세계적인 침입해충 담배가루이 (Bemisia tabaci Gennadius)의 한국 계통과 중국 계통의 유연관계를 알아보기 위하여 2019년에 채집한 두 계통들의 biotype 분포, 살충제 반응, 바이러스 보독율을 조사하고 차이를 분석하였다. 미토콘드리아 COI 유전자 서열을 이용하여 집단 분석한 결과 국내는 모든 지역계통에서 Q biotype만 발견되었으며, 중국은 B biotype (14.3%)과 Q biotype (85.7%)이 동시에 발견되었다. 담배가루이 Q biotype의 haplotpye 구성도 중국은 모두 Q1 그룹만 관찰되었고 Q1H1 (79.8%), Q1H2 (20.2%)로 구성되어 있었으며, 한국은 Q1이 우세한 가운 데 Q2도 관찰되었으며 Q1 그룹의 구성도 Q1H1 (1.7%), Q1H2 (97.5%)로 중국과는 크게 달랐다. 15종 살충제에 대한 약제반응은 국내 계통은 일부 약제를 제외하고 대부분 약제에서 충분한 살충력 (mortality≥80%)을 보여주었으나 중국 계통은 40% 이하의 살충력을 보인 약제들이 다수 있었으며 한국보다는 높은 저항성을 갖고 있었다. 토마토 황화잎말림바이러스 (TYLCV)의 보독율은 국내 계통에서는 발견되지 않았으며 중국의 경우 0∼60% (평균 21.4%) 가 발견되었다. 따라서 한국와 중국의 담배가루이 계통 간에는 유전적 조성과 살충제 반응, 바이러스 보독율에 있어서 큰 차이를 보여주었으며 양국의 담배가루이가 서로 다른 유입 패턴을 갖고 있음을 알 수 있었다.

‘티와이썬’은 농촌진흥청 국립원예특작과학원에서 육성한 토마토황화잎말림바이러스(Tomato yellow leaf curl virus, TYLCV) 저항성 품종이다. 모계로는 TYLCV에 저항성으로 알려진 자원 ‘08-9-59’를 도입, 세대진전하여 사용하였으며 부계로 사용한 ‘원예9002호’는 1997년 ‘트러스트’ x ‘모모타로 요쿠’ 교배조합에서 계통 분리하여 2002년까지 내병성 검정 및 계통 선발을 통해 육성하였다. 2010년 두 계통을 이용한 교배조합을 작성하였으며 2011년 내병성 분자마커 검정, 2012년 대만 AVRDC에서 담배가루이를 이용한 TYLCV 저항성 유묘검정을 실시하였다. 그 결과 TYLCV에 저항성이며 반신 위조병(Ve), 시듦병(I2, I3), 고구마뿌리혹선충(Rex), 세균성반점 병(Pto), 줄기마름병(Asc1), 토마토모자이크바이러스(ToMV)에 복합내병성으로 인정되어 ‘티와이썬’이라고 명명하였다. ‘티와 이썬’은 무한생장형에 과형은 원형이며 평균과중 240g 정도, 당도는 4.2°Brix 정도이다.

Vector-borne plant virus transmission is a complex mechanism. Plant viruses modify development and behavior of vectorinsects in a positive, negative, or neutral manner. Bemisia tabaci transmits Tomato yellow leaf curl virus (TYLCV) whichis a virus that seriously damaged tomato cultivars all around the world. We compared several behavioral and physiologicalcharacteristics between non-viruliferous (NV) and TYLCV-viruliferous (V) of whiteflies. When B. tabaci acquired TYLCV,total life span was shorter and fecundity was lower than NV ones. V whiteflies were more susceptible to thermal stressby increasing hsp mRNA levels but higher in mortality by either heat or cold shocks. Further, V whiteflies increasedthe rates of plant sap probing and light attraction behaviors than NV ones. Our results provide insights to understandvector’s role in relation to the acquisition and transmission of plant viruses.

Tomato yellow leaf curl virus (TYLCV) causes a highly serious disease in tomatoes in many countries. The most important thing in management is the prevention of virus transmission. TYLCV had been known to be only transmitted by a vector, the sweetpotato whitelfy, Bemisia tabaci. However, we identified two other important routes of TYLCV transmission into tomatoes. It is seed-transmissible. Many seeds available in domestic and global markets were infected by TYLCV. It is also infective into various weeds and other horticultural crops and transmit virus through vector insects. Therefore, we need a new strategy for the virus and vector management.

