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  • Author or Editor: M. A. Mikel x
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Abstract

Six sweet com (Zea mays L.) inbreds homozygous for the genes sugary (su) and sugary enhancer (se) have been developed at the Illinois Agricultural Experiment Station. The se gene is a recessive modifier of the su genotype (2) and results in increased kernel sugar content, sweetness, and tenderness (3). Kernels with the su se genotype contain amounts of sugar comparable to those found in lines homozygous for the shrunken-2 (sh 2) gene but without a concomitant reduction in phytoglycogen (water-soluble polysaccharides) content (4). The high level of phytoglycogen found in su and su se cultivars contributes to their tender, creamy texture.

Open Access

Abstract

Maize dwarf mosaic (MDM) is an economically serious viral disease of sweet corn (Zea mays L.) in the United States. Early infection by the virus in sweet com can cause stunted growth, delayed maturity, reduced yield, and poor ear quality (5). To aid in alleviating this problem, the Illinois Agricultural Experiment Station announces the release of 8 lines of sweet com germplasm homozygous for the sugary (su) gene with improved resistance to maize dwarf mosaic virus (MDMV). These new lines have been designated: ILM6161a, lLM6222a, ILM6222b, ILM6222c, ILM6222d, ILM6222e, ILM6223a, and ILM6223b.

Open Access

Tomato spotted wilt virus (TSWV) and Phytophthora infestans (late blight) in tomato (Solanum lycopersicum) have a worldwide distribution and are known to cause substantial disease damage. Sw-5 (derived from S. peruvianum) and Ph-3 (derived from S. pimpinellifolium) are, respectively, TSWV and late blight resistance genes. These two genes are linked (within 5 cM on several maps) in repulsion phase near the telomere of the long arm on chromosome 9. The tomato lines NC592 (Ph-3) and NC946 (Sw-5) were crossed to develop an F2 population and subsequent inbred generations. Marker-assisted selection (MAS) using three polymerase chain reaction-based codominant markers (TG328, TG591, and SCAR421) was used in F2 progeny with the goal of selecting for homozygous coupling-phase recombinant lines. From 1152 F2 plants, 11 were identified with potential recombination events between Ph-3 and Sw-5; of those, three were male sterile (ms-10). F3 progeny were generated from the remaining eight F2 recombinants, and resistance to both pathogens, or Ph-3 and Sw-5 in coupling phase, was confirmed in three of those. Recombination was suppressed fivefold in our F2 population to 1.11 cM between genes when compared with published maps of the same region. However, MAS was an efficient tool for selecting the desirable recombination events for these two pathogen resistance genes.

Free access