Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-derm...Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-dermis that maintains the inner cell layer as the endodermis and generates the middle cortex to the outside.Through regulation of the cell cycle regulator CYCLIND6;1(CYCD6;1),the transcription factors SCARECROW(SCR)and SHORT-ROOT(SHR)play critical roles in this process.In the present study,we found that loss of function of NAC1,a NAC transcription factor family gene,causes markedly increased periclinal cell divisions in the root endodermis.Importantly,NAC1 directly represses the transcription of CYCD6;1 by recruiting the co-repressor TOPLESS(TPL),creating a fine-tuned mechanism to maintain proper root ground tissue patterning by limiting production of middle cortex cells.Biochemical and genetic analyses further showed that NAC1 physically interacts with SCR and SHR to restrict excessive periclinal cell divisions in the endo-dermis during root middle cortex formation.Although NAC1-TPL is recruited to the CYCD6;1 promoter and represses its transcription in an SCR-dependent manner,NAC1 and SHR antagonize each other to regu-late the expression of CYCD6;1.Collectively,our study provides mechanistic insights into how the NAC1-TPL module integrates with the master transcriptional regulators SCR and SHR to control root ground tissue patterning by fine-tuning spatiotemporal expression of CYCD6;1 in Arabidopsis.展开更多
Sugars promote lateral root formation at low levels but become inhibitory at high C/N or C/P ratios. How sugars suppress lateral root formation is unclear, however. Here we report that WOX7, a member of the WUSCHEL re...Sugars promote lateral root formation at low levels but become inhibitory at high C/N or C/P ratios. How sugars suppress lateral root formation is unclear, however. Here we report that WOX7, a member of the WUSCHEL related homeobox （WOX） family transcription factors, inhibits lateral root development in a sugar-dependent manner. The number of lateral root primordia increased in wox7 mutants but decreased in plants over-expressing WOX7o Plants expressing the WOX7-VP16 fusion protein produced even more lateral roots than wox7, suggesting that WOX7 acts as a transcriptional repressor in lateral root develop- ment. WOX7 is expressed at all stages of lateral root development, but it is primarily involved in lateral root initiation. Consistent with this, the wox7 mutant had a higher mitotic activity only at early stages of lateral root development. Further studies suggest that WOX7 regulates lateral root development through direct repression of cell cycle genes, particularly CYCD6;1. WOX7 expression was enhanced by sugar, reduced by auxin, but did not respond to salt and mannitoh In the wox7 mutant, the effect of sugar on lateral root formation was mitigated. These results together suggest that WOX7 plays an important role in coupling the lateral root development program and sugar status in plants.展开更多
基金supported by the National Natural Science Foundation of China(32170338 and 32061143005)Innovative Research Groups of Shandong University(2020QNQT014)+3 种基金the Shandong Province Natural Science Foundation of the Major Basic Research Program(2017C03)(to Z.D.)by the National Natural Science Foundation of China(32170311 and 31970192)the Shandong Province Funds for Excellent Young Scholars(ZR2020YQ19)the Program of Shandong University Qilu Young Scholars(to X.K.).
文摘Precise spatiotemporal control of the timing and extent of asymmetric cell divisions(AcDs)is essential for plant development.In the Arabidopsis root,ground tissue maturation involves an additional AcD of the endo-dermis that maintains the inner cell layer as the endodermis and generates the middle cortex to the outside.Through regulation of the cell cycle regulator CYCLIND6;1(CYCD6;1),the transcription factors SCARECROW(SCR)and SHORT-ROOT(SHR)play critical roles in this process.In the present study,we found that loss of function of NAC1,a NAC transcription factor family gene,causes markedly increased periclinal cell divisions in the root endodermis.Importantly,NAC1 directly represses the transcription of CYCD6;1 by recruiting the co-repressor TOPLESS(TPL),creating a fine-tuned mechanism to maintain proper root ground tissue patterning by limiting production of middle cortex cells.Biochemical and genetic analyses further showed that NAC1 physically interacts with SCR and SHR to restrict excessive periclinal cell divisions in the endo-dermis during root middle cortex formation.Although NAC1-TPL is recruited to the CYCD6;1 promoter and represses its transcription in an SCR-dependent manner,NAC1 and SHR antagonize each other to regu-late the expression of CYCD6;1.Collectively,our study provides mechanistic insights into how the NAC1-TPL module integrates with the master transcriptional regulators SCR and SHR to control root ground tissue patterning by fine-tuning spatiotemporal expression of CYCD6;1 in Arabidopsis.
文摘Sugars promote lateral root formation at low levels but become inhibitory at high C/N or C/P ratios. How sugars suppress lateral root formation is unclear, however. Here we report that WOX7, a member of the WUSCHEL related homeobox （WOX） family transcription factors, inhibits lateral root development in a sugar-dependent manner. The number of lateral root primordia increased in wox7 mutants but decreased in plants over-expressing WOX7o Plants expressing the WOX7-VP16 fusion protein produced even more lateral roots than wox7, suggesting that WOX7 acts as a transcriptional repressor in lateral root develop- ment. WOX7 is expressed at all stages of lateral root development, but it is primarily involved in lateral root initiation. Consistent with this, the wox7 mutant had a higher mitotic activity only at early stages of lateral root development. Further studies suggest that WOX7 regulates lateral root development through direct repression of cell cycle genes, particularly CYCD6;1. WOX7 expression was enhanced by sugar, reduced by auxin, but did not respond to salt and mannitoh In the wox7 mutant, the effect of sugar on lateral root formation was mitigated. These results together suggest that WOX7 plays an important role in coupling the lateral root development program and sugar status in plants.
