Heterochromatic silencing is reinforced by ARID1-mediated small RNA movement in Arabidopsis pollen.
Heterochromatic silencing is reinforced by ARID1-mediated small RNA movement in Arabidopsis pollen.
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DOI：
10.1111/nph.16871
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发表时间：
2020-08
期刊：
影响因子：
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通讯作者：
Wenye Wu;Lei Li;Yi Zhao;Youshang Zhao;Ting Jiang;S. McCormick;Binglian Zheng
中科院分区：
文献类型：
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作者：
Wenye Wu;Lei Li;Yi Zhao;Youshang Zhao;Ting Jiang;S. McCormick;Binglian Zheng
在植物雄性生殖系中，转座因子（transposable elements，TE）在伴随营养核中被重新激活，这导致来自它们的siRNA的产生以及这些siRNA的细胞间运动以加强精子中的TE沉默。然而，siRNA运动调节的机制仍然未被探索。在这里，我们表明，ARID1，一个转录因子，这是组成性表达的营养核，但动态积累在生殖细胞（精子的祖先），以促进第二次花粉有丝分裂，介导siRNA运动，以加强异染色质沉默在雄性生殖系。为了寻找参与ARID1在生殖细胞中积累的调节因子，我们鉴定了AGO9，一种拟南芥中的生殖细胞特异性AGO，是ARID1在生殖细胞中积累所必需的。ARID1或AGO9中的突变不仅导致第二次花粉有丝分裂的中断，而且导致siRNA从营养核到雄性生殖系的移动的中断，从而导致雄性生殖系中异染色质沉默的释放。此外，生殖细胞中ARID1的有条件敲低导致双细胞和成熟花粉中异染色质沉默减少。这项研究提供了关于时空转录因子如何协调异染色质沉默和雄性生殖系成熟的见解。
In plant male germline, transposable elements (TEs) are reactivated in the companion vegetative nucleus, which results in siRNA production from them and the intercellular movement of these siRNAs to reinforce TE silencing in sperm. However, the mechanism by which siRNA movement is regulated remains unexplored. Here we show that ARID1, a transcription factor which is constitutively expressed in the vegetative nucleus but dynamically accumulates in the generative cell (the progenitor of sperm) to promote the second pollen mitosis, mediates siRNA movement to reinforce heterochromatic silencing in the male germline. Aiming to look for regulators involved in the accumulation of ARID1 in the generative cell, we identified that AGO9, a germline-specific AGO in Arabidopsis, is required for the accumulation of ARID1 in the generative cell. Mutations in either ARID1 or AGO9 lead to the interruption of not only the second pollen mitosis but also the siRNA movement from the vegetative nucleus to the male germline, causing released heterochromatic silencing in the male germline. Moreover, conditionally knock down of ARID1 in the generative cell causes reduced heterochromatic silencing in both bicellular and mature pollen. This study provides insights on how a spatiotemporal transcription factor coordinates heterochromatic silencing and male germline maturation.