탄저병 저항성 수박 계통을 육성하기 위하여 저항성 계통인 ‘AU-Producer’를 선발하여 탄저병 저항성 친으로, 고품질 계통인 ‘920533’을 반복친으로 1993년 교배하여 F1세대를 작성하였으며, 1994년부터 1996년까지 BC3F1세대를 진전하였고 중만생종인 ‘920532’를 반복친으로 추가하여 1997년 BC4F1세대를 작성하였다. 1998년부터 2001년까지 원예적 특성 고정을 위해 6회 자가수분하여 세대를 진전하였으며, 원예적 특성이 우

우리나라 수박 주산단지에 심한 피해를 주고 있는 수박 탄저병에 대한 저항성 계통 육성을 위하여 국내·외에서 수집한 수박 유전자원의 병 저항성 검정으로 탄저병 저항성이 강한 ‘AU-Producer’를 선발하여 저항성 친으로, 고품질 계통인 ‘920533’을 반복친으로 1993년 인공교배를 하였으며 1994년 부터 1998년까지 BC4F1세대를 진전하였다. 1998년부터 2001년까지 원예적 특성 고정을 위해 6회 자가수분하여 세대를 진전하였으며 원예적 특

Allium 속 근연종인 파와 양파간 종간교잡을 이용하여 양파로부터 새로운 형질을 도입하는 과정에서 유래되는 종간교잡 F1과 여교잡 세대들의 게놈크기의 변화를 flow cytometry를 이용하여 측정한 결과 다음과 같은 결과를 얻었다. 1. 양파와 파의 종간교잡 F1의 식물학적 특성은 양친의 중간형을 보였으나 여교잡이 진전됨에 따라 반복친인 파의 표현형이 우세하였다. flow cytometry를 이용하여 2C nuclear DNA content을 측정

To facilitate the introgression of F. esculentum into the traits of F. homotropicum, several accessions of the hybrids between these two species were pollinated with F. esculentum as the recurrent parent. The embryo in vitro rescue was performed to increase the recovery of backcross progenies. The F2 generation was more amenable than F1 hybrids to produce backcross progenies. The F1 hybrids were backcrossed twice with common buckwheat (pin-type F. esculentum) (recurrent backcrossing). Also, alternate backcrosses with common buckwheat and F. homotropicum (congruity backcrossing) were carried out. Pollen tube growth of BCF1 × F. esculentum (thrum) and F. homotropicum × BCF1 was the disturbed penetration exceeded for all initial interspecific hybrids, and its requirement was proportionally lower when the common buckwheat was used as the recurrent parent and as the last parent of congruity hybrids. Effects of both common buckwheat and F. homotropicum on seed success rate for hybridization were observed. Growth of hybrid embryos before rescue, regeneration of mature hybrids all increased recurrent and congruity backcrosses and inter-crosses between F1 plants and selected fertile plants of the second congruity backcrosses.

To facilitate the introgression of F. esculentum into the traits of F. homotropicum, several accessions of the hybrids between these two species were pollinated with F. esculentum as the recurrent parent. In vitro embryo rescue was performed to increase the recovery of backcross progenies. The F2 generation was more amenable than F1 hybrids to produce backcross progenies. The F1 hybrids were backcrossed twice with common buckwheat (pin-type F. esculentum, recurrent backcrossing). Also, alternate backcrosses with common buckwheat and F. homotropicum (congruity backcrossing) were carried out. Pollen tube growth of BCF1 x F. esculentum (thrum) and F. homotropicum x BCF1 was disturbed penetration exceeded for all initial interspecific hybrids, and its requirement was proportionally lower when the common buckwheat used as the recurrent parent and as the last parent of congruity hybrids. Effects of both common buckwheat and F. homotropicum on seed success rate for hybridization were observed. Growth of hybrid embryos before rescue, regeneration of mature hybrids all increased recurrent and congruity backcrosses, inter-crosses between F1 plants and selected fertile plants of the second congruity backcrosses.

