Brachytic2/ZmABCB1 functions in IAA export from intercalary meristems.
Brachytic2/ZmABCB1 functions in IAA export from intercalary meristems.
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DOI：
10.1093/jxb/erq180
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发表时间：
2010-08
影响因子：
6.9
通讯作者：
Murphy AS
中科院分区：
文献类型：
--
作者：
Knöller AS;Blakeslee JJ;Richards EL;Peer WA;Murphy AS
玉米的矮秆性状受多种因素的调控，包括激素生长素。矮秆brachytic 2（br 2）突变体在编码拟南芥ABCB 1的直向同源物的基因中存在病变，ABCB 1在茎和根的分生组织区域的生长素流出中起作用。Br 2中胚轴和胚芽鞘表现出降低的生长素运输。然而，br 2的矮小身材来自缩短的下部节间，而植株的上部完全正常。因此，这是违反直觉的属性br 2矮化专门减少生长素输出的茎尖。拟南芥abcb 1突变体表现出只有轻微的减少生长素运输和植物高度，除非结合突变ABCB 19生长素转运蛋白。系统发育建模分析排除了BR 2与ABCB 19关系更密切的可能性，ABCB 19在玉米中有三个更密切相关的直系同源物。BR 2在节分生组织中表达，生长素运输和含量的分析表明，BR 2在这些草特异性组织中的功能类似于ABCB 1在拟南芥的茎和根尖中的功能。这些结果表明，ABCB 1/BR 2功能是保守的双子叶植物和单子叶植物之间，但也表明，这种功能必须理解的上下文中的节段组织的草植物。
Dwarfism traits in Zea mays are regulated by multiple factors including the hormone auxin. Dwarf brachytic2 (br2) mutants harbour lesions in the gene encoding an orthologue of Arabidopsis thaliana ABCB1 which functions in auxin efflux out of meristematic regions in the shoot and root. br2 mesocotyls and coleoptiles exhibit reduced auxin transport. However, the dwarf stature of br2 derives from shortened lower internodes whilst the upper portion of the plant is completely normal. As such, it is counter-intuitive to attribute br2 dwarfism exclusively to reduced auxin export out of the shoot apex. Arabidopsis abcb1 mutants exhibit only minor reductions in auxin transport and plant height unless combined with mutations in the ABCB19 auxin transporter. Phylogenetic modelling analysis excludes the possibility that BR2 is more closely related to ABCB19 which has three more closely related orthologues in maize. BR2 is expressed in nodal meristems, and analyses of auxin transport and content indicate that BR2 function in these grass-specific tissues is analogous to ABCB1 function in the shoot and root apex of Arabidopsis. These results indicate that ABCB1/BR2 function is conserved between dicots and monocots, but also suggests that this function must be understood in the context of the segmental organization of grass plants.
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