Study of Orchid Resistance Induction Using Rhizoctonia Against ORSV Infection Based on Anatomical Characters of Roots and Leaves

Abstract

Background and Objective: Phalaenopsis amabilis and Dendrobium discolor are orchids that are widely cultivated in Indonesia. Orchid cultivation has several problems, one of which is infection with Odontoglossum ringspot virus (ORSV). Rhizoctonia can be used in the induction of orchid resistance by triggering lignification in roots and leaves. However, there is little information about the induction of mycorrhizal resistance. It is necessary to study to determine of orchids resistance to virus through analysis of anatomical character on root and leave. Materials and Methods: Factorial block random design. The factor I: Orchids types: P. amabilis (A1) dan D. discolor (A2). Factor II: Inoculation treatment: Control (K), Mycorrhiza (M), Virus (V) and Mycorrhiza-Virus (MV). Parameters observed were root anatomical structure includes lignification and the presence of peloton and leaf anatomical structure includes leaf damage and thickness. Results: All types of experimental plants experienced root and leaf tissue damage due to virus inoculation and mycorrhiza. The anatomy of the treated roots had differences in the thickness of the epidermal lignin and the thickness of the carrier bundle lignin. Meanwhile, changes in the anatomical character of leaves as a result of virus inoculation showed damage to the epidermis and stomata tissue. Conclusion:Based on the anatomical observations of roots and leaves, D. discolor was more resistant to ORSV infection than P. amabilis.The results of this study become a recommendation for the types of orchids cultivated in ORSV endemic area.