KURODA, Keiko

Research field

Interests 

• Movie of embolism & acoustic emission
• MR Imaging of water distribution in tree trunks

• Wilting mechanism: Outline
• Xylem dysfunction in spruce trees (PDF file download)

• Reaction of host cells against pathogen
• Formation of wound heartwood
• What is the indicator of healthy forest?

What's new

Recent reports written in English

1. Keiko Kuroda: Pine Wilt Disease, Zhao, Futai, Sutherland, Takeuchi (Eds.), Part V Host Responses and Wilting Mechanisms, 20 Introduction, 21 Physiological Incidences Related to Symptom Development and Wilting Mechanism. Springer, 202-222, 2008
2. Keiko Kuroda: Pine Wilt Disease: A Worldwide Threat to Forest Ecosystems, M.M. Mota, P. Vieira (eds.), Part 6 Defense Systems of Pinus Densiflora Cultivars Selected as Resistant to PineWilt Disease. Springer, 315-322, 2008
3. Kuroda, K.: Anatomical and noninvasive techniques to detect the first internal symptom in diseased trees.  Symposium: A Century of Wood Anatomy and 75 Years of IAWA, Botany 2006, Chico, California, USA July 29 - August 2.  Abstracts p.11, 2006
4. Kuroda, K.: Defense systems of Pinus densiflora cultivars selected as resistant to pine wilt.  Pine wilt disease: a worldwide threat to forest ecosystems. 10-14 July 2006, Lisbon, Portugal  Abstracts p. 47, 2006
5. Kuroda, K., Kanbara, Y., Inoue, T. and Ogawa, A.:  Magnetic resonance micro-imaging of xylem sap distribution and necrotic lesions in tree stems.  IAWA Journal 27(1):3-17. 2006. (PDF file download)
6. Kuroda, K., Ichihara, Y., Kanbara, Y., Inoue, T. and Ogawa, A.:  Visualization of a host reaction in oak stems infected with a wilt pathogen, Raffaelea quercivora, by magnetic resonance imaging. 6th Pacific Regional Wood Anatomy Conference 2005 Kyoto Japan, Abstracts p.64-65, 2005
   
7.  Kuroda, K.:  Xylem dysfunction in Yezo spruce (Picea jezoensis) after inoculation with the blue-stain fungus Ceratocystis polonica. Forest Pathology 35(5): 346-358. 2005.  (PDF file download)
   
8. Kuroda, K.:  Inhibiting factors of symptom development in several Japanese red pine (Pinus densiflora) families selected as resistant to pine wilt.  Journal of Forest Research 9: 217-224, 2004   (PDF file download)
9. Kuroda, K., Ichihara, Y., Kanbara, Y., Inoue, T. and Ogawa, A.: Magnetic Resonance imaging of xylem dysfunction in Quercus crispula infected with a wilt pathogen, Raffaelea quercivora.  Abstract of IUFRO Working Party 7.02.02  FOLIAGE, SHOOT & STEM DISEASES, June 13-19, 2004, Oregon, USA, P.16, 2004.
10. Kuroda, K.: Degradation of Conifer Plantations in the Kansai District.  Bulletin of the Forestry and Forest Products Research Institute,  2:247-254, 2003.     (PDF file download)
11. Kuroda, K., Kanbara, Y., Inoue, T. and Ogawa, A.: Analysis of NMR-CT images to detect the xylem dysfunction and lesions in tree trunks.  Abstract of 5th Pacific Regional Wood Anatomy Conference (Indonesia, Yogyakarta), IAWA Journal, 23:469-470, 2002
12. Kuroda, K.: The mechanism of tracheid cavitation in trees infected with wilt diseases. Proceedings of the IUFRO Working Party 7.02.02 shoot and Foliage Diseases, P.17-23, Hyytiala, Finland, 2001   
13. Kuroda, K.: Responses of Quercus sapwood to infection with the pathogenic fungus of a new wilt disease vectored by the barkbeetle Platypus quercivorus. J. Wood Science 47: 425-429 , 2001 (PDF file download,     Abstract)
    
