• Current Research on Agriculture and Life Sciences
• /
• v.30 no.2
• /
• pp.124-130
• /
• 2012

Sweetpotato whitefly, Bemisia tabaci, is a vector of more than 100 plant-diseased viruses, as well as a serious pest of various horticultural plants. This species harbors a primary endosymbiont Portiera along with several secondary endosymbionts such as Cardinium and Hamiltonella. We investigated whether or not TYLCV acquisition alters the densities of endosymbionts in the body of B. tabaci using quantitative real-time PCR. Our results showed that the densities of both Cardinium and Hamiltonella, but not Portiera, increased upon acquisition of TYLCV. In addition, expression of GroEL, a molecular chaperone produced by Hamiltonella, was significantly upregulated in TYLCV-infected whiteflies. Our results suggest that endosymbionts may play an important role in TYLCV transmission mechanism within the body of B. tabaci.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2016.05a
• /
• pp.140-140
• /
• 2016

수분 이용효율(Water Use Efficiency, WUE)은 식생이 흡수한 수분 중 증발산에 이용한 비율로, 육상생태계의 수문학적 순환 및 탄소 순환의 기능을 측정할 수 있는 중요한 지표이다. 또한 이는 특정 지역의 기후 조건이나 토지 피복과 같은 다양한 요인에 따라 변할 수 있다. 본 연구에서는 한반도에서 2010년부터 2014년까지의 기후 요인(강수, 기온)과 토지 피복에 따른 WUE의 변화를 살펴본다. MODerate resolution Imaging Spectroradiometer (MODIS) 기반 총일차생산성(Gross Primary Productivity, GPP), 증발산량(Evapotranspiration, ET), 잎면적지수(Leaf Area Index, LAI)와 Willmot의 기상자료 등 대상지역에 대한 격자 자료를 사용한다. 구체적으로 숲, 초원, 농지와 같이 다양한 토지 피복 조건에 대한 월간 및 연간 WUE(=GPP/ET)를 산정하고, 이의 LAI나 기후 조건(강수, 기온)과의 관계를 분석하고자 상관성 및 요인 분석을 진행한다. 기후 조건 및 토지 피복 조건을 고려한 15년간 한반도에서의 WUE의 변화에 대한 분석은 앞으로의 수자원 관리 및 산림 정책에 활용할 수 있을 것으로 판단된다.

• Journal of Korean Society of Forest Science
• /
• v.89 no.5
• /
• pp.666-676
• /
• 2000

For the study of morphological variation of Q. variabilis natural population in Korea, 19 populations were selected through the country in considering latitude, longitude, and geographical characters. Thirty trees were randomly selected from each population and 60 mature leaves were sampled from each tree. Four characters (leaf blade length, maximum blade width, petiole length, and vein number) were measured, and their ratios (the ratio of blade length to maximum blade width, the ratio of blade length to petiole length, the ratio of petiole length to vein number, upper 1/3 blade width to maximum blade width, and upper 1/3 blade width to lower 1/3 blade width) were calculated. 1. Analysis of variance for all leaf characters were significantly different among populations and among individuals within population. Contributions of variance among individuals within population in all the characters were higher than those among populations. Therefore, selection of plus trees may be preferable to desirable populations for breeding program of Q. variabilis. 2. Among principal component analysis for leaf characters, primary 2 principal components appeared to be major variables for leaf form of Q. variabilis because of the loading contribution of 80.5%. The first contribution component was petiole length/vein number and petiole length ; the second one was upper 1/3 blade width/maximum blade width, upper blade width/lower 1/3 blade width and vein number, respectively. 3. Latitude was positively correlated with blade length/maximum blade width and blade length/petiole length, but negatively correlated with petiole length/vein number, upper 1/3 blade width/maximum blade width, upper 1/3 blade width/lower 1/3 blade width, petiole length, and vein number. But, for longitude and altitude the former two traits and the later five traits exhibited the negative and positive correlation, respectively. 4. Cluster analysis using complete linkage method for leaf characters showed two groups to Euclidean distance 1.6. They were group I of population 1. 4, 5, and 13 and group II of population 2, 3, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, and 19. However, group II was divided again to Euclidean distance 1.3, that is a group including population 3, 7, 10, 14, 15, and 17(group II-1) and the other group comprising population 2, 6, 8, 9, 11, 12, 16, 18, and 19(group II-2). This cluster could be mainly observed due to difference among population in aspect (group I : NE, group II-1 : SE, and group II-2 : SW).

