Abstract
We present the following hypothesis; that lipo-oligochitin Nod-factors can act in an elicitor-like fashion inducing, amongst other effects, a plant chitolytic enzyme, capable of hydrolysing the oligochitin chain of the Nod-factor. Decorative groups on the oligochitin chain, e.g. sulphate, may confer partial resistance to hydrolysis upon particular Nod-factors. After entry into the plant, Nod-factor synthesis must be down-regulated in order to avoid further, unwanted, eli-citation and the consequent abortion of the symbiosis. The plant-derived compounds inhibiting the synthesis of bacterial Nod-factors are limiting in root tissue, leading to residual elicitation and the abortion of infection thread formation. Nod-gene anti-induction is, furthermore, inactivated by both light and nitrate, thus contributing to the inhibition of nodulation under these conditions. In nitrogen-fixing nodules, the bacteroids are exposed to both nod-gene inducing and repressing compounds. The slow accumulation of Nod-factors within the peribacteroid space eventually results in the elicitation of phytoalexin synthesis and nodule senescence.
| Original language | English |
|---|---|
| Journal | Journal of Experimental Botany |
| Volume | 46 |
| Issue number | 1 |
| Pages (from-to) | 1-18 |
| Number of pages | 18 |
| ISSN | 0022-0957 |
| DOIs | |
| Publication status | Published - 1 Jan 1995 |
Keywords
- Chitinase
- Elicitors
- Leguminosae
- Nod-factors
- Rhizobium
- Symbiosis.