MLP-PG1 identified from Cucurbita pepo confers drought tolerance via ABA-mediated signaling system

Major latex-like proteins (MLPs) play a crucial role in the contamination of Cucurbitaceae crops with hydrophobic organic pollutants. MLP genes are expressed in the roots, where MLPs bind to hydrophobic organic pollutants and form complexes in root cells. These complexes are then secreted into vascular bundles, especially xylem vessels, leading to the accumulation of hydrophobic organic pollutants in the aboveground parts of plants belonging to the Cucurbitaceae family. However, the precise functions of this long-distance transport of MLPs between plant organs remain poorly understood. Here, we demonstrate that MLP-PG1, identified in zucchini (Cucurbita pepo), confers drought tolerance through the abscisic acid (ABA)-mediated signaling pathway. Transgenic tobacco plants overexpressing MLP-PG1 exhibited enhanced drought tolerance. Further, drought treatment induced MLP-PG1 in the roots and reduced the amount of MLP-PG1 in the xylem vessels. In addition, transgenic tobacco plants overexpressing MLP-PG1 showed high sensitivity to exogenous ABA, and ABA-inducible gene expression was induced by ABA treatment. Our results demonstrated how MLPs confer drought tolerance and highlighted the involvement of MLPs to ABA-mediated signaling pathway in plants belonging to the Cucurbitaceae family.

The online version contains supplementary material available at 10.1007/s12298-025-01695-y.