The onion thrips, Thrips tabaci (Thysanoptera: Thripidae), is a worldwide pest that causes serious damage to Allium crop species and acts as a vector for iris yellow spot virus (IYSV). In a previous study, we established an emamectin benzoate (EB) resistant strain (EB-R) with a 490-fold higher resistance ratio than the susceptible strain (SUS). The EB-R exhibited significantly increased transcript levels of glycine receptor alpha, glutamate-gated chloride channel (GluCl) b, and cytochrome P450 (CYP450) 6EB2 compared to SUS. To identify EB resistance-related genes that are differentially expressed genes between SUS and EB-R, we established an isogenic backcrossing strain and conducted transcriptome analysis after the 4th cycle of isogenic backcrossing. Among the 85 up-regulated genes in the transcriptome data, six cuticular protein genes showed up-regulation. Additionally, CYP450 4g15, which catalyzes the synthesis of cuticular hydrocarbons, exhibited a 6 log2-fold higher expression level in EB-R compared to SUS. Therefore, the elevated expression of genes associated with cuticle protein modification may be significantly is involved in the development of EB resistance.

Phytophthora capsici an Oomycete pathogen is a major challenge to the pepper (Capsicum spp.) production around the world. Control measures are proved ineffective, so breeding resistant cultivars are the most promising strategy against the pathogen. Resistance against P. capsici is governed by quantitative trait loci (QTL). According to previous studies on QTL detection, the QTL on pepper chromosome 5 is a major contributor to resistance. In this study, to exploit the involvement of this QTL and identify its contributing genes, the F2 population derived from a cross between ECW30R and CM334 was inoculated with a medium virulence P. capsici strain JHAI1-7 zoospores at the 6-8 leaf stage. Composite interval mapping revealed two major QTLs; QTL5-1 from 7 days post inoculation (dpi) and QTL5-2 from 16 dpi on chromosome 5. To characterize and detect interactions of the two QTLs, near isogenic lines (NIL) were constructed by crossing Tean and recombinant inbred line (RIL) derived from a cross between YCM334 and Tean. RILs were screened with P. capsici strain MY-1 and resistant lines were selected. Among the resistance RILs most closely related to Tean were selected using AFLP and SSR genotyping data. These RILs were named as YT39-2 and YT143-2. To develop more advanced NILs, two rounds of marker-assisted backcrossing were done using a high-throughput SNP genotyping system (EPI Fluidigm, USA). Among the NILs derived from YT39-2, YT39-2-64 contains only QTL5-1 whereas YT39-2-61 and YT39-2-69 were identified to have both QTLs. On the other hand, YT143-2-55-7 with the highest Tean genetic background contains QTL5-1 only. In the next step, the 3 different NILs having QTL5-1, QTL5-2 individually and both QTLs will be identified. Furthermore, phenotyping and fine mapping will be done for the analysis of individual and interaction effects of QTLs.

Grain size is a major determinant of grain yield in rice. In a previous study, a QTL for grain width(GW), qgw1 was detected on chromosome 1 using 96 BC3F8 lines derived from a cross between ‘Hwaseongbyeo’ as a recurrent parent and ‘O. rufipogon’ as a donor parent. At this locus, the O. rufipogon allele increased GW. Among the 96 introgression lines, three ILs with the O. rufipogon qgw1 locus showed significantly increase in grain width compare to the recurrent parent. One of the three lines, CR572 was selected and crossed to ‘Hwaseongbyeo’. A total of 494 F2:3 were evaluated for grain width and agronomic traits in the field. QTL analysis in 494 F2:3 lines indicated that QTL for grain width was located in the interval RM495–RM5443. To narrow down the position of qgw1, substitution mapping using F4 lines with different cross-over breakpoints in the region is underway. The result will be discussed.

In previous studies, we reported that a QTL for 1000-grain weight (TGW), qTGW3 was located in the interval between RM60 and RM523 (1.2Mb) on chromosome 3 using advanced backcross lines derived from a cross between Oryza sativa ssp. Indica cv. Milyang 23 and O. glaberrima. The O. glaberrima alleles at this locus increased TGW and GL in the Milyang 23 background. To further confirm and narrow down the position of the QTLs on chromosome 3, twenty lines with different O. glaberrima segments in the target region were selected. Twenty lines were evaluated for seven agronomic traits including 1,000 grain weight and grain length and also genotyped with ten SSR markers. Sixteen lines(A, B, C groups) with the O. glaberrima segment flanked by SSR markers, RM60 and RM7332 displayed significantly higher values than Milyang 23 in TGW and GL whereas four lines(D, E groups) without the O. glaberrima segment displayed no difference in TGW and GL. The result indicates that two QTL, qTGW3 and qGL3 are located near RM60 and RM7332.

Near-isogenic lines (NILs) carrying bacterial blight resistance genes (Xa4, xa5 and Xa21) were developed in japonica rice using Suweon345 as genetic background. NILs were selected by gene specific DNA markers and inoculation of K1 or K3a race. NILs conferring Xa4 were resistant to K1, K2, K3, and moderately resistant to K3a. NILs conferring xa5 were resistant to K1, K2, K3, and K3a. NILs having Xa21 were susceptible to K1, while resistant to K2, K3 and K3a. Target genes of NILs with the genetic background of Suweon345 were also confirmed by using eleven Philippines races and International Rice Bacterial Blight (IRBB) NILs carrying Xa4, xa5 and Xa21. All NILs had no significant difference from their recurrent parents in the major agronomic traits except for panicle length and brown rice 1,000 grain weight. Heading date of NILs ranged from Aug. 10 to Aug. 11, which was similar to that of recurrent parent, Suweon345. Culm length, number of grains per panicle and ratio of ripened grain of NILs were similar to those of Suweon345. Milled rice of NILs was ranged from 4.82 to 4.93MT/ha. These NILs will be useful for improving resistance to K3a race of bacterial blight pathogens in Korean japonica cultivars.

