A phloem-enriched cDNA library from Ricinus: insights into phloem function.

The aim of this study was to identify genes that are expressed in the phloem. Increased knowledge of phloem regulation will contribute to our understanding of its many roles, from transport of solutes to information about interactions with pathogens. A cDNA library constructed from phloem-enriched sap exuding from cut Ricinus communis (L.) hypocotyls was sequenced. To assess contamination from other tissues, two libraries were constructed: one using the first 15 min of exudation and the other from sap collected after 120 min of exudation had elapsed. Of 1012 clones sequenced, 158 unique transcripts were identified. The presence of marker molecules such as profilin, the low occurrence of chloroplast-related mRNAs, and the sieve element localization of constituent mRNA using in situ hybridization were consistent with a phloem origin of the sap. Functional analysis of the cDNAs revealed classifications including ribosomal function, interaction with the environment, transport, DNA/RNA binding, and protein turnover. An analysis of the closest Arabidopsis thaliana (L.) homologue for each clone indicated that genes involved in cell localization, protein synthesis, tissue localization, organ localization, organ differentiation, and cell fate were represented at twice the level occurring in the whole Arabidopsis genome. The transcripts found in this phloem-enriched library are discussed in the context of phloem function and the relationship between the companion cell and sieve element.

[1]  K. Oparka.  Getting the message across: how do plant cells exchange macromolecular complexes? , 2004, Trends in plant science.

[2]  J. Amselem,et al.  Towards deciphering phloem: a transcriptome analysis of the phloem of Apium graveolens. , 2003, The Plant journal : for cell and molecular biology.

[3]  J. Carrington,et al.  Arabidopsis RTM1 and RTM2 genes function in phloem to restrict long-distance movement of tobacco etch virus. , 2001, Plant physiology.

[4]  Y. Gachet,et al.  The growth-related, translationally controlled protein P23 has properties of a tubulin binding protein and associates transiently with microtubules during the cell cycle. , 1999, Journal of cell science.

[5]  T. Masumura,et al.  Construction of a specialized cDNA library from plant cells isolated by laser capture microdissection: toward comprehensive analysis of the genes expressed in the rice phloem. , 2002, The Plant journal : for cell and molecular biology.

[6]  J. Jacquot,et al.  Isolation and characterization of a new peroxiredoxin from poplar sieve tubes that uses either glutaredoxin or thioredoxin as a proton donor. , 2001, Plant physiology.

[7]  W. J. Lucas,et al.  Characterization of Ricinus communis phloem profilin, RcPRO1 , 2000, Plant Molecular Biology.

[8]  A. V. van Bel,et al.  Sieve Tubes in Action , 1998, Plant Cell.

[9]  W. J. Lucas,et al.  Plant paralog to viral movement protein that potentiates transport of mRNA into the phloem. , 1999, Science.

[10]  A. Bel,et al.  The phloem, a miracle of ingenuity , 2003 .

[11]  F. Baluška,et al.  Sink plasmodesmata as gateways for phloem unloading. Myosin VIII and calreticulin as molecular determinants of sink strength? , 2001, Plant physiology.

[12]  W. J. Lucas,et al.  Plasmodesmata as a supracellular control network in plants , 2004, Nature Reviews Molecular Cell Biology.

[13]  F. Divol,et al.  Systemic response to aphid infestation by Myzus persicae in the phloem of Apium graveolens , 2005, Plant Molecular Biology.

[14]  E. Komor.  Source physiology and assimilate transport: the interaction of sucrose metabolism, starch storage and phloem export in source leaves and the effects on sugar status in phloem , 2000 .

[15]  P. Giavalisco,et al.  Proteomics of curcurbit phloem exudate reveals a network of defence proteins. , 2004, Phytochemistry.

[16]  L. Técsi,et al.  Phosphoenolpyruvate carboxykinase in cucumber plants is increased both by ammonium and by acidification, and is present in the phloem , 2004, Planta.

[17]  A. V. van Bel,et al.  Pathogen-induced resistance and alarm signals in the phloem. , 2004, Molecular plant pathology.

[18]  B. Veierskov,et al.  Ubiquitin- and proteasome-dependent proteolysis in plants. , 2001, Physiologia plantarum.

[19]  Philip J. White,et al.  Solute is imported to elongating root cells of barley as a pressure driven-flow of solution. , 2004, Functional plant biology : FPB.

[20]  Anna Kasprzewska.  Plant chitinases--regulation and function. , 2003, Cellular & molecular biology letters.

[21]  P. Hedley,et al.  Differential expression of invertase genes in internal and external phloem tissues of potato (Solanum tuberosum L.). , 2000, Journal of experimental botany.

[22]  A. Shirsat,et al.  The Brassica napus extA extensin gene negative regulatory region controls expression in response to mechanical stresses. , 2003 .

[23]  W. J. Lucas,et al.  Phloem long-distance trafficking of GIBBERELLIC ACID-INSENSITIVE RNA regulates leaf development. , 2005, The Plant journal : for cell and molecular biology.

[24]  Patrick S Schnable,et al.  Laser-capture microdissection, a tool for the global analysis of gene expression in specific plant cell types: identification of genes expressed differentially in epidermal cells or vascular tissues of maize. , 2003, The Plant cell.

