Sweetpotato (Ipomoea batatas L.) is a globally important food crop that is susceptible to infestation with the root-knot nematode, Meloidogyne incognita, which causes substantial crop losses. Previous transcriptomic and proteomic analyses identified several genes that displayed differential expression patterns in susceptible and resistant cultivars in response to root-knot nematode (RKN) infection. As a result of previous study, RKN infection was confirmed in the RKN-susceptible sweetpotato cultivar Yulmi. Transcriptome analysis confirmed that among the genes that respond in this process, there are many genes related to ethylene biosynthesis. Therefore, in this study, we focused on the ACC oxidase (ACO) gene, the final enzyme of ethylene biosynthesis, and analyzed the expression patterns under various abiotic stress conditions. Using transcriptome data from our previous study, various expression changes in the four ACO genes used in this study were confirmed during RKN infection. The expression of G25011|TU41034 decreased during RKN infection compared to the untreated control, while the expression of G31097|TU51009, G28360|TU46486, and G15447|TU25395 genes increased in the early stages of RKN infection. Expressions of four ACO genes in leaves of sweetpoato were investigated under abiotic stress conditions such as wounding, high salinity, dehydration, and low temperature stress treatment. Expression of the G25011|TU41034 was significantly increased under abiotic stress conditions except low temperature. G31097|TU51009 was hardly expressed under abiotic stress conditions. Although the expression pattern of G28360|TU46486 and G15447|TU25395 was slightly different depending on the type of abiotic stress, an overall increase in expression was observed. It is expected that this study will be used as basic data on how ethylene biosynthesis responds not only to nematode infection but also to various abiotic stress conditions and will be helpful in functional studies of various crops.

Expression changes of stress-induced peroxidase (swpa2 and swpa4) and storage root-specific sporamin (spo-A and spo-B) genes were examined using qRT-PCR after treatment with wounding and bacterial pathogens on leaves of sweetpotato (Ipomoea batatas) plants. As a result of examining the expression change in the wounding treatment condition for 48 hours after treatment, which is a representative physical stress, the expression of all genes increased after 12 hours of wounding treatment, but the expression pattern of each gene group showed distinct differences thereafter. Expression levels of swpa2 and swpa4 strongly increased up to 36 or 48 hours after wounding treatment, whereas spo-A and spo-B expression levels strongly decreased after 24 or 36 hours after wounding treatment. Peroxidase and sporamin genes are involved in the early response after wounding treatment and, in particular, the peroxidase swpa2 and swpa4 genes are also involved in the late response after wounding treatment. Gene expression analysis after infection with P. chrysanthemi, which causes softness in sweetpotato, showed that the swpa2 and swpa4 genes were weakly induced after 8 hours and then strongly induced after 20 hours during pathogen infection. Expression of the spo-A gene was weakly induced in the pathogen-treated group after 20 hours, whereas spo-B showed an expression pattern similar to that of the peroxidase genes. The above results indicate that expression of the stress-induced peroxidase gene used in this study is induced not only by abiotic stress but also by biological stress caused by bacterial pathogen invasion and that peroxidase plays an important function in the initial defense response.

1. 본 연구는 고구마의 큐어링 처리 및 저장기간에 따른 품종별 저장성 차이를 조사하여 품종별 적정 저장 조건을 설정하고자 수행하였다. 수확된 고구마는 온도 32±1℃, 상대습도 92±3% 조건에서 3일간 큐어링 처리를 실시하였고 대조구와 함께 13±℃의 저장고에 30주간 저장하였다. 2. 저장 기간에 따른 부패율 및 감모율은 품종별로 큐어링 처리 여부에 따라 다른 양상을 보였으며 대부분 품종에서 큐어링 처리구의 부패율과 감모율이 낮게 나타났다. 품종별로는 ‘호감미’, ‘풍원미’, ‘신건미’, ‘주황미’가 장기저장을 위해서 큐어링 처리가 필요한 품종으로 나타났으며, ‘다호미’, ‘연자미’ 품종은 큐어링 처리 여부에 따른 유의한 차이가 없었다. 3. 큐어링 처리 여부에 따른 부패율 차이가 없었던 ‘다호미’, ‘연자미’를 제외한 나머지 품종은 감모율 조사에서도 큐어링 처리가 장기 저장에 더 유리한 것으로 조사되었다. 4. ‘호감미’ 품종의 경우 저장기간별 부패율 및 감모율을 예측하고 조수입을 계산하였을 때 큐어링 처리 시에는 조수입이 증가하였으나 큐어링 무처리 시에는 저장기간이 길어질수록 조수입이 감소하였다. 5. 따라서 이러한 품종별 저장성 차이를 고려하여 각 품종에 맞는 수확 후 관리 및 적정 출하시기를 예측하는 것이 고구마 저장성 증대 및 농가 소득 향상에 유용하게 적용될 수 있을 것으로 판단된다.

