• The Plant Pathology Journal
• /
• 제28권2호
• /
• pp.164-171
• /
• 2012

Rice blast disease caused by Magnaporthe grisea (Hebert) Barr [teleomorph] is one of the most devastating diseases in rice plantation areas. Silicon is considered as a useful element for a large variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants receiving the different rates and sources of silicon. Silicon at all rates of application significantly (${\alpha}$ = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2004년도 The 2004 KSPP Annual Meeting & International Symposium
• /
• pp.48-52
• /
• 2004

We have found the role of rice mitogen-activated protein kinase kinase kinase (MAPKKK), OsEDR1, as controling hypersensitive response (HR) and increased disease resistance to rice blast fungus Magnaporthe grisea. Generation of transgenic rice plants through introduction of the over-expression construct of OsEDR1 using Agrobacterium-mediated transformation results in lesion mimic phenotype. Up-regulation of defense mechanism was detected through detection of increased transcription level of rice PBZ1 and PR1a. Inoculation of rice blast fungus on the lesion mimic transgenic lines displayed significantly increased resistance. The disease symptoms were arrested like HR responses which are commonly detected in the incompatible interactions. High accumulation of phenolic compounds around developing lesions was detected under UV light. There was variation among transgenic lines on the timing of lesion progression as well as the lesion numbers on the rice leaves. Transgenic lines with few lesions also show increased resistance as well as equal amount of grain yields compared to that of wild type rice cultivar Nipponbare. This is the first report of the MAPKKK as a positive regulator molecule on defense mechanism through inducing HR-like cell death lesion mimic phenotype. The application of OsEDR1 is highly expected for the development of resistant cultivars against rice pathogens.

• 한국응용곤충학회지
• /
• 제4권
• /
• pp.1-6
• /
• 1965

In Korea the most important plant industry is the rice-growing but she has not yet attained self-sufficiency with regard to rice which is the basic food of Korean. In the past, various measures of increasing rice production have been tried with some success but the increasing rate of did not show the sufficient result. Judging from experiences, disease control may be the most important factor which has influence on increasing of rice production in Korea. During the past 60 years three periods divided by the transition of rice diseases were noted, and especially the recent transition attracted much attention . That is, sheath blight and stripe which were minor diseases in the past have promptly spread all over the country and caused heavy losses to rice plant, and also local outbreak of bacterial leaf blight and dwarf were noticed. Various environmental factors are related to such transition of rice disease. Above all, cultivated varieties susceptible to these diseases, increase of application of nitrogenous fertilizer, earlier transplanting and density of transplanting are considered to be lucre closely related to the development of these diseases and successive development of blast. On the other hand. application of forage fungicides such as organic mercury compounds specific to blast contributed to reduce prevalent area if blast in spite of wide spread of susceptible varieties and increase of application of nitrogenous fertilizer. These facts were confirmed by Korean investigators At the present which various diseases to control coexist in the same region, no one variety resistant to all of these diseases is provided and cultural practices for the control of these diseases often do not produce sufficient yield of rice. it is emphasized that a role of pesticides is very great.

• 농업과학연구
• /
• 제11권1호
• /
• pp.61-67
• /
• 1984

출수기(出穗期)를 전후(前後)한 시기별(時期別) 벼 도열병균(病菌) 분생포자(分生胞子)의 비산량(飛散量) 및 잎 도열병(病) 발생량(發生量)과 이삭도열병(病) 발생(發生)과의 관계(關係)를 구명(究明)하여 방제(防除)의 기초자료(基礎資料) 및 병(病) 발생자찰자료(發生子察資料)를 얻고자 실시(實施)한 실험결과(實驗結果)는 다음과 같다. 출수(出穗) 5일전후(日前後)의 포자비산(胞子飛散)이 이삭도열병(病) 발생(發生)과 가장 밀접(密接)한 상관(相關)이 있었으며 출수기(出穗期) 잎도열병(病) 발생량(發生量)은 이병주율(罹病株率), 이병경율(罹病莖率) 모두 이삭도열병(病) 발생(發生)에 큰 영향(影響)이 없었다. 이삭도열병(病)의 방제적기(防除適期)는 도열병균(病菌)의 잠복기간(潛伏期間)을 고려(考慮)할 때 속효성(速效性) 약제(藥劑)는 출수(出穗)5~10일전(日前), 지효성약제(遲效性藥劑)는 10~15일전(日前)으로 추정(推定)된다.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
• /
• pp.66.2-66
• /
• 2003

A gain-of-function mutant, SHM-11 obtained through gamma-ray mutagenesis, is resistant to rice blast caused by Magnaporthe grisea while wild type Sanghaehyanghyella is highly susceptible to the same disease. The resistance in the mutant was not race-specific when we tested with four races (KJ-201, KI-1113a, KI-313, KI-409) of M. grisea. To identify genes involved disease resistance in the gain-of-function mutant, genes specifically expressed in the mutant were selected by suppression subtractive hybridization using cDNAS of blast-inoculated mutant and wild type as a tester and a driver, respectively, Random 200 clones from the subtracted library were selected and analyzed by DNA sequencing. The sequenced genes represented three major groups related with disease resistance； genes encoding PR proteins, genes probably for phytoalexin biosynthesis, and genes involved in disease resistance signal transduction. A gene encoding a putative receptor-like protein kinase was identified as highly expressed only in the gain-of-function mutant after blast infection. The role of the putative receptor-like protein kinase gene during blast resistance will be further studied.

