Light-dependent regulation of the jasmonate pathway

Abstract

Jasmonates (JAs) are plant hormones which are crucial for the response of plants to several biotic and abiotic stresses. Beside this important function, they are involved in several developmental processes throughout plant life. In this short review, we would like to summarize the recent findings about the function of JAs in photomorphogenesis with a main focus on the model plant rice. Early plant development is determined to a large extent by light. Depending on whether seedlings are raised in darkness or in light, they show a completely different appearance which led to the terms skoto- and photomorphogenesis, respectively. The different appearance depending on the light conditions has been used to screen for mutants in photoperception and signalling. By this approach, mutants for several photoreceptors and in the downstream signalling pathways could be isolated. In rice, we and others isolated mutants with a very intriguing phenotype. The mutated genes have been cloned by map-based cloning, and all of them encode for JA biosynthesis genes. The most bioactive form of JAs identified so far is the amino acid conjugate jasmonoyl-isoleucin (JA-Ile). In order to conjugate JA to Ile, an enzyme of the GH3 family, JASMONATE RESISTANT 1, is required. We characterized mutants of OsJAR1 on a physiological and biochemical level and found evidence for redundantly active enzymes in rice.

The role of sugar signaling in plant defense responses against fungal pathogens

“…It was shown that a significant role in the stimulation of resistance to fungal infection is played by phytochromes interacting with phytohormones (Roberts and Paul 2006;Xie et al 2011;Cerrudo et al 2012). Recently several reviews have been published, thoroughly describing the latest discoveries concerning the effect of light on plant resistance to pathogens, including also fungal pathogens (Kazan and Manners 2011;Ballaré et al 2012;Kangasjärvi et al 2012;Svyatyna and Riemann 2012).…”

Ethylene-Inhibited Jasmonic Acid Biosynthesis Promotes Mesocotyl/Coleoptile Elongation of Etiolated Rice Seedlings

“…The photoreceptor mutant osphyA-1 exhibits longer mesocotyls and coleoptiles under continuous far-red light (Takano et al, 2001). Furthermore, light inhibits mesocotyl and coleoptile growth by regulating jasmonic acid (JA) biosynthesis (Svyatyna and Riemann, 2012). Mutants of OsAOS1/CPM1, OsAOC/CPM2, and OsJAR1/OsGH3.5, which are involved in JA biosynthesis (Svyatyna and Riemann, 2012), showed a longer coleoptile phenotype under red light (Biswas et al, 2003;Riemann et al, 2003Riemann et al, , 2008Svyatyna and Riemann, 2012).…”

“…Furthermore, light inhibits mesocotyl and coleoptile growth by regulating jasmonic acid (JA) biosynthesis (Svyatyna and Riemann, 2012). Mutants of OsAOS1/CPM1, OsAOC/CPM2, and OsJAR1/OsGH3.5, which are involved in JA biosynthesis (Svyatyna and Riemann, 2012), showed a longer coleoptile phenotype under red light (Biswas et al, 2003;Riemann et al, 2003Riemann et al, , 2008Svyatyna and Riemann, 2012). Expansins are cell wall-loosening proteins that induce wall stress relaxation and volumetric extension of plant cells (Cho and Cosgrove, 2000;Li et al, 2003).…”

Light-hormone interaction in the red-light-induced suppression of photomorphogenesis in rice seedlings

“…Stress-responsive phytohormone, jasmonic acid (JA) has been reported to be involved in photomorphogenesis (Riemann et al 2008). In rice, the induction of JA biosynthesis genes AOC, AOS1 and OsJAR1 is regulated by phyA and phyB (Svyatyna and Riemann 2012).…”