Comparison of developmental and stress-induced nodule senescence in Medicago truncatula.
Mature indeterminate Medicago truncatula nodules are zonated with an apical meristem, an infection zone, a fixation zone with nitrogen-fixing bacteroids, and a "developmental" senescence zone that follows nodule growth with a conical front originating in the center of the fixation zone. In nitrogen-fixing cells, senescence is initiated coincidently with the expression of a family of conserved cysteine proteases that might be involved in the degradation of symbiotic structures. Environmental stress, such as prolonged dark treatment, interferes with nodule functioning and triggers a fast and global nodule senescence. Developmental and dark stress-induced senescence have several different structural and expression features, suggesting at least partly divergent underlying molecular mechanisms.
Pérez Guerra
Juan Carlos
JC
Department of Plant Systems Biology, Flanders Institute for Biotechnology, and Department of Plant Biotechnology and Genetics, Ghent University, B-9052 Ghent, Belgium.
Coussens
Griet
G
De Keyser
Annick
A
De Rycke
Riet
R
De Bodt
Stefanie
S
Van De Velde
Willem
W
Goormachtig
Sofie
S
Holsters
Marcelle
M
D000375:Aging; D057056:Cysteine Proteases / Q000235:genetics*; D003624:Darkness; D046913:Medicago truncatula / Q000235:genetics / Q000254:growth & development*; D009586:Nitrogen Fixation; D010802:Phylogeny; D018749:RNA, Plant / Q000235:genetics; D053204:Root Nodules, Plant / Q000235:genetics / Q000254:growth & development*; D013312:Stress, Physiological
D018749:RNA, Plant; D057056:Cysteine Proteases