Sphingolipids and Plant Defense/Disease: The “Death” Connection and Beyond

Abstract

Sphingolipids comprise a major class of structural materials and lipid signaling molecules in all eukaryotic cells. Over the past two decades, there has been a phenomenal growth in the study of sphingolipids (i.e., sphingobiology) at an average rate of ∼1000 research articles per year. Sphingolipid studies in plants, though accounting for only a small fraction (∼6%) of the total number of publications, have also enjoyed proportionally rapid growth in the past decade. Concomitant with the growth of sphingobiology, there has also been tremendous progress in our understanding of the molecular mechanisms of plant innate immunity. In this review, we (i) cross examine and analyze the major findings that establish and strengthen the intimate connections between sphingolipid metabolism and plant programmed cell death (PCD) associated with plant defense or disease; (ii) highlight and compare key bioactive sphingolipids involved in the regulation of plant PCD and possibly defense; (iii) discuss the potential role of sphingolipids in polarized membrane/protein trafficking and formation of lipid rafts as subdomains of cell membranes in relation to plant defense; and (iv) where possible, attempt to identify potential parallels for immunity-related mechanisms involving sphingolipids across kingdoms.

Involvement of Arabidopsis Hexokinase1 in Cell Death Mediated byMyo-Inositol Accumulation

“…In higher plants, inositol and inositol derivatives such as inositol phosphates, phosphatidylinositide, and sphingolipids are involved in gene expression regulation (Alcázar-Román and Wente, 2008), hormonal signaling (Tan et al, 2007), biotic and abiotic stress responses (Taji et al, 2006), and the control of cell death (Liang et al, 2003;Wang et al, 2008;Berkey et al, 2012). MI is also a precursor of the osmoprotectants galactinol and raffinose (Van den Ende, 2013).…”

Possible Role of Sphingolipids in Developmental Programmed Cell Death of Petunia Petals

“…turgor loss) in the entire petal was visible with the naked eye (data not shown). Figure 1 gives a scheme of sphingolipid biosynthesis in plants, according to Berkey et al (2012). The pathway seems different in animals, where dihydrosphingosine is converted by ceramide synthase to dihydroxyceramide, which can be desaturated to form ceramide.…”

“…In plants much less is known about the possible role of sphingolipids in PCD [10]. Feeding with sphingolipids induced PCD in plants [11][12][13]8].…”

Disruption of Fumarylacetoacetate Hydrolase Causes Spontaneous Cell Death under Short-Day Conditions in Arabidopsis

“…For example, the lesion-mimic phenotypes in the Arabidopsis mutants lesion initiation2 and accelerated cell death2 and the maize mutant lesion mimic22 result from an impairment of porphyrin metabolism (Hu et al, 1998;Ishikawa et al, 2001;Mach et al, 2001). Deficiency in fatty acid, sphingolipid, and myoinositol metabolism also causes cell death in Arabidopsis (Mou et al, 2000;Liang et al, 2003;Wang et al, 2008;Meng et al, 2009;Donahue et al, 2010;Berkey et al, 2012).…”