DON IN RICE
There are some summaries about the experiment to select rice mutants which are sensitive to DON： 1. Contamination of DON in rice 1) There are some articles show that the DON
could be detected in stored rice 2) Some papers show that it’s hard to detected DON in harvested rice, but in delayed lodging rice it’s could be detected in a low concentration way 3) The indoor assay show opposite results(Positive: M. Yoshida*,et al. 2004, Proceedings
of the 2nd International Symposium on Fusarium Head Blight;Negative: Rubella S., et al. 2005, phytopathology)
4) No DON and NIV was detected from cultivated and natural wild rice (zizaniapalustris) 5) After all,even the DON could be detected in rice, the concentration is much lower than in sensitive type of wheat or other cereals 2. Affection of DON to rice and other grains 1) DON would infects the root growth of cereals including rice(Shuichi Ohsato, et al.
2007, Plant Cell Rep)
2) DON application toflowering ears induced typical FHB symptoms in wheat(Marc Lemmens, et al. 2005, MPMI) 3. In vitro assay Bioassays and plant tissues used for toxin resistance tests to date have been diverse: a) growth inhibition of shoots and roots (Shimada and Otani 1990)or calli(Bruins et al.
inhibition of seed germination (Lemmens et al. 1994; Wakulinski 1989) coleoptile growth retardation (Wang and Miller 1988) electrolyte leakage induced by DON in cereal leaves (Wojciechowski et al. 1995) co-cultured in anther culturesfor in vitro selection since a large proportion of the plant genome is expressed in both the sporophyte and the gametophyte(Bruins, M.B.M., et al. 1993, Plant Sci;Fadel, F., et al.1993,Plant Breed; Eudes, F., et al. 2008,Can. J. Plant Sci) 4. Resistance mechanisms and Engineering for Resistance ? Examples of enzymes that may be involved in detoxification include epoxidases, acetyltransferases, andglycosyltransferases (Boutigny, A.L., et al. 2008, Eur. J. Plant Pathol). ? While there is no evidence of de-epoxidationin planta(Boutigny, A.L., et al. 2008, Eur. J. Plant Pathol), the epoxide group has been shown to be essential for trichothecene toxicity (Ehrlich, K.C., et al. 1987, Biochim. Biophys). ? Transgenic expression of TRI101(Trichothecene 3-O-acetyltransferase) in plants has shown improved FHB- and trichothecene-resistance(Alexander, N.J. 2008,World Mycotoxin J.;Ohsato, S., et al.2007, Plant Cell Rep.;Okubara, P.A., et al. 2002, Theor. Appl. Genet). ? Another Fusariumgene, Tri12, is a major facilitator superfamily (MFS) transporter responsible for trichothecene efflux from F. sporotrichioides, also has the potential to reduce trichothecene accumulation in plants(Alexander, N.J.
b) c) d) e)
et al. 1999, Mol. Gen. Genet).
Transgenic expression of UDP-glucosyltransferase might lead to improved FHB-resistance and reduced toxin accumulation; however, this approach may be dangerously misleading. Studies have shown than glycosylated-DON can be reconverted to DON in the intestinal tract of swine (Shuichi Ohsato, et al. 2007, Plant Cell Rep; Gareis, M. et al. 1990, Zentralbl. Veterinarmed. B). 5. Work to do 1) Choose an in vitro assay used for mutants selection. The seed germination selection method may not work, becauseroot growth of cereals was severely inhibited by DON in the medium, and theeffects on callusgrowth and seed germination were rather weak(M.B.M. Brulns, et al. 1993,
Plant Science; Dahleen and McCormick 2001, Cereal Res Commun;Daisuke Masuda, et al. 2007, Journal of Experimental Botany; Shuichi Ohsato, et al. 2007, Plant Cell Rep)
2) The DON infection to the spikelet of the rice, what’s the infection symptom? And the DON toleration of the spikelet; the degradation or conjunction of the DON 3) Whether the rice cell has the mechanism of degradation or conjunction the DON？What’s C14 labeled DON changing to in the rice cell culture？ 4) The histological analysis of the interaction between rice and F. graminearum.Recent work presented by Ilgenet al. shows that trichodiene synthase expression is induced when the growing hyphae comes in contact with the ovaries (Peter ILGEN, et al. 2008, Cereal Research Communications). It is likely that metabolite(s) present in the ovaries induces expression of trichothecene synthesis. 5) The toleration difference between rice and resistant wheat, e. g.,Sumai #3 6) The infection of trichothecene to F. graminearum itself. TRI 12 mutant?