Transcriptional profiling reveals no response of fungal pathogens to the durable, quantitative Lr34 disease resistance gene of wheat

Abstract

Durable resistance against fungal pathogens is highly valuable for disease management in agriculture. For its sustainable use, and to avoid pathogen adaptation, it is important to understand the underlying molecular mechanisms. Many studies on durable disease resistance in plants have focused exclusively on the host plant, whereas possible reactions and adaptations of pathogens exposed to this type of resistance have not been well researched. The wheat Lr34 gene, encoding a putative ABC‐transporter, provides broad‐spectrum and durable resistance against multiple fungal pathogens in wheat and is functional as a transgene in all major cereals. Lr34‐based resistance is partial, meaning pathogens can grow and reproduce to some degree on Lr34‐containing plants. Therefore, Lr34‐expressing plants are ideal for studying the response of pathogens to partial resistance. Here, transcriptomic responses of the two fungal pathogens Blumeria graminis f. sp. hordei (barley powdery mildew) and Puccinia triticina (wheat leaf rust) during growth on their respective host plants containing Lr34 were compared to their responses on control plants without Lr34. Two different time points after inoculation were chosen for analysis of powdery mildew on barley and one time point for wheat leaf rust. Transcriptome analyses revealed that there were no differences in the expression patterns of the two pathogens growing on susceptible versus partially resistant plants, even though pathogen growth was reduced in the presence of Lr34. This reflects the absence of observable reaction in the pathogen to the presence of the Lr34 resistance gene and, consequently, no major alteration of fungal pathogen metabolism.

Abscisic acid is a substrate of the ABC transporter encoded by the durable wheat disease resistance gene Lr34

“…Interestingly, an RNAseq study focusing on pathogens revealed no transcriptional response of P. triticina and B. graminis f.sp. hordei to the reduction of pathogen growth caused by the presence of Lr34res in wheat and barley, respectively (Sucher et al ., ). It is also possible that reduced local ABA concentrations in certain cells contribute to the Lr34res ‐mediated disease resistance.…”

Transcriptome Analysis Reveals the Important Role of WRKY28 in Fusarium oxysporum Resistance

“…In that regard, the results of this are consistent with previous studies. These previous studies used RNA sequencing methods to understand the response patterns of plants affected by pathogens (Rosli et al, 2013;Zeng et al, 2014;Sucher et al, 2017). However, little is known about the processes and mechanisms of Pdpap responses to F. oxysporum.…”

How Target-Sequence Enrichment and Sequencing (TEnSeq) Pipelines Have Catalyzed Resistance Gene Cloning in the Wheat-Rust Pathosystem

“…Two wheat adult plant resistance (APR) genes Lr34/Yr18/Sr57/Pm38 and Lr67/Yr46/Sr55/Pm46 are also examples of non-immunitymediated resistance genes (Krattinger et al, 2009;Moore et al, 2015). Both encode transporter proteins and confer resistance against multiple pathogens in wheat and can also function in other crops (Risk et al, 2013;Chauhan et al, 2015;Krattinger et al, 2016;Rinaldo et al, 2017;Schnippenkoetter et al, 2017;Sucher et al, 2018). These two genes have been important components of wheat breeding for rust resistance and often show additive or synergistic interactions with the other more "typical" R genes (immune receptors).…”