Suppression of Photosynthetic Gene Expression in Roots Is Required for Sustained Root Growth under Phosphate Deficiency
Suppression of Photosynthetic Gene Expression in Roots Is Required for Sustained Root Growth under Phosphate Deficiency
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缺磷条件下根部持续生长需要抑制根部光合基因表达
DOI：
10.1104/pp.114.238725
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发表时间：
2014-07-01
期刊：
影响因子：
7.4
通讯作者：
Liu, Dong
中科院分区：
文献类型：
--
作者：
Kang, Jun;Yu, Haopeng;Liu, Dong
植物通过调整其发育程序和代谢活动来科普环境中无机磷（Pi）的缺乏。对于拟南芥（Arabidopsis thaliana），发育反应包括抑制主根生长和促进侧根和根毛的形成。Pi缺乏还通过抑制光合基因的表达来抑制光合作用。早期的研究表明，光合基因的表达也被抑制在Pi缺乏的根，一个非光合器官，然而，这种现象的生物相关性仍然未知。在这项工作中，我们的特点是拟南芥突变体，超敏Pi饥饿7（hps 7），这是超敏Pi缺乏症，超敏反应包括根生长的抑制增加。HPS 7编码酪蛋白磺基转移酶。缺磷促进了HPS 7蛋白在根尖的积累。比较RNA测序分析表明，许多光合作用基因的表达被激活的hps 7的根。在缺磷条件下，hps 7光合基因的表达进一步增加，导致叶绿素、淀粉和蔗糖的积累增加。缺pi的hps 7根也产生高水平的活性氧。先前的研究表明，GOLDEN-like（GLK）转录因子在转基因拟南芥中的过表达激活了根中的光合作用。GLK过表达（GLK OX）系也表现出增加的根生长的抑制下，磷缺乏。在hps 7和GLK OX株系中，由于缺乏Pi而增加的根生长抑制通过在黑暗中生长植物而完全逆转。基于这些结果，我们提出，抑制光合基因的表达是需要持续的根生长在磷缺乏。
Plants cope with inorganic phosphate (Pi) deficiencies in their environment by adjusting their developmental programs and metabolic activities. For Arabidopsis (Arabidopsis thaliana), the developmental responses include the inhibition of primary root growth and the enhanced formation of lateral roots and root hairs. Pi deficiency also inhibits photosynthesis by suppressing the expression of photosynthetic genes. Early studies showed that photosynthetic gene expression was also suppressed in Pi-deficient roots, a nonphotosynthetic organ; however, the biological relevance of this phenomenon remains unknown. In this work, we characterized an Arabidopsis mutant, hypersensitive to Pi starvation7 (hps7), that is hypersensitive to Pi deficiency; the hypersensitivity includes an increased inhibition of root growth. HPS7 encodes a tyrosylprotein sulfotransferase. Accumulation of HPS7 proteins in root tips is enhanced by Pi deficiency. Comparative RNA sequencing analyses indicated that the expression of many photosynthetic genes is activated in roots of hps7. Under Pi deficiency, the expression of photosynthetic genes in hps7 is further increased, which leads to enhanced accumulation of chlorophyll, starch, and sucrose. Pi-deficient hps7 roots also produce a high level of reactive oxygen species. Previous research showed that the overexpression of GOLDEN-like (GLK) transcription factors in transgenic Arabidopsis activates photosynthesis in roots. The GLK overexpressing (GLK OX) lines also exhibit increased inhibition of root growth under Pi deficiency. The increased inhibition of root growth in hps7 and GLK OX lines by Pi deficiency was completely reversed by growing the plants in the dark. Based on these results, we propose that suppression of photosynthetic gene expression is required for sustained root growth under Pi deficiency.