Os02g0187800

The rice Os02g0187800 was reported as GH2 in 2006 and 2014 by researchers from China and Japan.

Annotated Information

Gene Symbol

• Os02g0187800 <=> OsGH2,CAD2,GH2,OsCAD2

Figure 2. Phenotype of wild type and gh2 mutant..

Function

• Rice (Oryza sativa) gold hull and internode phenotype is a classical morphological marker trait that has long been applied to breeding and genetics study.
• gh2 mutant is a lignin-deficient mutant, and GH2 encodes a cinnamyl-alcohol dehydrogenase (CAD).
• OsGH2 acts as a primarily multifunctional CAD to synthesize coniferyl and sinapyl alcohol precursors in rice lignin biosynthesis.

Phenotypic analysis

• gh2 exhibits an obvious reddish-brown pigment in the panicle (hull), internode, and basal leaf sheath at the heading stage (Fig. 1, A and B). The reddish-brown pigments gradually become intensive starting from the basal internode to the apical internode. During plant maturing, seed coloration becomes darker and finally changes to golden yellow at maturation.

Expression

• Since the mutation is a point mutation, GH2 gene expression was detected in the wild-type plants only at the heading stage. Researchers detected GH2 gene transcription in all seven tissues, including panicles, hulls, blades, midribs, leaf sheaths, internodes, and young roots.
• GH2 gene was expressed in the lignified tissues, including panicles, hulls, internodes, young roots, and leaf sheaths.
• In the leaves (blade and midrib), which are slightly lignified, the GH2 transcripts cannot be obviously detected by northern blot.
• Furthermore, GH2 gene expressed stronger in the first internode than in the second internode, suggesting that the gene ex- pressed gradually stronger starting from the basal internode to the apical internode (data not shown).
• Consequently, the GH2 expression pattern is closely related to the rice lignification pattern and the local- ization of reddish-brown pigments.

Evolution

• To determine the evolutionary relationship between GH2 and CAD family members from the rice and Arabidopsis CAD families as well as other representative identified CAD homologs, an unrooted tree was built using the neighbor-joining method based on full-length protein sequences (Fig. 3).
• All the CAD protein sequences are divided into two subfamilies: subA (GH2, sugarcane [Saccharum officinarum] CAD, maize CAD, aspen PtCAD, eucalyptus [Eucalyptus globules] CAD, tobacco [Nicotiana tabacum] CAD1, tobacco CAD2, Lucerne [Medicago sativa] MsaCad2, Arabidopsis CADC, Arabidopsis CADD, pine [Pinus taeda] CAD, and spruce [Picea abies] CAD) and subB (Lucerne MsaCad1,aspen PtSAD, OsCAD1, OsCAD3, OsCAD4, OsCAD5,OsCAD6, OsCAD7, OsCAD8A-D, OsCAD9, AtCAD1, AtCAD2, AtCAD3, AtCAD6, AtCAD7, AtCAD8, and AtCAD9).

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Labs working on this gene

• State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101 People’s Republic of China
• State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou 310006, People’s Republic of China
• Department of Agronomy, Yangzhou University, Yangzhou 225009, People’s Republic of China
• Graduate School of the Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
• Institute of Agriculture, Graduate School, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
• Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan
• Agricultural Research Institute,Toyama Agricultural, Forestry & Fisheries Research Center, Toyama, Toyama 939-8153, Japan
• Agrogenomics Research Center, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
• Institute of Radiation Breeding, National Institute of Agrobiological Sciences, Hitachiohmiya, Ibaraki 319-2293, Japan.