Vol. 20 >B. Research Notes>IV. Genetics of physiological traits and others |
22. | Identification of rice genes encoding a LEC1-type HAP3 subunit protein |
T. THIRUMURUGAN1,2, K. MIYOSHI1, Y. ITO1
and N. KURATA1,2 1) Plant Genetics Laboratory, National Institute of Genetics, Mishima, 411-8540 Japan 2) Department of Genetics, School of Life Sciences, The Graduate University for Advanced Studies, Kanagawa, 240-0193 Japan |
During seed development, several discrete phenomena, such as establishment
of shoot and root apical meristem, accumulation of storage reserves and
acquisition of desiccation tolerance and dormancy, progress in a coordinated
manner. Molecular genetic studies in Arabidopsis identified genes
affecting multiple aspects of the seed development. Of these, LEC1
and L1L have been intensively studied (West et al. 1994;
Lotan et al. 1998; Kwong et al. 2003). LEC1 and L1L
are members of an Arabidopsis HAP3 (AHAP3) gene family which
consists of ten genes and encode a component of a heterotrimeric CCAAT-box
binding transcription factor. Based on the amino acid identity of an evolutionally
conserved region called B domain, the AHAP3 proteins were divided into
two classes, LEC1-type and non-LEC1-type. Transgenic studies demonstrated
that only the LEC1-type genes (i.e. LEC1 and L1L) could
activate the expression of a set of genes required for embryo formation
in a precisely coordinated manner (Lee et al. 2003). The LEC1-type
HAP3 genes were found not only in Arabidopsis but also in many
other plant species. Comparative study of HAP3 gene(s) among plant
species would provide a tool for understanding of a general mechanism
of embryogenesis in higher plants.
predicted amino acid sequences of the B domain of eleven members of the
rice HAP3 and two LEC1-type Arabidopsis proteins, LEC1 and L1L.
Among the rice members, OsHAP3E exhibited highest similarity to LEC1 (83%
amino acid identity) and L1L (91%) followed by OsHAP3D (74% and 75% respectively).
In addition, most of amino acid residues characteristic to the LEC1-type
HAP3s were specifically conserved in OsHAP3D and OsHAP3E, but not in the
other rice members. These results indicate that OsHAP3D and OsHAP3E
encode the LEC1-type HAP3 protein. RT-PCR analysis revealed the expression
of OsHAP3D and OsHAP3E in developing rice seeds (data not
shown), suggesting the involvement of LEC1-type HAP3s in monocot embryogenesis. |
Vol. 20 >B. Research Notes>IV. Genetics of physiological traits and others |