CYP86A33-Targeted Gene Silencing in Potato Tuber Alters Suberin Composition, Distorts Suberin Lamellae, and Impairs the Periderm's Water Barrier Function      

Abstract

Suberin is a cell wall lipid polyester found in the cork cells of the periderm offering protection against dehydration and pathogens. Its biosynthesis and assembly, as well as its contribution to the sealing properties of the periderm, are still poorly understood. Here, we report on the isolation of the coding sequence CYP86A33 and the molecular and physiological function of this gene in potato (Solanum tuberosum) tuber periderm. CYP86A33 was down-regulated in potato plants by RNA interference-mediated silencing. Periderm from CYP86A33-silenced plants revealed a 60% decrease in its aliphatic suberin load and greatly reduced levels of C18:1 v-hydroxyacid (approximately 70%) and a,v-diacid (approximately 90%) monomers in comparison with wild type. Moreover, the glycerol esterified to suberin was reduced by 60% in the silenced plants. The typical regular ultrastructure of suberin, consisting of dark and light lamellae, disappeared and the thickness of the suberin layer was clearly reduced. In addition, the water permeability of the periderm isolated from CYP86A33-silenced lines was 3.5 times higher than that of the wild type. Thus, our data provide convincing evidence for the involvement of v-functional fatty acids in establishing suberin structure and function.

Identification of an Arabidopsis Feruloyl-Coenzyme A Transferase Required for Suberin Synthesis

“…However, TEM identifies a strong perturbation in suberin structure for cyp86a1 (Supplemental Fig. S4), also observed in the periderm of potato RNA interference lines where the homologous gene has been silenced (Serra et al, 2009). Figure 4 shows the results obtained for thin sections from 6-week-old asft-1 roots.…”

“…It is synthesized constitutively during development by a variety of internal and exposed plant tissues, and as a response to stresses and wounding (Kolattukudy, 2001;Schreiber et al, 2005). The role of suberin in controlling salt stress and permeability has recently been demonstrated in mutants compromised in its biosynthesis (Beisson et al, 2007;Höfer et al, 2008;Serra et al, 2009).…”

“…The first genes affecting Arabidopsis aliphatic suberin and suberin-associated wax composition have been identified. These include the glycerol-3-P acyltransferase GPAT5 (Beisson et al, 2007;Li et al, 2007b) and an orthologous pair of cytochrome P450 v-hydroxylases, CYP86A1 and CYP86A33 (Li et al, 2007a;Hö fer et al, 2008;Serra et al, 2009). However, knockout mutants of these cytochrome P450 genes do not reduce the levels of v-oxidized very-long-chain suberin monomers, so additional cytochrome P450 genes are required for this function.…”

Analyses of Tomato Fruit Brightness Mutants Uncover Both Cutin-Deficient and Cutin-Abundant Mutants and a New Hypomorphic Allele of GDSL Lipase

“…In the P5E1 and P26E8 mutants, the accumulation in cutin fraction of dicarboxylic acids, which are considered as markers for suberin, and the associated visual changes (Supplemental Figure S6) may be indicative of the constitutive upregulation of suberin biosynthetic pathway in these mutants. Indeed, the C18:1 unsaturated dicarboxylic acid content of P5E1 and P26E8 tomato fruit cuticle (approximately 99 mg cm 22 ; Supplemental Table S3) is close to that of potato (Solanum tuberosum) tuber periderm (approximately 80 to 100 mg cm 22 ; Serra et al, 2009). Because both species are closely related, these mutants may thus prove very interesting for investigating the relationships between cutin and suberin within the Solanaceae.…”

miRNA profiling in leaf and cork tissues of Quercus suber reveals novel miRNAs and tissue-specific expression patterns

“…In that work, a list of candidate genes isolated from cork tissues were identified including genes for the synthesis, transport, and polymerization of suberin monomers as well as a number of regulatory genes including members of the NO APICAL MERISTEM (NAM), MYB and WRKY transcription factor families with putative functions in meristem identity and cork differentiation. Since then, a number of studies have been published characterizing the role of a few selected candidate orthologues in potato tuber suberin formation by reverse genetics approaches (Serra et al 2010a;Serra et al 2010b;Serra et al 2009a;Serra et al 2009b) and identifying additional candidates in potato tuber periderm (Barel and Ginzberg 2008;Chaves et al 2009;Ginzberg et al 2009;Soler et al 2011). Despite the remarkable ability of cork oak to produce cork, potato has been the preferred model to study these processes since it is more amenable to in vitro manipulation and transformation having, in addition, its genome fully sequenced (Xu et al 2011).…”