxin transport capacity. Furthermore, effects of auxin treatment of decapitated plants on the expression of cytokinin biosynthetic genes suggest that D10 promotes cytokinin biosynthesis by reducing auxin levels. Besides, in D10- RNAi plants, decreased storage cytokinin levels in the shoot node may partly account for the increased active cytokinin contents, resulting in more tillering phenotypes.

Zhang S, Li G, Fang J, Chen W, Jiang H, Zou J, Liu X, Zhao X, Li X, Chu C, Xie Q, Jiang X, Zhu L (2010) The interactions among DWARF10, auxin and cytokinin underlie lateral bud outgrowth in rice. J. Integr. Plant Biol. 52(7), 626–638.

Abstract (Browse 4079)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
Characterization and Expression Analysis of Medicago truncatula ROP GTPase Family during the Early Stage of Symbiosis
Author: Wei Liu, Ai-Min Chen, Li Luo, Jie Sun, Lian-Pu Cao, Guan-Qiao Yu, Jia-Bi Zhu and Yan-Zhang Wang
Journal of Integrative Plant Biology 2010 52(7): 639-652
Published Online: May 4, 2010
DOI: 10.1111/j.1744-7909.2010.00944.x

ROPs (Rho-related GTPases of plants) are small GTPases that are plant-specific signaling proteins. They act as molecular switches in a variety of developmental processes. In this study, seven cDNA clones coding for ROP GTPases have been isolated in Medicago truncatula, and conserved and divergent domains are identified in these predicted MtROP proteins. Phylogenetic analysis has indicated that MtROPs are distributed into groups II, III, IV but group I. MtROP genes are expressed in various tissues at different levels. A quantitative reverse transcription PCR analysis indicated that these MtROP genes have different expression profiles in the roots in response to infection with rhizobia. The expression of MtROP3, MtROP5 and MtROP6 are increased, as the expression of Nod factor or rhizobial-induced marker genes—NFP, Rip1 and Enod11; MtROP10 has showed enhanced expression at a certain post-inoculation time point. No significant changes in MtROP7 and MtROP9 expression have been detected and MtROP8 expression is dramatically decreased by about 80%–90%. Additionally, ROP promoter-GUS analysis has showed that MtROP3, MtROP5 and MtROP6 have elevated expression in transgenic root hairs after rhizobial inoculation. These results might suggest a role for some ROP GTPases in the regulation of early stages during rhizobial infection in symbiosis.

Liu W, Chen AM, Luo L, Sun J, Cao LP, Yu GQ, Zhu JB, Wang YZ (2010) Characterization and expression analysis of Medicago truncatula ROP GTPase family during the early stage of symbiosis. J. Integr. Plant Biol. 52(7), 639–652.

Abstract (Browse 2551)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Molecular Physiology
Senescence-Inducible Expression of Isopentenyl Transferase Extends Leaf Life, Increases Drought Stress Resistance and Alters Cytokinin Metabolism in Cassava  
Author: Peng Zhang, Wen-Quan Wang, Gen-Liang Zhang, Miroslav Kaminek, Petre Dobrev, Jia Xu and Wilhelm Gruissem
Journal of Integrative Plant Biology 2010 52(7): 653-669
Published Online: May 13, 2010
DOI: 10.1111/j.1744-7909.2010.00956.x

Cassava (Manihot esculenta Crantz) sheds its leaves during growth, especially within the tropical dry season. With the production of SAG12-IPT transgenic cassava we want to test the level of leaf retention and altered cytokinin metabolism of transgenic plants via the autoregulatory senescence inhibition system. After confirmation of transgene expression by molecular analysis and phenotype examination in greenhouse plants, two transgenic plant lines, 529-28 and 529-48, were chosen for further investigation. Detached mature leaves of 529-28 plants retained high levels of chlorophyll compared with wild-type leaves after dark-induced senescence treatment. Line 529-28 showed significant drought tolerance as indicated by stay-green capacity after drought stress treatment. Field experiments proved that leaf senescence syndrome was significantly delayed in 529-28 plants in comparison with wild-type and 529-48 plants. Physiological and agronomical characterizations of these plants also revealed that the induced expression of IPT had effects on photosynthesis, sugar allocation and nitrogen partitioning. Importantly, the 529-28 plants accumulated a high level of trans-zeatin-type cytokinins particularly of corresponding storage O-glucosides to maintain cytokinin homeostasis. Our study proves the feasibility of prolonging the leaf life of woody cassava and also sheds light on the control of cytokinin homeostasis in cassava leaves.