The sweetpotato whitefly Bemisia tabaci is a serious pest and virus vector of many crops. To understand thermal tolerance of B. tabaci at molecular level, effects of rapid and acclimated thermal stress were analyzed by measuring mRNA levels of two heat shock proteins (hsp), hsp23 and hsp90, of B. tabaci using quantitative real-time RT-PCR. Mortality of adult whiteflies were 65.5% by 45°C for 1 h but 100% by 50°C for 1 h. However, mortality by subsequent exposures to 35°C for 1 h then 45°C for 1 h was 43.3%. Comparison between rapid and acclimated heat shock treatments showed that different patterns between hsp23 and hsp90 levels. At acclimated condition, hsp90 was higher but hsp23 was lower than rapid heat shock. The results suggest that the heat acclimation response is possibly advantageous to whiteflies that are often exposed to drastic temperature fluctuations.

The sweetpotato whitefly Bemisia tabaci (Gennadius) is one of the most important sap sucking pests causing economic losses in a variety of vegetables in Bangladesh and as well as around the world. In the present study, the mtCOI sequence of B. tabaci was analysed using samples collected from different host plants (Potato, Brinjal, Tomato, Sweet potato, Bean) from district Gazipur, Patuakhali, Rajshahi and Nilphamari of Bangladesh. Phylogenetic analysis of our samples and relative sequences of B. tabaci in NCBI database was shown three independent clusters. Samples in Bangladesh were most similar with those of Thailand, Vietnam, Pakistan, China and India but did not show any B and Q aggressive biotypes.

The most common method of vegetative propagation of virus free plantlets is the use of shoots meristem culture in solid medium culture. This study was to investigate the effect on liquid medium culture for the growth of virus-free sweetpotato plantlets. Single-nodes derived from meristem culture of sweetpotato was examined in this experiment and three sweetpotato varieties ‘Singeonmi’, ‘Sinhwangmi’, and ‘Sinjami’ was used. The growth of plnatlets was greater in liquid medium culture than that of solid medium culture after longer incubation in 3 varieties. The total fresh weight of 5 week old plantlets after planting in solid culture were 2.17 g (‘Singeonmi’), 2.49 g (‘Sinhwangmi’), and 2.18 g (‘Sinjami’), but the fresh weight in liquid medium culture was 3.87, 3.88, and 3.35 g, respectively. Leaf number of ‘Singeonmi’ and ‘Sinjami’ plantlets after 5 weeks of liquid medium culture was 21.1 and 22.6, respectively and liquid medium culture showed 3 and 6.2 more leaf number than that of solid medium culture. Plant height of ‘Sinhwangmi’ and ‘Sinjami’ plantlets after 3 weeks of liquid medium culture was 4.1 cm and 3.4 cm, respectively, and liquid medium culture showed 1.1 cm longer stem length than solid medium. Overall, liquid medium culture of sweetpotato plantlets was more effective than solid medium in terms of leaf and stem growth.

