Auxin signaling dynamics during Ceratopteris male development in response to antheridiogen. The six panels contain confocal time-lapse images showing auxin signaling dynamics in Ceratopteris male gametophytes expressing the DR5v2::ntdTomato transgenic reporter, grown on conditioned fern medium. A male gametophyte was live-imaged every day from 1 to 6 days after germination (DAG). The panels show projection views of tdTomato signals (Fire LUT). The white arrowhead (top left panel) indicates the initial DR5 signal in the early developing prothallus, while yellow arrowheads (top row) indicate DR5 signals in developing rhizoids. Cyan arrowheads and white dashed circles highlight DR5 signaling dynamics during antheridium initiation and maturation. Color bars represent the relative intensity of DR5 signals in Fire LUT images, with low intensity shown in black, intermediate intensity in blue to red, and high intensity in yellow to white. The color scale applies to the entire prothallus but excludes the spore coat. Scale bars: 50 µm.

Ferns alternate between asexual #sporophyte & sexual free-living #gametophyte. This study uncovers the mechanism of male-to- #hermaphrodite conversion in the #fern #Ceratopteris, revealing a novel role for #auxin biosynthesis during #meristem formation @plosbiology.org 🧪 plos.io/4k5EcAU

Auxin signaling dynamics during Ceratopteris male development in response to antheridiogen. The six panels contain confocal time-lapse images showing auxin signaling dynamics in Ceratopteris male gametophytes expressing the DR5v2::ntdTomato transgenic reporter, grown on conditioned fern medium. A male gametophyte was live-imaged every day from 1 to 6 days after germination (DAG). The panels show projection views of tdTomato signals (Fire LUT). The white arrowhead (top left panel) indicates the initial DR5 signal in the early developing prothallus, while yellow arrowheads (top row) indicate DR5 signals in developing rhizoids. Cyan arrowheads and white dashed circles highlight DR5 signaling dynamics during antheridium initiation and maturation. Color bars represent the relative intensity of DR5 signals in Fire LUT images, with low intensity shown in black, intermediate intensity in blue to red, and high intensity in yellow to white. The color scale applies to the entire prothallus but excludes the spore coat. Scale bars: 50 µm.

Ferns alternate between asexual #sporophyte & sexual free-living #gametophyte. This study uncovers the mechanism of male-to- #hermaphrodite conversion in the #fern #Ceratopteris, revealing a novel role for #auxin biosynthesis during #meristem formation @plosbiology.org 🧪 plos.io/4k5EcAU

Auxin signaling dynamics during Ceratopteris male development in response to antheridiogen. The six panels contain confocal time-lapse images showing auxin signaling dynamics in Ceratopteris male gametophytes expressing the DR5v2::ntdTomato transgenic reporter, grown on conditioned fern medium. A male gametophyte was live-imaged every day from 1 to 6 days after germination (DAG). The panels show projection views of tdTomato signals (Fire LUT). The white arrowhead (top left panel) indicates the initial DR5 signal in the early developing prothallus, while yellow arrowheads (top row) indicate DR5 signals in developing rhizoids. Cyan arrowheads and white dashed circles highlight DR5 signaling dynamics during antheridium initiation and maturation. Color bars represent the relative intensity of DR5 signals in Fire LUT images, with low intensity shown in black, intermediate intensity in blue to red, and high intensity in yellow to white. The color scale applies to the entire prothallus but excludes the spore coat. Scale bars: 50 µm.

Ferns alternate between asexual #sporophyte & sexual free-living #gametophyte. This study uncovers the mechanism of male-to- #hermaphrodite conversion in the #fern #Ceratopteris, revealing a novel role for #auxin biosynthesis during #meristem formation @plosbiology.org 🧪 plos.io/4k5EcAU

📢 New publication 'The B-class #auxin response factor MpARF2 is essential for #meristem organization in free-living #plant gametophytes' by Eduardo Flores-Sandoval et al. in Current Biology 🧪🌱

doi.org/10.1016/j.cu...

Three sketches. First, an outline of a plant with stem and leaves coming from it. The tip of the stem is marked as the shoot meristem, the stem cell niche. Sketch two and three are magnifications of this shoot meristem at the tip of the stem. The first shows the cellular structure, with distinct cell layers. Layer 1 is the single outer cell layer, the epidermis. Layer 2 is the single cell layer below. Layer 3 describes all the the cells below layers 1 and 2, so the third layer as well as the inner tissue. The third image, the second magnification of the SAM, show the stem cell niche as a small group of cells right in the center of the SAM, so the very tip of the stem, and only two cell layers deep. Source: Rüdiger Simon (2001) Function of plant shoot meristems.

Plants continue to grow for their entire life due to the activity of stable pools of stem cells. The shoot apical #meristem (SAM) is the stem cell niche responsible for producing all above ground cells and is located at the tip of the plant’s stem.