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|Title:||Clarification of the Genetic Nature of Sugary Enhancer, an Endosperm Character in Sweet Corn|
|Author(s):||La Bonte, Don Richard|
|Department / Program:||Horticulture|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The sugary enhancer (se) gene has been shown to double the kernel sucrose content in sugary-1 (su-1) cultivars when homozygous. Unlike other endosperm mutations, su-1 se kernels are not readily apparent in segregating populations. What is needed is a genetic marker which can readily and easily identify kernels containing se. To create a genetic marker system linked to the se gene, the chromosomal location of se in the maize (Zea mays L.) genome must first be determined.
Methodology was developed for extraction and quantitative analysis of kernel sugars and total carotene from single kernels of maize. Single-kernel sugar analysis of kernels from the inbreds Il 451b (su-1 Se) and Il 667a (su-1 se) revealed that genetic differences between the inbreds was the primary source of phenotypic variation in kernel sugar content. Kernel-to-kernel variation on ears was not significant. The light yellow kernel color, as measured by the total carotene content of the kernel, was also principally due to genetic differences between the inbreds. su-1 se inbreds are characteristically lighter yellow in color than su-1 Se kernels.
Single-kernel analysis and the B-A translocation procedure were used in conjunction to identify the chromosomal location of the se gene. A deficiency on the long arm of chromosome 4 permitted the expression of the se phenotype, high sugar and light kernel color, in a hemizygous condition.
Single-kernel analysis was successfully used to identify su-1 kernels in segregating populations that were homozygous for the se gene. It was determined that sucrose was the principle sugar affected by the expression of the se gene. It was also determined that characteristic high levels of maltose content in mature su-1 se seed and light yellow kernel color are not always associated with su-1 se kernels. These two traits likely represent gene linkage. Characteristic high levels of percent moisture content in su-1 se kernels at advanced stages of kernel development was identified as an expression of high sugar content in the kernel. su-1 se kernels were also found to weigh less at maturity than su-1 Se kernels. Expression of se was shown in a heterozygous condition and in a starchy (Su) background in the form of higher sucrose.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.
|Date Available in IDEALS:||2014-12-16|