1. 선행 연구에서 염색체 3번의 RM60~RM231 부근에서 종자중, 수당립수에 관여하는 QTL이 탐지되었고, 이를 확인하기 위하여 이 지역에 크기와 위치가 다른 O. glaberrima 단편이 이입된 5 계통을 선발하여 표현형을 조사하였다. 실험 결과 계통별로 출수기, 임실률, 수당립수, 종자중을 제외한 형태적 특성들이 밀양23호와 비슷한 양상을 보였다. 이는 대부분의 염색체 지역이 밀양23호로 회복되었기 때문이라고 보여진다. 2. 유전자의 위치를

Korean Japonica resistant rice cultivars mainly posses one of the genes, Xa1 or Xa3 for BB resistance. These resistance genes are becoming susceptible to K3a, resulting in the breakdown of resistance of Japonica cultivars. Especially, glutinous rice cultivars exhibit high susceptibility to bacterial blight(BB) in Korea. This study was carried out to develop glutinous Japonica near-isogenic lines(NILs) conferring useful single gene such as Xa2, Xa3, xa5, Xa21, etc. Six NILs conferring Xa2, Xa3, xa5, xa8, Xa14 and Xa21 genes were developed. Six NILs with Sangjuchalbyeo genetic background were selected by DNA markers and inoculation of K1, K2, K3 and K3a race. NILs having Xa14 was resistant to K1 and susceptible to K2, K3 and K3a. NILs with Xa2 and xa8 was resistant to K1, K2 and susceptible to K3 and K3a. NIL with Xa3 was resistant to K1, K2, K3, but susceptible to K3a. NIL with xa5 was resistant to K1, K2, K3, and K3a. NIL having Xa21 was susceptible to K1, while resistant to K2, K3 and K3a. Identification of xa5 and Xa21 genes were carried out by STS markers. Heading date of NILs ranged from Jul. 31 to Aug. 6. Culm length, No. of grains per panicle and ratio of ripened grain of NILs were a little different to those of Sangjuchalbyeo. Milled rice of NILs were ranged from 437kg/10a to 463. Agronomic traits of NILs containing Xa2, Xa3, xa5, xa8, Xa14 and Xa21 were similar or a little different to those of recurrent parent. These NILs would be useful to develop durable resistant glutinous varieties in Korea.

수박에서 종자크기가 다른 각 계통들간의 종자특성과 종자 크기의 변화에 따른 과특성을 살펴보기 위해 수박 유전자원 353 점을 대상으로 종자의 크기를 조사하고 6가지 대표적인 종자크기 형으로 분류하였으며 종자크기가 큰 순서부터 giant seed(GS), big seed(BS), medium size(NS), small size(SS), micro seed(MS), tomato seed(TS)라고 명명하였다. 종자크기가 작아질수록 종장, 종경이 작아졌고,

Grain weight (GW) or grain size is the most important target not only as a major component of grain yield, but also associated with the cooking quality in rice breeding program. In a previous study, two loci for grain weight, gw8 and gw9, have been fine map to about 306.4kb and 37.4kb, respectively, in backcross populations derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipigon (IRGC 105491). Both O.rufipogon alleles increased GW in the Hwaseongbyeo background despite the fact that O. rufipogon was the small-seeded parent. To test the effect of pyramiding the QTLs for grain weight, an F2 population consisted of 226 individuals was developed derived from the cross between the two QTLs (gw8 and gw9), and used MAS to select nearly isgenic lines for two QTLs and a pyramiding line. Molecular genotyping of F2 population revealed the existence of interaction between gw8 and gw9. Moreover, the interaction was also confirmed by phenotypic analysis of four QTL-NILs. The results suggest that epistasis interaction is important genetic basis in determining yield traits in rice.

Awn, one of the domestication-related traits in rice might play an important role in seed dispersal. In a previous study, one major QTL, awn8 was detected on chromosome 8 using 120 RILs and 62 ILs derived from a cross between Hwayeongbyeo and O. rufipogon Griff. (Acc. W1944). We developed 140 BC1F3, 341 BC1F4 and 1533 BC1F5 plants from selfing of one plant selected from former generation. Each of selected plant was Hwayeongbeyo/W1944 heterozygous in the target region of chromosome 8. The Target marker(RM256) significantly linked to awn8 explained 60.3% of the total phenotypic variance in BC1F4 generations and the W1944 allele increased awn length. Using several substitution mapping, The awn8 QTL could be narrow down to the interval between RM23338-RM5485, with a distance of about 85.29kb. Total of ten genes were predicted in this region. At the same time, 34 BC3F5 lines were developed as the diverse NILs on chromosme 8. Using these NILs, One QTL for primary branch was detected in the target region and W1944 allele increased branch number. Characterization of the awn8 QTL would contribute the understanding of rice domestication and evolution and additional experiment would be need to be clarified whether awn8 and pb8 was due to linkage drag of independent genes or pleiotropic effect of the same gene.