Isolation and identification of endophtic bacteria from safflower (Carthamus tinctorius) root and investigating their effect on seed germination and plant growth

The growth-promoting endophytic bacteria are highly regarded as bio-fertilizers. The aim of this study was to identify safflower endophytic bacteria and to detect their effects on seed germination and plant growth. Endophytic strains were isolated from safflower roots and their auxin production and phosphate solubility were evaluated. The effects of isolates were evaluated on the safflower seed germination and growth. Then, the activity of enzymes produced by the selected isolates were investigated. The antifungal effects of endophytic isolates were also evaluated by pour plate method. Endophytic bacteria including Micrococcus luteus, Pseudomonas corrugata, Pseudomonas fluorescens, Pseudomonas brassicacearum, and Bacillus megatrium were isolated from safflower roots. In treatment with Bacillus megatrium NMR isolate, the mean of germinated seeds by exposure to the concentration of 105 cfu/ml was significantly higher than concentration of 108 cfu/ml. Coleoptile length and root length in the control group were significantly shorter than the treatment groups. There was a direct relationship between the amount of auxin produced by endophytic isolates and their ability for phosphate solubility with increasing safflower coleoptile and root length, and germinated seeds. Pseudomonas brasicacearum NMR isolate produced all the four enzymes, pectinase, amylase, protease and xylanase. The Pseudomonas fluorescence NMR with the most effectiveness inhibited the growth of Aspergillus niger by 30.76%. The isolated endophytic bacteria in the present study are suggested as stimulants of plant growth in the field due to their ability to produce auxin and to dissolve phosphate and their direct effect on safflower growth factors.