Rice blast, caused by a fungus Magnaporthe oryzae, is one of the most devastating diseases of rice worldwide. Analyzing the valuable genetic resources is important in making progress towards blast resistance. Molecular screening of major rice blast resistance (R) genes was determined in 2,509 accessions of rice germplasm from different geographic regions of Asia and Europe using PCR based markers which showed linkage to twelve major blast R genes, Pik-p, Pi39, Pit, Pik-m, Pi-d(t)2, Pii, Pib, Pik, Pita, Pita/Pita-2, Pi5, and Piz-t. Out of 2,509 accessions, only two accessions had maximum nine blast resistance genes followed by eighteen accessions each with eight R genes. The polygenic combination of three genes was possessed by maximum number of accessions (824), while among others 48 accessions possessed seven genes, 119 accessions had six genes, 267 accessions had five genes, 487 accessions had four genes, 646 accessions had two genes, and 98 accessions had single R gene. The Pik-p gene appeared to be omnipresent and was detected in all germplasm. Furthermore, principal component analysis (PCA) indicated that Pita, Pita/Pita-2, Pi-d(t)2, Pib and Pit were the major genes responsible for resistance in the germplasm. The present investigation revealed that a set of 68 elite germplasm accessions would have a competitive edge over the current resistance donors being utilized in the breeding programs. Overall, these results might be useful to identify and incorporate the resistance genes from germplasm into elite cultivars through marker assisted selection in rice breeding.

Insect resistant genes encode insecticidal δ-endotoxins that are widely used for the development of insect-resistant crops. Common soybean is a crop of economic and nutritious importance in many parts of the world. Korean soybean variety Kwangan was transformed with Insect resistant genes. These genes were transformed into Kwangan using highly efficient soybean transformation system. Transgenic plants harboring Insect resistant genes were confirmed for gene introduction and their expression using PCR, real-time PCR and RT-PCR. The confirmation of stable gene introduction with Insect resistant genes was also performing by Southern blot analysis. In addition, Flanking sequence analysis and agronomic characters were also investigated

Rice blast (Magnaporthe oryza B.) is one of the most widespread and devastating diseases of rice. Screening of valuable genetic resources harboring resistance genes is one of the most efficient approaches against blast disease. Because the bioassay to rice blast in the field shows high variations, this study has performed to provide DNA profiles in the accessions of diverse countries using major blast resistant genes linked markers, identified and mapped in different genotypes of rice. Because durable resistance to blast is controlled by a combination of major resistance genes, we surveyed the distribution of blast resistant genes in the 1,500 accessions using major 12 blast resistance genes linked markers. These resistant genes found that the frequency distribution of Pi-39 (66.9%), Pik-m (41.9%), Pit (40.5%), Pii (21%), Pib (19.3%), Pi-d(t)2 (12.7%), but Pita, Pita/Pita-2, Pik, Piz-t, Pi5 genes were identified in less than 10% frequency. Most of accessions contain from 1 to 4 different resistant genes. Pi39 and Pik-m genes amplified in the 69.1% and 51.7% among 356 Korean accessions, Pi39 (79.6%) and Pib (55.8%) in 113 China, Pit (80.6%) and Pib (32%) in 103 Philippines, respectively. In this study, we evaluated the blast resistance degree and the information about the distribution of rice blast resistant genes in rice germplasm. This study will help to develop effective strategies for managing rice blast disease in rice germplasm.

The rice water weevil (RWW), Lissorhoptrus oryzophilus are major pests of aquatic rice plant in Korea as well as throughout the country. Larvae of RWW sucking the nourishment on roots, causes a stunted root system and reduces grain yields. To prevent these damages, we constructed various plant expression vectors, which were harbored by insecticidal genes, cryBP1 and cryIIIa, and fused with the actin promoter and/or the modified RCg2 root-preferential promoters for expressing the insect-toxic genes in leaves and roots. A cryBP1 was cloned from Bacillus popilliae, producing crystal toxin against Japanese beetle, and CryIIIa was modified from the δ-endotoxin gene of Bacillus thuringiensis ssp. tenebrionis, encoding the coleoptera-specific toxin. The vectors containing the insecticidal genes were transferred into Oryza sativa japonica cultivar, Nakdong, by Agrobacterium -mediated transformation method. Several independent transgenic lines were selected by Southern blotting and Western blotting, confirming that cryBP1 and cryIIIa genes were stably integrated into the plant genomes and were expressed in transgenic plants. Upon insect bioassay using RWW, the mortality of insect larvae on cryBP1 and cryIIIa transgenic rice lines recorded up to 41% and 34%, respectively. These results suggested that the transgenic lines can be used to develop Coleoptera-resistant cultivars and could be valuable for later application in crop breeding for insect resistance.

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.

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.

