Elucidation of defense‐related signaling responses to spot blotch infection in bread wheat (Triticum aestivum L.)

Abstract

SUMMARYSpot blotch disease, caused by Bipolaris sorokiniana, is an important threat to wheat, causing an annual loss of~17%. Under epidemic conditions, these losses may be 100%, yet the molecular responses of wheat to spot blotch remain almost uncharacterized. Moreover, defense-related phytohormone signaling genes have been poorly characterized in wheat. Here, we have identified 18 central components of salicylic acid (SA), jasmonic acid (JA), ethylene (ET), and enhanced disease susceptibility 1 (EDS1) signaling pathways as well as the genes of the phenylpropanoid pathway in wheat. In time-course experiments, we characterized the reprogramming of expression of these pathways in two contrasting genotypes: Yangmai #6 (resistant to spot blotch) and Sonalika (susceptible to spot blotch). We further evaluated the performance of a population of recombinant inbred lines (RILs) by crossing Yangmai#6 and Sonalika (parents) and subsequent selfing to F 10 under field conditions in trials at multiple locations. We characterized the reprogramming of defense-related signaling in these RILs as a consequence of spot blotch attack. During resistance to spot blotch attack, wheat strongly elicits SA signaling (SA biogenesis as well as the NPR1-dependent signaling pathway), along with WRKY33 transcription factor, followed by an enhanced expression of phenylpropanoid pathway genes. These may lead to accumulation of phenolics-based defense metabolites that may render resistance against spot blotch. JA signaling may synergistically contribute to the resistance. Failure to elicit SA (and possibly JA) signaling may lead to susceptibility against spot blotch infection in wheat.

Genome-wide characterization of cellulases from the hemi-biotrophic plant pathogen, Bipolaris sorokiniana, reveals the presence of a highly stable GH7 endoglucanase

“…Potato dextrose agar (PDA) has been used as a common medium for isolating Bipolaris from natural populations of wheat and barley and for maintaining and manipulating it in the laboratory [13–15, 40, 41]. The HD3069 strain with black morphology was maintained on PDA under complete darkness at 25 °C in a fungal incubator (Eyela, Model SU-1201) [13, 14]. The black strains are aggressive, produce maximum spores and are often used in characterization of plant responses to spot blotch attack [13–15].…”

“…The HD3069 strain with black morphology was maintained on PDA under complete darkness at 25 °C in a fungal incubator (Eyela, Model SU-1201) [13, 14]. The black strains are aggressive, produce maximum spores and are often used in characterization of plant responses to spot blotch attack [13–15]. Ten-day-old PDA plates were used for the collection of mycelial mass for isolation of nucleic acids.…”

“…Cochliobolus sativus (anamorph Bipolaris sorokiniana ) is a fungal pathogen that causes spot blotch of wheat and barley and poses a severe challenge to their farming worldwide [13]. This fungal pathogen displays an enormous variability in its pathogenic, morphological and physiological forms.…”

Neomycin: An Effective Inhibitor of Jasmonate-Induced Reactions in Plants

“…SYBR green assays were performed using the "Power SYBR green" kit (Life Technologies). Gene-specific primers for PDF2.2 and Tubulin were used for normalization in each sample as previously described (Sahu et al 2016). cDNA templates corresponding to 50 ng of total RNA before reverse-transcription were used in the quantitative real-time PCR (qPCR) assay.…”

Transcriptome profiling reveals distinct gene activations in barley responding to scald and spot blotch

“…They develop haustoria within the lumen of the host cell, which function to absorb nutrients (Kan 2006). Throughout infection, these fungi actively manipulate host cellular machinery that repress defenses and/or aid in disease progression (Lev et al 2005;Sahu et al 2016). Tremendous advance has been made in our understanding of pathosystems involving Rs and Cs pathogens.…”