Differential response of phytohormone signalling network determines nonhost resistance in rice during wheat stem rust (Puccinia graminis f. sp. tritici) colonization

Abstract

Stem rust caused by Puccinia graminis f. sp. tritici is one of the most devastating diseases of wheat. Breakdown of host resistance under field conditions triggered by the evolution of new pathogenic races and pathotypes is a perennial threat for wheat cultivation. Rice, often grown in a rice-wheat cropping system, is immune to rust infection. Our microscopic studies revealed that P. graminis f. sp. tritici, although displaying nearly identical uredospore germination, stomatal entry, and epi-and endophytic mycelial growth in rice and wheat, failed to sporulate to cause rust disease in rice.We identified 18 key defence signalling genes in rice and unravelled their elicitation dynamics in time-course studies during infection. ICS1, NPR1-3, PRs, EDS1, PAD4, FMO1 (salicylic acid [SA] signalling), and ethylene-related genes (ACO4 and ACS6) were strongly elicited in rice. However, genes from the jasmonic acid (JA) signalling pathway (LOX2, AOS2, MYC2, PDF2.2, JAZ8, JAZ10) showed a delayed response during colonization in rice compared to an early or no induction in wheat. However, the JA/ ethylene marker gene PDF2.2 was strongly induced in wheat as early as 12 hr postinoculation. Furthermore, rice and wheat displayed specific profiles of accumulation of various phenolic acids during P. graminis f. sp. tritici 40A infection. We propose a model where a differential modulation of the SA/JA-dependent defence network may modulate nonhost resistance. A deeper understanding of the molecular mechanism governing differential elicitation of defence signalling may provide a novel resistance mechanism for the sustainable management of rust diseases.

A bird’s-eye view: exploration of the flavin-containing monooxygenase (FMO) superfamily in common wheat

“…One of the B2α-2 homoeologous triads ( TraesCS5A03G0836200.1, TraesCS5B03G0873900.1, TraesCS5D03G0799100.1 ) shows greater upregulation of transcription after Pst infection at one day post-infection (dpi), which is sustained through 11 dpi; TraesCS5A03G0836200.1 is also reported by (Vikas et al, 2022) in a genome-wide association study (GWAS) to be likely involved in seedling resistance to the biotrophic fungal pathogen Puccinia triticina ( Pt ), the wheat leaf rust pathogen closely related to Pst . Another TaFMO in sub-clade B2β-4c(2), TraesCS7B03G1279500.1 , might be involved in Puccinia graminis f.sp tritici ( Pgt , stem rust) resistance (Sahu et al, 2021). In a QTL analysis by (Matros et al, 2016), the two triads in subclade B2α-2 were also detected as significantly enriched in SNPs associated with ornithine metabolism in wheat.…”

Tissue-specific proteome profile analysis reveals regulatory and stress responsive networks in passion fruit during storage

“…TET8 (tetraspanin 8) is involved in the JA signaling pathway in response to mechanical wounding 39 . PDF2.2 is an ethylene and jasmonic acid marker gene 40 . The gibberellin-regulated protein 8 (GRP8) was downregulated in passion fruit.…”

Molecular analyses in wheat and Aegilops tauschii reveals a new orthologue of the leaf rust resistance gene Lr19 on 7DL chromosome of Ae. tauschii

“…The collaboration of melatonin in upregulating genes such as plant resistance 1 (PR1), plant defensin1.2 (PDF1.2), an ethylene-related gene (ACS6), and Isochorismate synthase1 (ICS1) has been well studied (Zhao et al, 2021 ) . Likewise, Sahu et al (2021) reported that these genes are upregulated in rust resistant wheat under infected conditions . Altogether, the predicted gene network clearly illustrates the main pathways and components related to the OMT2, in the context of pathogen resistance.…”