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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Publications at this Location » Publication #62755
Title: GENETIC VARIATION IN DOSAGE EFFECTS IN MAIZE ANEUPLOIDS.

Author
item LEE, E - UNIVERSITY OF VERMONT
item Coe Jr, Edward
item Darrah, Larry

Submitted to: Genome Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/13/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Corn improvement is the result of identifying sources of germplasm containing genes and combining them by breeding hybrids chosen for optimum outcomes. These genes, which determine quantitative traits, have been and continue to be a challenge to identify in candidate germplasms. So that manipulative breeding of traits can be done, efficient new technologies are esought by breeders and geneticists. This study contributes a Dosage Difference method, by which to determine, in different germplasms, prospective locations on the chromosomes and in the genome for genes with these properties. Using modified chromosomes termed B-A translocations, crosses were made on 4 different inbred lines that produced designed changes in the number of copies (1, 2, or 3) of specific chromosome segments, parts of the genome. Plants with changed copy number were then subjected to measurement of 12 traits important to productivity. Over 2/3 of the genome was examined by this procedure. The experiment revealed different effects in different inbred lines, demonstrating that the method has potential in applications for screening germplasm.

Technical Abstract: In maize (Zea mays L.), the consequences of aneuploidy have been well documented, however, genetic variation in the responses to aneuploidy has not been examined. Using B-A translocation stocks to generate a dosage series for 14 chromosome arms, we tested for the presence of genetic variation for dosage responses by examining reciprocal and maternal effects on the dosage responses. Reciprocal effects examined whether there were differences between two distinctly different inbred backgrounds, Mo17Ht and B73Ht, in how they responded to loss or gain of a B73Ht arm in the Mo17Ht x B73Ht (TB) F1 cross versus a Mo17Ht arm in the B73Ht x Mo17Ht (TB) F1 cross. Maternal effects questioned whether 4 different inbred backgrounds responded differently to the loss or gain of a chromosome arm from the same male in an F1 cross. Numerous examples of reciprocal and maternal genetic effects were identified. Most of the genetic effects were due to differences in magnitude of response rather than direction. These experiments demonstrate that segmental aneuploidy can reveal differences between inbred lines in genetic effects on specific traits in different chromosome segments. One potential utility of the Dosage Difference technique is in screening of lines for segments with particular effects, preparatory to crossbreeding designs.