| The auxin in higher plants, has profound effects on plant growth and development. Although it was discovered more than100years ago, so far no single complete pathway of de novo auxin biosynthesis in plants has been firmly established.Our research group isolated and characterized the Arabidopsis CK induced root curling1(ckrcl) mutant, which displayed defective root gravitropic response (GR) and an increased resistance to CK in primary root growth. Based on this previously established screening system, we eventually isolated7mutants representing curved primary roots on the presence of0.1uM ZT medium. Conversely,110mutant exhibited curve growth on MS medium but the defects could be rescued by ZT.Tail-PCR amplification of T-DNA flanking sequences identified the T-DNA insertions. Consequently,111insersition site located between Atlgl7110and Atlg17120, T-DNA insertions of424and110were identified in At1g15780and At5g49665respectively. Whereas the cloned T-DNA insertion of424was not the target site after genetic linkage analysis.In the chemical complementation assays, several auxins were employed to treat mutations. The complementation results manifested that defects of111could be rescued by exogenous1-NAA,424mutants showed more sensitivity to2,4-D than WT and the curved primary roots of110were suppressed by ZT treatment, consistent with the outcome of root inhibition experiments compared with ecotype. At last, we substantiated that111,424was the allelic mutant of auxl, pin2respectively using allele crosses.Fortunately, not all of the isolated mutations were published allelic mutants. The mutant of110demonstrated enhanced gravitropism response on MS media with root waving growth, however which could be rescued by ZT. Moreover, it exhibits elongate primary root as well as was hypersensitive to ZT through root inhibition assays. Simultaneously,110light-grown seedlings have epinastic cotyledons and elongate hypocotyls. Further investigation on110mutant is under way. |
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