Abstract
AbstractThe existence of purple-pericarp super-sweetcorn based on the most common supersweet mutation,shrunken2(sh2), has not been previously reported, partly due to its extremely tight genetic linkage to a non-functional anthocyanin biosynthesis gene,anthocyaninless1(a1). Generally, both aleurone- and pericarp-pigmented purple corn is starchy, the latter of which contains significantly higher anthocyanin compared to the former. The development of purple-pericarp super-sweetcorn is dependent on breaking thea1-sh2tight genetic linkage, which occurs at a very low frequency of <1 in 1000 meiotic crossovers. Here, to develop purple-pericarp super-sweetcorn, an initial cross between a male purple-pericarp maize (purple-round seed), ‘Costa Rica’ (A1Sh2.A1Sh2) and a female whiteshrunken2super-sweetcorn (white-shrunken seed), ‘Tims-white’ (a1sh2.a1sh2), was conducted. Subsequent self-pollination based on purple-pericarp-shrunken kernels identified a small frequency (0.08%) of initial heterozygous F3 segregants (A1a1.sh2sh2) producing a fullysh2cob with a purple-pericarp phenotype, enabled by breaking the close genetic linkage between thea1andsh2genes. Resulting rounds of self-pollination generated a F6 homozygous purple-pericarp super-sweetcorn (A1A1.sh2sh2) line, ‘Tim1’. Genome sequencing revealed a recombination break between thea1andyz1genes of thea1-yz1-x1-sh2multigenic interval, with the sequence pattern of ‘Tim1’ similar to the ‘Costa Rica’ parent, and after the linkage break, similar to the ‘Tims-white’ parent. The novel purple-pericarp super-sweetcorn produced a similar concentration of anthocyanin and sugar as in its purple-pericarp maize and white super-sweetcorn parents, respectively, potentially adding a broader range of health benefits than currently exists with standard yellow/white sweetcorn.
Publisher
Cold Spring Harbor Laboratory