Cucurbita pepo contains characteristic proteins without a signal peptide in the xylem sap

Hideyuki Inui; Zoran Minic; Nico Hüttmann; Kentaro Fujita; Petya Stoykova; Ivanka Karadžić

doi:10.1016/j.jplph.2023.154038

Cucurbita pepo contains characteristic proteins without a signal peptide in the xylem sap

J Plant Physiol. 2023 Aug:287:154038. doi: 10.1016/j.jplph.2023.154038. Epub 2023 Jun 21.

Authors

Hideyuki Inui¹, Zoran Minic², Nico Hüttmann², Kentaro Fujita³, Petya Stoykova⁴, Ivanka Karadžić⁵

Affiliations

¹ Biosignal Research Center, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan; Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan. Electronic address: hinui@kobe-u.ac.jp.
² University of Ottawa, John L. Holmes Mass Spectrometry Facility, 10 Marie-Curie, Marion Hall, K1N 6N5, Ottawa, ON, Canada.
³ Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan.
⁴ Biosignal Research Center, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan; AgroBioInstitute, 8 "Dragan Tsankov" Blvd, 1164, Sofia, Bulgaria.
⁵ Department of Chemistry, Faculty of Medicine, University of Belgrade, Višegradska 26, 11000, Belgrade, Serbia.

PMID: 37413840
DOI: 10.1016/j.jplph.2023.154038

Abstract

Xylem sap is a fluid that transfers water and nutrients from the rhizosphere. This sap contains relatively low concentrations of proteins that originate from the extracellular space among the root cells. One of the characteristic proteins in the xylem sap of the Cucurbitaceae family, which includes cucumber and zucchini, is a major latex-like protein (MLP). MLPs are responsible for crop contamination through the transport of hydrophobic pollutants from the roots. However, detailed information on the content of MLPs in the xylem sap is not available. Proteomic analysis of root and xylem sap proteins from the Cucurbita pepo cultivars Patty Green (PG) and Raven (RA) showed that the xylem sap of cv. RA, a high accumulator of hydrophobic pollutants, contained four MLPs that accounted for over 85% of the total xylem sap proteins in this cultivar. The xylem sap of PG, a low accumulator, mainly contained an uncharacterized protein. The amount of each root protein between the PG and RA cultivars was significantly and positively correlated in spite of being with and without a signal peptide (SP). However, the amount of xylem sap proteins without an SP was not correlated. These results suggest that cv. RA is characterized by MLPs in the xylem sap.

Keywords: Cucurbita pepo; Major latex-like protein; Proteomic analysis; Root protein; Secretion; Xylem sap protein.