Gene duplication confers enhanced expression of 27-kDa γ-zein for endosperm modification in quality protein maize.
The maize opaque2 (o2) mutant has a high nutritional value but it develops a chalky endosperm that limits its practical use. Genetic selection for o2 modifiers can convert the normally chalky endosperm of the mutant into a hard, vitreous phenotype, yielding what is known as quality protein maize (QPM). Previous studies have shown that enhanced expression of 27-kDa γ-zein in QPM is essential for endosperm modification. Taking advantage of genome-wide association study analysis of a natural population, linkage mapping analysis of a recombinant inbred line population, and map-based cloning, we identified a quantitative trait locus (qγ27) affecting expression of 27-kDa γ-zein. qγ27 was mapped to the same region as the major o2 modifier (o2 modifier1) on chromosome 7 near the 27-kDa γ-zein locus. qγ27 resulted from a 15.26-kb duplication at the 27-kDa γ-zein locus, which increases the level of gene expression. This duplication occurred before maize domestication; however, the gene structure of qγ27 appears to be unstable and the DNA rearrangement frequently occurs at this locus. Because enhanced expression of 27-kDa γ-zein is critical for endosperm modification in QPM, qγ27 is expected to be under artificial selection. This discovery provides a useful molecular marker that can be used to accelerate QPM breeding.
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Hongjun
H
Liu
State Key Laboratory of Agrobiotechnology and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China;
Junpeng
J
Shi
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Chuanlong
C
Sun
National Center for Gene Research, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China;
Hao
H
Gong
Institute of Food Crops, Yunnan Academy of Agricultural Sciences, Kunming 650205, China;
Xingming
X
Fan
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China;
Fazhan
F
Qiu
National Center for Gene Research, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China;
Xuehui
X
Huang
National Center for Gene Research, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China;
Qi
Q
Feng
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Xixi
X
Zheng
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Ningning
N
Yuan
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Changsheng
C
Li
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Zhiyong
Z
Zhang
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Yiting
Y
Deng
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
Jiechen
J
Wang
Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Ministry of Agriculture; Maize Research Institute, Sichuan Agricultural University, Chengdu 611130, China.
Guangtang
G
Pan
National Center for Gene Research, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200233, China;
Bin
B
Han
State Key Laboratory of Agrobiotechnology and National Maize Improvement Center, Department of Plant Genetics and Breeding, China Agricultural University, Beijing 100193, China;
Jinsheng
J
Lai
National Key Laboratory of Plant Molecular Genetics, Chinese Academy of Sciences Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China; yrwu@sibs.ac.cn.
Yongrui
Y
Wu
D032461:Chromosomes, Plant; D056625:Endosperm; D020440:Gene Duplication; D017343:Genes, Plant; D040641:Quantitative Trait Loci; D003313:Zea mays / Q000235:genetics*; D015028:Zein / Q000235:genetics*
D015028:Zein
QPM; artificial selection; endosperm; gene duplication; o2 modifiers