FERONIA Receptor Kinase Controls Seed Size in Arabidopsis thaliana
FERONIA Receptor Kinase Controls Seed Size in Arabidopsis thaliana
复制标题
FERONIA 受体激酶控制拟南芥种子大小
DOI：
10.1093/mp/ssu010
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发表时间：
2014
期刊：
影响因子：
27.5
通讯作者：
Luan Sheng
中科院分区：
文献类型：
--
作者：
Yu Feng;Li Jian;Huang Yuan;Liu Li;Li Dongping;Chen Liangbi;Luan Sheng
尊敬的编辑，植物已经进化出复杂的机制，通过这些机制将细胞伸长调节与环境信号相结合。质膜受体激酶 FERONIA (FER) 已成为控制细胞伸长和激素串扰的重要调节节点 (Guo et al., 2009; Deslauriers and Larsen, 2010; Duan et al., 2010; Yu et al., 2012)。最初报道称 FER 在受精过程中抑制花粉管伸长（Escobar-Restrepo 等，2007），后来发现 FER 可以促进叶和根毛细胞伸长（Guo 等，2009；Duan 等，2010）。 GEF-ROP/ARAC 信号网络可能导致 FER 正向调节生长素诱导的细胞伸长，负向调节营养组织中的 ABA 反应（Duan 等，2010；Yu 等，2012）。我们在此报告，FER 还可能使用 GEF-ROP/ARAC 信号网络来抑制种子发育过程中的细胞伸长，从而控制种子大小。这在控制不同组织中的细胞大小方面提供了有趣的 FER 功能多样性。当对两个 FER-null 突变体（fer-4 和 srn；Yu 等，2012）进行表型分析时，我们发现 fer-4 和 srn 突变体与其野生型对照相比，表现出更大的种子尺寸（图 1A），并且较大的种子产生更大的子叶，如图 1B 所示。我们使用 100 颗种子的平均重量进行定量测定，进一步证实了这种表型差异。与其野生型种子相比，fer-4 和 srn 分别大 38% 和 61.9%（补充图 1）。我们在 fer-4 突变体和野生型之间进行了相互杂交，发现更大的种子是由 fer-4 突变的母体效应产生的（补充图 2）。接下来，我们通过在显微镜下检查透明的胚珠，对不同发育阶段的 fer-4 突变体种子进行了详细分析。我们发现，在受精前，突变型和野生型胚珠的大小和结构相似（补充图3a和3f）。受精后，合子、胚乳和珠被细胞相互通讯，导致合子和胚乳分裂，以及珠被细胞伸长以确定种子大小（Garcia 等，2005）。在胚胎达到四细胞阶段之前，fer-4突变体和野生型的胚珠大小基本相似，fer-4胚珠比野生型稍长（补充图3b与3g相比）。这种差异在球状胚胎阶段变得更加明显，此时 fer-4 明显显示出比野生型更大的种子体积，而胚胎大小没有显着差异（补充图 3c 和 3h）。然而，在球状阶段之后，突变体胚胎逐渐超过野生型胚胎（图1A和1B，以及补充图3d、3i、3e和3j）。接下来，我们通过解剖种子中的各种细胞来检查突变体种子体积较大的可能原因。为了对同一发育阶段的突变体和野生型种子进行详细分析，对突变体和野生型花去雄后同时进行人工授粉。授粉后 50 小时，当大多数胚胎达到球形阶段时，对透明的整体胚珠进行分析。如图1C所示，突变体胚珠比野生型大得多，但胚胎大小保持不变。较大的体积被更多的胚乳细胞填充。我们还检查了野生型和 fer-4 胚珠中的两层背面珠被：oi2，外珠被的外层； ii1，跨越部分胚囊的内珠被层（Schruff et al., 2006）。我们发现……之间的细胞数量没有差异。
Dear Editor, Plants have evolved elaborate mechanisms by which cell elongation regulation is coupled to the environmental signals. The plasma membrane receptor kinase FERONIA (FER) has emerged as an important regulatory node in controlling cell elongation and hormone crosstalk (Guo et al., 2009; Deslauriers and Larsen, 2010; Duan et al., 2010; Yu et al., 2012). Initially reported to inhibit pollen tube elongation during fertilization (Escobar-Restrepo et al., 2007), FER has been since found to promote cell elongation in leaves and root hairs (Guo et al., 2009; Duan et al., 2010). A GEF–ROP/ARAC signaling network may lead FER to positively regulate auxininduced cell elongation and negatively regulate ABA response in vegetative tissues (Duan et al., 2010; Yu et al., 2012). We report here that FER may also use the GEF–ROP/ARAC signaling network to inhibit cell elongation in seed development and thus control seed size. This provides intriguing diversity of FER functions in controlling cell sizes in different tissues. When conducting the phenotypic analysis of two FER-null mutants (fer-4 and srn; Yu et al., 2012), we found that both fer-4 and srn mutants exhibited larger seed size compared with their wild-type control (Figure 1A), and larger seeds produced bigger cotyledons as shown in Figure 1B. We further confirmed this phenotypic difference using a quantitative assay using average weight of 100 seeds. Compared with its wild-type seeds, fer-4 was 38% larger and srn was 61.9% larger, respectively (Supplemental Figure 1). We performed reciprocal crosses between fer-4 mutant and wild-type and found that larger seeds resulted from the maternal effect of fer-4 mutation (Supplemental Figure 2). We next carried out a detailed analysis of the fer-4 mutant seeds at different developmental stages by examining cleared ovules under the microscope. We found that, before fertilization, the mutant and wild-type ovules were similar in size and structure (Supplemental Figure 3a and 3f). After fertilization, zygote, endosperm, and integument cells communicate with each other, leading to division of zygote and endosperm, and elongation of integument cells to determine the seed size (Garcia et al., 2005). Before the embryos reach the four-cell stage, the fer-4 mutant and wild-type were largely similar in their ovule size, with fer-4 ovules slightly longer than wildtype (comparing Supplemental Figure 3b with 3g). This difference became more obvious at the globular embryo stage when fer-4 clearly showed a larger seed volume than wildtype, whereas the embryo size has no significant difference (Supplemental Figure 3c and 3h). Following the globular stage, however, the mutant embryo gradually outgrew the wild-type embryo (Figure 1A and 1B, and Supplemental Figure 3d, 3i, 3e, and 3j).We next examined the possible cause of a larger volume in the mutant seed by dissecting the various cells in the seeds. In order to conduct a detailed analysis of the mutant and wild-type seeds at the same development stage, mutant and wild-type flowers were artificially pollinated at the same time after emasculation. The cleared whole-mount ovules were analyzed 50 h after pollination when most of the embryos reached globular stage. As shown in Figure 1C, the mutant ovule was much larger than the wild-type, but the embryo size remained the same. The larger volume was filled by more endosperm cells. We also examined two layers of abaxial integuments in wild-type and fer-4 ovules: oi2, the outer layer of the outer integument; and ii1, a layer of the inner integument that spans part of the embryo sac (Schruff et al., 2006). We found no difference in cell number between the …