The Effect of Salinity on Growth, Antagonistic Potential, Protease Activity, and Proline Content of Trichoderma harzianum

Abstract

Salinity is one of the major limiting factors for sustainable crop production and the growth of beneficial microorganisms. Screening of biocontrol agent Trichoderma harzianum isolates under saline conditions could be necessary to select more efficient strains to alleviate salt stress through biopriming in plants. The present study aimed to investigate the antagonistic capacity of 14 T. harzianum isolates against Macrophomina phaseolina as well as the growth, protease activity, and proline content under different concentrations of salt. All isolates except Th15 and Th18 exhibited an over 85% inhibition against M. phaseolina at 0 mM NaCl in c and showed a noticeable decline in their antagonistic capacity as salt concentration increased. Colony growth decreased with increasing salt concentrations in all isolates tested. The growth of all isolates at 0 mM was significantly higher than the other NaCl treatments except at 70 mM NaCl. Protease activity also declined with the increased level of salt. Isolates displayed a wide range of protease expression patterns even at the same salinity as in the case of proline content. Unlike protease enzyme, proline content significantly increased at 240 mM NaCl. Salinity played a significant role in T. harzianum isolates with regards to the growth, antagonistic capacity, protease activity, and proline content.