Phenotyping a new maize shoot mutant in inbred and F1 hybrid genetic backgrounds

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McLaughlin, Sean
Major Professor
Vollbrecht, Erik
Hufford, Matthew
Anderson, Sarah
Committee Member
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Genetics, Development and Cell Biology
Maize mutants are best characterized by first converging mutant alleles into a uniform, typically inbred genetic background and then phenotyping, to understand specific effects of a mutation independently of other factors that may segregate in a population. Similarly, researchers working with mutants are anecdotally familiar with mutant phenotypes differing between inbred and hybrid genetic backgrounds. On the other hand, in industry hybrid maize is used for crops and an F1 hybrid displays phenotypes distinct from its inbred parents. Therefore, we are quantifying phenotypic differences for a shoot architecture mutant allele between inbreds and hybrids by conducting field phenotyping and comparing observed traits. We have addressed this question by studying a novel, recessive mutant initially discovered in a B73/W22 hybrid background given the temporary name leafy* (lfy*) due to some resemblance to mutants of the maize zfl genes, homologs of the Arabidopsis LEAFY gene. lfy* mutants have a range of phenotypes including altered leaf number, shortened internodes and feminized tassel branches, making them appropriate for studying this question. The original mutant allele was introgressed into four standard corn belt inbreds (A619, B73, Mo17 and W22) which were then used to also produce segregating wildtype and mutant lfy* progeny within uniform, F1 hybrid backgrounds. Inbred and hybrid populations were phenotyped in the field for developing and mature plant phenotypes such as phase change, plant height and other potentially mutant-affected characteristics. From these results we will present an overview of the lfy* mutant phenotype and compare it in hybrids versus inbreds. We are also working to clone the causal gene for this mutant phenotype. From map-based approaches we previously narrowed to a genomic interval of about twelve candidate genes. By using a nearby Ds transposon in a targeted tagging approach we have now identified an additional allele which should aid in gene identification.
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