Functional Studies of FIN219 and SPA1 in the Integration of Far-Red Light and Jasmonic Acid Signaling in Arabidopsis
Date Issued
2011
Date
2011
Author(s)
Chen, Chih-Hao
Abstract
In Arabidopsis, phytochrome A is one of the photoreceptors and responsible for far-red light signal transduction. FAR-RED INSENSITIVE 219 (FIN219)/JAR1 is a positive component in the downstream of phytochrome A signaling and encodes a jasmonic acid (JA)-amido synthatase, catalyzing the synthesis of JA-isoleucine (JA-Ile). In this study, it is found that the transcript of SUPPRESSOR OF PHYA-105 1 (SPA1), a repressor of phytochrome A-mediated responses, is greatly enhanced in the fin219-2 mutant under continuous far-red light (FRc). To determine functional regulation between FIN219 and SPA1, we generated the mimic double mutant (miSPA1/fin219-2), SPA1 overexpression in fin219-2 (SPA1ox/fin219-2), and FIN219 overexpression in spa1 (FIN219ox/spa1) transgenic plants, and the results showed that SPA1 acts downstream of FIN219 in FRc. Phenotypic analysis of the spa1 mutant suggests that SPA1 is required for hypocotyl response to MeJA; besides, Real-time PCR results indicated that the induction of two JA-responsive genes, VSP1 and MYC2, is reduced in spa1 mutant. These data indicate that SPA1 is a positive regulator in JA signaling under FRc condition. Thus, FIN219 may serve as a negative feedback through inhibiting SPA1 to control the magnitude and duration of JA responses in far-red light. By examining JA responses of these transgenic plants, the results reveal that FIN219 plays a major role in JA signaling compared with SPA1. Taken together, these data indicate that FIN219 and SPA1 show genetic interactions and regulatory relation to provide a critical mechanism in the integration of far-red light and JA signaling.
Subjects
far-red light
jasmonic acid
Type
thesis
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