ZmMYB31 directly represses maize lignin genes and redirects the phenylpropanoid metabolic flux.
Few regulators of phenylpropanoids have been identified in monocots having potential as biofuel crops. Here we demonstrate the role of the maize (Zea mays) R2R3-MYB factor ZmMYB31 in the control of the phenylpropanoid pathway. We determined its in vitro consensus DNA-binding sequence as ACC(T)/(A) ACC, and chromatin immunoprecipitation (ChIP) established that it interacts with two lignin gene promoters in vivo. To explore the potential of ZmMYB31 as a regulator of phenylpropanoids in other plants, its role in the regulation of the phenylpropanoid pathway was further investigated in Arabidopsis thaliana. ZmMYB31 downregulates several genes involved in the synthesis of monolignols and transgenic plants are dwarf and show a significantly reduced lignin content with unaltered polymer composition. We demonstrate that these changes increase cell wall degradability of the transgenic plants. In addition, ZmMYB31 represses the synthesis of sinapoylmalate, resulting in plants that are more sensitive to UV irradiation, and induces several stress-related proteins. Our results suggest that, as an indirect effect of repression of lignin biosynthesis, transgenic plants redirect carbon flux towards the biosynthesis of anthocyanins. Thus, ZmMYB31 can be considered a good candidate for the manipulation of lignin biosynthesis in biotechnological applications.
Centre for Research in Agricultural Genomics (CRAG), Consortium CSIC-IRTA-UAB, 08034 Barcelona, Spain.
Silvia
S
Fornalé
Xinhui
X
Shi
Chenglin
C
Chai
Antonio
A
Encina
Sami
S
Irar
Montserrat
M
Capellades
Elisabet
E
Fuguet
Josep-Lluís
JL
Torres
Pere
P
Rovira
Pere
P
Puigdomènech
Joan
J
Rigau
Erich
E
Grotewold
John
J
Gray
David
D
Caparrós-Ruiz
D000872:Anthocyanins / Q000096:biosynthesis; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002473:Cell Wall / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008031:Lignin / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D008969:Molecular Sequence Data; D010649:Phenylalanine / Q000378:metabolism; D010666:Phenylpropionates / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011401:Promoter Regions, Genetic; D052156:SELEX Aptamer Technique; D013312:Stress, Physiological; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
C079164:2-O-sinapoylmalate; D000872:Anthocyanins; D008293:Malates; D010666:Phenylpropionates; D010940:Plant Proteins; D010649:Phenylalanine; D008031:Lignin