Piriformospora indica alters Na+/K+ homeostasis, antioxidant enzymes and LeNHX1 expression of greenhouse tomato grown under salt stress

Mohamed E Abdelaziz,Mohamed Abdelsattar,Emad A Abdeldaym,Mohamed A M Atia,Abdel Wahab M Mahmoud,Maged M Saad,Heribert Hirt

doi:10.1016/j.scienta.2019.05.059

Abstract

The utilization of symbiosis with beneficial microorganisms provides a strategy to alleviate salt stress that reduces existing gaps in crops production. The root endophytic fungus Piriformospora indica has shown to improve plant growth in diverse plant species under biotic stress, while limited reports have discussed the interaction of P. indica with tomato under salt stress. In this study, the impact of P. indica on tomato exposed to 200 mM NaCl for one month in soil-free culture was examined. Growth performance, marker osmolytes, antioxidant enzymes and expression of LeNHX1-4 genes of tomato leaves were measured. Results show that colonization of roots by P. indica improved root branching, fresh and dry weight of salt-stressed plants. Likewise, P. indica colonization increased levels of chlorophyll b, indole acetic acid, catalase and superoxide dismutase in leaves of tomato under salt stress. Meanwhile, P. indica reduced the increase of abscisic acid and proline levels when compared to non-colonized plants. Importantly, Na+/K+ ratios in shoots and roots of colonized plants were lower than in the corresponding non-colonized plants, which may be attributed to the higher K+ concentration observed in leaves and roots of colonized plants under saline water irrigation condition. This change in ion homeostasis was combined with an increase in LeNHX1 transcripts in leaves of colonized plants. Moreover, compared to non-treated plants, colonization with P. indica enhanced fruit yield by 22% and 65% under normal and saline water irrigation, respectively. Our study shows that P. indica enhances the growth and yield of tomato plants under normal and salt stress conditions, opening up a window of opportunity for its application in desert agriculture.

Highlights

Tomato (Solanum lycopersicum L.) is a vegetable crop that is affected by diverse abiotic stresses
P. indica colonization resulted in an increased fresh weight (26%) and dry weight (33%) when compared to non-colonized plants (Fig. 1D,E)
P. indica-colonized plants showed significantly higher levels of superoxide dismutases (SOD) and CAT enzyme activities than non-colonized plants under salt stress conditions (Fig. 3). These results suggest that the activation of reactive oxygen species (ROS) scavenging enzymes may have contributed to the improved salt stress tolerance caused by P. indica colonization in tomato (Hosseini et al, 2017)

Summary

Introduction

Tomato (Solanum lycopersicum L.) is a vegetable crop that is affected by diverse abiotic stresses. Salinity is one of the major abiotic stress that increasingly obstructs cash crop production in arid and semi-arid areas (Schmöckel et al, 2017). By the year 2050, approximately 50% of the cultivated soils are expected to suffer from salinity unless efficient management strategies are applied (Blumwald and Grover, 2006). Plants suffering from salt stress regulate Na+ and K+ homeostasis through several mechanisms (Jha et al, 2010). The tonoplast Na+/H+ antiporters (NHXs) play an important role during ionic homeostasis by activating K+ uptake into vacuoles; regulating cell turgor and stomatal function (Barragán et al, 2012), and by Na+ sequestration into the vacuole; maintaining pH and intracellular cation homeostasis (Bassil and Blumwald, 2014).

Methods

Results

Conclusion