OS1 functions in the allocation of nutrients between the endosperm and embryo in maize seeds

• Published in: Journal of integrative plant biology Vol. 61; no. 6; pp. 706 - 727
• Main Authors: Song, Weibin, Zhu, Jinjie, Zhao, Haiming, Li, Yingnan, Liu, Jiangtao, Zhang, Xiangbo, Huang, Liangliang, Lai, Jinsheng
• Format: Journal Article
• Language: English
• Published: China (Republic : 1949- ) Wiley Subscription Services, Inc 01.06.2019
• Subjects: Alleles; Corn; Crop yield; Embryos; Endosperm; Endosperm - metabolism; Endosperm - ultrastructure; Gene Expression Regulation, Plant; Gene Ontology; Gene sequencing; Genes; Genes, Plant; Molecular Sequence Annotation; Mutation - genetics; Nutrients; Phenotype; Phylogeny; Plant Proteins - genetics; Plant Proteins - metabolism; Protein Domains; Ribonucleic acid; RNA; Seeds; Starch; Transcription Factors - chemistry; Transcription Factors - metabolism; Transcriptome - genetics; Transformation, Genetic; Zea mays; Zea mays - embryology; Zea mays - genetics; Zea mays - ultrastructure; Zein; Zein - metabolism; Zein - ultrastructure
• ISSN: 1672-9072; 1744-7909
• DOI: 10.1111/jipb.12755

Uncovering the genetic basis of seed development will provide useful tools for improving both crop yield and nutritional value. However, the genetic regulatory networks of maize (Zea mays) seed development remain largely unknown. The maize opaque endosperm and small germ 1 (os1) mutant has opaque endosperm and a small embryo. Here, we cloned OS1 and show that it encodes a putative transcription factor containing an RWP‐RK domain. Transcriptional analysis indicated that OS1 expression is elevated in early endosperm development, especially in the basal endosperm transfer layer (BETL), conducting zone (CZ), and central starch endosperm (CSE) cells. RNA sequencing (RNA‐Seq) analysis of the os1 mutant revealed sharp downregulation of certain genes in specific cell types, including ZmMRP‐1 and Meg1 in BETL cells and a majority of zein‐ and starch‐related genes in CSE cells. Using a haploid induction system, we show that wild‐type endosperm could rescue the smaller size of os1 embryo, which suggests that nutrients are allocated by the wild‐type endosperm. Therefore, our data imply that the network regulated by OS1 accomplishes a key step in nutrient allocation between endosperm and embryo within maize seeds. Identification of this network will help uncover the mechanisms regulating the nutritional balance between endosperm and embryo. OS1 (opaque endosperm and small germ 1) encodes a putative RWP‐RK transcription factor, which is responsible for nutrients allocation in maize seed. Its mutation leads to unbalanced nutrients allocation between the endosperm and embryo, thus resulting in opaque endosperm and small embryo.