Loop-mediated isothermal amplification (LAMP) is a rapid, specific, cost-effective detection method by amplifying nucleic acid under isothermal conditions. In this study, we used LAMP for detection of Hamiltonella defensa that lives as a facultive endosymbiont of whitefly ‘Bemisia tabaci’. We designed the Hamiltonella-specific primers by targeting 16S ribosomal RNA gene and validated the specificity of one primer set. To find the optimum temperature for our primer set, the LAMP reaction was held at the temperature, 60℃, 62℃ and 65℃. As a result, 62℃ was the optimum reation temperature for LAMP reaction. Specificity of primer set was tested by the reaction to both Trialeurodes vaporariorum and B. tabaci. After the whole procedure, the amplicons by LAMP were visualized by adding SYBR Green to the reaction tube.

The sweetpotato whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is a disastrous pest in horticultural plants worldwide. B. tabaci is a species complex including at least 24 biotypes in the world. In Korea, B-biotype has been invaded in 1998, Q-biotype in 2005 and widely spread into the country. B. tabaci is also a vector of more than 100 plant viruses, especially begomoviruses. Since 2008, Tomato yellow leaf curl virus (TYLCV) has been invaded into Korea and severely damaged tomato cultivar in all over of the country. B. tabaci is the only vector insect of TYLCV. Here we demonstrated whether TYLCV influence on the vector physiology during virus transmission. Pesticide susceptibility of whiteflies on TYLCV acquisition was determined in B. tabaci using the two-layered parafilm feeding chamber which containing 20% sugar solution including different doses of imidacloprid. Our result showed that TYLCV-viruliferous whiteflies were more susceptible to imidacloprid ingestion than non-viruliferous whiteflies. This study suggests that plant virus can manipulate the physiological conditions of vector insects.

토마토 TYLCV는 병이 발생되면 약제나 다른 방법으로 방제가 어려우므로 내병성 품종의 개발이 반드시 필요하다. 특히, TYLCV 저항성 유전자 Ty-1,2,3(부분우성)을 한 개체 내로 집적을 시켜서 저항성이 증대된 품종의 개발이 필요하다. 토마토 TYLCV 저항성 11-TY1-AV 등 7계통을 대상으로 보독인 담배가루이를 이용하여 표현형을 조사하였다. 이병성 대비(11-TY5-AV; 슈퍼썬로드)와 F3 세대 3계통 및 F2 세대 4계통을 TYLCTHV 균주를 이용하여 접종하였다. 접종 13일 후에 이병성 대비가 100% 이병증상을 나타내었으며, 이때 11-TY4-AV는 48개체 중에서 23개체가 이병되었으며, 11-TY6-AV는 42개체 중에서 14개체, 11-TY7-AV는 48개체 중에서 14개체, 11-TY8-AV는 48개체 중에서 15개체가 이병 되었다. F2 세대 4 집단 모두 p>0.05 수준에서 TYLCV 접종 후 표현형이 정상적인 유전분리비(3:1)를 보이는 것을 확인 하였다. 또, TYLCV에 저항성인 동일한 자원을 부계로 사용하더라도 모계로 어떤 것을 사용 하느냐에 따라서 저항성 정도가 다르게 나타나는 것을 확인할 수 있었다.

Vector-borne plant virus transmission is a complex mechanism involving various interactions of viruses, vectors and plants. Plant viruses modify, either directly or indirectly, the rates of development, reproduction and behavior of vector insects in a positive, negative, or neutral manner. The sweetpotato whitefly, Bemisia tabaci, is the only known vector of Tomato Yellow Leaf Curl Virus (TYLCV) which is a virus that seriously damaged tomato cultivars all around the world. Acquisition of TYLCV influences on various developmental, physiological and molecular mechanisms of Q1 biotype B. tabaci. We compared several behavioral and physiological characteristics between non-viruliferous (NV) and TYLCV-viruliferous (V) of Q1 biotype whiteflies. When B. tabaci acquired TYLCV, total life span was shorter and fecundity was lower than NV ones. V whiteflies were more susceptible to thermal stress by increasing hsp mRNA levels but higher in mortality by either heat or cold shocks. Furthermore, V whiteflies increased the rates of plant sap probing and light attraction behaviors than NV ones. All together, our results show that TYLCV acquisition regulates B. tabaci to enhance the rates of development and environmental susceptibility. Our results provide insights to understand vector’s role in relation to the acquisition and transmission of plant viruses.

The sweetpotato whitefly, Bemisia tabaci, acts as a vector of more than 100 plant viruses. B. tabaci is known to harbor a primary endosymbiont (Portiera) and 6 secondary endosymbionts (Arsenophonus, Cardinium, Fritschea, Hamiltonella, Rickettsia and Wolbachia). These endosymbionts play important roles in the acquisition and transmission of plant viruses. Using PCR analysis, we identified endosymbiotic bacteria in various B. tabaci populations collected from different places of Korea. Distribution of endosymbionts was different according to the biotype of B. tabaci. Subsequently, their relative densities of endosymbionts were compared between TYLCV-viruliferous and non-viruliferous populations of the Q biotype using quantitative realtime PCR. We found that the densities of Portiera, Cardinium and Hamiltonella are higher in viruliferous than non-viruliferous whiteflies. Our results suggest the role of endosymbiont for the TYLCV transmission of whiteflies.

