Plants adapted to grow in nutrient-poor soils do so in collaboration with microbes that trade nutrients for plant-produced sugars, but the precise nature of these relationships has been unclear. Two papers in 27 June Nature, describe the proteins that mediates a plant's ability to communicate to and engage in symbiotic relationships with bacteria.

Silke Stracke and colleagues at The Sainsbury Laboratory, John Innes Centre, Norwich, cloned orthologous SYMRK ('symbiosis receptor-like kinase') genes from Lotus and pea. They found that SYMRK is required for a symbiotic signal transduction pathway leading from the perception of microbial signal molecules to rapid symbiosis related gene activation (Nature 2002, 417:959-962).

In the second paper, Gabriella Endre and colleagues at Biological Research Center of the Hungarian Academy of Sciences cloned a Medicago sativa gene, which is observed in the symbiotic root nodule development. The gene codes for the 'nodulation receptor kinase' (NORK) that is predicted to function in the Nod-factor perception/transduction system (the NORK system). NORK initiates a signal cascade leading to nodulation and is broadly distributed in the plant kingdom (Nature 2002, 417:962-966).

Similar microbe-recognition mechanisms could underlie the animal innate immune system, "…so unraveling microbe recognition mechanisms in plants should also provide lessons for medical science" suggests Herman Spaink of Leiden University, the Netherlands in an accompanying News and Views article.