Chubu University
Bioscience & Biotechnology
Research Institute for Biological Functions
Figure11, Genetic and Molecular analysis of genes involved in the morphogenesis of plants

We are interested in the molecular mechanisms responsible for plant shape, based on functional analysis of genes related to proliferation and differentiation. Machida et al. have isolated the ASYMMETRIC LEAVES2 (AS2) gene of Arabidopsis thaliana. This gene is involved in the formation of symmetric flat leaf lamina. Leaves of the as2 mutant plant and those of plants overexpressing AS2 exhibited extremely unique shapes (Figs. 1). The as2 mutant exhibits pleiotropic abnormal phenotypes including asymmetric leaf lobes, leaflet-like structures, malformed venation patterns (Fig. 2). Transcripts of the class 1 KNOX gene family, which is involved in the formation and maintenance of a meristem state, ectopically accumulate in the mature leaves of as2. This suggests that the AS2 gene plays a role in repressing the expression of the KNOX genes in mature leaves, which might cause the maintenance of the determinate cell state of leaf cells. We have shown that AS2, together with other genes, is also involved in the establishment of adaxial-abaxial polarity in the development of leaves. The AS2 gene encodes a novel nuclear protein that belongs to the plant specific protein family designated AS2/LOB family. We will attempt to apply the results to plant rearing. We collaborate with researchers studying roses and orchids in order to investigate the molecular mechanisms of development in garden plants (Machida Ref. 7, 10, 12, 13).

2, Application of analytical methods of bioinformatics

Kobayashi et al. developed a microarray analytical system for medical science (Fig. 3) This system would allow the identification of novel genes controlled by the genes involved in proliferation and differentiation in plants (Kobayashi Ref. 1-25).
3, Development of methods of regeneration and transformation for garden plants

Methods for individual reproduction after genes are identified have not yet been established for garden plants. Banno et al. isolated the ESR1 and ESR2 genes that control shoot formation in Arabidopsis thaliana. The frequency of shoot formation increases by about ten-fold when either ESR1 or ESR2 is overexpressed (Banno Ref. 2 Fig. 4). Figure4 Moreover, Sakakibara et al. succeeded in identifying the genes related to the cytokinin synthesis system (Sakakibara Ref. 20, 21). The aim is to improve the regeneration efficiency of various garden plants by making good use of these genes. If we can improve the regeneration systems for a variety of plants, gene manipulation can be facilitated.
4, Basic molecular research for producing charming rose

Great variety of flower morphology is an important characteristic of modern-day roses. Until now, many floral organ identity MADS-box genes including the so-called, A, B, C, D and E classes of homeotic genes have been cloned and characterized from many plants. The five different classes of gene act in combination to specify organ identity. A alone specifies sepal identity; A + B + E specifies petal identity; B + C + E specified stamen identity; and C + D + E specifies carpel and ovule identity. In Arabidopsis thaliana, the class A genes APETALA1 (AP1) and AP2, the class B genes PISTILLATA (PI) and AP3, class C gene AGAMOUS (AG), class D gene SEEDSTICK (STK), and class E genes SEPALLATA1, 2 and 3 (SEP1 to 3) play an essential role in floral organ identity.
Until now, we isolated rose PI, AP3, AG and SEP homologues, MASAKO BP, MASAKO B3 and euB3, MASAKO C1 and D1, and MASAKO S1 and S3, respectively, from Rosa rugosa Thunb. ex Murray (Hibino et al., 2006; Matsumoto Ref. 6, 11, 20, 23). We established the major portion of rose ABCDE model for floral development from their structural and functional analyses (Fig. 5). A further functional analysis of rose class B, C and E genes using transgenic rose plants is in progress.

5, Isolation and Characterization of genes involved in leaf and flower development in the orchid Phalaenopsis amabilis

Semiarti et al.have developed a convenient method for the genetic modification of P. amabilis using Agrobacterium tumefaciens. T-DNA vectors containing kanamycin resistance gene and the Arabidopsis class 1 KNOX gene, BP/KNAT1, under the control of 35S promoter, that were used as marker genes, successfully introduced into intact protocorms, which are young orchid seedlings of P. amabilis. We have isolated of cDNA of class 1 KNOX genes homolog in P. amabilis orchid. We also would like to isolate genes that are involved in leaf and flower development in Phalaenopsis amabilis.
6, Research on volatile compounds emitted from plants and their analytical methods

Negishi is attempting to develop a system evaluate the components of plant scents using both instrumental analysis and the human sense of smell. Such a system would facilitate widespread molecular research on plant scents.
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