Plant Biotechnology, Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.
Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, 79104, Freiburg, Germany.
New Phytol. 2023 Mar;237(6):2118-2135. doi: 10.1111/nph.18691. Epub 2023 Jan 25.
The auxin efflux PIN-FORMED (PIN) proteins are conserved in all land plants and important players in plant development. In the moss Physcomitrella (Physcomitrium patens), three canonical PINs (PpPINA-C) are expressed in the leafy shoot (gametophore). PpPINA and PpPINB show functional activity in vegetative growth and sporophyte development. Here, we examined the role of PpPINC in the life cycle of Physcomitrella. We established reporter and knockout lines for PpPINC and analysed vegetative and reproductive tissues using microscopy and transcriptomic sequencing of moss gametangia. PpPINC is expressed in immature leaves, mature gametangia and during sporophyte development. The sperm cells (spermatozoids) of pinC knockout mutants exhibit increased motility and an altered flagella phenotype. Furthermore, the pinC mutants have a higher portion of differentially expressed genes related to spermatogenesis, increased fertility and an increased abortion rate of premeiotic sporophytes. Here, we show that PpPINC is important for spermatogenesis and sporophyte retention. We propose an evolutionary conserved way of polar growth during early moss embryo development and sporophyte attachment to the gametophore while suggesting the mechanical function in sporophyte retention of a ring structure, the Lorch ring.
生长素外排 PIN 形成蛋白（PIN）在所有陆地植物中保守，是植物发育的重要参与者。在苔藓植物（Physcomitrella patens）中，三个典型的 PIN（PpPINA-C）在叶状枝（配子体）中表达。PpPINA 和 PpPINB 在营养生长和孢子体发育中表现出功能活性。在这里，我们研究了 PpPINC 在 Physcomitrella 生命周期中的作用。我们建立了 PpPINC 的报告基因和敲除系，并通过显微镜和苔藓配子体的转录组测序分析了营养组织和生殖组织。PpPINC 在未成熟叶片、成熟配子体和孢子体发育过程中表达。pinC 敲除突变体的精子（精子）表现出运动性增加和鞭毛表型改变。此外，pinC 突变体中与精子发生相关的差异表达基因的比例更高，受精率增加，前减数分裂孢子体的流产率增加。在这里，我们表明 PpPINC 对精子发生和孢子体保留很重要。我们提出了一种在早期苔藓胚胎发育和孢子体附着到配子体过程中保守的极性生长方式，同时表明环结构（Lorch 环）在孢子体保留中的机械功能。
