Anti-fungal and bio-control properties of chitinolytic bacteria against safflower Fusarium root rot

A total of 78 rhizobacterial strains were isolated from 48 rhizospheric soil and root samples, collected from safflower Carthamus tinctorius L. fields located in different regions of Iran. The chitinolytic activity was measured in the presence of colloidal chitin as the sole carbon source. Eleven isolates were identified as chitinolytic bacteria, based on the formation of a clearly visible zone on the growth media. Four isolates including EM9, ES41, ES7 and ER13 exhibited the highest chitin degradation activity based on a clear zone diameter of more than 10 mm. According to a ribotyping analysis, EM9, ES41, and ES7 isolates were identified as Bacillus cereus and ER13 was found to be Pantoea agglomerans. In a dual-culture assay, morphogenic changes such as severely collapsed hyphae, decreased hyphal diameter with condensation and granulation of cytoplasm and highly rolled with formation of big clamydoconida in anomalous sporodochia -like structures were also observed using light microscope. Under greenhouse conditions, the application of selected chitinolytic isolates, i.e., EM9, ES41, ES7 and ER13, on safflower seeds significantly reduced seedling damping-off caused by Fusarium solani. In addition, the results revealed that root and shoot dry weight in infected plants that were treated with EM9 isolate suspension, increased by 14 and 22%, respectively.