OsbZIP58, a basic leucine zipper transcription factor, regulates starch biosynthesis in rice endosperm

• Published in: Journal of experimental botany Vol. 64; no. 11; pp. 3453 - 3466
• Main Authors: Wang, Jie-Chen, Xu, Heng, Zhu, Ying, Liu, Qiao-Quan, Cai, Xiu-Ling
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press [etc.] 01.08.2013; Oxford University Press
• Subjects: amylopectin; amylose; Basic-Leucine Zipper Transcription Factors; Basic-Leucine Zipper Transcription Factors - genetics; Basic-Leucine Zipper Transcription Factors - metabolism; Biological and medical sciences; Biosynthesis; chemical reactions; cooking quality; Endosperm; Endosperm - genetics; Endosperm - metabolism; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Genes; genetics; Grains; leucine zipper; metabolism; mutants; Oryza; Oryza - genetics; Oryza - metabolism; Plant physiology; Plant physiology and development; Plant Proteins; Plant Proteins - genetics; Plant Proteins - metabolism; Plants, Genetically Modified; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; quality control; RESEARCH PAPER; Rice; seed quality; seed yield; seeds; Starch; Starch - biosynthesis; Starches; taste; transcription (genetics); transcription factors; Transcriptional regulatory elements; Yeasts; Monocotyledones; Starch; Biosynthesis; Leucine; rice; coordination; Oryza; starch biosynthesis; Gramineae; Angiospermae; Botany; Herbaceous plant; Spermatophyta; Endosperm; Transcription factor; OsbZIP58
• ISSN: 0022-0957; 1460-2431; 1460-2431
• DOI: 10.1093/jxb/ert187

Starch composition and the amount in endosperm, both of which contribute dramatically to seed yield, cooking quality, and taste in cereals, are determined by a series of complex biochemical reactions. However, the mechanism regulating starch biosynthesis in cereal seeds is not well understood. This study showed that OsbZIP58, a bZIP transcription factor, is a key transcriptional regulator controlling starch synthesis in rice endosperm. OsbZIP58 was expressed mainly in endosperm during active starch synthesis. osbzip58 null mutants displayed abnormal seed morphology with altered starch accumulation in the white belly region and decreased amounts of total starch and amylose. Moreover, osbzip58 had a higher proportion of short chains and a lower proportion of intermediate chains of amylopectin. Furthermore, OsbZIP58 was shown to bind directly to the promoters of six starch-synthesizing genes, OsAGPL3, Wx, OsSSIIa, SBE1, OsBEIIb, and ISA2, and to regulate their expression. These findings indicate that OsbZIP58 functions as a key regulator of starch synthesis in rice seeds and provide new insights into seed quality control.