Inoculation of Halotolerant Yeast Meyerozyma guilliermondii Regulates Tomato (Lycopersicon esculentum) Salt Tolerance

Abstract

How to improve plant tolerance and yield under salt stress is critical for ensuring sufficient food supply since plant survival and agricultural productivity are both affected by salinity. Some evidence has showed that beneficial microorganisms have a high ability to improve plant salt tolerance and increase crop yield. But few studies were involved in effects of halotolerant yeasts on plants under salt stress. In this present research, Meyerozyma guilliermondii, a halotolerant yeast, was inoculated with tomato plants followed by salt treatment of four different NaCl concentrations (0, 100, 200, and 300 mM). Our results showed that inoculation of M. guilliermondii increased the chlorophyll biosynthesis and photosynthetic machinery effectiveness under salt stress, contributing to biomass accumulation. Under salt treatment of 300 mM NaCl, the yeast inoculation significantly increased ascorbate concentrations in leaves, yet showed no effects on levels of glutathione and proline. Antioxidant enzymes were affected differently by the yeast inoculation. It was found that the yeast inoculation increased superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities under 300, 100, and 200 mM NaCl, respectively. Total soluble sugar levels increased in inoculated tomato plant leaves; however, there were no significant differences between different NaCl concentrations. Under 300 mM NaCl, the yeast inoculation significantly decreased H2O2 levels and reduced malondialdehyde levels. All together, our results showed that halotolerant yeast M. guilliermondii inoculation might be a strong candidate for regulating tomato growth under salt stress by increasing ability to scavenge reactive oxygen species and chlorophyll intactness, and by strengthening photosynthetic machinery.