Plant Class III acyl-CoA binding proteins can protect against necrotrophs: A review

Abstract

<p>Acyl-CoA-binding proteins (ACBPs) play important roles in stress and development. Four classes designated I to IV coexist in the representative dicot, Arabidopsis, as well as the monocot, rice. Recombinant ACBPs have been demonstrated to bind lipids such as acyl-CoA esters. Arabidopsis acbp mutants display changes in lipid composition and stress susceptibility. The aim of this review is to consolidate the role of ACBPs in plant defense against necrotrophic pathogens. An overview of the experimental evidence and molecular mechanisms that support their role in plant defense is presented. Specifically, Arabidopsis Classes I, III and IV ACBPs protect against necrotrophs based on evidence using mutants (acbp6, acbp3, and acbp4, respectively) which were compromised after infection by the necrotroph, Botrytis cinerea. Also, transgenic Arabidopsis plants overexpressing the rice Class III OsACBP5 were conferred broad spectrum pathogen resistance inclusive of fungal necrotrophs, Rhizoctonia solani, B. cinerea and Alternaria brassicicola. This review also illustrates that transgenic rice harboring OsACBP5 is protected against infection from necrotrophs such as R. solani and Cercospora oryzae, representing a promising strategy to sustain food security because rice is a global crop that feeds more than half of the world population. Our current understanding indicates that enhanced resistance of OsACBP5-overexpressors is jasmonate (JA)-dependent because progeny from a cross between a JA-signaling deficient rice mutant and an OsACBP5-overexpressor line showed greater susceptibility to R. solani infection than the wild type. Consistently, in transgenic rice expressing a construct of the OsACBP5 5′-flanking region fused to the gene encoding β-glucuronidase (GUS), GUS activity was upregulated upon methyl JA, salicylic acid or R. solani treatment. This review provides an overview and future perspectives on the potential of Class III ACBPs, particularly OsACBP5, for applications in protection against necrotrophs</p>