CHISINAU (KISHINEV), MOLDOVA
Institute of Genetics, Acad. Sci. Mold. Rep. Maize productivity: an example of non-allelic interaction --Chernov, AA, Mihailov, ME The question of heterosis may be reduced to a question of factors causing advantage for heterozygous organisms. The great role of allelic interaction (dominance and overdominance) has been demonstrated theoretically and experimentally, but non-allelic interactions remain less investigated, especially these, in which effects of different loci can't be summarized.

Here we show an example of such an interaction between the loci wx1 and R1. Maize productivity was measured in F2 hybrids Ku123 x 2-9m and Uit757 x 2-9m (see Table).

Table. The productivity of F2 plants (gm/plant) in the combinative classes wx1-R1
 
Hybrid and year
Genotype
UIT-757 x 2-9m 1993
Ku123 x 2-9m 1993
UIT-757 x 2-9m 1995
wx1+/+ R1+/+
111+8 (15)*
132+12 (16)
159+13 (6)
R1+/- 
132+8 (27)
134+7 (31)
159+15 (13)
R1-/-
147+12 (11)
133+11 (13)
172+19 (10)
wx1+/- R1+/+
149+13 (13)
161+11 (20)**
170+15 (15)*
R1+/-
155+8 (37)
152+6 (57)
173+10 (31)
R1-/-
146+11 (19)
143+10 (22)
130+12 (16) 
Total
142+4 (122)
145+4 (159)
162+6 (91)

Comment 1. The number of plants is given in brackets.

Comment 2. The asterisks relate to whole cell and show

significance of effect of the R1 locus.

It is seen in the table that details of this interaction depend on genetical environment and year conditions. Nevertheless, here is a common feature. The R1 locus regulates productivity, and the wx1 locus regulates the R1 locus. One allelic state of wx1 (+/+ for UIT-757 x 2-9m and +/- for Ku123 x 2-9m) allows R1 to be regulator, another allelic state blocks this regulative function.

The productivity of the heterozygous genotypic class wx1+/- R1+/- in all cases is higher than the mean value. Therefore, gene interactions of such a type can provide a role in heterosis.
 
 

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