Since 1980 authors Lee and Choe have studied the prospects for development of maize hybrids with multi-tillers and ears. Toward the breeding of a new type of maize hybrid with multiple tillers and ears, a few inbred lines with multi-tillers and ears were developed: IK1, IK2, IK3, IK4 (MNL 68:100, 1994), Waesungri, and PI213749 inbred.
The tillering traits in these lines were determined to be controlled by a single dominant gene in studies with each line. Only the tillering gene in IK1 has been evaluated for chromosome location (Kang et al., Korean J. Breed. 23:285-289, 1992). To determine the location of additional tillering genes, the PI213749 inbred was crossed with a non-tillered inbred, KV1IK1, which has been selfed for six generations, and an F2 was produced for RFLP mapping.
F2 individuals were grown in the field in 1994 at Columbia, Missouri. Plants were rated for tillers as follows: 0, 1, 2, and 3 or more tillers. Leaf tissue was collected from individual F2 plants and parents. After freeze drying, genomic DNA was extracted using the CTAB method (UMC Maize RFLP Laboratory Manual 1995, p. 34). DNA was digested with EcoRI, HindIII and DraI. DNA of parental lines, 0-tiller and 3+ tiller individuals was loaded onto 0.8% agarose gels and electrophoresed. DNA was transferred to Magnacharge membrane according to standard laboratory protocols. Hybridization using dCTP32 oligolabelled probes from the Maize Core Marker Set indicated that tillering is linked to umc76 on the short of chromosome 1 (Fig. 1). Additional probings to establish whether the locus is proximal or distal to umc76 are in progress. Future testing will be needed to determine whether the gene from PI213749 and tlr1 (of Neuffer) are allelic.
1. Southern blot of EcoRI-digested genomic DNA hybridized with
32P-dCTP labelled umc76 probe.
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