Abstract
The AlSAP gene, which has been isolated from the C4 halophyte grass Aeluropus littoralis, a member of the stress-associated protein gene family. Like other members of this family, AlSAP contains A20 and AN1 zinc-finger domains, and its transcription is induced by abiotic stresses such as salinity, drought, and temperature as well as by several hormones, including abscisic and salicylic acids. Additionally, AlSAP overexpression in rice has been demonstrated to enhance cold and drought stress tolerance. In the present study, we investigated the transcriptional deregulation of stress-related genes following ectopic expression of the AlSAP gene in two transgenic rice lines, namely, RN4 and RN5. Compared with control plants, a total of 1734 and 3650 annotated genes were found to be differentially expressed in the leaves and roots of the RN4 and RN5 lines, respectively. AlSAP transcript accumulation primed the expression of abiotic-stress-related genes involved in transcription, signaling, protein degradation, and hormonal homeostasis in rice plants grown under unstressed conditions. We hypothesized that this priming underlies the enhanced tolerance to abiotic stresses previously reported in AlSAP rice lines. Notably, AlSAP also induces transcript accumulation of genes known to be major negative regulators of pathogen response in rice. Consistently, our results showed that abiotic stress-tolerant AlSAP rice lines also exhibit enhanced susceptibility to rice blast fungus Magnaporthe oryzae.