Nonreciprocal, partial cross-incompatibility

The phenotypic expression of this nonreciprocal, partial cross-incompatibility (NPC) is a reduced seed set (RSS) (Sukhapinda and Peterson, 1983). NPC occurs in our experiments only in crosses between certain parents: an En controlling element genotype or derivatives of it as a female--e.g., a-m(papu) (Peterson 1970, TAG) and a et/a et as male. A crossing design was developed to distinguish between gametophytic and sporophytic control. This is illustrated in Figure 1.

The results (Table 1) show a nonsignificant difference from the expected "all NSS" (Figure 1, line 4) if this incompatibility is gametophytically controlled.

Hence, it is concluded that the transmission of this incompatibility factor is under the gametophytic system of control.

Figure 1. Diagram of crossing design used to distinguish betwen gametophytic vs. sporophytic control of incompatibility.

Table 1. Observed seed set (kernels per ear) in the cross RSS x various male genotypes (figure 1, line 3) for two years.

Paul Bdliya and Peter A. Peterson

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors.

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