Functional diversity and plant growth-promoting activity of endophytic fungi isolated from Thottea siliquosa.

Endophytic fungi are an important part of the plant holobiont that can form an intricate and balanced relationship with their host to reside within the plant without inducing host resistance. In the current study, we isolated 14 endophytic fungi from the medicinal plant T. siliquosa and were analyzed for their growth promoting activity. Identification was carried out by ITS sequencing followed by phylogenetic analysis. The isolates were then subjected to in vitro and in vivo tests to assess their ability to promote plant growth. Fungi were tested for their ability to solubilize phosphate, produce growth hormones, ammonia, siderophore and extracellular enzymes. Effect of fungi on germination and growth of a plant was analyzed using rolled paper towel and growing on assay. Further, translation of observed activity into characters in planta was assessed by pot cultures. Principal component analysis (PCA) was carried out to determine the major contributing characters to plant growth. The study showed that phosphate solubilization varied between 0.21 and 0.004 mg/ml. IAA and GA production was highly variable with Fusarium spp., being the highest producers. Ammonia and siderophore have indirect plant growth promoting properties. In vivo studies showed that the fungal treatment doesn't decrease germination or growth of tomato seedlings in most cases. Fungal treatments performed on par with controls in pot cultures. PCA revealed distinct physiological and biochemical strategies employed by different endophytes in promoting growth. The current study demonstrated the diverse plant growth promoting characteristics of these fungi and their potential for agricultural application.