Biological function of A Methyl jasmonate-inducible gene MJI2 in Arabidopsis (Arabidopsis thaliana)

Abstract

Methyl jasmonate (MeJA) is a volatile plant cellular regulator that modulates expression of various genes involved in diverse developmental and defensive processes. In Arabidopsis DNA microarray experiment previously performed in our laboratory, numerous MeJA-inducible genes were screened out. Among them, MJI2 (At3g15356) gene was selected and further characterized in this study to identify its biological role(s) in MeJA-responsive cellular metabolism. Computer-based sequence analysis showed that MJI2 protein contains a lectin-like domain. As revealed by Northern blot analysis, MJI2 was strongly expressed in rosette leaves, stems, and roots. Moreover, it was observed that MJI2 was induced by MeJA and ethylene treatments, exhibiting synergistic effect between the two phytohormones on its expression. And MJI2 was induced by chitin treatments. Transgenic Arabidopsis over-expressing the gene exhibited enhanced resistance to a fungal pathogen Alternaria brassicicola, which is known to be relied on jasmonate-dependent defense responses. Thus, our data indicates that MJI2 functions as a MeJA-responsive defenserelated gene.