Arabidopsis ECERIFERUM9 involvement in cuticle formation and maintenance of plant water status.
Mutation of the ECERIFERUM9 (CER9) gene in Arabidopsis (Arabidopsis thaliana) causes elevated amounts of 18-carbon-length cutin monomers and a dramatic shift in the cuticular wax profile (especially on leaves) toward the very-long-chain free fatty acids tetracosanoic acid (C₂₄) and hexacosanoic acid (C₂₆). Relative to the wild type, cer9 mutants exhibit elevated cuticle membrane thickness over epidermal cells and cuticular ledges with increased occlusion of the stomatal pore. The cuticular phenotypes of cer9 are associated with delayed onset of wilting in plants experiencing water deficit, lower transpiration rates, and improved water use efficiency measured as carbon isotope discrimination. The CER9 protein thus encodes a novel determinant of plant drought tolerance-associated traits, one whose deficiency elevates cutin synthesis, redistributes wax composition, and suppresses transpiration. Map-based cloning identified CER9, and sequence analysis predicted that it encodes an E3 ubiquitin ligase homologous to yeast Doa10 (previously shown to target endoplasmic reticulum proteins for proteasomal degradation). To further elucidate CER9 function, the impact of CER9 deficiency on interactions with other genes was examined using double mutant and transcriptome analyses. For both wax and cutin, cer9 showed mostly additive effects with cer6, long-chain acyl-CoA synthetase1 (lacs1), and lacs2 and revealed its role in early steps of both wax and cutin synthetic pathways. Transcriptome analysis revealed that the cer9 mutation affected diverse cellular processes, with primary impact on genes associated with diverse stress responses. The discovery of CER9 lays new groundwork for developing novel cuticle-based strategies for improving the drought tolerance and water use efficiency of crop plants.
Division of Chemical and Life Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia. shiyou.lu@kaust.edu.sa
Shiyou
S
Lü
Huayan
H
Zhao
David L
DL
Des Marais
Eugene P
EP
Parsons
Xiaoxue
X
Wen
Xiaojing
X
Xu
Dhinoth K
DK
Bangarusamy
Guangchao
G
Wang
Owen
O
Rowland
Thomas
T
Juenger
Ray A
RA
Bressan
Matthew A
MA
Jenks
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D003001:Cloning, Molecular; D055864:Droughts; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D050356:Lipid Metabolism; D008055:Lipids; D009154:Mutation / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity / Q000235:genetics; D019441:Plant Epidermis / Q000166:cytology / Q000254:growth & development* / Q000648:ultrastructure; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018547:Plant Stems / Q000378:metabolism; D018526:Plant Transpiration; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics; D059467:Transcriptome / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D014867:Water / Q000502:physiology*; D014885:Waxes / Q000378:metabolism
D029681:Arabidopsis Proteins; D008055:Lipids; D012333:RNA, Messenger; D014885:Waxes; D014867:Water; C065875:suberin; C575855:CER9 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases