벌목 개미과의 일본열마디개미는 국내 토착종이다. 지금까지 야외에서 이 종의 월동기작을 이해하기 위한 내한성 연구는 진행되지 않았다. 저온에서 다양한 온도별 노출시간에 따른 발육태별 저온 저항성을 조사하였다. 성충인 일개미가 다른 발육태와 비교하여 5°C와 10°C의 저온에서 높은 생존율을 보였으며, 급속내한성 유기 조건인 15°C에서 12시간 노출 후 내한성을 획득하였다. 급속내한성 유기는 10°C에서 최대 44%까 지 생존율이 향상되었으며, 체내과냉각점과 체내빙점은 각각 -10.0°C에서 -14.2°C, -11.3°C에서 -15.3°C까지 낮아졌다. 저온처리는 저온 또는 스트레스 관련 유전자인 글리세롤 인산화효소와 열충격 단백질의 발현을 증가시켰다. 이상의 결과는 일본열마디개미의 내한성이 급속내한성 유기에 의해 야기된다는 것을 의미한다.

The Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae), produces final instar larvae of overwintering stage in response to decreasing day-length and temperature, and then those larvae pupate after about 6-8 month. In this study, we investigated a few properties related to cold hardiness during overwintering of the insect. Overwintering larvae collected in December could survive at least for 16 days at -20oC, while all larvae of a laboratory colony, which was reared at 25oC, 15L/9D, died within 2 hours. Supercooling points of overwintering larvae were below -20oC, and the temperatures were significantly lower than those (ca. -10oC) of the laboratory colony. It was estimated that higher content of hemolymph glycerol is responsible for cold-hardiness as a cryoprotectant during overwintering of O. furnacalis.

‘원황’ 배(Pyrus pyrifolia Nakai)나무에 착과수준을 주당 54개(60%착과), 90개[100%착과구(관행)], 126개 (140%착과)로 조절 하였을 때 가지의 생장, 저장양분 및 과실생산과 익년에 삽수의 생장에 미치는 영향을 조사하기 위하여 2년간 수행되었다. 주당 착과량이 증가하면 도장지 생장이 감소하였고 1년생 가지의 탄수화물 과다량 무기원소 및 유리당 농도가 감소하는 경향이 나타났다. 관행 대비 140% 착과처리구는 두 해 모두 수량이 약 35톤으로 가장 높았지만 평균과중과 과실 크기 및 과육당도는 다소 낮은 수준이었다. 하지만 140% 착과처리구는 60%와 100% 착과 처리구 보다 년간 천 만원 이상의 소득증대가 관찰되었다. -20oC 처리에서 삽수의 발아율은 뚜렷한 감소가 나타나지 않았고, - 30oC에서는 140% 착과처리구에서 70% 이하로 감소되었다. 저온에서 삽수의 전해질 누출률은 적과수준에 따라서 크게 차이는 없었다.

복숭아 네 품종 ‘오도로끼’, ‘가납암백도’, ‘진미’, ‘장호원황 도’ 신초의 저온순화 및 탈순화 동안 시기별 내한성 변화는 전해질 누출률을 분석하여 나타냈다. 또한 내한성 결정 요인 을 분석하고자 SDS-PAGE를 이용하여 dehydrin 함량 변화를 확인하였으며, 그와 관련된 유전자 발현 분석은 quantitative real-time RT-PCR을 이용하여 수행하였다. 네 품종의 내한성 은 2012년 12월까지 꾸준히 증가하였으며 그 후 2013년 4월 까지 감소하였다. PpDhn1 유전자가 인코딩하는 60kDa의 dehydrin 단백질은 탈순화기(2013년 3-4월)에 비하여 저온순화 기(2012년11월-2013년 1월) 동안 높은 축적이 확인되었다. PpDhn1 유전자와 PpDhn3 유전자 발현양상은 복숭아 네 품 종에서 내한성 변화와 평행하게 나타난 반면, PpDhn2 유전자 는 뚜렷한 시기별 패턴을 나타내지 않았다.

