title: A transposable element insertion within ZmGE2 gene is associated with increase in embryo to endosperm ratio in maize.
abstract: Most of the maize kernel oil is located in the embryo while the majority of starch is located in the endosperm. Maize kernel composition and value are affected significantly by the ratio of the embryo size to the endosperm size; however, the genetic regulation of embryo to endosperm ratio (EER) in maize is unknown. Here we identified ZmGE2 gene, which encodes a cytochrome p450 protein, as a gene associated with EER variation in maize. We first expressed rice Giant Embryo (GE) gene driven by oleosin promoter in maize and detected a 23.2 % reduction in EER in transgenic seeds, demonstrating the existence of evolutionarily conserved mechanisms for EER determination in rice and maize. We next identified maize GE2, a homolog of rice GE sharing 70 % identity in amino sequence, as a candidate based on the similar expression pattern and co-localization with a previously detected QTL for EER. Followed by linkage and association mapping, a 247-bp transposable element (TE) insertion in 3'-untranslated region of ZmGE2 gene was identified to be associated with increase in EER and kernel oil content. Expression level of the favorable ZmGE2 allele containing the 247-bp TE insertion was strongly reduced. In addition, the 247-bp TE insertion site was a selection target during the artificial long-term selection for the high EER trait in a high oil population. This is the first report that demonstrates an association of ZmGE2 with EER variation in maize and identifies ZmGE2 gene as a promising target for manipulation of EER and grain composition by either transgenic approach or molecular breeding in maize.
authors: National Maize Improvement Center of China, Beijing Key Laboratory of Crop Genetic Improvement, China Agricultural University, Yuanmingyuan West Road, Haidian, Beijing, 100193, China.
authors: Pan
authors: P
authors: Zhang
authors: William B
authors: WB
authors: Allen
authors: Nobuhiro
authors: N
authors: Nagasawa
authors: Ada S
authors: AS
authors: Ching
authors: Elmer P
authors: EP
authors: Heppard
authors: Hui
authors: H
authors: Li
authors: Xiaomin
authors: X
authors: Hao
authors: Xiaowei
authors: X
authors: Li
authors: Xiaohong
authors: X
authors: Yang
authors: Jianbing
authors: J
authors: Yan
authors: Yasuo
authors: Y
authors: Nagato
authors: Hajime
authors: H
authors: Sakai
authors: Bo
authors: B
authors: Shen
authors: Jiansheng
authors: J
authors: Li
mesh_terms: D000483:Alleles; D002874:Chromosome Mapping; D003433:Crosses, Genetic; D004251:DNA Transposable Elements / Q000235:genetics*; D056625:Endosperm / Q000235:genetics*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005787:Gene Frequency / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D056726:Genetic Association Studies; D007178:Inbreeding; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics*; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D010938:Plant Oils / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000033:anatomy & histology* / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D010938:Plant Oils; D010940:Plant Proteins