April 2013, Volume 55 Issue 4, Pages 294C408.

Cover Caption: Plant Vascular System
About the cover: This issue focuses on the plant vascular system, with a comprehensive review article written by Lucas et al. (pp. 294C387). The cover drawing illustrates the phosphate-stress signaling and response network (pp. 347C351). A Pi deficiency signal is generated in roots and transported to shoots via the xylem (blue lines). This signal is recognized by source leaves to activate the Pi stress response pathway and then to load the subsequent signals into the phloem (red lines). Phloem-mobile RNAs move to roots to increase Pi uptake and alter root architecture . Different phloem-mobile RNAs are also delivered from source leaves to developing leaves and the shoot apex where they regulate development under Pi-stress conditions.


          Invited Expert Reviews
The Plant Vascular System: Evolution, Development and Functions  
Author: William J. Lucas, Andrew Groover, Raffael Lichtenberger, Kaori Furuta, Shri-Ram Yadav, Ykä Helariutta, Xin-Qiang He, Hiroo Fukuda, Julie Kang, Siobhan M. Brady, John W. Patrick, John Sperry, Akiko Yoshida, Ana-Flor López-Millón, Michael A. Grusak and Pradeep Kachroo
Journal of Integrative Plant Biology 2013 55(4): 294-388
Published Online: April 10, 2013
DOI: 10.1111/jipb.12041

The emergence of the tracheophyte-based vascular system of land plants had major impacts on the evolution of terrestrial biology, in general, through its role in facilitating the development of plants with increased stature, photosynthetic output, and ability to colonize a greatly expanded range of environmental habitats. Recently, considerable progress has been made in terms of our understanding of the developmental and physiological programs involved in the formation and function of the plant vascular system. In this review, we first examine the evolutionary events that gave rise to the tracheophytes, followed by analysis of the genetic and hormonal networks that cooperate to orchestrate vascular development in the gymnosperms and angiosperms. The two essential functions performed by the vascular system, namely the delivery of resources (water, essential mineral nutrients, sugars and amino acids) to the various plant organs and provision of mechanical support are next discussed. Here, we focus on critical questions relating to structural and physiological properties controlling the delivery of material through the xylem and phloem. Recent discoveries into the role of the vascular system as an effective long-distance communication system are next assessed in terms of the coordination of developmental, physiological and defense-related processes, at the whole-plant level. A concerted effort has been made to integrate all these new findings into a comprehensive picture of the state-of-the-art in the area of plant vascular biology. Finally, areas important for future research are highlighted in terms of their likely contribution both to basic knowledge and applications to primary industry.

Lucas WJ, Groover A, Lichtenberger R, Furuta K, Yadav SR, Helariutta Y, He XQ, Fukuda H, Kang J, Brady SM, Patrick JW, Sperry J, Yoshida A, L´ opez-Mill´an AF, Grusak MA, Kachroo P (2013) The plant vascular system: Evolution, development and functions. J. Integr. Plant Biol. 55(4), 294–388.

Abstract (Browse 7179)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
CLE Peptides in Vascular Development
Author: Yi Qiang, Jinbin Wu, Huibin Han and Guodong Wang
Journal of Integrative Plant Biology 2013 55(4): 389-394
Published Online: April 10, 2013
DOI: 10.1111/jipb.12044

The plant vascular system consists of two conductive tissues, phloem and xylem. The vascular meristem, namely the (pro-)cambium, is a stem-cell tissue that gives rise to both xylem and phloem. Recent studies have revealed that CLAVATA3/Embryo Surrounding Region-related (CLE) peptides function in establishing the vascular system through interaction with phytohormones. In particular, TDIF/CLE41/CLE44, phloem-derived CLE peptides, promote the proliferation of vascular cambium cells and prevent them from differentiating into xylem by regulating WOX4 expression through the TDR/PXY receptor. In this review article, we outline recent advances on how CLE peptides function in vascular development in concert with phytohormones through mediating cell-cell communication. The perspective of CLE peptide signaling in vascular development is also discussed.

Qiang Y, Wu J, Han H,Wang G (2013) CLE peptides in vascular development. J. Integr. Plant Biol. 55(4), 389–394.

Abstract (Browse 1340)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
          Plant-environmental Interactions
Classical Ethylene Insensitive Mutants of the Arabidopsis EIN2 Orthologue Lack the Expected hypernodulation Response in Lotus japonicus  
Author: Pick Kuen Chan, Bandana Biswas and Peter M. Gresshoff
Journal of Integrative Plant Biology 2013 55(4): 395-408
Published Online: April 10, 2013
DOI: 10.1111/jipb.12040

Three independent ethylene insensitive mutants were selected from an EMS- mutagenized population of Lotus japonicus MG-20 (Miyakojima). The mutants, called ‘Enigma’, were mutated in the LjEIN2a gene from Lotus chromosome 1, sharing significant homology with Arabidopsis EIN2 (ethylene-insensitive2). All three alleles showed classical ethylene insensitivity phenotypes (e.g., Triple Response), but lacked the increased nodulation phenotype commonly associated with ethylene insensitivity. Indeed, all showed a marginal reduction in nodule number per plant, a phenotype that is enigmatic to sickle, an ethylene-insensitive EIN2 mutant in Medicago truncatula. In contrast to wild type, but similar to an ETR1-1 ethylene ethylene-insensitive transgenic of L. japonicus, enigma mutants formed nodules in between the protoxylem poles, demonstrating the influence of ethylene on radial positioning. Suppression of nodule numbers by nitrate and colonisation by mycorrhizal fungi in the enigma-1 mutant were indistinguishable from the wild-type MG-20. However, reflecting endogenous ethylene feedback, the enigma-1 mutant released more than twice the wild-type amount of ethylene. enigma-1 had a moderate reduction in growth, greater root mass (and lateral root formation), delayed flowering and ripening, smaller pods and seeds. Expression analysis of ethylene-regulated genes, such as ETR1, NRL1 (neverripe-like 1), and EIL3 in shoots and roots of enigma-1 and MG-20 illustrated that the ethylene-insensitive mutation strongly affected transcriptional responses in the root. These mutants open the possibility that EIN2 in L. japonicus, a determinate nodulating legume, acts in a more complex fashion possibly through the presence of a duplicated copy of LjEIN2.

Chan PK, Biswas B, Gresshoff PM (2013) Classical ethylene insensitive mutants of the Arabidopsis EIN2 orthologue lack the expected ‘hypernodulation’ response in Lotus japonicus. J. Integr. Plant Biol. 55(4), 395–408.

Abstract (Browse 1697)  |  References  |  Full Text HTML  |  Full Text PDF  |  Cited By       
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