월동 후 맥류 재배지에서 나타나는 이상 증상으로는 주로 잎에 황화등의 변색과 모자이크성 반점 등이 조사되었다. 이들 증상을 가진 잎의 바이러스 검정 결과 78~% 이상에서 바이러스 감염이 확인되었으며, 주로 BaYMV와 BaMMV에 의해 발생하였다. 전국일원의 맥류 재배지에서 4개년간 BaYMV, BaMMV SBWMV와 BYDV-MAV(2003년) 등 4종의 바이러스의 발생율을 조사한 결과 대상 바이러스 중 BaYMV가 가장 높은 감염율을 나타내었다. BaYMV는 조사 4개년 동안 평균 발생율이 70~% 이상으로 전국적으로 큰 차이 없이 가장 높은 발생율을 보였다. 그러나 경기지역의 경우는 20~% 정도로 다른 지역의 65~~85~% 에 비해 낮은 발생율을 보였다. BaMMV는 전북, 전남, 경기, 강원, 경남지역에서 20~~40~% 를 보인 반면, 경북, 충남, 경기지역에서는 발생이 적었다. SBWMV와 BYDV-MAV는 현재까지 국내 보리 재배지에서 다발생되고 있지는 않았다. 저항성 유전자원에 대해 바이러스에 대한 저항성 반응을 검정한 결과 BaYMV와 BaMMV가 단독 또는 복합 감염되는 형태로 나타났으며, SBWMV는 감염이 확인되지 않았다. 저항성 유전자별 반응을 검정한 결과에서 익산 발생하고 있는 BaYMV-Ik strain과 BaMMV에 대해 모두 저항성인 유전자는 확인되지 않았으나 국내 맥류 재배지에서 가장 발생이 많은 BaYMY-lk체 대해 저항성 반응을 보인 유전자는 Ishukushirazu, Chosen에 들어있는 rym 3, Tokushima Mochi Hadaka의 rym 4y 및 Hakei I-41의 rym 5a로 나타났다. 그러나 BaYMY-lk에 대해 저항성으로 확인된 rym 3, rym 4y 및 rym 5a의 경우 BaMMV에는 모두 감염이 확인되었으며, rym 1+5 두개의 저항성 유전자를 가지고 있으며 일본의 모든 BaYMV strain에 저항성인 Mokusekko 3도 감염이 확인되었다. 유전자에 따른 병징 발생 양상을 조사한 결과 일반적인 바이러스 병징과 같이 대부분 모자이크나 황화가 발생하였다. 그러나 저항성 유전자에 따라 고사, 괴사 반점, 조직 괴사, 줄무늬성 증상과 잎 말림등의 다양한 증상이 확인되었다

우리나라 자포니카 품종의 흰잎마름병 저항성 유전자와 연관된 마커를 탐색하기 위하여, 밀양121호, 밀양123호 및 HB10624-AC5 등을 교배친으로 한 두 조합의 약배양 계통을 재료로 흰잎마름병 저항성 유전자(Xa-1 and Xa-3)와 DNA 마커간의 연관분석을 통하여 유전자 지도를 작성하고자 수행하였던 결과를 요약하면 다음과 같다. 1. K1 균주에 대한 흰잎마름병 저항성 검정결과, 밀양121호/HRl1650-1-4-2에서는 저항성과 감수성이 1:1로 분리하였으며, 밀양123호/HR10624-AC5 조합의 K1 및 K3 균주에 대한 검정결과는 각각 3:1과 1:1로 분리하여 이론치에 합당하였다. 2. 교배친에 대하여 DraI. HindIII, EcoRI, EcoRV, PstI등 5가지 제한효소에 대한 다형현상을 검정한 결과, RZ590, RG303, RZ536 등 3개의 마커가 다형현상을 나타내었다. 3. 흰잎마름병 포장저항성 검정결과와 RFLP 마커와의 연관분석 결과 Xa-1 유전자는 RZ590과 4번 염색체 상에서 3.1 1.5 cM으로 연관되어 있었으며, Xa-3 유전자는 Rz536 및 RG303과 11번 염색체 상에서 각각 7.6 2.3 및 16.0 3.2 cM으로 연관되어 있었다. 4. 11번 염색체 상에서 Xa-3와 Rz536 및 RG303은 "Xa-3-RZ536-RG303" 순으로 위치하였다.순으로 위치하였다.

This study was carried out to map Bphl and bph2 gene in Mudgo and Sangju13 (Oryza sativa L.) respectively conferring resistance to brown plan-thopper (BPH) and to establish the marker-assisted selection (MAS) system. Bulked seedling (grown for 20 days) test was conducted with the 73 F4 lines derived from a cross between Nagdongbyeo and Mudgo for Bphl and with 53 BC3F5 lines derived from the Milyang95/Sangju13 cross for bph2. Bph1 was mapped between RG413 and RG901 on chromo-some 12 at a distance of 7.5 cM from RG413 and 8.4 cM from RG90l. A recessive gene bph2 was located near RZ76 on chromosome 12 at a distance of 14.4 cM. Bphl and bph2 were linked to each other with a distance of about 30 cM. An RFLP marker, RG413 linked to Bphl, was converted to an STS marker to facilitate the marker-assisted selection. BPH resistant genotypes could be selected with 92% accuracy in a population derived from a line of NM47-B-B.