Biopriming of Begonia seedlings with endophytic fungal isolates Beauveria bassiana led to significant increase in growth characteristic

Abstract The ornamental species Begonia rex has a high commercial demand in the flower industry, including plant tissue culture techniques. To develop this approach for mass production of begonia, the disadvantages of post-transplant stress need to be mitigated. For this purpose, the effect of inoculation with entomopathogenic endophyte Beauveria bassiana conidia in B. rex seedlings obtained from in vitro culture was investigated. Throughout the course of the experiment, treated specimens exhibited a consistently high level of fungal invasion, with colonization rates ranging from 60 % to 80 %. During this study, seedlings were not fertilized at any stage so as not to disturb the mutualistic plant-fungus relationship. Inoculated by the “substrate treatment” method, B. bassiana had positive effects on root and leaves area of seedlings: total leaf blade area increased by 50%, while the root system increased threefold. B. bassiana also promoted water-holding root capacity of B. rex seedlings. Under transplantation stress conditions, the fresh weight and relative water content of in vitro produced begonia plants increased significantly (2-2.5-fold) after colonization with B. bassiana. It can be assumed that under conditions of nutrient deficiency, the fungus, which promotes both the transport and absorption of nutrients, can also enhance the growth of begonia seedlings by changing the level of phytohormones. Thus, it was found that inoculation with B. bassiana, which helps B. rex to tolerate water and nutrient deficiency during ex vitro transplantation, could be beneficial for the production of high-quality begonia plants.