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bioRxiv · 10.1101/2022.07.13.499986

BREAKING THE TIGHT GENETIC LINKAGE BETWEEN THE a1 AND sh2 GENES LED TO THE DEVELOPMENT OF ANTHOCYANIN-RICH PURPLE-PERICARP SUPER-SWEETCORN

Anirban, A.·Hayward, A.·Hong, H. T.·Masouleh, A. K.·Henry, R. J.·O'Hare, T. J.
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Abstract

The 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 the a1-sh2 tight 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 white shrunken2 super-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 fully sh2 cob with a purple-pericarp phenotype, enabled by breaking the close genetic linkage between the a1 and sh2 genes. Resulting rounds of self-pollination generated a F6 homozygous purple-pericarp super-sweetcorn (A1A1.sh2sh2) line, Tim1. Genome sequencing revealed a recombination break between the a1 and yz1 genes of the a1-yz1-x1-sh2 multigenic 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.

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Anirban, A., Hayward, A., Hong, H. T., Masouleh, A. K., Henry, R. J., O'Hare, T. J.. 2022-07-15. BREAKING THE TIGHT GENETIC LINKAGE BETWEEN THE a1 AND sh2 GENES LED TO THE DEVELOPMENT OF ANTHOCYANIN-RICH PURPLE-PERICARP SUPER-SWEETCORN. https://doi.org/10.1101/2022.07.13.499986

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