14. Kuroda, K.: Anatomical assessment of age of infection with resinous stem canker in hinoki cypress (Chamaecyparis obtusa) and the factors promoting resinosis. J. Jpn Wood Res Soc, 46(6), 503-509, 2000
15. Kuroda, K. Kuroda, H. Lewis, A. M.: Detection of embolism and acoustic emissions in tracheids under a microscope: Incidence of diseased trees infected with pine wilt. New Horizons in wood Anatomy, ed. by YS Kim, Chonnam Nat'l Univ. Press, Kwangju, Korea, 372-377, 2000 (The 4th Pacific Regional Wood Anatomy Conference in Korea, 1998
16. Kuroda, K.: Seasonal variation in traumatic resin canal formation in Chamaecyparis obtusa phloem. IAWA J. 19: 181-189, 1998
17. Kuroda, K. and Kiyono, Y.: Seasonal Rhythms of Xylem Growth Measured by the Wounding Method and with a Band-Dendrometer: An instance of Chamaecyparis Obtusa . IAWA Journal 18:291-299, 1997. 
18. Kuroda, K. and Yamada, T.: Discoloration of sapwood and blockage of xylem sap ascent in the trunks of wilting Quercus spp. following attack by Platypus quercivorus. J. Jpn. For. Soc. 78(1):84-88, 1996.  
19. Kuroda, K.: Acoustic emission technique for the detection of abnormal cavitation in pine trees infected with pine wilt disease. International symposium on pine wilt disease caused by pine wood nematode (China). Proceedings 53-58, 1996 (PDF file download)
    
20. Kuroda, K., Yamada, T. and Ito, S.: Bursaphelenchus xylophilus induced pine wilt: Factors associated with resistance. Eur. J. For. Path. 21, 430-438, 1991 (PDF file download)
21. Kuroda, K.: Mechanism of cavitation development in the pine wilt disease. Eur. J. For. Path. 21, 82-89, 1991  (PDF file download)
22. Kuroda, K.: Terpenoids causing tracheid-cavitation in Pinus thunbergii infected by the pine wood nematode (Bursaphelenchus xylophilus ). Ann. Phytopath. Soc. Jpn. 55, 170-178, 1989  (PDF file download)
23. Kuroda, K., Yamada, T. and Mineo, K. Tamura, H.: Effects of cavitation on the development of pine wilt disease caused by Bursaphelenchus xylophilus. Ann. Phytopath. Soc. Jpn. 54, 606-615, 1988  (PDF file download)

    

Abstracts of publications: '96-2001

Kuroda, K.:
Anatomical assessment of age of infection with resinous stem canker in hinoki cypress (Chamaecyparis obtusa) and the factors promoting resinosis. J. Jpn Wood Res Soc, 46(6), 503-509, 2000
    Highly frequent traumatic resin canal formation in the phloem is characteristic of resinous stem canker disease. A fungus, Cistella japonica, was reported as a candidate for causal agent, and some environmental factors may affect extensive and long-term resinosis in tree trunks. At several plantations in Maizuru and Kanazawa in Japan, resin canal formation and resin production appear to be active under conditions that promote tree growth. In the plantations where this disease was frequently observed, even trees without resinosis contained traumatic resin canals. Such trees are not healthy, but 'diseased trees without visible symptoms'. Extensive resinosis is often discovered at mature plantations about 20 years old. However, the onset of this disease was estimated to occur at the very young age of about 5 to 8 years, based on the fact that wound resin canals are not formed in the phloem more than three years old. Disease-promoting factors should therefore be surveyed tracing back to the earlier period. The distribution of resin canals throughout a trunk circumference suggests that the stimuli that induce epithelial cell differentiation affect the entire trunk. Some physiological aspects of trees may relate to the sensitivity to resin canal formation. Partial necrosis of cambium was observed in the specimens with resinosis, except for the youngest of age 11, and was associated with resin pockets. Well-grown trees have a tendency to promote resinosis and cambium necrosis.

Kuroda, K. Kuroda, H. Lewis, A. M.:
Detection of embolism and acoustic emissions in tracheids under a microscope: Incidence of diseased trees infected with pine wilt. New Horizons in wood Anatomy, ed. by YS Kim, Chonnam Nat'l Univ. Press, Kwangju, Korea, 372-377, 2000 (The 4th Pacivic Resional Wood Anatomy Conference in Korea, 1998, IAWA Journal 19(4) P.463-464 1998).
    Xylem-sap in the water conduits is kept under tension when transpiration is active. The conduit's water columns can break under high tension and form bubbles (emboli). In healthy plants, water columns recover by rehydration when the tension is reduced. In trees infected with wilting diseases, however, sap ascent finally stops without recovering in dehydrated xylem areas. We observed embolism in light-microscope sections of diseased trees and confirmed the relationship between bubble development and acoustic emissions (AEs) that are detected at embolism. We discuss the mechanism of water blockage in pine wilt disease.
     Three-year-old Japanese red-pines (Pinus densiflora), inoculated with pine wood nematodes (Bursaphelenchus xylophilus) and healthy trees, were used. Embolism was observed on radial sections (1x6mm) of 60 µm thick that contain a layer of intact tracheids, and was recorded on videotape (Lewis' method). At the same time, AEs were monitored with an AE-transducer attached to the sections. As the second experiment, the time necessary for the rehydration of healthy and infected pines following the addition of water was compared.
     First, dehydration without AEs occurred from cut-ends of tracheid injured during sectioning. Then, bubbles emerged near the centers of intact tracheids, abruptly swelled, and filled whole tracheids. Such bubble expansion is thought to occur by the evaporation of water into a very tiny bubble. During high-rate bubble formation, AEs were produced. We successfully recorded AEs as audible-sound through the audio terminal of the VTR. The AEs coincided with almost all of the rapid bubble development. This result supports the idea that AEs detected in the trunks of living trees are produced by embolism in tracheids. Two weeks after inoculation of the pathogen, water blockage by embolism had just occurred in a part of the xylem. In such trees, the time necessary for rehydration is longer than in healthy trees. It suggests that certain substances that inhibit bubble dissolution may exist in xylem.
In detail, see movie