The effect of transplanting and harvesting dates on growth, yield, and quality of sweetpotato varieties was studied. Three sweetpotato varieties, Yulmi, Singeonmi, and Dahomi, were transplanted on 23 Apr., 21 May, 5 June, 15 June, 25 June, 5 July, 15 July, and 25 July. Fresh vine weight and marketable storage root yield of the three varieties were the highest in transplanting plots on 23 April and 21 May, respectively, and those tended to decrease when transplanting dates were late after May. GDD (Growing Degree Days) and cumulative radiation seemed to be related to marketable storage root yield. Number of marketable storage root per plant, average weight of marketable storage root, and marketable storage root yield were significantly different according to transplanting dates. Marketable storage root yield showed significantly positive correlations with fresh vine weight, number of marketable storage roots, and average weight of marketable storage roots. Hardness and dry matter content of storage root showed significantly positive correlations with starch content and decreased with late transplanting dates in Yulmi and Singeonmi varieties. Pasting temperature showed significantly positive correlations with soluble solid content, dry matter content, and amylose content, but it showed significantly negative correlations with breakdown. Setback was significantly different among varieties, but it was not significantly different in transplanting dates.

수확과정에서 버려지고 있는 고구마 잎을 이용한 기능성 식품소재로서 활용가능성을 검토하고자, 밀가루 중량 대비 고구마 잎 분말을 2, 3, 5, 7%의 비율로 첨가하여 식빵을 제조 하고, 반죽 및 제빵 특성, 생리활성 및 기능성분 등을 조사하 였다. 반죽의 수분흡수량은 7% 첨가 시 가장 높았고, 반죽시 간은 유의적인 차이를 보이지 않았으며, 반죽의 저항도는 2~3% 첨가할 때가 가장 안정적이었다. 식빵의 수분 함량은 첨가량이 증가하여도 큰 차이를 보이지 않았고, 식빵의 내부색은 첨가량이 증가할수록 L값과 a값은 감소하였으나, b값은 증가하였다. 식빵의 부피와 비용적 및 굽기 손실률은 첨가량 이 증가할수록 감소하였으나, 항산화 활성과 총 폴리페놀, 루 테인 및 베타카로틴 함량은 증가하였다. 관능평가의 결과, 고 구마 잎 분말의 2~3% 첨가 시 맛과 색깔, 조직감, 입안에서의 씹힘성과 종합적인 기호도에서 가장 우수한 값을 얻었다. 이 상의 결과에서 고구마 잎 분말의 2~3% 첨가 시, 제빵 적성과 기능성, 상품성이 우수한 식빵을 제조할 수 있었다.

담배가루이(Bemisia tabaci)는 외래해충으로 바이러스벡터로 작용하여, 토마토의 토마토황하잎말림병바이러스(TYLCV)를 비롯한 약 100여종의 바이러스를 매개하는 중요한 해충이다. 본 연구에서는 VIGS vector를 이용하여 담배가루이 방제를 위한 target 유전자들을 선발하기 위 해 gateway system을 이용한 담배가루이 cDNA library 제작을 시도하였다. 첫 번째 방법으로 oligo d(T) primer를 사용하였을 때, 평균 약 1 kb의 insert와 1.4×10 4 cfu의 titer를 확인하였다. 그러나 insert size가 너무 커서 적절하지 않았다. 두 번째 방법으로 attB-N25 random primer를 이 용하고, sonication을 6초 실시하여 다시 진행하였다. 그러나 확인되는 insert size는 다소 컸고, 몇몇은 insert가 너무 작아서 밴드가 확인 되지 않았으며, 1.04×10 5 cfu의 titer를 확인할 수 있었다. 세 번째 방법으로는 oligo d(T) primer를 이용하였고, sonication을 2초 실시하였다. 그 결 과 300 bp~600 bp size의 insert가 확인되었으나, electro transformation을 사용한 첫번째, 두번째 방법에 비해 heat shock transformation을 사용하여 titer가 5.2×10 2 cfu로 매우 낮은 것을 확인 할 수 있었다. 결과적으로 cDNA library를 만들 때 먼저 random primer를 사용하여 First strand를 합성하여 poly A를 제거하고, 다음으로 sonication을 1초 실시하여 300~700 bp정도의 적절한 size의 insert를 생성하고, 마지막으로 electro-transformation을 실시하여 transformation 효율을 높인다면 VIGS vector에 적합한 cDNA library를 만들 수 있을 것으로 사료된다.

The sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) is a species complex, including at least 24 biotypes which express different ecological and physiological characteristics. B. tabaci is one of the most serious pests in the horticultural crops in worldwide level. B. tabaci infests over 600 plant species and also indirectly damages plants by the honeydew excretion. Moreover, whiteflies transmit more than 100 plant viruses, especially begomoviruses. Tomato yellow leaf curl virus (TYLCV) which infested severely in tomato cultivars is transmitted by the vector insect, B. tabaci. Here, we demonstrated whether gene expression of B. tabaci is regulated by the oral ingestion of dsRNA. Double strand RNA (dsRNA) of heat shock protein 70 gene (hsp70) was produced from cDNA by using the specific primer. Whitefly adults were allowed to ingest sugar solution containing dsRNA for 3 hr in the two-layered parafilm feeding tube. Quantitative realtime PCR showed that whiteflies which ingest hsp70 dsRNA completely knockdown its transcript expression. Whiteflies ingestded dsRNA increased mortality by heat shock but not by cold shock. Further research will focus the role of hsp70 in various environmental stresses against insects.

본 연구에서는 2년간 수원 밭작물 시험포장에서 단옥수수 품종인 고당옥과 구슬옥을 파종시기에 따른 생육 및 이삭 특성을 검토한 결과이다. 1. 고당옥과 구슬옥 모두 파종시기가 늦어질수록 파종에서 출사기까지의 일수가 짧아졌고, 출사에서 수확기간은 증가하였다. 2011년의 출사일수는 43 ~ 53일, 2012년은 44 ~ 54일이었고, 출사에서 수확까지는 2011년은 22 ~ 36일, 2012년에는 20 ~ 34일이었다. 2. 파종에서 출사기까지 생장온도일수(GDD)는 출사 후부터 수확기까지는 약 213 ~ 353oC 범위로 비슷하였으나 파종에서 수확까지의 GDD는 2011년(약 916 ~ 1,067oC)과 2012년(약 911 ~ 1,055oC) 모두 큰 차이가 없었다. 특히 8월 5일 파종에서 등숙기 중의 생장온도일수가 다른 파종시기에 비하여 크게 낮았는데 이는 등숙기의 기온이 상대적으로 낮은 것이 원인으로 판단된다. 3. 파종시기에 따른 생육특성을 보면 간장과 착수고는 파종시기가 늦어질수록 짧아졌으며 7월 말 파종 재배에서 유의하게 짧았으며, 경태는 파종시기가 늦어질수록 유의하게 얇아지는 경향을 보였다. 이삭직경은 고당옥은 4.37mm, 구슬옥은 4.43mm로 차이가 없으나 6월, 8월 파종보다 7월 파종구에서 두꺼운 것으로 나타났다. 4. 이삭무게는 두 품종 모두 6월, 8월 파종구 보다 7월 파종구에서 높고, 7월 25일 파종구를 보면 고당옥은 201g, 구슬옥은 140g으로 높았다. 2년간 단위면적당 이삭수량은 고당옥은 715kg/10a이고, 구슬옥은 677kg/10a이었다. 5. 파종시기에 따른 단옥수수 재배는 파종기가 늦을수록 생육이 지연되고 이삭수량이 감소되는 경향이 있고, 단옥수수 만식재배에 따른 최적 파종시기는 7월 20일 ~ 25일로서, 두 품종 모두 7월 25일에 이삭 수량성이 높은 것으로 나타났다. 7월 20 ~ 25일 파종 시 생육이 지연되고 이삭수량이 감소되는 단점 이 있지만 6월 말에 재배한 단옥수수 보다 습해의 피해가 적고, 수확적기가 짧고 전분축적 시간의 지연으로 수확시기를 연장할 수 있다는 장점이 될 수 있을 것으로 판단되어진다. 따라서 추후 단옥수수 만식재배 시 수량과 상품성 향상을 위한 최적 수확적기, 저장방법에 대한 연구가 이루어져야 할 것이다.

