Reference "GOLD HULL AND INTERNODE2 (GH2) Encodes a Primarily Multifunctional Cinnamyl-Alcohol Dehydrogenase (CAD) in Oryza sativa"

Reference ID

11035

Title

GOLD HULL AND INTERNODE2 (GH2) Encodes a Primarily Multifunctional Cinnamyl-Alcohol Dehydrogenase (CAD) in Oryza sativa

Source

Plant physiology, 2006, vol. , pp. -

Authors (10)

Zhang-K	Qian-Q
Huang-Z	Wang-Y
Li-M	Hong-L
Zeng-D	Gu-M
Chu-C	Cheng-Z

Abstract

Lignin content and composition are two important agronomic traits for the
utilization of agricultural residues. Rice gold hull and internode phenotype is
a classical morphological marker-trait that has long been applied to breeding
and genetics study. In the present study, we have cloned GOLD HULL AND
INTERNODE2 (GH2) gene in rice using a map-based cloning approach. The result
shows that gh2 mutant is a lignin-deficient mutant, and GH2 encodes a cinnamyl-
alcohol dehydrogenase (CAD). Consistent with this finding, extracts from roots,
internodes, hulls and panicles of the gh2 plants exhibited drastically reduced
CAD activity and undetectable sinapyl alcohol dehydrogenase (SAD) activity. When
expressed in Escherichia coli (E. coli), purified recombinant GH2 was found to
exhibit strong catalytic ability towards coniferaldehyde and sinapaldehyde,
while the mutant protein gh2 completely lost the corresponding CAD and SAD
activities. Further phenotypic analysis of the gh2 mutant plants revealed that
the p-hydroxyphenyl, guaiacyl and sinapyl monomers were reduced in almost the
same ratio compared to the wild type. Our results suggest GH2 acts as a
primarily multifunctional CAD to synthesize coniferyl and sinapyl alcohol
precursors in rice lignin biosynthesis.