MicroRNA399 is a long-distance signal for the regulation of plant phosphate homeostasis.
MicroRNA399 is a long-distance signal for the regulation of plant phosphate homeostasis.
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DOI：
10.1111/j.1365-313x.2007.03363.x
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发表时间：
2008-03
期刊：
影响因子：
7.2
通讯作者：
Scheible, Wolf-Ruediger
中科院分区：
文献类型：
--
作者：
Pant, Bikram Datt;Buhtz, Anja;Kehr, Julia;Scheible, Wolf-Ruediger
植物韧皮部汁液中存在microRNA物种表明通过基因表达的长距离调节的潜在信号传导作用。缺乏韧皮部移动microRNA的这种作用的证据。在这里，我们表明，磷酸盐（Pi）饥饿诱导的microRNA399（miR 399）是存在于两种不同的植物物种，油菜籽和南瓜的韧皮部汁液中，并且在Pi剥夺期间韧皮部汁液中的水平强烈且特异性地增加。通过使用拟南芥进行微嫁接实验，我们进一步表明，嵌合体植物组成型过表达miR399在地上部积累成熟miR399物种在其野生型根非常高的水平，而相应的初级转录物几乎不存在于根中，证明了地上部到根的运输。嵌合植物表现出（i）野生型根中miR399靶转录物（PHO2）的下调，其编码维持Pi稳态的关键组分，和（ii）芽中的Pi积累，这是pho2突变体、miR399过表达者或根中PHO2基因敲除的嵌合植物的表型。因此，转运的miR399分子保留生物活性。这是通过韧皮部移动的microRNA对生物过程的系统控制，即维持植物Pi稳态的证明。
The presence of microRNA species in plant phloem sap suggests potential signaling roles by long-distance regulation of gene expression. Proof for such a role for a phloem-mobile microRNA is lacking. Here we show that phosphate (Pi) starvation-induced microRNA399 (miR399) is present in the phloem sap of two diverse plant species, rapeseed and pumpkin, and levels are strongly and specifically increased in phloem sap during Pi deprivation. By performing micro-grafting experiments using Arabidopsis, we further show that chimeric plants constitutively over-expressing miR399 in the shoot accumulate mature miR399 species to very high levels in their wild-type roots, while corresponding primary transcripts are virtually absent in roots, demonstrating shoot-to-root transport. The chimeric plants exhibit (i) down-regulation of the miR399 target transcript (PHO2), which encodes a critical component for maintenance of Pi homeostasis, in the wild-type root, and (ii) Pi accumulation in the shoot, which is the phenotype of pho2 mutants, miR399 over-expressers or chimeric plants with a genetic knock-out of PHO2 in the root. Hence the transported miR399 molecules retain biological activity. This is a demonstration of systemic control of a biological process, i.e. maintenance of plant Pi homeostasis, by a phloem-mobile microRNA.