Zhang P, Wang WQ, Zhang GL, Kaminek M, Dobrev P, Xu J, Gruissem W (2010) Senescence-inducible expression of isopentenyl transferase extends leaf life, increases drought stress resistance and alters cytokinin metabolism in cassava. J. Integr. Plant Biol. 52(7), 653–669.

Abstract (Browse 2555)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant Reproduction Biology
Identification of gamyb-4 and Analysis of the Regulatory Role of GAMYB in Rice Anther Development
Author: Zhenhua Liu, Wenjie Bao, Wanqi Liang, Jingyuan Yin and Dabing Zhang
Journal of Integrative Plant Biology 2010 52(7): 670-678
Published Online: May 25, 2010
DOI: 10.1111/j.1744-7909.2010.00959.x

In higher plants, male reproductive development is a complex biological process that includes cell division and differentiation, cell to cell communication etc., while the mechanism underlying plant male reproductive development remains less understood. GAMYB encodes a gibberellins acid (GA) inducible transcription factor that is required for the early anther development in rice (Oryza sativa L.). Here, we report the isolation and characterization of a new allele gamyb-4 with a C base deletion in the second exon (+2308), causing a frame shift and premature translational termination. Histological analysis showed that gamyb-4 developed abnormal enlarged tapetum and could not undergo normal meiosis. To understand the regulatory role of GAMYB, we carried out quantitative reverse transcription- polymerase chain reaction analysis and comparison of microarray data. These results revealed that the expression of TDR (TAPETUM DEGENERATION RETARDATION), a tapetal cell death regulator, was downregulated in gamyb-4 and udt1 (undeveloped tapetum1). While the GAMYB expression was not obviously changed in tdr and udt1-1, and no apparent expression fold change of UDT1 in tdr and gamyb-4, suggesting that TDR may act downstream of GAMYB and UDT1, and GAMYB and UDT1 work in parallel to regulate rice early anther development. This work is helpful in understanding the regulatory network in rice anther development.

Liu Z, Bao W, Liang W, Yin J, Zhang D (2010) Identification of gamyb-4 and analysis of the regulatory role of GAMYB in rice anther development. J. Integr. Plant Biol. 52(7), 670–678.

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          Molecular Ecology and Evolution
Effective Isolation of Retrotransposons and Repetitive DNA Families from the Wheat Genome
Author: Motonori Tomita, Munenori Asao and Aya Kuraki
Journal of Integrative Plant Biology 2010 52(7): 679-691
Published Online: May 25, 2010
DOI: 10.1111/j.1744-7909.2010.00954.x

New classes of repetitive DNA elements were effectively identified by isolating small fragments of the elements from the wheat genome. A wheat A genome library was constructed from Triticum monococcum by degenerate cleavage with EcoO109I, the recognition sites of which consisted of 5'-PuGGNCCPy-3' multi-sequences. Three novel repetitive sequences pTm6, pTm69 and pTm58 derived from the A genome were screened and tested for high copy number using a blotting approach. pTm6 showed identity with integrase domains of the barley Ty1-Copia-retrotransposon BARE-1 and pTm58 showed similarity to the barley Ty3-gypsy-like retrotransposon Romani. pTm69, however, constituted a tandem array with useful genomic specificities, but did not share any identity with known repetitive elements. This study also sought to isolate wheat D-genome-specific repetitive elements regardless of the level of methylation, by genomic subtraction. Total genomic DNA of Aegilops tauschii was cleaved into short fragments with a methylation-insensitive 4 bp cutter, MboI, and then common DNA sequences between Ae. tauschii and Triticum turgidum were subtracted by annealing with excess T. turgidum genomic DNA. The D genome repetitive sequence pAt1 was isolated and used to identify an additional novel repetitive sequence family from wheat bacterial artificial chromosomes with a size range of 1 395–1 850 bp. The methods successfully led pathfinding of two unique repetitive families.

Tomita M, Asao M, Kuraki A (2010) Effective isolation of retrotransposons and repetitive DNA families from the wheat genome. J. Integr. Plant Biol. 52(7), 679–691.

Abstract (Browse 2086)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
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