Mutations in an auxin receptor homolog AFB5 and in SGT1b confer resistance to synthetic picolinate auxins and not to 2,4-dichlorophenoxyacetic acid or indole-3-acetic acid in arabidopsis
Mutations in an auxin receptor homolog AFB5 and in SGT1b confer resistance to synthetic picolinate auxins and not to 2,4-dichlorophenoxyacetic acid or indole-3-acetic acid in arabidopsis
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DOI：
10.1104/pp.106.085969
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发表时间：
2006-10-01
期刊：
影响因子：
7.4
通讯作者：
Davies, John P.
中科院分区：
文献类型：
--
作者：
Walsh, Terence A.;Neal, Roben;Davies, John P.
虽然各种各样的结构不同的小分子可以作为生长素，但目前还不清楚是否所有这些化合物都通过与2，4-二氯苯氧基乙酸（2，4-D）和吲哚-3-乙酸（IAA）相同的机制起作用。为了解决这个问题，我们使用了一个新的成员的吡啶甲酸类的合成生长素，是结构上不同的2，4-D筛选拟南芥（拟南芥）突变体，显示化学选择性生长素抗性。我们在两个不同的遗传基因座上发现了七个等位基因，这些等位基因对毒氨吡啶等吡啶酸生长素具有显着的抗性，但对2，4-D或IAA的交叉抗性最小。双突变体的抗性水平和选择性与单突变体相同。通过位置作图将突变位点鉴定为At 4g 11260和At 5g 49980。At 5g 49980是以前未表征的，编码生长素信号F-box蛋白5，拟南芥基因组中TIR 1的五个同源物之一。TIR 1是Skp 1-cullin-F-box复合物的识别组分，该复合物与参与生长素信号传导的泛素-蛋白酶体途径相关，并且最近已被证明是IAA和2，4-D的受体。At 4g 11260编码的四肽蛋白SGT 1b也已与Skp 1-cullin-F-box介导的泛素化生长素信号和其他途径。突变株系与其相应的野生型基因互补恢复了对吡啶甲酸生长素的敏感性。这些结果表明，生长素信号传导的化学特异性可以由生长素反应途径的上游组分赋予。他们还展示了使用结构多样的化学物质进行遗传筛选以发现新的途径组分的实用性。
Although a wide range of structurally diverse small molecules can act as auxins, it is unclear whether all of these compounds act via the same mechanisms that have been characterized for 2,4-dichlorophenoxyacetic acid (2,4-D) and indole-3-acetic acid (IAA). To address this question, we used a novel member of the picolinate class of synthetic auxins that is structurally distinct from 2,4-D to screen for Arabidopsis ( Arabidopsis thaliana) mutants that show chemically selective auxin resistance. We identified seven alleles at two distinct genetic loci that conferred significant resistance to picolinate auxins such as picloram, yet had minimal cross-resistance to 2,4-D or IAA. Double mutants had the same level and selectivity of resistance as single mutants. The sites of the mutations were identified by positional mapping as At4g11260 and At5g49980. At5g49980 is previously uncharacterized and encodes auxin signaling F-box protein 5, one of five homologs of TIR1 in the Arabidopsis genome. TIR1 is the recognition component of the Skp1-cullin-F-box complex associated with the ubiquitin-proteasome pathway involved in auxin signaling and has recently been shown to be a receptor for IAA and 2,4-D. At4g11260 encodes the tetratricopeptide protein SGT1b that has also been associated with Skp1-cullin-F-box-mediated ubiquitination in auxin signaling and other pathways. Complementation of mutant lines with their corresponding wild-type genes restored picolinate auxin sensitivity. These results show that chemical specificity in auxin signaling can be conferred by upstream components of the auxin response pathway. They also demonstrate the utility of genetic screens using structurally diverse chemistries to uncover novel pathway components.