Back to Search Start Over

Involvement of specific calmodulin isoforms in salicylic acid-independent activation of plant disease resistance responses

Authors :
Heo, Won Do
Lee, Sang Hyoung
Kim, Min Chul
Kim, Jong Cheol
Chung, Woo Sik
Chun, Hyun Jin
Lee, Kyoung Joo
Park, Chan Young
Park, Hyeong Cheol
Choi, Ji Young
Moo, Je Cho
Source :
Proceedings of the National Academy of Sciences of the United States. Jan 19, 1999, Vol. 96 Issue 2, p766, 6 p.
Publication Year :
1999

Abstract

The [Ca.sup.2+] signal is essential for the activation of plant defense responses, but downstream components of the signaling pathway are still poorly defined. Here we demonstrate that specific calmodulin (CAM) isoforms are activated by infection or pathogen-derived elicitors and participate in [Ca.sup.2+]-mediated induction of plant disease resistance responses. Soybean CaM (SCaM)-4 and SCaM-5 genes, which encode for divergent CaM isoforms, were induced within 30 rain by a fungal elicitor or pathogen, whereas other SCaM genes encoding highly conserved CaM isoforms did not show such response. This pathogen-triggered induction of these genes specifically depended on the increase of intracellular [Ca.sup.2+] level. Constitutive expression of SCaM-4 and SCaM-5 in transgenic tobacco plants triggered spontaneous induction of lesions and induces an array of systemic acquired resistance (SAR)-associated genes. Surprisingly, these transgenic plants have normal levels of endogenous salicylic acid (SA). Furthermore, coexpression of nahG gene did not block the induction of SAR-associated genes in these transgenic plants, indicating that SA is not involved in the SAR gene induction mediated by SCaM-4 or SCaM-5. The transgenic plants exhibit enhanced resistance to a wide spectrum of virulent and avirulent pathogens, including bacteria, fungi, and virus. These results suggest that specific CaM isoforms are components of a SA.independent signal transduction chain leading to disease resistance.

Details

ISSN :
00278424
Volume :
96
Issue :
2
Database :
Gale General OneFile
Journal :
Proceedings of the National Academy of Sciences of the United States
Publication Type :
Academic Journal
Accession number :
edsgcl.54119702