Secondary vascular development is a key biological characteristic of woody plants and the basis of wood formation.Our understanding of gene expression regulation and dynamic changes in microRNAs(miRNAs)during secondar...Secondary vascular development is a key biological characteristic of woody plants and the basis of wood formation.Our understanding of gene expression regulation and dynamic changes in microRNAs(miRNAs)during secondary vascular development is still limited.Here we present an integrated analysis of the miRNA and mRNA transcriptome of six phase-specific tissues-the shoot apex,procambium,primary vascular tissue,cambium,secondary phloem,and secondary xylem-in Populus tomentosa.Several novel regulatory modules,including the PtoTCP20-miR396d-PtoGRF15 module,were identified during secondary vascular development in Populus.A series of biochemical and molecular experiments confirmed that PtoTCP20 activated transcription of the miR396d precursor gene and that miR396d targeted PtoGRF15 to downregulate its expression.Plants overexpressing miR396d(35S:miR396d)showed enhanced secondary growth and increased xylem production.Conversely,during the transition from primary to secondary vascular development,plants with downregulated PtoTCP20expression(PtoTCP20-SRDX),downregulated miR396 expression(35S:STTM396),and PtoGRF15 overexpression(35S:PtoGRF15)showed delayed secondary growth.Novel regulatory modules were identified by integrated analysis of the miRNA and mRNA transcriptome,and the regulatory role of the PtoTCP20-miR396d-PtoGRF15 signaling cascade in secondary vascular development was validated in Populus,providing information to support improvements in forest cultivation and wood properties.展开更多
Leaf development has been extensively studied on a genetic level. However, little is known about the inter- play between the developmental regulators and the cell cycle machinery--a link that ultimately affects leaf f...Leaf development has been extensively studied on a genetic level. However, little is known about the inter- play between the developmental regulators and the cell cycle machinery--a link that ultimately affects leaf form and size. miR319 is a conserved microRNA that regulates TCP transcription factors involved in multiple developmental pathways, including leaf development and senescence, organ curvature, and hormone biosynthesis and signaling. Here, we analyze the participation of TCP4 in the control of cell proliferation. A small increase in TCP4 activity has an immediate impact on leaf cell number, by significantly reducing cell proliferation. Plants with high TCP4 levels have a strong reduction in the expression of genes known to be active in G2-M phase of the cell cycle. Part of these effects is mediated by induction of miR396, which represses Growth-Regulating Factor （GRF） transcription factors. Detailed analysis revealed TCP4 to be a direct regulator of MIR396b. However, we found that TCP4 can control cell proliferation through additional pathways, and we identified a direct connection between TCP4 and ICK1/KRP1, a gene involved in the progression of the cell cycle. Our results show that TCP4 can activate different pathways that repress cell proliferation.展开更多
基金This work was supported by the National Natural Science Foundation of China(32071726 and 32271825).
文摘Secondary vascular development is a key biological characteristic of woody plants and the basis of wood formation.Our understanding of gene expression regulation and dynamic changes in microRNAs(miRNAs)during secondary vascular development is still limited.Here we present an integrated analysis of the miRNA and mRNA transcriptome of six phase-specific tissues-the shoot apex,procambium,primary vascular tissue,cambium,secondary phloem,and secondary xylem-in Populus tomentosa.Several novel regulatory modules,including the PtoTCP20-miR396d-PtoGRF15 module,were identified during secondary vascular development in Populus.A series of biochemical and molecular experiments confirmed that PtoTCP20 activated transcription of the miR396d precursor gene and that miR396d targeted PtoGRF15 to downregulate its expression.Plants overexpressing miR396d(35S:miR396d)showed enhanced secondary growth and increased xylem production.Conversely,during the transition from primary to secondary vascular development,plants with downregulated PtoTCP20expression(PtoTCP20-SRDX),downregulated miR396 expression(35S:STTM396),and PtoGRF15 overexpression(35S:PtoGRF15)showed delayed secondary growth.Novel regulatory modules were identified by integrated analysis of the miRNA and mRNA transcriptome,and the regulatory role of the PtoTCP20-miR396d-PtoGRF15 signaling cascade in secondary vascular development was validated in Populus,providing information to support improvements in forest cultivation and wood properties.
基金National High Technology Research and Development Program of China(863 Program)(2006AA02Z129)National Natural Science Foundation of China(90408022)+1 种基金Science Foundation of Yunnan Province(2004C0051M)"Hundredtalents" Program of the Chinese Academy of Sciences
文摘Leaf development has been extensively studied on a genetic level. However, little is known about the inter- play between the developmental regulators and the cell cycle machinery--a link that ultimately affects leaf form and size. miR319 is a conserved microRNA that regulates TCP transcription factors involved in multiple developmental pathways, including leaf development and senescence, organ curvature, and hormone biosynthesis and signaling. Here, we analyze the participation of TCP4 in the control of cell proliferation. A small increase in TCP4 activity has an immediate impact on leaf cell number, by significantly reducing cell proliferation. Plants with high TCP4 levels have a strong reduction in the expression of genes known to be active in G2-M phase of the cell cycle. Part of these effects is mediated by induction of miR396, which represses Growth-Regulating Factor （GRF） transcription factors. Detailed analysis revealed TCP4 to be a direct regulator of MIR396b. However, we found that TCP4 can control cell proliferation through additional pathways, and we identified a direct connection between TCP4 and ICK1/KRP1, a gene involved in the progression of the cell cycle. Our results show that TCP4 can activate different pathways that repress cell proliferation.
