Evidence for a role of the N terminus and leucine-rich repeat region of the Mi gene product in regulation of localized cell death.
The tomato Mi gene confers resistance against root-knot nematodes and potato aphids. Chimeric constructs of the functional gene, Mi-1. 2, with a homolog, Mi-1.1, were produced, and their phenotypes were examined in Agrobacterium rhizogenes-transformed roots. Exchange of the leucine-rich repeat (LRR) region of Mi-1.1 into Mi-1.2 resulted in the loss of ability to confer nematode resistance, as did substitution of a 6-amino acid sequence from the Mi-1.1 LRR into Mi-1.2. Introduction of the Mi-1.2 LRR-encoding region into Mi-1.1 resulted in a lethal phenotype, as did substitution of the fragment encoding the N-terminal 161 amino acids of Mi-1.1 into Mi-1.2. Transient expression of the latter two chimeric constructs in Nicotiana benthamiana leaves produced localized cell death. The cell death caused by the N-terminal exchange was suppressed by coinfiltration with a construct expressing the N-terminal 161 amino acids of Mi-1.2. The phenotypes of these and other constructs indicate that the LRR region of Mi-1.2 has a role in signaling localized cell death and that the N-terminal 161 amino acids have a role in regulating this death.
Hwang
C F
CF
Center for Engineering Plants for Resistance Against Pathogens, University of California, Davis, California 95616, USA.
Bhakta
A V
AV
Truesdell
G M
GM
Pudlo
W M
WM
Williamson
V M
VM
D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000502:physiology; D016923:Cell Death; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005804:Genes, Lethal / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006790:Host-Parasite Interactions; D007930:Leucine / Q000235:genetics / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000166:cytology* / Q000235:genetics / Q000469:parasitology*; D051739:Microphthalmia-Associated Transcription Factor; D008954:Models, Biological; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics / Q000469:parasitology; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000469:parasitology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000469:parasitology; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D018749:RNA, Plant / Q000032:analysis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D012231:Rhizobium / Q000235:genetics; D016415:Sequence Alignment; D015398:Signal Transduction; D014026:Nicotiana / Q000166:cytology / Q000235:genetics / Q000469:parasitology; D014157:Transcription Factors; D014431:Tylenchoidea / Q000502:physiology
D004268:DNA-Binding Proteins; D051739:Microphthalmia-Associated Transcription Factor; D012333:RNA, Messenger; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D007930:Leucine