국내에서 가장 많이 재배되고 있는‘신고’(Pyrus pyrifolia cv. Niitaka) 배의 재배 중 착과량 조절 및 휴면기 저온처리에 따른 내한성을 분석하여 재배적지 설정 및 동해 방지를 위한 기초자료로 활용코자 본 연구를 실시하였다. 착과량은 주당 36개, 60개, 84개로 조절하였으며, 수확시 10a당 착과량은 주당 36개 착과한 경우 2,393 kg으로 표준수량 보다 낮게 나왔다. 주당 60개를 착과한 경우에는 3,439 kg으로 표준수량과 비슷하였고, 84개를 착과한 경우에는 4,270 kg으로 과다 착과가 되었다. 동해 실험은 착과량을 달리한 나무에서 1년생 가지 및 꽃눈을 채취하여 온도를 -15℃, -20℃, -25℃, -30℃ 의 4수준으로 처리한 후 발아율과 갈변율, 전해질 누출율, triphenyl tetrazolium chloride(TTC)검정, 무기성분 및 전분 함량을 조사하였다. 꽃눈을 포함한 1년생 가지의 발아율은 착과량이 증가하고 온도가 낮아질수록 낮아졌고 착과량이 증가할수록 동해피해를 받는 것으로 나타났다. 갈변율은 착과량이 증가하고 온도가 낮을수록 증가하였다. TTC검정에서는 표준수량 보다 과다 착과한 경우에는 각 온도처리별로 흡광률이 낮게 나타나 조직의 활성 정도가 낮아짐을 알 수 있었다.

Glycerol is a polyol that is responsible for the cold hardiness of insects. Glycerol kinase gene, which is an important key enzyme for glycerol biosynthesis, was predicted from whole genome sequencing data from the diamondback moth, Plutella xylostella. Four of P. xylostella glycerol kinase genes (PxGKs) were determined as a functional glycerol kinase through in silico study. Pre-exposure of P. xylostella larvae to 4°C for 7 h significantly enhanced survival (rapid cold hardiness: RCH) under a freezing temperature (-10°C) and increased glycerol titers. To determination of functional GK gene, expressions of all GK genes were measured by RT-PCR analysis. All GK genes were expressed in all larval stage and tissues (gut, hemocyte, and fat body). Expressions of all GK genes were suppressed by its specific dsRNA treatment into 4 th instar larva. Each 150 ng of dsRNA PxGK2 treatment significantly decreased glycerol amount in hemolymph by HPLC analysis. Larval treated by dsRNA PxGK2 also significantly lost the RCH under -10°C exposure. These results indicate that glycerol is a crucial RCH agent and its synthesis is regulated by a specific PxGK2 gene among GK gene isoforms in P. xylostella. In addition, the beet armyworm, Spodpotera exigua, encodes RCHassociated SeGK1, which has been functionally identified by RNA interference.

Cold tolerance of the palm thrips, Thrips palmi Karny, was investigated to predict its survival in field during winter. Supercooling temperatures of T. palmi ranged from -26.4 to -18.4°C. However, exposure to subzero temperatures (from -5°C to -15°C) gave significant mortality to all developmental stages of T. palmi. Thus, T. palmi was determined to be a freeze-susceptible and suffered with cold injury. A brief pre-exposure to a low temperature (4°C) for 7 h significantly increase the cold tolerance of all stages of T. palmi with respect to survival at -10°C and supercooling capacity. A pre-exposure of T. palmi at 4°C significantly increased the survival rate on all developmental stages at -10°C. The rapid cold hardiness (RCH) was dependent on the duration of the pre-exposure period at 4°C in adult stage. Cryoprotectant analysis using an HPLC showed that the pre-exposure treatment increased the adult to synthesize glycerol, trehalose, mannitol, and mannose, at which trehalose represented the highest content. This study suggests that all stages of T. palmi are able to become cold-hardy by RCH, in which several polyols may play crucial roles as cryoprotectant.

