Exploration of plant recognition receptors as tools to engineer crop immunity

Abstract

Plants employ pattern recognition receptors (PRRs) to sense pathogen-associated molecular patterns (PAMPs) and innate pattern-triggered immunity (PTI) to fend off microbe invaders. Interfamily transfer of a single PRR into plants has been proven to gain enhanced resistance to infection of corresponding individual pathogen species. Here we investigated whether pyramid PRRs (SlCORE, SlFLS3, SlEIX2, and SmELR) can confer broad-spectrum resistance to distinct pathogens or robust resistance to one species infection when expressed in A. thaliana and N. benthamiana plants. The expressions of SlCORE, SlFLS3, and SlEIX2 confer immune responses upon cognate PAMP (csp22, flgII-28, xylanase) treatment. We show that the transgenic Arabidopsis expressing SlCORE-SmELR-SlEIX2 exhibits broad-spectrum resistance to Pst DC3000, A. laibachii, and B. cinerea infection, and the N. benthamiana plants expressing SlCORE-SlFLS3-SlEIX2 show resistance to B. cinerea and robust resistance to Pstab. Moreover, the expression of RLP23, RLP42, and EFR confers ethylene production when cognate PAMP (nlp20, pg13, elf18) treatment. Thus, we demonstrate that the signaling pathways are conserved in these plant species, and stacking PRRs in plants can achieve broad-spectrum resistance in disease control and crop improvement. To investigate whether quintuple mutants (efr fls2 sobir1 cerk1 lym3) in Arabidopsis are susceptible to pathogen infection, we generated quintuple mutants and showed the susceptibility of mutants in Pst DC3000 and B. cinerea infection. Our results suggest that stacking PRRs can be exploited in engineering broad-spectrum resistance, and PRRs have different additive functions in resistance to bacteria and fungi.