2.1. Isolation and identification of the endophytic fungus

Isolation of the endophytic fungus was carried out as described by Hallmann et al. [18], with little modifications. Fresh leaves of R. sativus (Radish) were collected from Sultanpur, Solan district of Himachal Pradesh, India. The collected leaves were thoroughly washed under running tap water for 5 min to remove dust and debris adhering to them. The leaf samples were surface sterilized by immersing sequentially in 70% ethanol for 3 min, 0.5% sodium hypochloride for 1 min and again 70% ethanol for 30 s and finally rinsed three times in sterile distilled water to remove sterilants and then allowed to dry under sterile condition. Then, leaf samples were cut into small pieces and inoculated on potato dextrose agar plates (PDA) and incubated at 28 °C for 5 days. Then with a sterile scalpel, the leaves of 0.5 cm size were carefully dissected and placed in Petri plates containing PDA supplemented with streptomycin sulfate (100 mg/l) to suppress the bacterial growth. The plates were sealed using parafilm and incubated at 25 ± 1 °C until endophytic fungi emerged. As and when the hyphal tips emerged out from plant segments they were isolated, subcultured and brought to pure culture by serial subculturing. Lactophenol cotton blue staining method was used for staining the fungal culture and visualized under microscope (Quasmo, India) [39]. Identification of fungal endophytes was carried out based on morphotaxonomic characteristics (i.e. the color, shape and growth of cultured colonies), microscopic characteristics (i.e. the structure of hyphae, conidia and conidiophores) and using standard identification manuals [36]. Isolated endophytic fungus (Fig. 1) is identified as Alternaria sp.

Microscopic view of endophytic fungus Alternaria sp.