Differential Ability of Two Degenerative Sweet Corn Mutants to Stimulate Hybrid Vigor1

Abstract

A novel procedure was used to test for single locus heterosis in a substantially isogenic background in corn, (Zea mays L.). It was determined that the rd gene and its rdPw allele do not contribute to single locus heterosis for plant height. To explain why C30 induces heterosis in F1 hybrids, while ‘Pee Wee’ is relatively impotent, a hypothesis is proposed to the effect that C30 evolved from P39 by the addition of a mutagenic and heterotic duplicated chromosomal segment when Rd mutated to rd. In turn, ‘Pee Wee’ developed with the loss of the segment at the time rd mutated to rdPw.

Molecular Variation and F1 Performance among Strains of the Sweet Corn Inbred P39

“…Variation was observed for ear weight, plant height, and ear height among the crosses, the highest yielding crosses involved C30. These results confirm previous results (Singleton, 1943; Lachman, 1972, 1974). Breeding experiments indicated that the differences in yield were due to a number of genetic factors (Singleton, 1948) Molecular data support this hypothesis.…”

“…previous results (Singleton, 1943;Lachman, 1972Lachman, , 1974. It is interesting to speculate about the role of transpos-Breeding experiments indicated that the differences in able elements in generating diversity among the strains.…”

“…( Sprague et al, 1960). Subsequently they studied mutation rates in longtime inbreds and estimated a rate of The crosses differed significantly in ear weight and plant and ear height.…”

“…(Smith, 1933). The strains of P39 that had been maintained separately are designated P39a and P39b solely for the purpose Sprague and Suwartardon (1975) reported a very simof this report. ilar case in field maize.…”

“…These differences were found to be due to the reduced gene ( rd1 ). Singleton (1943, 1944a, 1947) observed significant high parent heterosis for yield and plant height when C30 was backcrossed to P39 and Lachman (1971, 1974) observed high parent heterosis for plant height in the same cross. Singleton thought this was an example of single gene heterosis and that rd1 was responsible (1943).…”