• Journal of Crop Science and Biotechnology
• /
• 제11권3호
• /
• pp.205-214
• /
• 2008

Blast disease caused by the fungal pathogen, Magnaporthe oryzae, is one of the most damaging diseases in rice. The use of resistant varieties is an effective measure to control the disease, however, many resistant varieties were broken down to their resistance effects by the differentiating of new virulent isolates. This study was done to analyze the haplotypes of 31 microsatellite markers linked to five major R genes and two QTLs and to identify the alleles for the putatively novel genes related to durable resistance to blast in 56 Korean japonica and four indica varieties. The 31 microsatellite markers produced 2 to 13 alleles(mean = 5.4) and had PICi values ranging from 0.065 to 0.860(mean=0.563) among the 60 rice accessions. Cluster analysis based on allele diversities of 31 microsatellite markers grouped into 60 haplotypes and ten major clusters in 0.810 genetic similarity. A subcluster IV-1 grouped of early flowering varieties harboring Piz and/or Pi9(t) on chromosome 6 and Pita/Pita-2 gene on chromosome 12. The other subcluster V-1 consisted of four stable resistance varieties Donghae, Seomjin, Palgong and Milyang20. The analysis of putative QTLs associated with seven blast resistance genes using ANOVA and linear regression showed high significance to blast resistance across regions and isolates in the markers of two genes Piz and/or Pi9(t) and Pita/Pita-2. These results illustrate the utility of microsatellite markers to identify rice varieties is likely carrying the same R genes and QTLs and rice lines with potentially novel resistant gene.

• The Plant Pathology Journal
• /
• 제32권1호
• /
• pp.8-15
• /
• 2016

To identify a novel biopesticide controlling rice blast disease caused by Magnaporthe oryzae, 700 plant extracts were evaluated for their inhibitory effects on mycelial growth of M. oryzae. The L. foenum-graecum Herba extract showed the lowest inhibition concentration ($IC_{50}$) of $39.28{\mu}g/ml$, which is lower than the $IC_{50}$ of blasticidin S ($63.06{\mu}g/ml$), a conventional fungicide for rice blast disease. When treatments were combined, the $IC_{50}$ of blasticidin S was dramatically reduced to $10.67{\mu}g/ml$. Since ABC transporter genes are involved in fungicide resistance of many organisms, we performed RT-PCR to investigate the transcriptional changes of 40 ABC transporter family genes of M. oryzae treated with the plant extract, blasticidin S, and tetrandrine, a recognized ABC transporter inhibitor. Four ABC transporter genes were prominently activated by blasticidin S treatment, but were suppressed by combinational treatment of blasticidin S with the plant extract, or with tetrandrine that didn't show cellular toxicity by itself in this study. Mycelial death was detected via confocal microscopy at 24 h after plant extract treatment. Finally, subsequent rice field study revealed that the plant extract had high control efficacy of 63.3% and should be considered a biopesticide for rice blast disease. These results showed that extract of L. foenum graecum Herba suppresses M. oryzae ABC transporter genes inducing mycelial death and therefore may be a potent novel biopesticide.

• The Plant Pathology Journal
• /
• 제21권2호
• /
• pp.87-92
• /
• 2005

The structural differences between healthy and diseasedpanicle necks caused by Pyricularia oryzae were observed using electron-microscope. In the diseased panicle neck, the infection hyphae of the rice blast pathogen grew through the sclerenchymatous fiber tissue and reached to the central internal lacuna. Since the pathogen grew through the sclerenchymatous fiber tissues, the vascular bundle composed with xylem and phloem had been destroyed and finally the nutrients from the leaf and stem were not able to be transported into the grains. Infection of panicle base by the blast pathogen until 20 days after heading caused more than 50% of yield loss in both Jinmibyeo and Chucheongbyeo. There was a positive correlation between incidence of the panicle blast and rice yield losses. The regression equations between incidence of the panicle blast and yield losses were y= -3.61+496.7 ($R^2$=0.70) in Jinmibyeoand y=-3.93+520.2 ($R^2$=0.82) in Juanbyeo. The panicleblast caused deterioration of grain quality. Healthy grain rate was reduced by increase of panicle blast infection.

• 한국자원식물학회지
• /
• 제29권6호
• /
• pp.658-669
• /
• 2016

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.

• 식물병연구
• /
• 제9권2호
• /
• pp.68-71
• /
• 2003

이삭도열병 발병시기가 빠를수록 벼 수량은 비례하여 감소되는데 조생종인 진미벼의 경우 출수 초기에 발병된 벼는 2년간의 조사결과 83.9%와 81.6%가 각각 감수되었으며, 출수 30일과 42일 후에 발병될 경우에도 44.3%와 33.1%가 감수되었다. 이삭도열병 발생식기가 벼 수량에 미치는 영향을 추정하기 위하여 회귀 분석을 한 결과, 1999년은 y =-1.9729x + 71.878($R^2$ = 0.9764), 2000년은 y = ?1.6421x + 97.212($R^2$ = 0.8569)로 발병시기와 수량감소와는 매우 높은 부의 상관관계가 있었다. 중만생종인 추청벼의 경우에도 2년간의 조사결과 출수 초기에 발병된 벼는 64.9%와 47.8%가 감수되었으며, 출수 40일 후 발병된 경우 29.1%와 8.9%가 감수되었으며, 1999년은 y =-1-.2717x + 79.523($R^2$ = 0.9487), 2000년은 y = ?1.6872x + 74.545($R^2$ = 0.7993)로 발병시기와 수량감소와는 매우 높은 부의 상관관계가 있었다. 천립중 조사결과도 출수초기에 발별된 경우 백수가 많았으며, 건전구 대비 진미벼는 38.3%, 추청벼는 57.3% 정도였으며, 출수 40일 후 발병된 경우 건전구 대비 진미벼는 87.9%, 추청벼는 92.9%로 천립중이 가벼워 벼가 충실하게 성숙되지 않음을 알 수 있었다.