The sweetpotato whitefly, Bemisia tabaci, is a vector of more than 100 plantdiseased viruses as well as a serious pest to various horticultural crops. Virus acquisition affects the vector’s development and reproduction, but its mechanism is largely unknown. Here we compared the temperature responses between non-viruliferous and TYLCV-viruliferous Q biotype of B. tabaci. When both non-viruliferous and viruliferous whiteflies were exposed for 1 and 3 h at 4, 25, and 35°C, the mortality rate of viruliferous whiteflies is higher than nonviruliferous after exposure at 4°C and 35°C, but no differences at 25°C between them. Analysis of the expression levels of heat shock protein (hsp) genes using the quantitative realtime PCR showed that viruliferous whiteflies has higher expression in hsp70, and hsp90 at both 4°C and 35°C, but no differences at 25°C. The results suggest that vector insects may not be durable to unfavorable temperature conditions when they acquisite plant viruses.

The purpose of the research is to analyze damages of TYLCV (Tomato Yellow Leaf Curl Virus) in the context of climate changes and to find the spatial distribution of the damages and characteristics of regions. A TYLCV is generally known for a plant disease related to temperature. Its occurrence rate increases when temperature rises. This disease first occurred in 2008 and rapidly spread nationwide. Due to the spread of a TYLCV, a number of Tomato farms in Korea were damaged severely. To analyze damages of the pest in the context of climate changes, this research estimated production loss under the current situation and RCP scenarios. Additionally, Hot Spot Analysis, LISA, and Cluster analysis were conducted to find spatial distribution and properties of largely damaged regions under RCP scenarios. The results explained that additional production loss was estimated differently by regions with the same temperature rising scenario. Also, largely damaged regions are spatially clustered and factors causing large damages were different across regional cluster groups. It means that certain regions can be damaged more than others by diseases and pests. Furthermore, pest management policy should reflect the properties of each region such as climate conditions, cultivate environment and production technologies. The findings from this research can be utilized for developing rural management plans and pest protection policies.

토마토(Solamum lycopersicum L.)는 전 세계적으로 생산량이 연간 146백만 톤이며 재배면적은 4,339천ha에 달하는 채소작물로 경제적 가치가 매우 높다. 최근 국내 및 미국, 남미, 유럽, 동남아시아, 일본, 중국 등지로 토마토황화잎 마름바이러스 (Tomato yellow leaf curl virus; TYLCV)가 급격히 확산되고 있어 토마토 생산량과 농가소득 감소 등 의 심각한 피해를 입히고 있다. 토마토의 TYLCV 저항성 유전자는 야생종에서 Ty-1, Ty-2, Ty-3, Ty-4, Ty-5 등이 보고 되고 있으며 이들 유전자원을 활용한 계통 및 품종 육성이 활발하게 이루어지고 있다. 자사에서도 TYLCV의 피해 를 최소화할 수 있는 저항성 품종 육성을 주요 목표로 하여 품종 육성을 활발하게 진행하고 있다. 최근에는 내병계 품종 육성에 분자마커를 활용함으로써 신품종 개발기간을 단축시키고자 하는 노력이 많이 이루어지고 있다. Ty-1, Ty-2, Ty-3에 대한 CAPS 또는 SCAR 마커 개발이 보고되고 있으나(Hoogstraten et al., 2005; Garcia et al., 2007; Ji et al., 2007), gel-based 마커로 검정에 많은 시간과 노력이 필요하다. 본 연구에서 TYLCV 내병계 육성을 위해 보다 신 속하고 효율적인 분자마커 검정을 실시하고자 Ty-1과 Ty-3의 SNP마커를 개발하였다. 기 개발 마커를 활용하여 내 병계 계통 및 도입품종 20개의 Ty-1과 Ty-3의 염기서열을 분석하여 20개의 프라이머 셋트를 제작하였다. Ty-1 SNP2와 Ty-3 hrm3 마커를 선발하고 계통 및 품종으로 HRM (high resolution melting)분석을 통해 실효성을 판단하였 다. 또한 자사의 시판 이병계와 내병계 종자를 대상으로 검정을 실시하여 Ty-1 SNP2와 Ty-3 hrm3 마커의 실효성을 확인하였다. 개발된 마커를 활용하여 2014년 봄작기 파종 F2 분리세대 50 계통과 도입품종 21 품종에 대한 검정을 실시하여 품종육성을 위한 자료로 활용하였다.