Responses of stomata and xylem parenchyma cells to abrupt water disappearance in xylem of saplings infected with pine wilt disease

2014 Fiscal Year Final Research Report

• Project/Area Number: 23780190
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Wood science
• Research Institution: Forestry and Forest Products Research Institute
• Principal Investigator: YAZAKI Kenichi 独立行政法人森林総合研究所, 植物生態研究領域, 主任研究員 (30353890)
• Research Collaborator: TAKANASHI Takuma 森林総合研究所, 森林昆虫研究領域, 主任研究員 (60399376) ; KANZAKI Natsumi 森林総合研究所, 森林微生物研究領域, 主任研究員 (70435585)
• Project Period (FY): 2011-04-28 – 2015-03-31
• Keywords: 松枯れ / cryo-SEM / 木部柔細胞 / vulnerability curve / 水ポテンシャル / 光合成 / 透水係数

Outline of Final Research Achievements

To clarify the physiological mechanism of a tree death caused by pine wilt disease, the relationship between the physiological traits of needles and the hydraulic traits of xylem in the saplings of Pinus thumbergii inoculated with pine wood nematodes was investigated. Water dynamics in tracheids was also investigated by using cryo-SEM to examine the status of parenchyma cells.
Inoculated saplings decreased in stomatal conductance with their embolisms occured from the surrounding cells of resin canals, but maintained high daily water potential (ψ) until the disease symptom was visible. No relationship between water dynamics of tracheids and the deterioration of adjacent parenchyma cells was observed. Controled saplings under ceased irrigation conserved water in tracheids despite their decreasing in ψ, and they showed recovery of gas exchanges by re-irrigation. In conclusion, abnormal embolism would not be avoided by the stomatal closure and obstruct drought resistance of pine saplings.

Free Research Field

樹木生理