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Root nodule formation is initiated, when the soil contains a low level of nitrogen. The two symbiotic partners use cell signalling for the association and developing nodules. Steps of nodulation are: Roots of legumes secrete flavonoids, which attracts rhizobia towards the root. Rhizobia congregate around root hairs.
For example, endogenous ethylene plays a role in the formation and position of nodule primordia [33,34,35].Two ethylene inhibitors silver ions (Ag+) and aminoethoxy-vinylglycine (AVG) can counteract the interfering effect of ethylene, we therefore measured the position of nodule formation in the presence of AVG or Ag + to test whether the endogenous ethylene provided the position information ...
Mar 1, 2013 · External factors can also regulate legume nodule numbers. For example, the plant hormone ethylene is a strong inhibitor of nodulation and is produced following stress, enabling the plant to reduce nodule production when growing conditions are sub-optimal. 19 Many nitrogenous compounds are also strong inhibitors of nodule formation.
- Brett J. Ferguson, Meng-Han Lin, Peter M. Gresshoff
- 10.4161/psb.23426
- 2013
- Plant Signal Behav. 2013 Mar 1; 8(3): e23426.
The nodule functioning has many peculiarities, involving a plant-microbe crosstalk associated to a metabolism which needs a high energy level under micro-oxic conditions. Nodule development and senescence also have specific features. Whereas multiple review articles have described the early steps of nodu le formation and functioning, the rupture of
Apr 18, 2014 · The effects of root temperature on the four main stages of nodule formation and function are reviewed. Compared with results obtained under optimal conditions, lower root temperatures retard root hair infection more than they affect nodule initiation, nodule development (including bacteroid tissue development and degeneration), or nitrogen assimilation. Higher root temperatures upset the ...
- A. H. Gibson
- 1971
The formation and development of functional nodules in legumes is energy intensive, and up to ~25% of the net photosynthetic products of legumes are used for nodule development . Therefore, legumes must strictly regulate the number and activity of nodules to balance the ratio between (1) carbon invested, and nitrogen gained, and (2) plant growth and nodule growth, to ensure efficient energy ...
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Nodule formation and functioning in legumes are regulated by various mechanisms according to environ-mental conditions. These observations are not surprising because nodulation is not only an energy-consuming process but also requires the tight control of a bacterial invader (Tjepkema & Winship 1980).
