Chromosome structure and behaviour in Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae) germ cells and early embryo

Chromosome structure and behaviour in both meiosis of the germ cells and mitosis of the embryo from fertilisation to the two-cell stage in Bursaphelenchus xylophilus were examined by DAPI staining and three-dimensional reconstruction of serial-section images from confocal laser-scanning microscopy. By this method, each chromosome’s shape and behaviour were clearly visible in early embryogenesis from fertilisation through the formation and fusion of the male and female pronuclei to the first mitotic division. The male pronucleus was bigger than that of the female, although the oocyte is larger and richer in nutrients than the sperm. From the shape of the separating chromosomes at anaphase, the mitotic chromosomes appeared to be polycentric or holocentric rather than monocentric. Each chromosome was clearly distinguishable in the male and female germ cells, pronuclei of the one-cell stage embryo, and the early embryonic nuclei. The haploid number of chromosomes (N) was six (2n = 12), and all chromosomes appeared similar. The chromosome pair containing the ribosomal RNA-coding site was visualised by fluorescence in situ hybridisation. Unlike the sex determination system in Caenorhabditis elegans (XX in hermaphrodite and XO in male), the system for B. xylophilus may consist of an XX female and an XY male

Pine Wilt Disease : Various Biological Relationships and Resulting Events

京都大学Proceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:14－19 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

The Effect of Acid Rain on the Defense Response of Pines to Pinewood Nematodes

京都大学Proceedings : IUFRO Kanazawa 2003 "Forest Insect Population Dynamics and Host Influences"., Scedule:14－19 September 2003, Vemue: Kanazawa Citymonde Hotel, Kanazawa, Japan, Joint metting of IUFRO working groups : 7.01.02 Tree resistance to Insects | 7.03.06 Integrated management of forset defoloating insects | 7.03.07 Population dynamics of forest insects, Sponsored by: IUFRO-J | Ishikawa Prefecture | Kanazawa City | 21st-COE Program of Kanazawa University, Editors: Kamata, Naoto | Liebhold, Nadrew M. | Quiring, Dan T. | Clancy, Karen M

Comparative Secretome and Functional Analyses Reveal Glycoside Hydrolase Family 30 and Cysteine Peptidase as Virulence Determinants in the Pinewood Nematode Bursaphelenchus xylophilus

Pine wilt disease, caused by the pinewood nematode, Bursaphelenchus xylophilus, is one of the world’s most serious tree diseases. Although the B. xylophilus whole-genome sequence and comprehensive secretome profile have been determined over the past decade, it remains unclear what molecules are critical in pine wilt disease and govern B. xylophilus virulence in host pine trees. Here, a comparative secretome analysis among four isolates of B. xylophilus with distinct virulence levels was performed to identify virulence determinants. The four candidate virulence determinants of B. xylophilus highly secreted in virulent isolates included lipase (Bx-lip1), glycoside hydrolase family 30 (Bx-GH30), and two C1A family cysteine peptidases (Bx-CAT1 and Bx-CAT2). To validate the quantitative differences in the four potential virulence determinants among virulence groups at the protein level, we used real-time reverse-transcription polymerase chain reaction analysis to investigate these determinants at the transcript level at three time points: pre-inoculation, 3 days after inoculation (dai), and 7 dai into pine seedlings. The transcript levels of Bx-CAT1, Bx-CAT2, and Bx-GH30 were significantly higher in virulent isolates than in avirulent isolates at pre-inoculation and 3 dai. A subsequent leaf-disk assay based on transient overexpression in Nicotiana benthamiana revealed that the GH30 candidate virulent factor caused cell death in the plant. Furthermore, we demonstrated that Bx-CAT2 was involved in nutrient uptake for fungal feeding via soaking-mediated RNA interference. These findings indicate that the secreted proteins Bx-GH30 and Bx-CAT2 contribute to B. xylophilus virulence in host pine trees and may be involved in pine wilt disease

The Behavioral Role of Males of Platypus Quercivorus Murayama in Their Subsocial Colonies

The behavioral role of male ambrosia beetles, Platypus quercivorus, in subsocial colonies both field and laboratory has been investigated. The entrance tunnels, where the male beetles are staying, are short, with a mean 4 cm long and mostly incline upwards from outside to inside at an angle of around 20º. To examine the role of males, another male or female (as the invader) was placed into a tunnel. When inhabitant males stayed in the tunnel they quickly expelled the invaders, regardless of their sex of the invaders. However, when an inhabitant male was removed an introduced male or female could freely enter the tunnel and was accepted by the inhabitant female. Upon replacing an inhabitant male with an invader male or female and then putting another invader male or female into the tunnel, no rejection occurred, suggesting that invader males and females play no role in guarding the tunnel. Based on the results an inhabitant male seems to have three responsibilities; protection of the gallery from invaders, protection of progeny (larva) from falling down and also keeping the gallery clean from frass. The 20º angle of the entrance tunnel tends to aid both in gallery protection and in frass clearing

Discrimination among host tree species by the ambrosia beetle Platypus quercivorus

The ambrosia beetle Platypus quercivorus is a vector for the fungus that causes Japanese oak wilt, and susceptibility to infestation by P. quercivorus varies by tree species. We postulated that P. quercivorus discriminates among host tree species differing in susceptibility to attack. To test this postulate, we counted the number of flying male beetles (NFM), the number of holes bored by male beetles (NH), and the number of flying female beetles (NFF) per unit area of bark surface in three fagaceous tree species: Quercus crispula (with high susceptibility to infestation) and Q. serrata and Castanea crenata (both with low susceptibility). NFM and NH were used to calculate the proportion of male beetles that bored holes out of those that flew to the tree (PBM). We used generalized additive models to predict NFM, NFF, and PBM. The locations of trees, expressed as x and y coordinates, numbers of weeks after the first male beetle’s flying (WEEK), diameters of trees 130 cm above ground (DBH), and tree species (SP) were incorporated into the models as candidate explanatory variables. The best-fit models for NFM and NFF included WEEK and DBH and the effect of location; SP was not included in the models. For PBM, the best-fit model included WEEK, DBH, and SP. The results indicate that male P. quercivorus prefer Q. crispula to Q. serrata and C. crenata and that selection is made before boring holes on trees, but that P. quercivorus do not discriminate among host species when they fly to trees

Pine Wilt Disease : Various Biological Relationships and Resulting Events

Abstract – Pine wilt disease is one of the most serious forest diseases in East Asian countries. The infection chain of this disease, which is filled with various biological relationships, is briefly reviewed. The affinity between host pine trees and pathogenic nematodes, one of the most decisive phases of the disease, is subsequently examined in a series of experiments

マツノザイセンチュウトソノキシュノシンワセイニカンスルケンキュウ

京都大学0048新制・課程博士農学博士甲第2379号農博第316号新制||農||291(附属図書館)学位論文||S55||N1139(農学部図書室)6335UT51-55-E55京都大学大学院農学研究科農林生物学専攻(主査)教授 瀧本 敦, 教授 上山 昭則, 教授 巌 俊一学位規則第5条第1項該当Kyoto UniversityDA