July 7, 2019  |  

Gene duplication confers enhanced expression of 27-kDa ?-zein for endosperm modification in quality protein maize.

Authors: Liu, Hongjun and Shi, Junpeng and Sun, Chuanlong and Gong, Hao and Fan, Xingming and Qiu, Fazhan and Huang, Xuehui and Feng, Qi and Zheng, Xixi and Yuan, Ningning and Li, Changsheng and Zhang, Zhiyong and Deng, Yiting and Wang, Jiechen and Pan, Guangtang and Han, Bin and Lai, Jinsheng and Wu, Yongrui

The maizeopaque2(o2) mutant has a high nutritional value but it develops a chalky endosperm that limits its practical use. Genetic selection foro2modifiers 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 ?-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 (q?27) affecting expression of 27-kDa ?-zein.q?27was mapped to the same region as the majoro2 modifier(o2 modifier1) on chromosome 7 near the 27-kDa ?-zein locus.q?27resulted from a 15.26-kb duplication at the 27-kDa ?-zein locus, which increases the level of gene expression. This duplication occurred before maize domestication; however, the gene structure ofq?27appears to be unstable and the DNA rearrangement frequently occurs at this locus. Because enhanced expression of 27-kDa ?-zein is critical for endosperm modification in QPM,q?27is expected to be under artificial selection. This discovery provides a useful molecular marker that can be used to accelerate QPM breeding.

Journal: Proceedings of the National Academy of Sciences of the United States of America
DOI: 10.1073/pnas.1601352113
Year: 2016

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