The beet armyworm, Spodoptera exigua, is a freeze-susceptible species and overwinters without diapause in temperate zone. Depression of supercooling point (SCP) and rapid cold hardiness (RCH) allow S. exigua to survive at low temperatures. This study reports a polyol which is responsible for the cold hardiness of S. exigua. Pre-exposure of S. exigua larvae to 4°C for 6 h significantly enhanced survival under a freezing temperature (-10°C). This pre-exposure treatment also significantly depressed larval SCPs. Analysis of polyols indicated that glycerol titers significantly increase with increase of pre-exposure time. Glycerol kinase (GK) and glycerol-3-phosphate dehydrogenase (GPDH) are involved in glycolysis pathway of insect. The S. exigua GK (SeGK1) and G3PDH (SeG3PDH1) genes were predicted from 454 pyrosequencing transcripts from fifth instar larvae of the beet armyworm, S. exigua. The SeGK1 and SeG3PDH1 genes both were expressed in all larval stage by RT-PCR analysis. Expression of SeGK1 and SeG3PDH1 genes were suppressed by its specific dsRNASeGK1 or dsRNASeG3PDH1 injection into hemocoel of 5th instar larva. Each 200 ng of dsRNASeGK1 or dsRNASeG3PDH1 injection also significantly decreased glycerol amount in hemolymph. Larval treated by either dsRNASeGK1 or dsRNASeG3PDH1 significantly lost the RCH under -10°C exposure. These results indicate that glycerol is a crucial RCH agent and its synthesis is regulated by SeGK1 and SeG3PDH1 genes in S. exigua.

Cold hardiness is an important trait for insects, that enables them to survive during the winter and develop in the next season, and to extend their range. Lycorma delicatula (White), which became an important sporadic pest in grapevines and some other fruit trees, has spread rapidly to the most of regions in South Korea. This study was conducted to determine the cold hardiness of overwintered L. delicatula eggs according to geographical variation. We collected overwintering eggs in the five sites, Chuncheon, Suwon, Yeongdong, Gunsan, Daegu, on 22~25th Feb. in 2011. We treated eggs to combinations of different temperatures (-15℃, -20℃, -25℃) and exposure time (12hr, 24hr, 3days, 5days, 7days) after chilling them for 24~26 days at 5℃. And then, they were kept in the room temperature. We only analysed three sites of Suwon, Gunsan and Daegu, because of very low hatching rate at Chuncheon and Yeongdong. There were significant effects of time (F=36.97 d.f.=4 P<0.0001), sites (F=17.28 d.f.=2 P<0.0001), and the interaction of time and temperature (F=5.77 d.f.=5 P<0.0001) at -15℃. At -20℃, eggs hatched only at 12hr and 24hr of exposure treatment. All eggs treated at -25℃ failed to hatch. It appears that -25℃ is around the critical temperature.

본 연구는 알팔파의 품종과 재식밀도가 식물의 형태, 월동 및 내한성에 미치는 영향을 구명하기 위하여 주구는 알팔파 품종('Vernal'과 'Algonquin')과, 세구는 재식밀도(16, 45, 100, 278과 494 p l a n t s / m − 2 )로 분할구 배치법으로 캐나다 앨버타주의 애드먼톤에서 수행되었다. 식물 지상부의 형태는 재식밀도의 영향을 받았으며, 밀도가 증가함에 따라 식물 개체당 줄기수, 줄기당 무게, 개체당 무게, 그리고 줄기의 직경이 유의적으로 감소하였다. 월동률은 식물 개체수가 45개 이하에서 100%를 보였으며, 그 이상의 식물 재식밀도에서는 유의적으로 낮은 월동률을 보였다. 뿌리에 있는 비구조 저장탄수화물(TNC)의 양은 식물 재식밀도가 증가할수록 유의성있게 감소하였다. 가장 낮은 LT50은 25cm의 식물간격을 지닌 개체 수가 16개인 처리구와, 가장 높은 LT50은 4.5cm의 식물간격을 지닌 개체 수가 494개인 처리구에서 각각 관찰되었다. 그러나 알팔파 Vernal과 Algonquin 두 품종간 식물형태, 월동률 및 내한성은 유의적인 차이가 인정되지 않았다. 결론적으로 높은 재식밀도 즉, 평방미터당 식물개체 수가 278개 이상인 처리구는 낮은 재식밀도에 비해 알팔파의 월동률과 내한성에 있어서 전혀 유리한 점이 없었다.