Bemisia tabaci is a serious pest in various horticultural crops in the world. Due to use of chemical pesticide for their management they develop pesticide resistance and environmental contamination. It is necessary to develop alternative bio-pesticides using natural products from plants and natural enemies. Nicotiana benthamiana is a variety of wild tobacco plants and produce acyl sugars from glandular trichomes in the leaves. When adult whiteflies were reared with fresh N. benthamiana leaves, they were completely dead within 84 h. Oral feeding of 20% N. benthamiana extracts using ethanol and water showed complete mortality of whiteflies within 48 hours. Spray of N. benthamiana extracts into the leaves was lethal to eggs but not to nymphs of whiteflies. Further, tomato plants sprayed with N. benthamiana extracts were highly repellent to adult whiteflies. Quantitative real-time PCR indicated that the expression of various genes of B. tabaci was changed by oral feeding of N. benthamiana extract. This study suggests N. benthamiana extract is a useful for the control of whiteflies and can be used as an alternative natural pesticide for the whitefly management.

Bemisia tabaci is a serious pest in various horticultural crops in the world. The management of B. tabaci has been typically carried out by chemical pesticides. Due to the development of pesticide resistance and environmental contamination, however, it is necessary to develop alternative biopesticides using natural products from plants and natural enemies. Nicotiana benthamiana is a variety of wild tobacco plants and produce acyl sugars from glandular trichomes in the leaves. Acyl sugars are known to be highly toxic to various plant sapping insects such as whiteflies, aphids and thrips. Here, we extracted acyl sugars in two different ways from the leaves. At first, collected leaves were simply washed with water. Otherwise, collected leaves firstly dried and homogenized into the powder, then extracted with ethanol. Spray of 10% water-extracted solution into adult whiteflies showed 80% mortality. Otherwise, spray of 10% ethanol-extracted solutions showed complete mortality at 48 h after treatment and also strong repellency of adult whiteflies into the treated tomato plants. Our results suggest N. benthamiana is a useful for the control of whiteflies and can be used as an alternative natural pesticide for the whitefly management.

Bemisia tabaci, sweetpotato whitefly, has been recognized one of the most destructive insect pests worldwide because of increased resistance to some insecticide groups requiring alternative strategies for its control. We conducted a study of the influence of relative humidity, temperature and different developmental stages on the susceptibility of sweetpotato whitefly to conidia of Isaria javanica isolate, which had been reported high virulence against Q biotype of B. tabaci. The mortality of tobacco whitefly was low at low constant relative humidities, but was high when kept high humidity for first 24 hours and transferred to low humidity. The Isaria isolate had wide range of temperature (15℃ to 35℃) to control sweetpotato whitefly. The isolate has virulence to the egg and all developmental stages of nymph of B. tabaci. These results indicated that the isolate had good control effects at various environmental conditions and is an excellent candidate to develop a microbial pesticide to control sweetpotato whitefly.

Sweetpotato whitefly (Bemisia tabaci), especially Q biotype, has been recognized one of the most destructive insect pests worldwide because of increased resistance to some insecticide groups requiring alternative strategies for its control. We studied the conidia production of entomopathogenic fungus Isaria javanica Pf04, which had been reported high virulence isolate against Q biotype of B. tabaci, using grain. Brown rice was most suitable for conidia mass production of the isolate of I. javanica. Conidia was produced high at 25 ~ 27.5℃. The isolate produced more spores when conidia suspension directly inoculated onto media than two-phase fermentation. When concentration of inoculum was high spore production was high, but increasing rate of conidia production was highest at low inoculum concentration (1×105 conidia/ml) as 6,700 times increase compared with 20 times increase at high inoculum concentration (1×108 conidia/ml). These results indicated that the isolate can produce more conidia with cheap agricultural product and can develop as a microbial pesticide to control sweetpotato whitefly.

