Identification and expression analysis of pathogenicity-related genes in Tilletia indica inciting Karnal bunt of wheat

Karnal Bunt: A Re-Emerging Old Foe of Wheat

“…It is a heterothallic (producing opposite mating types for sexual reproduction and characterized by presence of individual self-sterility) fungus with bipolar mating (governed by a single allelic mating locus) system ( Duran and Cromarty, 1977 ) leading to large scale genetic recombination just before infection ( Gurjar et al, 2017 ) making the pathogenesis mechanism complex to dissect and eventually the disease difficult to handle. The sexual recombination, when compatible allantoid sporidia (+ and -) come in contact prior to the infection, is responsible for the high pathogenic as well as genetic diversity in T. Indica ( Gurjar et al, 2019 ; Singh J. et al, 2020 ). There is a significant difference in susceptibility among wheat cultivars as far as KB infection is concerned and some are highly susceptible, resulting in a significantly greater percentage of infected kernels per spike.…”

“…It was observed that the virulence proteins identified have their own functions in response to stress, host cell wall degradation and other processes crucial for a successful infection including contact, penetration, localization, establishment, signal transduction pathway activation and morphogenesis ( Pandey et al, 2019 ). The mining of whole genome sequence and transcriptome data has been recently successfully used by Singh J. et al (2020) for pathogenicity related genes in the T. indica and identified seven genes with potential roles in host penetration, infection and sporulation. This new genomic information on the pathogen will open more avenues in understanding and management of the pathogen.…”

“…Among these, the smut fungus Tilletia indica Mitra (syn. Neovossia indica (Mitra) Mundkur), causing Karnal bunt (KB), is an important and old disease of wheat with restricted occurrences in Asia, Africa, and North and South America ( Emebiri et al, 2019a ; Emebiri et al, 2019b ; Gurjar et al, 2019 ; Singh J. et.al., 2020 ).…”

“…This makes KB a challenge to the grain industry as it constitutes a global non-tariff barrier to the wheat trade. Most wheat importing countries have zero-tolerance limit for the KB causal pathogen that is considered a biosecurity threat ( Singh J. et al, 2020 ). Even if a country, due to some reason, allows wheat grain consignment from another country with a reported occurrence of the disease, such situation would inflict a significant extra cost on the importing country in the form of inspection, interception, quarantine, and disposal etc.…”

“…This is evident from the fact that despite the existing regulations and restrictions, the Karnal bunt pathogen- T. indica is being regularly intercepted in the consignments to countries of the European Union ( ). At present, KB is considered to be a disease which is staging a resurgence in the north-western plain zone (NWPZ) of India ( Singh et al, 2007 ; Gurjar et al, 2019 ; Singh J. et.al., 2020 ) with the eastern parts of Pakistan and Afghanistan being at a high risk of an outbreak ( CIMMYT, 2011 ).…”