Abstract
To identify molecule(s) which mediates As(III) uptake in plants, we screened for As(III) tolerant mutants expecting that loss-of-function mutant of As(III) transporter would be tolerant to As(III). After screening of EMS-mutagenized Arabidopsis thaliana M2 seeds, we identified 3 independent mutants. We also analyzed tolerance of T-DNA mutants of NIPs, which are homologues of aquaglyceroporins. Among the lines tested, nip1;1 mutant showed As(III) tolerance. Sequencing of the NIP1;1 in the mutants revealed that each mutants had an independent mutation in NIP1;1, establishing that NIP1;1 is the causal gene of As(III) tolerance. Xenopus oocytes injected with NIP1;1 cRNA accumulated much As(III) than control oocytes injected with water. The promoter-GUS and real-time PCR analysis showed that NIP1;1 was highly expressed in roots. From these data, we conclude that NIP1;1 is the major As(III) transporter involved in As(III) uptake in roots in A. thaliana.
