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A Nodule-Specific Protein Secretory Pathway Required for Nitrogen-Fixing Symbiosis

2010; American Association for the Advancement of Science; Volume: 327; Issue: 5969 Linguagem: Inglês

10.1126/science.1184096

1095-9203

Dong Wang, Joel S. Griffitts, Colby G. Starker, Elena Fedorova, Erik Limpens, Sergey Ivanov, Ton Bisseling, Sharon R. Long,

Plant nutrient uptake and metabolism

The nitrogen-fixing symbiosis between Sinorhizobium meliloti and its leguminous host plant Medicago truncatula occurs in a specialized root organ called the nodule. Bacteria that are released into plant cells are surrounded by a unique plant membrane compartment termed a symbiosome. We found that in the symbiosis-defective dnf1 mutant of M. truncatula, bacteroid and symbiosome development are blocked. We identified the DNF1 gene as encoding a subunit of a signal peptidase complex that is highly expressed in nodules. By analyzing data from whole-genome expression analysis, we propose that correct symbiosome development in M. truncatula requires the orderly secretion of protein constituents through coordinated up-regulation of a nodule-specific pathway exemplified by DNF1.