These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Graminan breakdown by fructan exohydrolase induced in winter wheat inoculated with snow mold.
    Author: Kawakami A, Yoshida M.
    Journal: J Plant Physiol; 2012 Feb 15; 169(3):294-302. PubMed ID: 21983139.
    Abstract:
    Fructan structures vary widely among plant species. Graminan-type fructans, extensions of sucrose through β-(2,6)-linked fructosyl units with branches of β-(2,1)-linked fructosyl units, accumulate in tissues of winter wheat (Triticum aestivum) during cold hardening and are metabolized under persistent snow cover. Snow molds such as Typhula ishikariensis and Microdochium nivale opportunistically infect wheat under snow cover. Snow mold-resistant wheat cultivars tend to heavily accumulate and slowly metabolize water-soluble carbohydrates including graminans in comparison with snow mold-susceptible cultivars. We observed time-dependent changes in the amounts of water-soluble carbohydrates in snow mold-inoculated wheat tissues, and accumulated fructan levels significantly decreased as a result of snow mold inoculation and incubation under snow cover, especially in a snow mold-susceptible wheat cultivar. Three candidates for fructan exohydrolase (FEH) cDNAs with high homology to cell wall invertases were isolated from wheat leaf tissues inoculated with snow mold and incubated under snow cover. The substrate specificity of enzymes encoded by the isolated clones was analyzed by recombinant proteins expressed in Pichia pastoris. The recombinant protein (Wfh-sm3m) encoded by one (Wfh-sm3) of the isolated clones preferentially degraded 6-kestotriose and possessed minor hydrolase activity to 1-kestotriose and 1,1-kestotetraose. Moreover, Wfh-sm3m hydrolyzed almost all graminans that accumulated in hardened wheat tissues. Wfh-sm3 transcripts increased in wheat leaf tissues inoculated with snow mold and incubated under snow cover. These results suggest that Wfh-sm3 encodes a 6-FEH with minor 1-FEH activity and is associated with degradation of fructans in wheat leaf tissues during inoculation and incubation under snow cover.
    [Abstract] [Full Text] [Related] [New Search]