Abstract
Jasmonic acid (JA) is a plant hormone that plays important roles for a large number of processes in stress adaptation and development in vascular plants. The functions and signal transduction of JA in vascular plants have been studied extensively however those in non-vascular plants have been overlooked. The UPLC-MS/MS analysis of JA showed the presence of JA in Physcomitrella patens that is a model plant in mosses. The genomic database and protein homology searches predicted that P. patens would possess two allene oxide synthases, PpAOS1 and PpAOS2, evolved in JA biosynthesis. Recombinant PpAOSs were tried to obtain by overexpression in Escherichia coli. Only recombinant PpAOS1 was obtained as a soluble form. PpAOS1 had AOS activity and showed a pH optimum of approximately pH 6.0 using 13-HPOT as a substrate. PpAOS1 had substrate specificity for 13-HPOT, showing that it was 13-AOS. Semi-quantitative RT-PCR of PpAOSs showed that the expression of PpAOS1 was higher than that of PpAOS2 this indicated that PpAOS1 might operate JA biosynthesis in P. patens predominantly. These data suggest that the octadecanoid pathway also exists in P. patens.
