AUTHOR=Gleason Cynthia , Leelarasamee Natthanon , Meldau Dorothea , Feussner Ivo 

TITLE=OPDA Has Key Role in Regulating Plant Susceptibility to the Root-Knot Nematode Meloidogyne hapla in Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.01565

DOI=10.3389/fpls.2016.01565

ISSN=1664-462X

ABSTRACT=<p>Jasmonic acid (JA) is a plant hormone that plays important roles in regulating plant defenses against necrotrophic pathogens and herbivorous insects, but the role of JA in mediating the plant responses to root-knot nematodes has been unclear. Here we show that an application of either methyl jasmonate (MeJA) or the JA-mimic coronatine (COR) on <italic>Arabidopsis</italic> significantly reduced the number of galls caused by the root-knot nematode <italic>Meloidogyne hapla</italic>. Interestingly, the MeJA-induced resistance was independent of the JA-receptor COI1 (CORONATINE INSENSITIVE 1). The MeJA-treated plants accumulated the JA precursor <italic>cis</italic>-(+)-12-oxo-phytodienoic acid (OPDA) in addition to JA/JA-Isoleucine, indicating a positive feedback loop in JA biosynthesis. Using mutants in the JA-biosynthetic pathway, we found that plants deficient in the biosynthesis of JA and OPDA were hyper-susceptible to <italic>M. hapla.</italic> However, the <italic>opr3</italic> mutant, which cannot convert OPDA to JA, exhibited wild-type levels of nematode galling. In addition, mutants in the JA-biosynthesis and perception which lie downstream of <italic>opr3</italic> also displayed wild-type levels of galling. The data put OPR3 (OPDA reductase 3) as the branch point between hyper-susceptibility and wild-type like levels of disease. Overall, the data suggests that the JA precursor, OPDA, plays a role in regulating plant defense against nematodes.</p>