• Horticultural Science & Technology
• /
• v.33 no.3
• /
• pp.309-316
• /
• 2015

In this experiment, five commercial cultivars and one wild species of loquat were used to investigate frost tolerance and enzymatic activities in leaves and young fruits under cold stress at $-3^{\circ}C$. The frost injury, malondialdehyde (MDA) content, and oxygen-scavenging enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were studied. This results showed that the wild species 'Wild Oak-leaf' loquat was the most frost tolerant among accessions tested, followed by the cultivar 'Golden Block'. Other cultivars, 'Wu Gong Bai', 'Taicheng 4', 'Xiangzhong 11' and 'Zaozhong 6', were relatively weak in frost tolerance. The enzymatic activities of SOD, POD and CAT increased initially and then decreased as the exposure time increased. However, the enzymatic peak occurred later in the frost-tolerant accession than in the frost-sensitive accession. The correlation coefficients of MDA contents between leaves and immature fruits were from 0.93 to 0.99 in the five commercial loquat cultivars. For the 'Wild Oak-leaf' loquat, the correlation coefficients of MDA and POD were 0.98 and 0.95, respectively, but the coefficients for SOD, CAT and APX were relatively low. In general, there were good correlations between loquat leaves and immature fruits in MDA content and enzyme activities. These results indicate that analysis of these physiological and biochemical activities in loquat leaves could potentially be used to predict the cold tolerance in loquat at immature fruit stage and to accelerate breeding programs for cold tolerance in loquat.

• The Plant Pathology Journal
• /
• v.31 no.3
• /
• pp.245-251
• /
• 2015

Alternative hosts increase the difficulty of disease management in crops because these alternate hosts provide additional sources of primary inoculum or refuges for diversity in the pathogen gene pool. Agropyron cristatum (crested wheatgrass), Bromus inermis (smooth bromegrass), Pascopyrum smithii (western wheatgrass), Stipa viridula (green needlegrass), and Thinopyrum intermedium (intermediate wheatgrass), commonly identified in range, prairie, verge, and soil reclamation habitats, serve as additional hosts for Pyrenophora tritici-repentis, the cause of tan spot in wheat (Triticum aestivum L.). A. cristatum (five lines), B. inermis (seven lines), P. smithii (four lines), S. viridula (two lines), and T. intermedium (six lines) were tested for their reactions to 30 representative P. tritici-repentis isolates from races 1-5. Plants were grown until the two-three-leaf stage in a greenhouse, inoculated individually with the 30 isolates, held at high humidity for 24 h, and rated after 7 days. All lines developed lesion types 1-2 (resistant) based on a 1-5 rating scale. Also, leaves from an additional plant set were infiltrated with two host selective toxins, Ptr ToxA as a pure preparation and Ptr ToxB as a dilute crude culture filtrate. All lines were insensitive to the toxins. Results indicate that these grass hosts have a limited or nonsignificant role in tan spot epidemiology on wheat in the northern Great Plains. Additionally, the resistant reactions demonstrated by the grass species in this research indicate the presence of resistance genes that can be valuable to wheat breeding programs for improving wheat resistance to P. tritici-repentis.

• Korean Journal of Medicinal Crop Science
• /
• v.13 no.5
• /
• pp.270-275
• /
• 2005

Superoxide dismutases (SOD) are metalloenzymes that convert $O_2^-\;to\;H_2O_2$. Rehmannia glutinosa is highly tolerant to paraquat-induced oxidative stress. The primary objective of this study was to characterize regulation of SOD gene expression in R. glutinosa in response to oxidative stresses and hormones. A full-length putative SOD clone (RgCu-ZnSOD1) was isolated from the leaf cDNA library of R. glutinosa using an expressed sequence tag clone as a probe. RgCu-ZnSOD1 cDNA is 777 bp in length and contains an open reading frame for a polypeptide consisted of 152 amino acid residues. The deduced amino acid sequence of the clone shows highest sequence similarity to the cytosolic Cu-ZnSODs. The two to three major bands with several minor ones on the Southern blots indicate that RgCu-ZnSOD1 is a member of a small multi-gene family. RgCuZnSOD1 mRNA was constitutively expressed in the leaf, flower and root. The expression of RgCu-ZnSOD1 mRNA was increased about 20% by wounding and paraquat, but decreased over 50% by ethylene and $GA_3$. This result indicates that the RgCu-ZnSOD1 expression is regulated differentially by different stresses and phytohormones at the transcription level. The RgCu-ZnSOD1 sequence and information on its regulation will be useful in investigating the role of SOD in the paraquat tolerance of R. glutinosa.