담배거세미나방(Spodoptera litura Fabricius)의 체내빙결점과 내한성이 검정되었다. 체내빙결점은 발육시기에 따라 다양했다. 알(약 -)이 가장 낮았고 용과 성충(약 )이 다음이었으며 유충이 (-1~-) 가장 높은 온도를 기록했다. 유충의 체내빙결점은 유충의 영기가 진행함에 따라 상승했다. 각 발육단계의 치사저온온도는 각자의 체내빙결점보다 높았다. 알과 유충을 아치사온도에 미리 노출시킴으로서 치사온도에 대한 생존력을 높였다. 아치사온도는 또한 5령충의 혈림프 삼투압을 증가시켰으며 저온에 특이적인 단백질들(20과 27kD)을 발현하게 했다. 이상의 결과는 이 해충이 동결감수성 곤충류에 속함을 나타낸다.

Recent climate changes due to global warming are gradually introducing adverse circumstances for winter survival of temperate fruit trees. Particularly, late winter or early spring thaws followed by hard freezes can cause severe injury to deacclimated flower buds. Thus, the selection of later or slower deacclimating cultivars is needed to avoid frost injury in late winter or early spring. This study was performed to investigate relationship between cold hardiness and bud development under an experimental deacclimation condition for 10 Prunus persica cultivars (Aikawanakajima, Daewol, Izumi Hakuto, Janghowon Hwangdo, Kiraranokiwami, Mihong, Misshong, Soomee, Suhong, and Sun Gold). The rate of deacclimation was not correlated with hardiness before the deacclimation treatment. On the other hand, a strong positive correlation was found between cold hardiness and stage of bud opening.

Changes in cold hardiness were confirmed with relative electrolyte leakage (REL) method in the shoots of two peach cultivars (Prunus persica Janghowon Hwangdo and Odoroki) during cold acclimation and deacclimation. Changes in proline (Pro) content and related gene expressions were also analyzed. Particularly, transcript accumulations of P5CS and P5CR were examined using quantitative real-time RT-PCR. REL in the shoots of two peach cultivars was significantly different during the entire experimental period. Cold hardiness of two cultivars increased gradually to December 2012, and then decreased to April 2013, whereas Pro contents of ‘Janghowon Hwangdo’ and ‘Odoroki’ were reduced from the beginning of the experiment to February 2012 and then increased in the spring. Interestingly, P5CS gene encoding an enzyme, which catalyzes conversion from glutamic acid (Glu) into glutamic-γ-semialdehyde (GSA) in the first step of Pro pathway, showed the contrasting patterns with Pro contents of two cultivars. On the other hand, P5CR gene encoding an enzyme, which catalyzes conversion from Δ1-pyrroline-5-carboxylate(P5C)intoPro in the final step of Pro pathway, showed the similar patterns to Pro contents in two cultivars. Our results demonstrate that Pro responds negatively to low temperatures in the shoot of different peach cultivars, including the supplemental 10 peach cultivars, and expression of both P5CS and P5CR genes could show contrasting patterns from each other. Our results suggest that identification of both P5CS and P5CR genes are required necessarily for accurate analysis of Pro biosynthesis because Pro accumulation is affected more by expression of P5CR gene.

“Baechal”, a winter wheat (Triticum aestivum L.) cultivar was developed by the National Institute of Crop Science, RDA, Iksan, Korea, during the period from 2006 to 2012. The heading and maturing dates of this variety were May 1 and June 5 in upland, and May 2 and June 8 in paddy field, respectively. It is an It is an awned, semi-dwarf and hard white wheat. Culm and spike length of “Baekchal” were 75cm and 8.7cm. It had lower test weight (794g/ℓ) and 1,000 grain weight (35.7g) than “Keumkang”. It showed moderate to pre-harvest sprouting, which lower rate of pre-harvest sprouting (13.7%) than “Keumkang”. “Baekchal” had similar ash content (0.47%) and protein content (13.1%) to “Keumkang”. It showed lower gluten content (9.6%), SDS-sedimentation volume (38.2㎖) and amylose content (6.5%) than “Keumkang”. It showed higher high viscosity (643BU), water absorption (213%), expansibility of cooking (357%). It showed different composition in HMW-GS compositios (2*), PPO18 (876bp), GBSS (waxy type) and Puroindolines composition compared th “Keumkang”. Average yield of “Baekchal” in the regional adaptation yield trial test was 4.89 ton/ha in upland and 4.83 ton/ha in paddy field. “Baekchal” would be suitable for the area above –10℃ of daily minimun temperature in January in Korean peninsula