Return to Recent papers

    Trunks of Chamaecyparis obtusa were injured to examine the seasonal differences in traumatic resin canal formation in secondary phloem. Even after the wounding during winter, differentiation of axial parenchyma into epithelium was initiated, and vertical resin canals formed. After winter wounding, resin canal development was slower, the tangential extent of resin canals was narrower, and it took one to two months until resin secretion began. After spring wounding, the sites of resin canal formation were the one- and 2-year-old annual ring of phloem. In August, the location shifted into the current and one-year-old annual ring. Resin canals never formed in areas that were 3 or more years old. In C. obtusa trunks that are affected by the resinous stem canker, numerous tangential lines of resin canals are found throughout the phloem, not just recent and 1--2 year old phloem. The present research indicates that these many lines of resin canals were not formed at one time, and that the stimuli that induce traumatic resin canals must occur repeatedly over many years. The data on artificial wounding effects are useful for understanding resinous stem canker.
Key words: Traumatic resin canal, secondary phloem, Chamaecyparis obtusa, resinous stem canker, injury

Keiko Kuroda and Yoshiuki Kiyono:
Seasonal Rhythms of Xylem Growth Measured by the Wounding Method and with a Band-Dendrometer: An instance of Chamaecyparis Obtusa. IAWA Journal 18:291-299, 1997.
    The pinning method for the measurement of xylem growth was modified for easier application. Trunks of Chamaecyparis obtusa were monthly incised with a knife instead of a thin needle. Two years later, xylem blocks including wounded areas were all harvested, and xylem growth curves for two years were reconstructed from the sites of wound tissue. Circumferential increases were measured with the band-dendrometer on the same trees for comparison. Measurement by wounding method indicated a tendency for cambial cell production to accelerate twice a year, around May and August. Circumferential increase measured with the band dendrometer differed from radial growth. It was very small around August and continued after the cessation of cell-production. The climatic data near the plantation suggested circumferential size of trunks is probably affected by the physical shrinkage of trunks because of water shortage during the drought season and trunk swelling following precipitation. Circumferential increments did not reflect the seasonal rhythms of xylem growth. Therefore, for the detailed information on the radial growth within a season, the wounding method is recommended. Key words: Xylem growth, pinning method, wounding method, band- dendrometer, drought shrinkage, Chamaecyparis obtusa .

K. Kuroda and T. Yamada:
Discoloration of sapwood and blockage of xylem sap ascent in the trunks of wilting Quercus spp. following attack by Platypus quercivorus. J. Jpn. For. Soc. 78:84-88, 1996.
    Many deciduous oak trees, Quercus serrata and Q. crispula are wilting during summer in the wide areas of Honshu island of Japan along the Japan sea. Such forests that had been used for charcoal production are not managed appropriately now. Prior to wilting, mass attacks by an ambrosia beetle, Platypus quercivorus , into trunks were observed. A specific fungus, which is carried into xylem via beetles' mycangia, had been detected from wilting trees. We discussed on the determinant factor of this oak wilting, from the observation of tree tissues taken from trees attacked by the beetle. Following the beetles' invasion, xylem discoloration had occurred in sapwood surrounding long galleries whether the tree is wilting or not. Fungal hyphae were found in vessels near the galleries. The xylem sap ascent was blocked at such discolored xylem like heartwood. Discolored area became maximum where beetles' gallery elongated in high density usually from the base to the breast height of trunks. Before the start of wilting symptom, sap ascent had been completely blocked in trunks at the height of maximum discoloration for most vessels became dysfunctional in the current annual ring, and occasionally cambium was necrotic.