Abstract: cis-Jasmone has been discovered to be useful as a semiochetnical that changes the behaviour of insects and/or the physiology of plants. It has direct signalling roles with plant-feeding aphids, in attraction of aphid predators and parasitoids, and may act as an airborne signal inducing production of volatile plant semiochemicals, including the monoterpene (E)-?-ocimene, that stimulate foraging by parasitoids. It is an extremely benign compound having, to human beings, a pleasant aroma and gives a long-lasting effect after removal of the stimulus.

Abstract: Formation of nitrogen fixing root nodules in legumes is induced by perception of lipochitin-oligosaccharide signal molecules secreted by compatible Rhizobium bacteria, which triggers a common symbiotic pathway. The present invention provides a spontaneous nodule formation (snf2) mutant, in which the formation of symbiotic nodules is spontaneous, leading to nodule development in the absence as well as in the presence of Rhizobium bacteria and/or exogenous rhizobial signals. The invention further provides an isolated DNA sequence encoding a mutant cytokinin-independent histidine kinase whose activity results in this ‘gain of function’ dominant phenotype of spontaneous nodule formation. Furthermore the snf2 gene is shown to confer a phenotype, characterised by regulated organogenesis of spontaneous nodules, to plants having a nodulation deficient genetic background.