Content area
Full Text
Theor Appl Genet (2015) 128:445452 DOI 10.1007/s00122-014-2443-3
ORIGINAL PAPER
The sh2R allele of the maize shrunken2 locus was caused by a complex chromosomal rearrangement
Vance Kramer Janine R. Shaw M. Lynn Senior L. Curtis Hannah
Abstract
Key message The mutant that originally dened the shrunken2 locus of maize is shown here to be the prod uct of a complex chromosomal rearrangement.
Abstract The maize shrunken-2 gene (sh2) encodes the large subunit of the heterotetrameric enzyme, adeno-sine diphosphate glucose pyrophosphorylases and a rate-limiting enzyme in starch biosynthesis. The sh2 gene was dened approximately 72 years ago by the isolation of a loss-of-function allele conditioning a shrunken, but viable seed. In subsequent years, the realization that this allele, termed zsh2-R or sh2-Reference, causes an extremely high level of sucrose to accumulate in the developing seed led to a revolution in the sweet corn industry. Now, the vast majority of sweet corns grown throughout the world contain this mutant allele. Through initial Southern analysis followed by genomic sequencing, the work reported here shows that this allele arose through a complex set of events involving at least three breaks of chromosome 3 as well as an intra-chromosomal inversion. These ndings provide an explanation for some previously reported, unexpected
Communicated by Natalia de Leon.
V. Kramer
Syngenta Biotechnology, 3054 East Cornwallis Rd, Durham, NC 27603, USA
J. R. Shaw L. C. Hannah (*)
Program in Plant Molecular and Cellular Biology and Horticultural Sciences, University of Florida, P.O. Box 110690, Gainesville Florida 32611, USA e-mail: [email protected]
M. L. Senior
Syngenta Seeds, Inc., 3054 East Cornwallis Rd, Durham, NC 27603, USA
Received: 16 October 2014 / Accepted: 6 December 2014 / Published online: 14 December 2014 Springer-Verlag Berlin Heidelberg 2014
observations concerning rates of recombination within and between genes in this region.
Introduction
The maize shrunken-2 gene (sh2) on chromosome 3 encodes the large subunit of the starch biosynthetic gene, adenosine diphosphate glucose pyrophosphorylase (AGPase) (Hannah and Nelson 1976; Bhave et al. 1990). This enzyme plays a rate-limiting role in starch biosynthesis as evidenced by a series of mutational and transgenic approaches in which enhanced AGPases were placed into the genomes of cereals and other plants resulting in increased starch synthesis (Stark et al. 1992; Giroux et al. 1996; Smidansky et al....