Optimization of conditions for the induction of Tagetes patula L. hairy roots

Abstract

The hairy root cultures are promising sources of secondary metabolites of plants, including rare and endangered species. They possess genetic and biochemical stability, unlimited growth rate in free-hormone medium, short doubling times, high biosynthetic activity and ecological purity of plant raw materials. The hairy root cultures of Tagetes patula L. can be used to produce biologically active substances with biocidal activity. The study aimed to determine the virulent strain of Agrobacterium rhizogenes and the most effective period of co-cultivation of T. patula leaf explants with an agrobacterium to induce actively growing hairy root cultures. We used 3 strains (A-4b, 8196RT and 15834). The time of infection ranged from 3 to 33 hours in increments of 3 hours. We found that 24 h is the best time of infection to induce hairy roots with the highest transformation efficiency (92%). The wild strain A. rhizogenes 15834 turned out to be the most virulent when infected leaf explants of spreading marigold. This strain provided the maximum transformation effect, reaching 85.4%. We have identified 5 actively growing clones of hairy roots with intensive branching, the growth indices of which were 64-75. In the future, they will be transferred to a liquid medium for biomass accumulation and scaling.