• Korean Journal of Soil Science and Fertilizer
• /
• v.37 no.1
• /
• pp.31-35
• /
• 2004

This experiment was performed to observe morphological changes in rice leaf tissue caused by a successive UV-B radiation. Effect of UV-B radiation on the structural alteration of tissue was not visually found, however, Photosynthate containing phosphate was sharply reduced in proportion with an increase of UV-B radiation. Fundamental components of cuticle layer were being degraded after 6 h of UV-B radiation compared to the control. UV-B-induced mesophyll cell appeared altered because of water stress, the shape of chloroplast appeared to be considerably shrunk and chloroplast thylakoid membranes were severely destructed. Primary cell wall of UV-B-stressed tissue was entirely scattered or disappeared, and the secondary cell wall due to lignin synthesis and deposition resulted in being thickened, almost 2-times, compared with the control.

• Journal of Crop Science and Biotechnology
• /
• v.11 no.1
• /
• pp.23-30
• /
• 2008

The relationship between three phenological parameters and somatic embryogenesis was investigated during a two-year period. Staminodes and petals from six hybrids and two clones as controls were sowed on three distinct primary callus growth media. Flowering level, fructification level, and leaf thrusts rhythm as phenological parameters were measured simultaneously during the weekly harvest of flower buds. Mean and coefficient of variation of the measured parameters highlighted stable phenological phases. The relationship between phenological parameters and somatic embryogenesis was investigated first by comparing the variation of somatic embryogenesis and that of the phenological parameters, and second by using Pearson's linear correlation. Except for the fructification level in both control clones the first year, the other parameters recorded stable phenological phases, regardless of the genotype and year. Favorable and unfavorable phases for the somatic embryogenesis were identified. In hybrids, favorable phases included February, August, September, and October. In both control clones, time interval propitious to embryogenesis stretched from February to December. The significance of the coefficient of correlation seemed to establish a relationship between somatic embryogenesis and phenology. However, a causal link could not be established. Leaf thrusts rhythm was revealed to be the phenological parameter most linked to somatic embryogenesis. Attempts to optimize embryogenesis during unfavorable phases, showed that a correction of 2.4 D/TDZ concentration is not the solution.

• Applied Biological Chemistry
• /
• v.37 no.4
• /
• pp.248-254
• /
• 1994

Bromoxynil is an antidicot herbicide widely used on cereal crops and has a short half life in the soil. A bxn gene, encoding a specific nitrilase that converts bromoxynil to its primary metabolite 3,5-dibromo-4-hydroxybenzoic acid, was inserted in plant binary vector pGA482, and then introduced into tobacco and lettuce plants via Agrobacterium mediated leaf-disc transformation method. Transgenic plants with the bxn gene were selected by kanamycin and regenerated to whole plants. The regenerated transgenic plants were determined level of expression of bxn gene by Northern blot analysis. Leaf-disc analysis and pot-assay confirmed that the transgenic tobacco and lettuce plants were resistant to high doses of bromoxynil.

• Korean Journal of Plant Tissue Culture
• /
• v.26 no.1
• /
• pp.7-14
• /
• 1999

In order to survey anthraquinone productivity from in vitro root culture, transformed hairy roots of Rumex crispus were induced from leaf segments by infection with Agrobacterium rhizogenes strain $A_4$ and compared with adventitious roots. The optimum condition of adventitious root formation from leaf segments was 5 $\mu$M NAA added to MS medium. Mannopine was detected in the extract of hairy roots by paper electrophoresis, but not in adventitious roots. Secondary root tips of both adventitious roots and hairy roots elongated without lateral root branching in hormone free MS medium, but primary root tips showed more rapid growth with extensive lateral root branching. MS basal medium was the best for growth of the adventious roots and hairy roots for anthraquinone content. Adventitious root tips and hairy root tips cultured in liquid MS medium supplemented with 0.05 $\mu$M NAA and 0.1 $\mu$M kinetin (contained 5% sucrose) showed the maximal growth and anthraquinone content. Anthraquinone content of hairy roots was increased by the culture periods, but was reduced after 25 days of culture.