MYB107 and MYB9 Homologs Regulate Suberin Deposition in Angiosperms

Abstract

Suberin, a polymer composed of both aliphatic and aromatic domains, is deposited as a rough matrix upon plant surface damage and during normal growth in the root endodermis, bark, specialized organs (e.g., potato [Solanum tuberosum] tubers), and seed coats. To identify genes associated with the developmental control of suberin deposition, we investigated the chemical composition and transcriptomes of suberized tomato (Solanum lycopersicum) and russet apple (Malus x domestica) fruit surfaces. Consequently, a gene expression signature for suberin polymer assembly was revealed that is highly conserved in angiosperms. Seed permeability assays of knockout mutants corresponding to signature genes revealed regulatory proteins (i.e., AtMYB9 and AtMYB107) required for suberin assembly in the Arabidopsis thaliana seed coat. Seeds of myb107 and myb9 Arabidopsis mutants displayed a significant reduction in suberin monomers and altered levels of other seed coat-associated metabolites. They also exhibited increased permeability, and lower germination capacities under osmotic and salt stress. AtMYB9 and AtMYB107 appear to synchronize the transcriptional induction of aliphatic and aromatic monomer biosynthesis and transport and suberin polymerization in the seed outer integument layer. Collectively, our findings establish a regulatory system controlling developmentally deposited suberin, which likely differs from the one of stressinduced polymer assembly recognized to date.

Disruption of glycosylphosphatidylinositol‐anchored lipid transfer protein 15 affects seed coat permeability in Arabidopsis

“…The large reductions of ω‐hydroxy fatty acids and α,ω‐dicarboxylic acids with 22 and 24 carbon atoms in fatB and gpat5 caused remarkable increases in seed coat permeability to tetrazolium salt (Beisson et al ., ). The increased seed coat permeability was also detected in several mutants, which were defective in suberin biosynthesis ( far1 far4 far5 and rwp1 ) and export ( ltpg4 ltpg6 , awake1 , and abcg2 abcg6 abcg20 ), and transcriptional activators that regulate suberin biosynthesis ( myb9 and myb107 ) (Gou et al ., , ; Vishwanath et al ., ; Edstam and Edqvist, ; Yadav et al ., ; Lashbrooke et al ., ; Fedi et al ., ). Consistent with previous reports, increased seed coat permeability of ltpg15 was observed in tetrazolium penetration assay (Figure ).…”

A comparative transcriptomic approach to understanding the formation of cork

“…Although a set of transcription factors belonging to MYB and NAC families has very recently been related to suberin accumulation (Kosma et al 2014;Gou et al 2017;Lashbrooke et al 2016;Legay et al 2016;Verdaguer et al 2016), only MYB102 and MYB107 were highlighted as upregulated in cork oak tissue according to DEGseq. Nevertheless, we identified several genes that may be involved in regulating phellogen activity.…”

Apple fruit superficial scald resistance mediated by ethylene inhibition is associated with diverse metabolic processes

“…Among the set identified here, one in particular, MDP0000835211, is predicted to encode a protein with relatively high sequence similarity to DCR, which in A. thaliana plays a key role in incorporating 9(10),16‐dihydroxy‐hexadecanoic acid into polymeric cutin (Panikashvili et al ., ). This gene also shows high amino acid similarity (48%, 3e −62 ) with Solyc03g025320, a tomato BAHD ortholog of A. thaliana DCR (Lashbrooke et al ., ), which incorporates cutin monomers into cutin.…”