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. 2021 Feb 2;33(4):901–916. doi: 10.1093/plcell/koab029

Figure 1.

Figure 1

Haploid induction. Haploid induction occurs by crossing a male haploid inducer (RWSK C1-I; R-nj) to a female hyperploid heterozygote, for example, TB-1La (1, 1La-B, B-1La, B-1La). The number or letter before the hyphen denotes the arm has a centromere. The number “1” refers to chromosome 1. The uppercase letter “L” denotes the long arm and the lowercase “a” represents the first B-A translocation produced for that chromosome (chromosome 1 in this case; The “b” designation represents the second B-A translocation recovered for that chromosome, e.g. TB-1Sb). A dominant anthocyanin marker gene, Bz2, is on the 1L arm (long arm of chromosome 1) that allows purple anthocyanin production. RWSK contains C1-I that can inhibit the expression of the normal C1 allele and thus can silence anthocyanin production. Following meiosis, the TB-1La heterozygote produces two major kinds of female gametes, balanced egg (1La-B, B-1La) and imbalanced egg (1, B-1La; producing disomy after fertilization). After double fertilization, diploid kernels will have yellow embryos and yellow endosperms because the expression of C1 is inhibited by the C1-I from RWSK, which blocks the anthocyanin pathway. If the chromosomes from RWSK are eliminated in the embryo, via haploid induction, the haploid kernels have purple embryos and yellow endosperms, which are distinguishable from the diploid kernels.