고구마 재배농가에서 무병묘를 손쉽게 자가증식할 수 있는 간편한 수경재배 시스템을 도입하기 위하여, 점적호스를 이용한 순환식 자루재배 시스템을 시설하여 배지 혼합비율 및 삽수종류에 따른 무병묘의 생육을 조사하였다. 연황미와 맛나미 모두 15일경까지는 배지 종류에 따른 생육에 유의한 차이를 보이지 않았으나, 20일경부터는 원예용상토(TKS-2)와 펄라이트 함량이 높은 혼합배지(코코피트 : 펄라이트, 3 : 7 v/v)에서 생육이 양호하였다. 품종 간에는 연황미의 생육이 맛나미보다 양호하였으며, 1마디 삽수보다 정단 삽수로 증식하는 것이 효과적이었다. 연황미와 맛나미의 줄기생육은 정단 삽식에서 1마디 삽식보다 10cm 및 2cm 이상 신장하였으며, 코코피트와 펄라이트 3 : 7(v/v) 혼합배지에서의 건물중과 생체중은 원예용 상토 또는 코코피트와 펄라이트 7 : 3(v/v) 혼합배지에서보다 유의한 증가를 보였다. 따라서 코코피트와 펄라이트(3 : 7, v/v) 혼합배지를 이용한 자루재배는 고구마 무병묘 증식에 성공적으로 적용할 수 있었으며, 고구마 종순농가에서도 큰 경제적 부담없이 적용할 수 있을 것으로 기대되었다.

The oral toxicities of symbiotic bacteria Photorhabdus temperata ssp temperata (Ptt), mutually associated with entomopathogenic nematode Heterorhabditis megidis, and P. luminescens ssp. laumondii (TT01) with H. bacteriophora, were demonstrated to adults of the sweetpotato whitefly Bemisia tabaci. Sucrose solution (25%) containing bacteria-free supernatant of culture media of symbiotic bacteria was ingested into adult whiteflies within the glass tube. Whitefly mortalities were shown similar patterns against two bacterial media. Mortalities were significantly increased to 60-64% at 36 hours and almost 100% at 60 hours after treatments. In addition, We demonstrated the effect of oral ingestion of symbiont culture media on the gene expression of B. tabaci. Several genes fluctuated those expression levels. Our results suggest that oral ingestion of symbiont culture media of entomopathogenic nematodes significantly changed metabolic rates and highly lethal to whiteflies. The use of symbiotic bacteria of entomopathogenic nematodes provides a great potential as an alternative genetic resource of Bacillus thuringiensis, a major resource of microbial insecticide.

Insect pest may move to near area to forage the food by adverse changes of their environments. Understanding these behaviors of searching the host will be helpful for further control. This study was performed to investigate the host preference and distribution of B. tabaci in a host plant when they needs. Once entered an area including hosts, B. tabaci will select a host rather than non-host and stayed for living. Dispersal within a niche (in a whole plant), B. tabaci was observed in lower part in tobacco and middle in tomato when seedlings, but they dispersed throughout the whole fully grown tomato plants with irregular inclined to the under, outer stretched leaves. Bemisia tabaci was also caught massively in yellow sticky traps in height of 30 cm above soil, and 30 cm above a plant. There was no attraction effect by flower model traps and fly catcher. When introduced with different densities (0, 10, 50, 100, 200, and 400) in square cages, the B. tabaci do damaged at the densities of 200 with mild and 400 with severe symptom on plants in two weeks and four weeks after inoculation.

This study was done to evaluate the susceptibility, systemic effect, residual effect and control effect in each developmental stages of biotype Q of sweetpotato whitefly against insecticides, acetamiprid+spinetoram SC and dinotefuran SG. Two insecticides were showed similar activity against the eggs, and showed higher activity in acetamiprid+spinetoram SC against the nymph and adult. In systemic effect, two insecticides have a similar activity. It was showed higher activity in root zone systemic application than leaf zone systemic application. Residual effect was showed higher in acetamiprid+spinetoram SC (92%) than dinotefuran SG (44 %) at seven days after treatment. Control effect was showed all over 90 % activity at tree- and seven days after treatment. Therefore, these insecticides are expected to control the sweetpotato whitefly effectively.