Okamoto Satoru, Kawasaki Azusa, Makino Yumiko
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan.
Life (Basel). 2022 Apr 16;12(4):592. doi: 10.3390/life12040592.
The xylem is the main pathway for the transport of water and molecules from roots to shoots. To date, it has been reported that secreted oligopeptides mediate root-to-shoot signaling, and some long-distance mobile oligopeptides have been detected in xylem exudates. However, the conservation of a number of oligopeptides and the overall features of peptide fragments contained in xylem exudates are poorly understood. Here, we conducted a comprehensive analysis of small proteins and peptides in tomato () xylem exudates and characterized the identified peptide fragments. We found that putative secreted proteins were enriched in xylem exudates compared with all proteins in the tomato protein database. We identified seven oligopeptides that showed common features of bioactive oligopeptides, including homologs of CLV3/ESR-related (CLE), C-TERMINALLY ENCODED PEPTIDE (CEP), and CASPARIAN STRIP INTEGRITY FACTOR (CIF) peptides. Furthermore, five of the identified oligopeptides were homologs of the soybean xylem exudate-associated oligopeptides that we previously reported. Our results suggest that oligopeptides in xylem exudates are conserved across plant species and provide insights into not only root-to-shoot signaling but also the maintenance of the xylem conduit.
木质部是水分和分子从根部运输到地上部分的主要途径。迄今为止，已有报道称分泌的寡肽介导根到地上部分的信号传导，并且在木质部渗出液中检测到了一些长距离移动的寡肽。然而，对于许多寡肽的保守性以及木质部渗出液中所含肽片段的整体特征了解甚少。在此，我们对番茄木质部渗出液中的小蛋白和肽进行了全面分析，并对鉴定出的肽片段进行了表征。我们发现，与番茄蛋白质数据库中的所有蛋白质相比，假定的分泌蛋白在木质部渗出液中富集。我们鉴定出七种寡肽，它们表现出生物活性寡肽的共同特征，包括CLV3/ESR相关（CLE）、C末端编码肽（CEP）和凯氏带完整性因子（CIF）肽的同源物。此外，鉴定出的七种寡肽中有五种是我们先前报道的大豆木质部渗出液相关寡肽的同源物。我们的结果表明，木质部渗出液中的寡肽在植物物种间具有保守性，这不仅为根到地上部分的信号传导提供了见解，也为木质部导管的维持提供了见解。
