Jin-Kyo Jung

Sequence Information on Simple Sequence Repeats and Single Nucleotide Polymorphisms through Transcriptome Analysis of Mungbean

Mungbean (Vigna radiata (L.) Wilczek) is a unique species in its ability to fix atmospheric nitrogen, with early maturity, and relatively good drought resistance. We used 454 sequencing technology for transcriptome sequencing. A total of 150 159 and 142 993 reads produced 5 254 and 6 374 large contigs (≥ 500 bp) with an average length of 833 and 853 for Sunhwa and Jangan, respectively. Functional annotation to known sequences yielded 41.34% and 41.74% unigenes for Jangan and Sunhwa. A higher number of simple sequence repeat (SSR) motifs was identified in Jangan (1 630) compared with that of Sunhwa (1 334). A similar SSR distribution pattern was observed in both varieties. A total of 8 249 single nucleotide polymorphisms (SNPs) and indels with 2 098 high-confidence candidates were identified in the two mungbean varieties. The average distance between individual SNPs was approximately 860 bp. Our report demonstrates the utility of transcriptomic data for implementing a functional annotation and development of genetic markers. We also provide large resource sequence data for mungbean improvement programs.

Expression of BrD1, a plant defensin from Brassica rapa, confers resistance against brown planthopper (Nilaparvata lugens) in transgenic rices.

Plant defensins are small (5-10 kDa) basic peptides thought to be an important component of the defense pathway against fungal and/or bacterial pathogens. To understand the role of plant defensins in protecting plants against the brown planthopper, a type of insect herbivore, we isolated the Brassica rapa Defensin 1 (BrD1) gene and introduced it into rice (Oryza sativa L.) to produce stable transgenic plants. The BrD1 protein is homologous to other plant defensins and contains both an N-terminal endoplasmic reticulum signal sequence and a defensin domain, which are highly conserved in all plant defensins. Based on a phylogenetic analysis of the defensin domain of various plant defensins, we established that BrD1 belongs to a distinct subgroup of plant defensins. Relative to the wild type, transgenic rices expressing BrD1 exhibit strong resistance to brown planthopper nymphs and female adults. These results suggest that BrD1 exhibits insecticidal activity, and might be useful for developing cereal crop plants resistant to sap-sucking insects, such as the brown planthopper.

Occurrence of lepidopteran insect pests and injury aspects in adzuki bean fields.

Three lepidopteran insect pests of the legume pod borer, Maruca vitrata (Lepidoptera: Pyralidae), the soybean pod worm, Matsumuraeses phaseoli (Lepidoptera: Tortricidae) and an Ostrinia spp. (Lepidoptera: Pyralidae) attacking adzuki bean, Vigna angularis, were confirmed as the major insect pests during the reproductive developmental stage of adzuki bean, and M. vitrata existed dominantly. Almost all plants in the adzuki bean field were injured by at least one of the three species, and of reproductive organs were injured. Unbloomed inflorescence occurred continuously through the reproductive stage of adzuki bean. While the flower was many at the early stage and its number soon decreased, the pod was few at the early stage, but its number increased soon and maintained at a constant level. The results suggested that the adzuki bean injured by insect pests compensate the flower loss by developing new inflorescence, but the compensation do not cause the development of new pods. While M. vitrata and M. phaseoli were observed in flowers, pods and stem mainly during the first half of reproductive stage of adzuki bean, Ostrinia spp. was observed only in pods and stem during the second half. In addition, while all instars of larvae of M. vitrata were observed, larvae between the third and fifth instars for M. pahseoli and Ostrinia spp. were observed.

Developmental Characteristics of Soybean Podworm, Matsumuraeses phaseoli (Lepidoptera: Tortricidae) and Legume Pod Borer, Maruca vitrata (Lepidoptera: Pyralidae) on Semi-synthetic Artificial Diets

Two lepidopteran species, Matsumuraeses phaseoli (Matsumura) and Maruca vitrata (syn. M. testulalis) (Fabricius) were reared on artificial diets, and analyzed in their developmental characteristics. Photoperiod was supplied with 16L/8D for M. phaseoli and with 13L/11D for M. vitrata, respectively. Both species passed five larval instars with discrete sizes of head capsule width. In a constant environment ( and 65%RH), the developmental period of M. phaseoli egg, larva and pupa was 3.9, ca. 16.0 and 8.9 days, respectively, and over 80% of M. phaseoli larvae could develop into pupae, most of which emerged into adults. Newly laid eggs could be stored at for 15 days with over 50% hatchability. Similar developmental traits were shown in M. vitrata. However, a low temperature preservation was not applicable to M. vitrata eggs.

