Eukaryotic translation initiation factor 2B‐beta (eIF2Bβ), a new class of plant virus resistance gene

Abstract

SUMMARYRecessive resistances to plant viruses in the Potyvirus genus have been found to be based on mutations in the plant eukaryotic translation initiation factors, eIF4E and eIF4G or their isoforms. Here we report that natural, monogenic recessive resistance to the Potyvirus Turnip mosaic virus (TuMV) has been found in a number of mustard (Brassica juncea) accessions. Bulked segregant analysis and sequencing of resistant and susceptible plant lines indicated the resistance is controlled by a single recessive gene, recessive TuMV resistance 03 (retr03), an allele of the eukaryotic translation initiation factor 2B-beta (eIF2Bb). Silencing of eIF2Bb in a TuMV-susceptible mustard plant line and expression of eIF2Bb from a TuMV-susceptible line in a TuMV-resistant mustard plant line confirmed the new resistance mechanism. A functional copy of a specific allele of eIF2Bb is required for efficient TuMV infection. eIF2Bb represents a new class of virus resistance gene conferring resistance to any pathogen. eIF2B acts as a guanine nucleotide exchange factor (GEF) for its GTP-binding protein partner eIF2 via interaction with eIF2ÁGTP at an early step in translation initiation. Further genotyping indicated that a single non-synonymous substitution (A120G) in the N-terminal region of eIF2Bb was responsible for the TuMV resistance. A reproducible marker has been developed, facilitating marker-assisted selection for TuMV resistance in B. juncea. Our findings provide a new target for seeking natural resistance to potyviruses and new opportunities for the control of potyviruses using genome editing techniques targeted on eIF2Bb.

NbEXPA1, an α‐expansin, is plasmodesmata‐specific and a novel host factor for potyviral infection

“…Through the intimate virus-host interactions, viruses remodel cellular membranes, hijack cellular pathways and co-opt diverse host factors to accomplish their life cycle (Wang, 2015;Hyodo and Okuno, 2016;Nagy, 2016). Genetic resistance is the preferred strategy for the control for viral infection (Shopan et al, 2017). Molecular identification of host factors and elucidation of their functional roles in the viral infection process could assist in the development of novel genetic resistance to viral disease (Wang and Krishnaswamy, 2012;Wang, 2015;Sanfac ßon, 2017).…”

The iTRAQ-based chloroplast proteomic analysis of Triticum aestivum L. leaves subjected to drought stress and 5-aminolevulinic acid alleviation reveals several proteins involved in the protection of photosynthesis

“…A core set of EIFs is conserved to facilitate the assembly of a translation-competent ribosome at the initiation codon of a mRNA [38]. An increasing number of studies have shown that plant EIFs play roles in stress resistance, such as eiF (iso)4E in B. rapa [39] and eif2Bbeta in B. juncea [40] in response to TuMV. In the present study, two isoforms of EIF, 6 and 3 L, were downregulated in response to drought stress, while five isoforms of EIF, 5A, 6, 3B, 3C, and 3 L, accumulated in the drought-stressed wheat seedlings pretreated with exogenous ALA. Eukaryotic translation initiation is a highly regulated and complex stage of gene translation, which requires the action of at least 13 core initiation factors and five auxiliary factors [38,41].…”

An update on the arsenal: mining resistance genes for disease management of Brassica crops in the genomic era

“…retr01 represents the first mapped recessive gene in Brassica species 25 ; other recessive genes from B. rapa include rnt1 and trs, which were mapped to R6 and A4, respectively 26,27 . Using bulked segregant analysis by sequencing (BSA-seq), Shopan et al 28 identified another recessive gene, retr03, in B. juncea. These mapping studies have facilitated the isolation of candidate genes.…”