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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Publications at this Location » Publication #423422
Research Project: Conservation, Management, and Genetic Improvement of Tropical and Subtropical Fruit, Nut, and Beverage Crop Germplasm for the Pacific Region

Location: Tropical Plant Genetic Resources and Disease Research

Title: In vitro assessment of salt secretion and its correlation with transporter gene expression in Zoysiagrasses

Author
item ZHAO, ZIXIAO - Texas A&M University
item LYU, HAOMIN - Hawaii Agricultural Research Center
item XU, YI - Texas A&M University
item WANG, FANGFANG - Texas A&M University
item CHANDRA, AMBIKA - Texas A&M University
item Yu, Qingyi

Submitted to: Grass Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2025
Publication Date: 10/28/2025
Citation: Zhao, Z., Lyu, H., Xu, Y., Wang, F., Chandra, A., Yu, Q. 2025. In vitro assessment of salt secretion and its correlation with transporter gene expression in Zoysiagrasses. Grass Research. 5:e026. https://doi.org/10.48130/grares-0025-0023.
DOI: https://doi.org/10.48130/grares-0025-0023

Interpretive Summary: Salinity stress is a growing global threat to agriculture, impacting an estimated 1,381 million hectares of land, representing 10.7% of the total land area. Zoysiagrass possess unique salt glands that enable them to secrete excess salt. Understanding the molecular mechanisms underlying salt secretion could enable the introduction of salt secretion in other grasses, thereby improving their salt tolerance. In this study, we developed an in vitro leaf assay and investigated salt secretion patterns and the expression of key sodium transporters in zoysiagrasses. Our findings suggest that both Zoysia matrella and Zoysia japonica possess alternative salt tolerance mechanisms in addition to secretion, with Zoysia matrella potentially utilizing an endosomal NHX -related pathway. This research provides valuable insights into the molecular mechanisms underlying salt secretion and tolerance in zoysiagrass.

Technical Abstract: Soil salinity is a major threat to global agriculture. The recretohalophytic turfgrass species Zoysia matrella and Zoysia japonica possess unique salt glands that enable them to secrete excess salt. Understanding the molecular mechanisms underlying salt secretion could enable the introduction of salt secretion in other grasses, thereby improving their salt tolerance. In this study, we developed an in vitro leaf assay to investigate salt secretion patterns and the expression of key sodium transporters, including HKTs and endosomal NHXs. Our study revealed that Z. matrella consistently exhibited a higher salt secretion rate than Z. japonica. In both species, salt secretion increased with rising salinity, peaking at 300 mM NaCl. Beyond this threshold, further increases in salinity did not significantly enhance secretion, suggesting a maximum capacity for the salt glands. Interestingly, at 900 mM NaCl, salt secretion was completely inhibited in Z. japonica, whereas Z. matrella maintained a low level of secretion. Among the HKT genes, HKT1;4 was the most highly expressed in the leaves of both species, and its expression was negatively correlated with salt secretion. Additionally, NHX6 expression in Z. matrella was negatively associated with secretion, a pattern not observed in Z. japonica. The contrasting expression patterns of endosomal NHXs may contribute to the differential salt tolerance between the two species. The in vitro leaf assay provides an efficient tool for evaluating salt secretion in breeding programs. Our findings offer valuable insights into salt secretion and tolerance mechanisms in zoysiagrasses, paving the way for the development of new salt-tolerant varieties.