Identification and bacterial characteristics of Xenorhabdus hominickii ANU101 from an entomopathogenic nematode, Steinernema monticolum

An entomopathogenic nematode, Steinernema monticolum, was collected in Korea. Its identity was confirmed by morphological and molecular characters. Its symbiotic bacterium, Xenorhabdus hominickii ANU101, was isolated and assessed in terms of bacterial characteristics. Sixty-eight different carbon sources were utilized by X. hominickii ANU101 out of 95 different sources from a Biolog assay. Compared to other Xenorhabdus species, X. hominickii ANU101 was relatively susceptible to high temperatures and did not grow above 34°C. Furthermore, its growth rate was much slower than other Xenorhabdus species. X. hominickii exhibited insecticidal activities against coleopteran, dipteran, and lepidopteran insect pests. The bacterial virulence was not correlated with its host nematode virulence with respect to relative insecticidal activity against target insects. X. hominickii ANU101 exhibited antibiotics tolerance. The bacterium possesses four different plasmids (Xh-P1 (104,132bp), Xh-P2 (95,975bp), Xh-P3 (88,536bp), and Xh-P4 (11,403bp)) and encodes 332 open reading frames. Subsequent predicted genes include toxin/antitoxins comprising a multidrug export ATP-binding/permease. This study reports bacterial characters of X. hominickii and its entomopathogenicity.

A Molecular Marker Discriminating the Soybean Podworm, Matsumuraeses phaseoli and the Podborer, M. falcana (Lepidoptera: Tortricidae)

Two closely related species, the soybean podworm, Matsumuraeses phaseoli, and the podborer, M. falcana, gives differential economic damages on crops. It is difficult to discriminate these potential sympatric species by morphological characters. The goal of this study was to develop a discriminating molecular marker based on polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). A partial genomic fragment (500 bp) of mitochondrial cytochrome oxidase I (mtCOI) was sequenced in both species, in which restriction site by Rsa I was selected as a dichotomous marker. PCR-RFLP in the mtCOI region clearly discriminated both species.

Oviposition Preference of The Bean Bug, Riptortus clavatus (Thunberg) (Hemiptera: Alydidae), on Soybean and Mungbean Plants

Oviposition preference of the bean bug, Riptortus clavatus to sites on a plant and within a field, to plants at different developmental stages, and to different leguminous germplasms was observed. The insect layed its eggs mainly on the back surface of leaf in the upper half of plant in both observation from oviposition cage and soybean field. The egg number in fields were observed at a statistically-same rate in marginal and inside area, and at a median value of one egg per leaf in oviposited leaves. Full seed stage of soybean hardly affected oviposition preference of the insect. A statistically-significant difference in oviposition to different leguminous germplasms was observed.

Characterization of joining sites of a viral histone H4 on host insect chromosomes

A viral histone H4 (CpBV-H4) is encoded in a polydnavirus, Cotesia plutellae bracovirus (CpBV). It plays a crucial role in parasitism of an endoparasitoid wasp, C. plutellae, against diamondback moth, Plutella xylostella, by altering host gene expression in an epigenetic mode by its N-terminal tail after joining host nucleosomes. Comparative transcriptomic analysis between parasitized and nonparasitized P. xylostella by RNA-Seq indicated that 1,858 genes were altered at more than two folds in expression levels at late parasitic stage, including 877 up-regulated genes and 981 down-regulated genes. Among parasitic factors altering host gene expression, CpBV-H4 alone explained 16.3% of these expressional changes. To characterize the joining sites of CpBV-H4 on host chromosomes, ChIP-Seq (chromatin immunoprecipitation followed by deep sequencing) was applied to chromatins extracted from parasitized larvae. It identified specific 538 ChIP targets. Joining sites were rich (60.2%) in AT sequence. Almost 40% of ChIP targets included short nucleotide repeat sequences presumably recognizable by transcriptional factors and chromatin remodeling factors. To further validate these CpBV-H4 targets, CpBV-H4 was transiently expressed in nonparasitized host at late larval stage and subjected to ChIP-Seq. Two kinds of ChIP-Seqs shared 51 core joining sites. Common targets were close (within 1 kb) to genes regulated at expression levels by CpBV-H4. However, other host genes not close to CpBV-H4 joining sites were also regulated by CpBV-H4. These results indicate that CpBV-H4 joins specific chromatin regions of P. xylostella and controls about one sixth of the total host genes that were regulated by C. plutellae parasitism in an epigenetic mode.

Injury of Full Seed Stage Soybeans by The Bean Bug, Riptortus pedestris

Soybean seed injury was analyzed in the experiments in which the bean bug, Riptortus pedestris(Hemiptera: Alydidae), was released into screen-caged pots containing full seed stage(R6) of soybean. When the different stages of insects, from the 3rd instar nymphs to adults, were released into pots during 8 days in soybean R6 stage, soybean seeds with injury marks (B-type seeds) increased. The weight reduction ratio in B-type seeds was highest in the injury by the 5th instar nymphs, while the daily-produced number ratio of B-type seeds was small in the treatment. In the injury by the different number of adult released into pots, 4, 8, 16 adults caused a significant increase of B-type seeds, while 16 adults caused the significant increase of the deformed (C-type) seeds. In the injury by the different release period of adults, the total number of pods was not significantly different among treatments, while the total seed number harvested was significantly small in the release for 48 days. The release for 8 and 16 days caused a significant increase of B-type seeds, while the release for 48 days caused the increase of C-type seeds. The results indicated that injury of soybean R6 stage by the bean bug produced soybean seeds with distinct injury marks at relatively low density and during short term attack period, while it produced deformed seeds at high density and during long attack period.