Isolation and characterization of a jasmonic acid carboxyl methyltransferase gene from hot pepper(capsicum annuum L.)

Abstract

Methyl jasmonate, the methyl ester of jasmonic acid, is a volatile plant hormone that acts as an important cellular regulator, mediating diverse developmental processes and defense responses. Methyl jasmonate is synthesized by methylation of jasmonic acid; this reaction is catalyzed by jasmonic acid carboxyl methyltransferase (JMT). Although JMT cDNA had previously been described only for Arabidopsis thaliana, here we used PCR to isolate it from Capsicum annuum L. The 389-amino-acid sequence deduced for the JMT gene showed 92% identity to that from A. thaliana. Southern blot analysis revealed thatJMT is present in the genome as two copies. Our preliminary northern blot detected no JMT transcript, but, through RT-PCR and subsequent Southern blot analysis of products using gene. specific probes, we found that transcript levels increased after leaf-wounding, Likewise, 10 ~M methyl jasmonate inducedJMTgene expressio n in leaves. Transcription levels began to increase 10 rain after wounding, and were maintained for I to 4 h. Moreover, expression of the CaJMT and PIN2 genes was increased by both wounding and MeJA applications, but was not enhanced by treatment with H202.

Seed Germination and Vigor

“…Biochemically characterized members of this family methylate the nitrogen atom or carboxyl groups found in a variety of plant hormones, thereby affecting their homeostasis in plant tissues. These hormones include salicylic acid, jasmonic acid, indole-3-acetic acid, and GAs (133,144,149,155), all of which are involved in regulation of seed germination (see above).…”

Herbivore-Induced SABATH Methyltransferases of Maize That Methylate Anthranilic Acid Using S-Adenosyl-l-Methionine

“…SAMT enzymes are considered part of a larger family of methyltransferases called SABATH methyltransferases . The SABATH family also includes methyltransferases producing other methyl esters such as methyl benzoate, methyl jasmonate, and methyl indole-3-acetate (Seo et al, 2001;Effmert et al, 2005;Qin et al, 2005;Song et al, 2005;Zhao et al, 2007). An activity forming methyl anthranilate has not been described in the SABATH family, despite the striking structural similarity between methyl anthranilate and methyl salicylate or methyl benzoate.…”

Transcript profile of transgenicArabidopsis constitutively producing methyl jasmonate

“…Identification of the genes encoding JA carboxyl methyltransferase has provided basic information on the role(s) of this volatile phytohormone (Song et al, 2000;Seo et al, 2001;Song et al, 2005;Barkman, 2006). Transgenic Arabidopsis overexpressing the AtJMT gene contain three-fold more endogenous MeJA without altering the JA content (Seo et al, 2001).…”