Reference "The heterotrimeric G protein alpha subunit acts upstream of the small GTPase Rac in disease resistance of rice"

Reference ID

8203

Title

The heterotrimeric G protein alpha subunit acts upstream of the small GTPase Rac in disease resistance of rice

Source

Proceedings of the National Academy of Sciences of the United States of America, 2002, vol. 99, pp. 13307-13312

Authors (6)

Suharsono-U	Fujisawa-Y
Kawasaki-T	Iwasaki-Y
Satoh-H	Shimamoto-K

Abstract

We used rice dwarf1 (d1) mutants lacking a single-copy Galpha gene and addressed
Galpha's role in disease resistance. d1 mutants exhibited a highly reduced
hypersensitive response to infection by an avirulent race of rice blast.
Activation of PR gene expression in the leaves of the mutants infected with rice
blast was delayed for 24 h relative to the wild type. H(2)O(2) production and PR
gene expression induced by sphingolipid elicitors (SE) were strongly suppressed
in d1 cell cultures. Expression of the constitutively active OsRac1, a small
GTPase Rac of rice, in d1 mutants restored SE-dependent defense signaling and
resistance to rice blast. Galpha mRNA was induced by an avirulent race of rice
blast and SE application on the leaf. These results indicated the role of Galpha
in R gene-mediated disease resistance of rice. We have proposed a model for the
defense signaling of rice in which the heterotrimeric G protein functions
upstream of the small GTPase OsRac1 in the early steps of signaling.