Amino-cyclopropane-1-carboxylate deaminase (ACCD) producing yeasts improved salinity tolerance of Triticum aestivum L.

Abstract

Few studies investigated yeasts potentiality as plant growth promoters as well as the yeasts ability to mitigate unfavorable conditions for plants by improving their compliance with stress. In this study, we tested eight yeast strains (Yarrowia lipolytica YEAST-1, Candida diddensiae YEAST-2, Trichosporon gamsii YEAST-5, T. ovoides YEAST-6, Y. lipolytica YEAST-16, C. subhashii YEAST-17, Saccharomyces cerevisiae YEAST-30, and S. cerevisiae YEAST-34) involving plant growth-promotion (PGP) traits to alleviate salinity stress on the early seed germination of Triticum aestivum L. Also, their ability to form biofilm was detected. Y. lipolytica YEAST-1 yeast strain enhanced the plumule length of T. aestivum seedling by more than 4.0, 3.0, and 2.0 cm at salinity stress of 50, 100, and 200 mM NaCl, respectively, after 96 h. The genes required for the synthesis of the extracellular amino-cyclopropane-1-carboxylate deaminase (ACCD) displayed the highest expression level in S. cerevisiae YEAST-34, at 5 mM ACC. S. cerevisiae YEAST-34, Y. lipolytica YEAST-1, and C. subhashii YEAST-17 exhibited a significant (P < 0.05) increase in the ACCD gene expression by adding different levels of ACC. Y. lipolytica YEAST-1 inoculation enhanced the radicle length of T. aestivum seedling significantly by 2.0 cm at 0.0 mM NaCl, 0.8 cm at 50 mM NaCl, 0.7 at 100 mM NaCl, and 0.06 cm at 200 mM NaCl stress. This improvement of plant growth under salinity stress may be due to the yeast's ability to secrete the extracellular amino-cyclopropane-1-carboxylate deaminase.