A peroxisomal ABC transporter promotes seed germination by inducing pectin degradation under the control of ABI5
A peroxisomal ABC transporter promotes seed germination by inducing pectin degradation under the control of ABI5
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DOI：
10.1111/j.1365-313x.2010.04205.x
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发表时间：
2010-06-01
期刊：
影响因子：
7.2
通讯作者：
Hayashi, Makoto
中科院分区：
文献类型：
--
作者：
Kanai, Masatake;Nishimura, Mikio;Hayashi, Makoto
种子休眠是大多数植物控制发芽时间所必需的。在拟南芥中，PED3是一个单拷贝基因，编码atp结合盒转运体，该转运体是过氧化物酶体脂肪酸β氧化所必需的。PED3参与向过氧化物酶体输入几种生物学上重要的分子，包括与种子储备脂质分解相关的长链脂肪酸，以及生长素和茉莉酸的前体。ped3突变体的萌发明显受损，提示ped3调控休眠和萌发。转录组分析显示，许多在启动子区域含有ABA响应元件（ABRE）核心基序的基因，以及与ABRE结合的ABA不敏感5 （ABI5）转录因子，在吸收的ped3种子中异常上调。多半乳糖醛酸酶抑制蛋白（PGIPs）的表达也在抑制后的ped3中特异性上调。相比之下，ped3 abi5双突变体没有表现出任何这些表达模式。结果表明，abi5突变使PGIP表达正常化，并恢复了pe3突变体受损的萌发表型。PGIPs被认为是降解果胶的聚半乳糖醛酸酶的抑制剂。PGIP1转录本的数量调节着神经根突出的时间。利用外源聚半乳糖醛酸酶或酸性条件去除种皮上的果胶也可以恢复pe3的萌发。总的来说，我们的研究结果表明，在ABI5的控制下，过氧化物酶体ABC转运体PED3通过抑制PGIPs来促进种子萌发。
P>Seed dormancy is essential for most plants to control the timing of germination. In Arabidopsis thaliana, PED3 is a single-copy gene encoding an ATP-binding cassette transporter that is required for peroxisomal fatty acid beta-oxidation. PED3 is involved in the import of several biologically important molecules into the peroxisome, including very-long-chain fatty acids associated with the breakdown of seed-reserve lipids, and precursors of auxin and jasmonic acid. The germination of ped3 mutants is significantly impaired, suggesting that PED3 regulates dormancy and germination. A transcriptome analysis revealed that many genes containing the core motif of the ABA responsive element (ABRE) in their promoter regions, and the ABA insensitive 5 (ABI5) transcription factor that binds to ABRE, are abnormally up-regulated in imbibed ped3 seeds. Expression of polygalacturonase inhibiting proteins (PGIPs) is also up-regulated specifically in ped3 after imbibition. By contrast, the ped3 abi5 double mutant does not show any of these expression patterns. The results indicate that the abi5 mutation normalizes PGIP expression and rescues the impaired germination phenotype of the ped3 mutant. PGIPs are known to act as inhibitors of polygalacturonases that degrade pectin. The amount of PGIP1 transcript regulates the timing of radicle protrusion. The impaired germination of ped3 could also be rescued by removal of pectin from the seed coat using exogenous polygalacturonase or acidic conditions. Overall, our results suggest that PED3, a peroxisomal ABC transporter, promotes seed germination by suppressing PGIPs under the control of ABI5.