Breaking the tight genetic linkage between the a1 and sh2 genes led to the development of anthocyanin-rich purple-pericarp super-sweetcorn

• Published in: Scientific reports Vol. 13; no. 1; p. 1050
• Main Authors: Anirban, Apurba, Hayward, Alice, Hong, Hung T., Masouleh, Ardashir Kharabian, Henry, Robert J., O’Hare, Tim J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.01.2023; Nature Publishing Group; Nature Portfolio
• Subjects: 631/208; 631/449; 631/45; Anthocyanins; Anthocyanins - genetics; Biosynthesis; Chromosome Mapping; Corn; Genes, Plant; Genomes; Humanities and Social Sciences; Meiosis; multidisciplinary; Pericarp; Phenotype; Phenotypes; Plant reproduction; Pollination; Recombination; Science; Science (multidisciplinary); Zea mays - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-023-28083-4

The existence of purple-pericarp super-sweetcorn based on the supersweet mutation, shrunken2 ( sh2 ), has not been previously reported, due to its extremely tight genetic linkage to a non-functional anthocyanin biosynthesis gene, anthocyaninless1 ( a1 ). Generally, pericarp-pigmented starchy purple corn contains significantly higher anthocyanin. 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, ‘Costa Rica’ ( A1Sh2.A1Sh2 ) and a female white shrunken2 super-sweetcorn, ‘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. 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.