[25]  Luguang Wu,et al.  A xylem-specific cellulose synthase gene from aspen (Populus tremuloides) is responsive to mechanical stress. , 2000, The Plant journal : for cell and molecular biology.

[26]  J. Pritchard.  Aphid stylectomy reveals an osmotic step between sieve tube and cortical cells in barley roots , 1996 .

[27]  D. Inzé,et al.  Arabidopsis RADICAL-INDUCED CELL DEATH1 Belongs to the WWE Protein–Protein Interaction Domain Protein Family and Modulates Abscisic Acid, Ethylene, and Methyl Jasmonate Responses , 2004, The Plant Cell Online.

[28]  Takahisa Hayashi,et al.  Evidence That Sucrose Loaded into the Phloem of a Poplar Leaf Is Used Directly by Sucrose Synthase Associated with Various β-Glucan Synthases in the Stem , 2004, Plant Physiology.

[29]  R. D. Sjolund,et al.  Monoclonal antibodies against phloem P-protein from plant tissue cultures. I. Microscopy and biochemical analysis , 1994 .

[30]  M. McCann,et al.  Specific plasma membrane aquaporins of the PIP1 subfamily are expressed in sieve elements and guard cells , 2005, Biology of the cell.

[31]  D. Jackson.  In-situ hybridisation in plants , 1992 .

[32]  J. Milburn.  Phloem exudation from castor bean: Induction by massage , 1970, Planta.

[33]  C. Constantinidou,et al.  Determining protein identity from sieve element sap in Ricinus communis L. by quadrupole time of flight (Q-TOF) mass spectrometry. , 2004, Journal of experimental botany.

[34]  W. J. Lucas,et al.  Phloem long-distance transport of CmNACP mRNA: implications for supracellular regulation in plants. , 1999, Development.

[35]  H. Hayashi,et al.  Proteins in the sieve element-companion cell complexes : their detection, localization and possible functions , 2000 .

[36]  W. J. Lucas,et al.  Rice phloem thioredoxin h has the capacity to mediate its own cell-to-cell transport through plasmodesmata , 1998, Planta.

[37]  J. Pritchard,et al.  Use of aphid stylectomy and RT-PCR for the detection of transporter mRNAs in sieve elements. , 2002, Journal of experimental botany.

[38]  L. Williams,et al.  Sugar transporters in higher plants--a diversity of roles and complex regulation. , 2000, Trends in plant science.

[39]  M. Boutry,et al.  The plant plasma membrane H(+)-ATPase: structure, function and regulation. , 2000, Biochimica et biophysica acta.

[40]  J. Kangasjärvi,et al.  Ozone-Induced Programmed Cell Death in the Arabidopsis radical-induced cell death1 Mutant1 , 2005, Plant Physiology.

[41]  J. Milburn,et al.  Osmoregulation and the control of phloem-sap composition in Ricinus communis L. , 1980, Planta.

[42]  Jae-Yean Kim.  Regulation of short-distance transport of RNA and protein. , 2005, Current opinion in plant biology.

[43]  K. Koch,et al.  Companion-Cell Specific Localization of Sucrose Synthase in Zones of Phloem Loading and Unloading , 1993, Plant physiology.

[44]  W. J. Lucas,et al.  Identification of immunologically related proteins in sieve-tube exudate collected from monocotyledonous and dicotyledonous plants , 1998, Planta.

[45]  A. V. van Bel.  Transport phloem: low profile, high impact. , 2003, Plant physiology.

[46]  A. Pécsváradi,et al.  Sieve-tube exudate from Ricinus communis L. seedlings contains ubiquitin and chaperones , 1995, Planta.

[47]  Sarah J. Gurr,et al.  Molecular plant pathology : a practical approach , 1992 .

[48]  G. Bolwell,et al.  Inducible UDP-glucose dehydrogenase from French bean (Phaseolus vulgaris L.) locates to vascular tissue and has alcohol dehydrogenase activity. , 1996, The Biochemical journal.

[49]  T. Fujiwara,et al.  Detection of several mRNA species in rice phloem sap. , 1998, Plant & cell physiology.

[50]  J. Kehr,et al.  Evidence for the presence and activity of a complete antioxidant defence system in mature sieve tubes. , 2002, The Plant journal : for cell and molecular biology.

[51]  I. Baldwin,et al.  An analysis of plant–aphid interactions by different microarray hybridization strategies , 2004, Molecular ecology.

[52]  S. Hoffmann-Benning,et al.  Comparison of peptides in the phloem sap of flowering and non-flowering Perilla and lupine plants using microbore HPLC followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry , 2002, Planta.

[53]  T. Moriguchi,et al.  Analysis of sucrose synthase genes in citrus suggests different roles and phylogenetic relationships. , 2002, Journal of experimental botany.

[54]  François Parcy,et al.  The mRNA of the Arabidopsis Gene FT Moves from Leaf to Shoot Apex and Induces Flowering , 2005, Science.

[55]  K. Zhu‐Salzman,et al.  Transcriptional Regulation of Sorghum Defense Determinants against a Phloem-Feeding Aphid1 , 2004, Plant Physiology.