Gene expression profiling of fatty acid biosynthetic pathway during interaction of oil palm (Elaeis guineensis Jacq.) with the mutualistic fungus Glomus etunicatum

Abstract

In addition to the major phytohormone-mediated defense pathways, fatty acid (FA) pathways play significant roles in plant defense response and are involved in cross-talk with various phytohormones. Using volume-based analyses we have conducted a gene expression profiling of FA biosynthetic pathway during interaction of oil palm (Elaeis guineensis Jacq.) with the mutualistic fungus Glomus etunicatum. Inoculation with G. etunicatum stimulated growth and biomass production in oil palm. Here we demonstrated that there is an identical response in root and leaf tissues in gene expression during interaction of oil palm with G. etunicatum at different time points. We find that the expression of acetyl-CoA carboxylase (ACC), β-ketoacyl-ACP synthases (KAS) II and III, palmitoyl-ACP thioesterase (PTE), oleoyl-ACP thioesterase (OTE) and glycerol-3-phosphate acyltransferase (ACT) increased in both root and leaf tissues at 21 and 42 days post-inoculation (dpi). The expression level of these genes was up-regulated approximately threefold in both tissues at 63 dpi, which correlated with the colonization of roots with G. etunicatum and promotion of plant growth. These are likely to be key genes in the defense response of oil palm during symbiotic interaction with G. etunicatum. Together, the results provide a valuable resource to plant resistance mechanism and growth promotion with G. etunicatum. Given the capability of G. etunicatum to colonize oil palm root and enhance expression of FA pathway genes, it is suggested that the fungus has evolved efficient strategies to overcome plant immunity. The fungus can be used to establish a proper transformed progeny of oil palm with increase resistance to biotic stress and promote healthy growth for better oil yield.