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

ABSTRACT: 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 ?-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?27 was mapped to the same region as the major o2 modifier (o2 modifier1) on chromosome 7 near the 27-kDa ?-zein locus. q?27 resulted 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 of q?27 appears 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?27 is expected to be under artificial selection. This discovery provides a useful molecular marker that can be used to accelerate QPM breeding.

SUBMITTER: Liu H 

PROVIDER: S-EPMC4983849 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature