Abstract
Sensitivity to ACR-toxin and hence specificity of the interaction between A. alternata rough lemon pathotype and rough lemon is due to differential post-transcriptional processing of a mitochondrial gene, ACRS (ACR-toxin Sensitivity gene). ACRS is present in the mitochondrial genome of both toxin-sensitive and insensitive citrus, and sensitivity/or insensitivity to ACR-toxin is due to differential post-transcriptional processing of ACRS. Transcripts of ACRS suffer a processing to be dysfunctional in toxin-insensitive citrus, while those in toxin-sensitive rough lemon remain intact without the processing. To identify and characterize citrus genes that respond to pathogens, an expression profile of genes induced by nonpathogenic A. alternata on rough lemon leaves was obtained by sequencing 500 subtractive PCR clones generated from mRNA of leaves inoculated with the fungus after subtraction with that of uninoculated leaves, and the effect of various stresses and volatiles were also examined on the gene expressions.