BC1F7 RILs were cultivated and harvested in field. Two methods were adopted to classify ecotype of the RILs. First method was based on the seed length, width, length/width ratio, phenol reaction of the seed, and response to potassium chlorate of young seedling. Second was the classification using the polymorphism in SSR analysis. The results of UPGMA cluster analysis indicated that 168 RILs were classified into two ecotypes, 32 Japonica and 136 Tongil-type lines when first method was adopted. When second method was adopted, 35 and 99 lines among 134 RILs tested were belonged to Japonica and Tongil-type, respectively. The RILs belonged to same ecotype in both methods was 65.6% in Japonica, 91.9% in Tongil-type and 83.6 % in overall. The parents and BC1F7 RILs showed polymorphism in 20 among 21 RM primers used in SSR analysis. The proportion showing band pattern of each primer corresponded with ecotypes grouped by two methods ranged 29.7 to 99.1%. RM131, RM124, RM567, RM559, and RM348, which are located on chromosome 4, showed high proportion of correspondence over 94%. It was suggested that they would be used as molecular markers for rice ecotype classification. Japonica RILs grouped by two methods showed shorter grain length, no seed response to phenol solution and higher resistance to potassium chlorate solution in seedling stage compared with those of Tongil-type lines.

Brown planthopper (BPH) is a major insect pest of tropical indica and temperate japonica rice in Asia and Africa. A major BPH resistance gene, Bph18 derived from IR65482-7-216-1-2 has been fine mapped on chromosome 12 and confers strong resistance to the Korean biotype of BPH. The Bph18 gene is tightly linked to the STS marker, 7312.T4A and is non-allelic to previously reported resistance genes present on chromosome 12. The Bph18 gene has been transferred into two elite japonica cultivars (Jinbubyeo and Junambyeo) background through marker-assisted backcross breeding (MAB) strategy. Foreground selection using STS markrs linked to the Bph18 gene in advanced backcross progenies confirmed homozygous marker alleles associated with BPH resistance. Background selection of the breeding lines with 260 simple repeat (SSR) markers revealed rapid conversion toward recurrent parent genotypes with less donor chromosomal segments (5.3-16.7%). Major agronomic traits of the progenies were analyzed and some breeding lines have agronomic traits comparable to the recurrent parent. One breeding line (S.523) with multiple-resistance to BPH and major diseases, desirable agronomic traits and grain quality has been recommended for regional testing in Korea. MAB is the suitable strategy to incorporate new genes into susceptible japonica to develop elite breeding lines.

In the previous study, 141 BC3F2 lines from a cross between the Oryza sativa cv. Milyang 23 and O. glaberrima were used to identify favorable wild QTL alleles for yield component traits. In this study, we carried out QTL analysis of four grain morphology as well as four yield component traits using 141 BC3F5 lines from the same cross and compared QTLs detected in two different generations. The mean number of O. glaberrima segments in the 141 BC3F5 lines ranged from 1 to 13 with 2.69 and 5.71 of the average means of homozygous and heterozygous segments, respectively. There was a three-fold difference in the number of QTLs detected for four traits commonly evaluated in two generations (seven QTLs in the BC3F5 vs 21 in the BC3F2 population). The percentages of the phenotypic variance explained by QTLs in the BC3F5 population were similar to or less than those in the BC3F2 population. This is probably due to the difference in the genetic composition of two populations and the environmental effects. The locations of the QTLs commonly detected in both generations were in good agreement except for one QTL for spikelets per panicle. The yield QTL, yd3 was colocalized with the spikelets per panicle, spp3. Yield increase at this locus is due to the increase in spikelets per panicle, because both traits were associated with increase in spikelets per panicle and yield due to the presence of an O. glaberrima allele. Clusters of QTLs for grain morphology traits were observed in two chromosome regions. One cluster harboring five QTLs near SSR markers RM106 and RM263 was detected on chromosome 2. This population would serve as a foundation for development of the introgression line population from a cross between Milyang 23 and O. glaberrima.