The transposable element is a DNA sequence that can be changed its position within the genome, sometimes it can create or reverse mutations and altering the cell's genome size. Target region amplification polymorphism (TRAP) is a rapid and efficient PCR-based marker technique, which uses bioinformatics tools and expressed sequence tag (EST) database information to generate polymorphic markers around targeted candidate gene sequences. TE-TRAP is a new marker system which used terminal inverted repeat (TIR) instead of targeted candidate gene sequences. Sorghum holds a good potential plant organism for transposon tagging due to its small genome size, low amount of repetitive DNA and co-linearity with other cereal genomes, which allows the use of information derived from sorghum in other cereal grasses. IS2868 of sorghum accession was treated Gamma irradiation on seed. To define availability and utilization of TE-TRAP, twenty-one accessions were used to evaluate the genetic diversity and underlying relationships. One-thousand thirty-three TE-TRAP markers were amplified by thirty-one primer combination. Altogether, 712 (62.8%) markers were observed polymorphic segregation, whereas 421 (37.2%) showed monomorphic patterns. To estimate genetic differentiation of population by various gamma radiation doses, the analysis of molecular variance (AMOVA) was performed using 4 to 5 different radiation doses population of M1 sorghum individuals. This study and marker system will provide valuable information to assist radiation mutation breeding.

This study was conducted to determine the optimal dose of gamma-ray for mutation breeding in sorghum (Sorghum bicolor M.). Gamma-rays irradiated to dry seeds with various doses (0 to 1000 Gy) at Korea Atomic Energy Research Institute. Lethal dosage (LD50) was approximately 256 Gy. Significant decreases in growth characteristics (plant height, tiller number and fresh weight) were observed by dose of increased over 300 Gy. Reduction doses (RD50) was approximately 363 Gy in plant height. We also conducted comet assay to observe nucleus DNA damage due to gamma irradiation. In comet assay, a clear difference was identified over 100 Gy treatments. With increasing doses of gamma-ray in the range of 100 to 400 Gy, the rate of head DNA was decreased significantly from 93.52% to 67.57%. The most of the Sorghum cells were severely damaged in the integrity of DNA by gamma-ray. These data provide valuable information when the optimal dose should be chosen for purpose of mutation breeding program of Sorghum.

Major characteristics of new Waesungri maize inbred line has multi-tiller and ears: five to six tillers and seven to eight ears per plant and flowering date of Waesungri was delayed about 18 and 24 days compared to Mo17 U.S line and IK4 Korean local lines, respectively. Number of ears, fresh and dry weight per plant were significantly different among all tested hybrids including Waesungri/Sinkihong hybrid under different planting times and densities. Especially, both fresh and dry weight of IK1/FR140//Waesungri F1hybrid were significantly higher at high planting density. In kernel weight per unit area, Wnesungri/Sinkihong hybrid was high at high density and IK1/FR140//Waesungri hybrid was high at low planting density. As results of analysis of variance, flowering date was shown a significantly different both planting times and varieties, while other characters including stem height were shown very variable in interactions with enviromental factors.