Poster: Root Biology
Abs #
530: Proton rhizotoxicity is different from aluminum rhizotoxicity in Arabidopsis thaliana.
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Presenter: |
Koyama, Hiroyuki , koyama@cc.gifu-u.ac.jp |
Authors | Koyama, Hiroyuki (A) Kobayashi, Yuriko (A) Toda, Tomomi (A) Ikka, Takashi (A) Hasegawa, Mayumi (A) Hara, Tetsuo (A) | | Affiliations: |
(A): Plant Cell Tech. Lab., Faculty of Agriculture, Gifu University
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Rhizotoxicity in acid soil, which involves the action of Al3+, H+ and Mn2+, is considered a major environmental stress that limits world food production. It is important to examine the mechanisms of each rhizotoxicity and tolerance in plants to improve crop productivity in acid soil. Aluminum toxicity has been well investigated and mechanisms of Al tolerance have been proposed. In contrast, little has been reported on proton rhizotoxicity. As we reported previously, Arabidopsis is very sensitive to Al, but also to proton rhizotoxicity. Both aluminum and low pH damages are evident in growing roots, suggesting several processes involved in ggrowingh would be target of these rhizotoxicities. To understand the nature of proton rhizotoxicity, we compared the pattern of Aluminum and proton rhizotoxicity in Arabidopsis with histochemical and genetic approaches.
When growing roots of A. thaliana (Ler) were exposed to solutions at low pH (4.8 and below), viability of root elongation zone disappeared within two hours judged by FDA-PI staining. On the other hand, root-tip possessed viability at least three hours in aluminum solution (pH 5.0 with AlCl3) if elongation was totally inhibited. Addition of Ca2+ and other divalent cations (Sr2+ and Ba2+) totally ameliorated damages in the root tips, suggesting the target of proton rhizotoxicity would be essential processes for root elongation required Ca2+, possibly relating to the formation of pectin network. On the other hand, ameliorative effect of Ca2+ and other ions on aluminum rhizotoxicity was limited, and thus these rhizotoxicity have different toxic actions on the growing roots. Cluster analysis with accessions and QTL analysis with RI lines indicated that different genes would regulate each stress factor tolerance.
