LORELEI-LIKE GPI-ANCHORED PROTEINS 2/3 Regulate Pollen Tube Growth as Chaperones and Coreceptors for ANXUR/BUPS Receptor Kinases in Arabidopsis
LORELEI-LIKE GPI-ANCHORED PROTEINS 2/3 Regulate Pollen Tube Growth as Chaperones and Coreceptors for ANXUR/BUPS Receptor Kinases in Arabidopsis
复制标题
LORELEI 样 GPI 锚定蛋白 2/3 作为拟南芥中 ANXUR/BUPS 受体激酶的伴侣和共受体调节花粉管生长
DOI：
10.1016/j.molp.2019.09.004
复制
发表时间：
2019-12-02
期刊：
影响因子：
27.5
通讯作者：
Li, Chao
中科院分区：
文献类型：
--
作者：
Feng, Hanqian;Liu, Chen;Li, Chao
花粉管生长是受精成功的关键。在拟南芥中，ANXUR（ANX）/BUPS受体激酶复合物响应自分泌快速碱化因子4/19（RALF 4/19）信号，控制并维持花粉管生长;然而，ANX/BUPS介导的花粉管生长调控的分子和细胞机制尚不清楚。在这项研究中，我们发现花粉特异性LORELEI样GPI锚定蛋白2和3（LLG 2/3）促进花粉管生长在体外和体内。LLG 2/3与ANX/BUPS的相互作用呈RALF 4浓度依赖性，提示ANX/BUPS与LLG 2/3可能形成受体-辅助受体复合物，以感知RALF肽信号。ANX/BUPS-LLG 2/3相互作用的破坏导致ANX 1/2的细胞质保留，无论是在lig 2/3敲除突变体中还是在缺乏J区的anx 1/2突变体中，J区介导ANX/BUPS-LLG 2/3相互作用。此外，我们发现RALF 4诱导活性氧簇（ROS）的产生，从而刺激花粉管生长并降低花粉爆发率。外源H2 O2处理可部分挽救LLG 213 RNAi株系的花粉管生长缺陷。综上所述，我们的研究确定LLG 2/3作为新的调控花粉管生长的成分，并表明它们陪伴ANX/BUPS分泌到花粉管顶端质膜，并作为ANX/BUPS的共受体激活ROS的产生，促进花粉管生长。
Pollen tube growth is crucial for successful fertilization. In Arabidopsis thaliana, the ANXUR (ANX)/BUPS receptor kinase complex controls and maintains pollen tube growth in response to autocrine rapid alkalin-ization factor 4/19 (RALF4/19) signaling; however, the molecular and cellular mechanisms underlying the ANX/BUPS-mediated regulation of pollen tube growth remain unclear. In this study, we found that pollen-specific LORELEI-like GPI-anchored proteins 2 and 3 (LLG2/3) promote pollen tube growth in vitro and in vivo. LLG2/3 interacte with ANX/BUPS in a RALF4-concentration-dependent manner, suggesting that ANX/BUPS and LLG2/3 might form a receptor-coreceptor complex for perceiving RALF peptide signals. Disruption of the ANX/BUPS-LLG2/3 interaction led to the cytoplasmic retention of ANX1/2, in either lig2/3 knockdown mutants or in anx1/2 mutants lacking the J region, which mediates the ANX/BUPS-LLG2/3 interaction. Moreover, we found that RALF4 induced the production of reactive oxygen species (ROS), which stimulate pollen tube growth and reduce pollen burst rate. ROS levels are reduced in the pollen tubes of LLG213 RNAi lines, and application of exogenous H2O2 could partially rescue the defective pollen tube growth of LLG213 RNAi lines. Taken together, our study identifies LLG2/3 as novel regulatory components of pollen tube growth, and shows that they chaperone ANX/BUPS for secretion to the apical plasma membrane of pollen tube and act as coreceptors of ANX/BUPS in the activation of ROS production for promoting pollen tube growth.