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. 2018 Apr 6;30(4):780–795. doi: 10.1105/tpc.17.00787

Figure 7.

Figure 7.

Evolution of SyGI via Actinidia-Specific Duplication.

(A) Evolutionary relationship between the Shy Girl-Achn384741 duplication event and the timing of divergence between Actinidia species. The black circles labeled “d” and “a” indicate the node of SyGI-Achn384741 duplication and the divergence between Actinidia species, respectively. The white circle labeled “c” indicates the hypothetical timing of the evolution of cis-elements in the Shy Girl promoter sequence. The rate of silent divergence from the current SyGI to the SyGI-Achn384741 duplication (Ks = 0.1108) is only slightly bigger than to the divergence of Actinidia species (Ks = 0.1099). The estimated time between the two (Ks = 0.0009) corresponds to ∼0.16 million years (MY), suggesting very rapid fixation of the proto-SyGI after the hypothetical evolution of the cis-element.

(B) Model for the establishment of SyGI function as a dominant suppressor of feminization. According to the two-mutation model, a male-promoting factor (M/m) could be present in the same haploblock, and the male-sterility mutation might have predated the establishment of duplicated SyGI.