Cloning, in silico characterization and induction of TiKpp2 MAP kinase in Tilletia indica under the influence of host factor(s) from wheat spikes.

In order to understand the molecular mechanism(s) associated with floret specificity, morphogenetic and disease development of Karnal bunt (KB) pathogen in wheat spikes, host factor(s) was isolated from KB prone susceptible stage of wheat spikes. An orthologue of Kpp2 gene involved in pheromone response and fungal development was isolated from Tilletia indica for analyzing its role in fungal development. The maximum expression of TiKpp2 gene was observed at 14th day and decreased thereafter. To investigate whether the fungus alters the expression levels of same kinase upon interaction with plants, T. indica cultures were treated with 1% of host factor(s). Such treatment induced the expression of TiKpp2 gene in time dependent manner. Host factor(s) treatment tends to increase the myelination in fungal cultures by lowering the sporidial production. Increase in myelination led to impose more pathogenicity levels in the host and prolific multiplication of pathogen inside host causing more damage to developing grains. In silico characterization and protein-protein interaction studies further suggests that isolated gene showed similarity with Ustilago maydis Kpp2 and induction of TiKpp2 might further activate a downstream transcription factor Prf1. The results of present study clearly suggest that host factor(s) derived from wheat spikes provide certain signal(s) which activate TiKpp2 gene during morphogenetic development of T. indica and affect the fungal growth and pathogenicity. In turn it also provides a plausible explanation for floret specificity of KB fungus in wheat.