Seven in absentia proteins affect plant growth and nodulation in Medicago truncatula.
Protein ubiquitination is a posttranslational regulatory process essential for plant growth and interaction with the environment. E3 ligases, to which the seven in absentia (SINA) proteins belong, determine the specificity by selecting the target proteins for ubiquitination. SINA proteins are found in animals as well as in plants, and a small gene family with highly related members has been identified in the genome of rice (Oryza sativa), Arabidopsis (Arabidopsis thaliana), Medicago truncatula, and poplar (Populus trichocarpa). To acquire insight into the function of SINA proteins in nodulation, a dominant negative form of the Arabidopsis SINAT5 was ectopically expressed in the model legume M. truncatula. After rhizobial inoculation of the 35S:SINAT5DN transgenic plants, fewer nodules were formed than in control plants, and most nodules remained small and white, a sign of impaired symbiosis. Defects in rhizobial infection and symbiosome formation were observed by extensive microscopic analysis. Besides the nodulation phenotype, transgenic plants were affected in shoot growth, leaf size, and lateral root number. This work illustrates a function for SINA E3 ligases in a broad spectrum of plant developmental processes, including nodulation.
Den Herder
Griet
G
Department of Plant Systems Biology, Flanders Institute for Biotechnology and Department of Molecular Genetics, Ghent University, B-9052 Gent, Belgium.
De Keyser
Annick
A
De Rycke
Riet
R
Rombauts
Stephane
S
Van de Velde
Willem
W
Clemente
María R
MR
Verplancke
Christa
C
Mergaert
Peter
P
Kondorosi
Eva
E
Holsters
Marcelle
M
Goormachtig
Sofie
S
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D046913:Medicago truncatula / Q000502:physiology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D005810:Multigene Family; D009687:Nuclear Proteins / Q000378:metabolism*; D010641:Phenotype; D018520:Plant Shoots / Q000254:growth & development; D030821:Plants, Genetically Modified / Q000254:growth & development / Q000378:metabolism; D053204:Root Nodules, Plant / Q000254:growth & development* / Q000648:ultrastructure; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*; D000098563:Seven in Absentia Proteins
D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; C466426:SINAT5 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins