AUTHOR=Wang Nan , Yin Zhiyuan , Zhao Yaning , Li Zhengpeng , Dou Daolong , Wei Lihui 

TITLE=Two divergent immune receptors of the allopolyploid Nicotiana benthamiana reinforce the recognition of a fungal microbe-associated molecular pattern VdEIX3

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.968562

DOI=10.3389/fpls.2022.968562

ISSN=1664-462X

ABSTRACT=<p>The allotetraploid Solanaceae plant <italic>Nicotiana benthamiana</italic> contains two closely related receptor-like proteins (RLPs), NbEIX2 and NbRXEG1, which regulate the recognition of VdEIX3 and PsXEG1, respectively. VdEIX3, PsXEG1, and their homologs represent two types of microbe-associated molecular patterns (MAMPs) that are widespread in diverse pathogens. Here, we report that NbRXEG1 also participates in VdEIX3 recognition. Both <italic>eix2</italic> and <italic>rxeg1</italic> single mutants exhibited significantly impaired but not abolished ability to mediate VdEIX3-triggered immune responses, which are nearly abolished in <italic>eix2 rxeg1</italic> double mutants. Moreover, a dominant negative mutant of <italic>eix2</italic> that contains a 60 bp deletion failed to respond to VdEIX3 and could suppress VdEIX3-induced cell death in the wild-type <italic>N. benthamiana</italic>. Further phylogenetic analyses showed that NbEIX2 and NbRXEG1 are obtained from different diploid ancestors by hybridization. These results demonstrate that the allotetraploid <italic>N. benthamiana</italic> recognizes two types of MAMPs by two homologous but diverged RLPs, which provides a model in which an allopolyploid plant probably exhibits defense hybrid vigor by acquiring divergent immune receptors from different ancestors.</p>