At Cold Spring Harbor that year (1978), Sy Fogel, a formidable figure in the yeast field, declared allegiance to the Meselson–Radding model in a magnum opus entitled “Meiotic gene conversion: a signal of the basic recombination event in yeast” (Fogel et al. 1979). These developments, combined with a wave of budding-yeast chauvinism, created a bandwagon for simple models, such as that of Meselson and Radding, with the result that deviant data from “weird” organisms tended to be ignored. Consequently, Kitani's (1978) demonstration that, in Sordaria, conversion crossovers lack interference while interfering crossovers lack conversion did not trigger investigations by others. No one appears to have asked whether features characteristic of Sordaria, but not of yeast, might underlie Kitani's observations. Instead, his discovery was allowed to die and could not be reborn until yeast caught up with Sordaria.

The rules were developed within the framework of the currently favored double-strand-break-repair model for meiotic recombination (Figure 1, C and D), building on the notion that MMR is guided by strand interruptions, as it is when operating at replication forks to diminish mutation rates. In this model there are two occasions when strand interruptions can guide MMR: (1) during the strand invasion that leads to the pictured intermediates (Figure 1, C and D), resulting in 6:2 conversion (Szostak et al. 1983; Haber et al. 1993), and (2) following or during resolution of the bimolecular intermediate (Foss et al. 1999), allowing the possibility of restoration of normal 4:4 segregation. Accordingly, Getz et al. (2008), working with yeast, proposed that a poorly repairable mismatch arising in the noninterference stage enjoys some MMR, but only at invasion. Such MMR would generate noninterfering 6:2 crossovers, as reported by Kitani (1978) for Sordaria. In contrast, MMR of poorly repairable mismatches in the interference stage was proposed by Getz et al. (2008) to occur invariably, but only at junction resolution. In an asymmetric heteroduplex, typical of yeast (Figure 1C), resolution-directed repair will yield interfering crossovers with either 6:2 or normal 4:4 segregation, depending on which of the two resolved junctions directs the MMR. In yeast, the interference in such 6:2 tetrads would mask the lack of interference of 6:2 tetrads derived from the noninterference pathway. By contrast, in the symmetric heteroduplex characteristic of Sordaria (Figure 1D), MMR directed by either of the two resolved junctions would restore normal segregation. Consequently, in Kitani's (1978) experiments, there would be no 6:2 interfering crossovers to mask the lack of interference in the 6:2 crossovers of the noninterference stage. At the same time, Kitani's normal 4:4 interfering crossovers would give no hint of their origin from intermediates that were heteroduplex for intragenic DNA. Thus, there seems to be no need to suppose, as Kitani (1978) did, that interfering crossovers occur only in spaces between genes.