Poster: Transcription Regulation

Abs # 1065: Developmental and light-dependent regulation of wheat mitochondrial gene expression

Presenter:	Wakamatsu, Hironori , h_wakamt@aoi.kpu.ac.jp
Authors	Wakamatsu, Hironori  (A)   Ishizaki, Yoko  (A)   Yamashita, Hirofumi  (A)   Takeba, Go  (A)   Shiina, Takashi  (A)
Affiliations:	(A): Kyoto Prefectural University

Plant cells contain two energy-generating organelles, mitochondria and chloroplasts. The function of mitochondria to produce ATP via oxidative phosphorylation is likely to be particularly important in cells with immature chloroplasts including roots. In contrast, the presence of chloroplasts as a second site of ATP production may lessen the demand for mitochondrial ATP synthesis in photosynthetically competent cells. Plants have to co-ordinate the gene expression between the three genomes present in mitochondria, chloroplasts and nucleus during growth and development. It is known that the expression of photosynthesis genes encoded in chloroplasts is programmed during leaf development. However, little is known about the developmental regulation of mitochondrial gene expression. The wheat primary leaf contains a linear progression of cellular age and differentiation from meristematic cells at the leaf base to photosynthetically matured cells at the distal tip. In this study, we investigated the expression of 33 mitochondrial genes in four sections of the wheat seedlings (root, base, middle and tip). Thirteen mitochondrial genes were constitutively expressed in all tissues. However, transcripts of 19 genes were detected dominantly in the basal portion of seedlings and roots containing non-photosynthetic plastids. In particular, expression of rps12 gene was root-specific. In contrast, the cox3 mRNA level was observed to decrease specifically in roots. Interestingly, transcripts of 10 genes including three cox and two atp genes were found to decrease in the illuminated tissues, while most ndh and rps genes were not regulated by light. These findings suggested that the expression of mitochondrial genes is differentially regulated dependent on plastid development and light.