Autoimmunity and effector recognition in Arabidopsis thaliana can be uncoupled by mutations in the RRS1-R immune receptor

2020-01-29lHit 2779

Autoimmunity and effector recognition in Arabidopsis thaliana can be uncoupled by mutations in the RRS1-R immune receptor

Plants have developed elaborate immunesystemsthrough coevolution with pathogens.Plantsperceive pathogensvia several types of signals, such assecretions from pathogens, their structural components, or even a part of plant cell that has been destroyed by pathogens.Pathogen secreted molecules are recognizedby receptors in plantcells, which areapproximately150 in Arabidopsis (a model plant witha very small genome)and 800 in pepper (one of the most important crops in South Korea).

Once a pathogen is detected by a receptor, plantspreparefor a fight, thickenthe cell wall,secreteantimicrobials, and quite oftencommitsuicide to prevent invasion and spread of the pathogen. These immune reactions protect the plant from pathogens and diseases, but can besimultaneouslycostly;therefore, these reactionsneed to be controlled precisely andcarefully.

Professor Cécile Segonzac, leader of HorticulturalCrop Molecular Physiology Laboratory, and her 토토 카지노 team are receiving attention for a recent paper decoding the detailed mechanism of a plant immune receptor activation usingautoimmunemutants.

RRS1, together with another receptor (RPS4),is a receptor in Arabidopsis that activates immuneresponses againstRalstonia solanacearum, which isthe causal agent of bacterial wilt disease.Thesetwo receptors forma heterodimer in absence ofa pathogen molecule, and it is thought that the immune response involves dissociation of the RRS1/RPS4complex.

Mutantslh1plants have amutationontheWRKY DNA binding domain of RRS1, a target site of a Ralstonia molecule. The mutationactivatesthe receptors in absence of bacteria,indicating thatthe immune response is always on. As shown in thefigureabove (arrowhead), plants withsuchtype ofautoimmunity growextremely smallowingto costly immunereactions.

In collaboration with the group ofProfessorSohn in Postech, the 토토 카지노 team has identified additional mutationsintheslh1plants,and some of the plants have recovered growth.Of these mutations, severalcarried another mutation in RRS1, implying thatautoimmunitytriggered byslh1mutation is suppressed by the othermutations. Some plants could not triggeranimmune response even with the bacterial molecule,whereassome plants coulddo so. By investigating which part of the signaling process is suppressed, they could understand themechanisms underlying theactivation–deactivation of immunereceptors.

This study is expected toimprove 토토 카지노 and development inbreeding resistant plants.RRS1 isnot only the known resistance gene for bacterial wilt disease but alsoanucleotide-binding leucine-rich repeat (NB-LRR) protein,indicating thatit has many applications in terms of genetic engineeringas the majority of plant resistance genes. For example, WRKY, a recognition site on this receptor, can be substituted with another protein that interacts withpathogens. The receptor witha new domain could now reactwithdifferentpathogens, conferringnew resistancegenesfor newpathogens. This strategy is especiallypotentialbecause of two reasons. First, it might lead to direct application of proteins attacked by pathogens. Second, it can be personalizedaccording toeach plant species by combiningthe signaling domainsof acceptor plant and recognizingthedomain of donorplants. Thisstudy is thought to contribute to plant breeding and engineering with this great potential.

HorticulturalCrop Molecular Physiology Laboratoryis currentlyexploring novelgenes that are involved in plant–pathogeninteractionsandinvestigatingtheir roles and functions. Professor Segonzac’s message for students is that “Curiosity is a great skill for becominga scientist, and critical thinking is worth investing time.”