JIPs and RIPs: the regulation of plant gene expression by jasmonates in response to environmental cues and pathogens.

After its first description as a fragrant constituent of the essentia1 oil of Jasminum grandiflorum (Demole et al., 1962), (-)-jasmonic acid methyl ester (methyl cis-2-(2-penten-l-yl)3-oxocyclopentenyl acetate, also known as methyl jasmonate [MeJA]), and related compounds were found to be widespread in the plant kingdom (Meyer et al., 1984). In addition, jasmonates occur in fungi and algae (for references, see Sembdner and Parthier, 1993). Interestingly, MeJA js also a component of female-attracting pheromones in certain moths (Baker et al., 1991). (-)-Jasmonic acid [(-)-JA] and its derivatives are cyclopentanone compounds that are synthesized from linolenic acid by a sequence of as yet poorly characterized reactions (Vick and Zimmerman, 1984). The natural biosynthetic product of this pathway in most plant species appears to be (+)-7-iso-JA, which is rapidly converted into (-)-JA by isomerization. (-)-JA has been shown to undergo various modifications, giving rise to numerous metabolites with differing structures and biological activities. Major physiologically active compounds are (-)-JA, MeJA, and the amino acid conjugates of (-)-JA with isoleucine, valine, or leucine (for review, see Sembdner and Parthier, 1993). (-)-JA and MeJA (which will be collectively referred to throughout this review as jasmonates) affect plant growth and development in a pleiotropic manner (for reviews, see Parthier, 1990,1991; Staswick, 1992; Sembdner and Parthier, 1993). Recently, jasmonates have been proposed to be stress-related compounds (Farmer and Ryan, 1990; Parthier, 1990, 1991; Enyedi et al., 1992; Farmer et al., 1992; Gundlach et al., 1992; Müller et al., 1993). MeJA, in particular, is a signal molecule that is released in plants in response to various stresses, such as wounding or pathogen attack (Creelman et al., 1992),