Overexpression of a Rice TIFY Gene Increases Grain Size through Enhanced Accumulation of Carbohydrates in the Stem

• Published in: Bioscience, biotechnology, and biochemistry Vol. 76; no. 11; pp. 2129 - 2134
• Main Authors: HAKATA, Makoto, KURODA, Masaharu, OHSUMI, Akihiro, HIROSE, Tatsuro, NAKAMURA, Hidemitsu, MURAMATSU, Masayuki, ICHIKAWA, Hiroaki, YAMAKAWA, Hiromoto
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Society for Bioscience, Biotechnology, and Agrochemistry 2012; Japan Society for Bioscience Biotechnology and Agrochemistry; Oxford University Press
• Subjects: Biological and medical sciences; Carbohydrate Metabolism - genetics; Edible Grain - genetics; Edible Grain - growth & development; Edible Grain - metabolism; full-length cDNA overexpressing gene hunting system (FOX hunting system); Fundamental and applied biological sciences. Psychology; Gene Expression; Genes, Plant - genetics; grain size; Oryza - genetics; Oryza - growth & development; Oryza - metabolism; Oryza sativa; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Leaves - metabolism; Plant Stems - metabolism; rice (Oryza sativa L.); Starch - metabolism; Sucrose - metabolism; TIFY/JAZ protein; transient starch accumulation; Fissipedia; Carnivora; Monocotyledones; Grains; Starch; Gene overexpression; full-length cDNA overexpressing gene hunting system (FOX hunting system); transient starch accumulation; Accumulation; Protein; Fox; Oryza sativa; rice (Oryza sativa L.); Vertebrata; grain size; Mammalia; Complementary DNA; Gene; Gramineae; Angiospermae; TIFY/JAZ protein; Spermatophyta; Carbohydrate; Rice
• ISSN: 0916-8451; 1347-6947
• DOI: 10.1271/bbb.120545

Screening of rice full-length cDNA overexpressing (FOX) lines allowed the identification of a TIFY gene, TIFY11b, as a growth-promoting gene whose overexpression increased plant height and seed size. The grains of TIFY11b-overexpressing plants exceeded those of non-transformants in length, width and thickness, resulting in 9-21% increases in grain weight. The increase was achieved by overexpressing the gene in the whole plant body, but not by seed-restricted expression, indicating that seed enlargement is attributable to overexpression in vegetative organs such as the leaf. The whole-body overexpressing plants developed longer leaves along with higher levels of starch and sucrose in the leaf sheath and culm at the heading stage than the non-transformants. Although overexpression of TIFY11b did not alter the photosynthetic rate per leaf area before and after heading, it caused an accumulation of higher levels of the carbohydrate assimilate, probably due to increased photosynthesis per plant, suggesting that the increase in grain size and weight is attained by enhanced accumulation and translocation of the carbohydrate in the culms and leaf sheaths of the transgenic plants. Thus, TIFY11b is a novel grain-size increasing gene.