Loss of a Callose Synthase Results in Salicylic Acid-Dependent Disease Resistance

Plants attacked by pathogens rapidly deposit callose, a β-1,3-glucan, at wound sites. Traditionally, this deposition is thought to reinforce the cell wall and is regarded as a defense response. Surprisingly, here we found that powdery mildew resistant 4 (pmr4), a mutant lacking pathogen-induced callose, became resistant to pathogens, rather than more susceptible. This resistance was due to mutation of a callose synthase, resulting in a loss of the induced callose response. Double-mutant analysis indicated that blocking the salicylic acid (SA) defense signaling pathway was sufficient to restore susceptibility to pmr4 mutants. Thus, callose or callose synthase negatively regulates the SA pathway.

[1]  S. Somerville,et al.  Isolation and characterization of powdery mildew-resistant Arabidopsis mutants. , 2000, Proceedings of the National Academy of Sciences of the United States of America.

[2]  J. Aist,et al.  Papillae and Related Wound Plugs of Plant Cells , 1976 .

[3]  N. Donofrio,et al.  Abnormal callose response phenotype and hypersusceptibility to Peronospoara parasitica in defence-compromised arabidopsis nim1-1 and salicylate hydroxylase-expressing plants. , 2001, Molecular plant-microbe interactions : MPMI.

[4]  C. Wasternack,et al.  The Arabidopsis Mutant cev1 Links Cell Wall Signaling to Jasmonate and Ethylene Responses Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.002022. , 2002, The Plant Cell Online.

[5]  J. Glazebrook,et al.  Genes controlling expression of defense responses in Arabidopsis--2001 status. , 2001, Current opinion in plant biology.

[6]  D. Meinke,et al.  A cytokinesis-defective mutant of Arabidopsis (cyt1) characterized by embryonic lethality, incomplete cell walls, and excessive callose accumulation. , 1998, The Plant journal : for cell and molecular biology.

[7]  N. Keen.  A Century of Plant Pathology: A Retrospective View on Understanding Host-Parasite Interactions. , 2000, Annual review of phytopathology.

[8]  Frederick M. Ausubel,et al.  Isochorismate synthase is required to synthesize salicylic acid for plant defence , 2001, Nature.

[9]  Ana I. Caño-Delgado,et al.  Reduced cellulose synthesis invokes lignification and defense responses in Arabidopsis thaliana. , 2003, The Plant journal : for cell and molecular biology.

[10]  J. Dangl,et al.  Runaway cell death, but not basal disease resistance, in lsd1 is SA- and NIM1/NPR1-dependent. , 2002, The Plant journal : for cell and molecular biology.

[11]  N. Donofrio,et al.  Salicylic acid and NIM1/NPR1-independent gene induction by incompatible Peronospora parasitica in arabidopsis. , 2001, Molecular plant-microbe interactions : MPMI.

[12]  Veena,et al.  Identification of Arabidopsis rat Mutants , 2003, Plant Physiology.

[13]  Jean-Pierre Métraux,et al.  EDS5, an Essential Component of Salicylic Acid–Dependent Signaling for Disease Resistance in Arabidopsis, Is a Member of the MATE Transporter Family Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.010376. , 2002, The Plant Cell Online.

[14]  O. Mattsson,et al.  An Arabidopsis callose synthase , 2002, Plant Molecular Biology.

[15]  Martin J. Mueller,et al.  NPR1 Modulates Cross-Talk between Salicylate- and Jasmonate-Dependent Defense Pathways through a Novel Function in the Cytosol Article, publication date, and citation information can be found at www.plantcell.org/cgi/doi/10.1105/tpc.009159. , 2003, The Plant Cell Online.

[16]  R. Tibshirani,et al.  Significance analysis of microarrays applied to the ionizing radiation response , 2001, Proceedings of the National Academy of Sciences of the United States of America.