The range of sap-sucking insect pests to which GNA, (the mannose specific lectin from snowdrops (Galanthus nivalis)) has been shown to be insecticidal in artificial diets has been extended to include the peach potato aphid (Myzuspersicae). A gene construct for constitutive expression of GNA from the CaMV35S gene promoter has been introduced into tobacco plants. A transgenic tobacco line which expresses high levels of GNA has been shown to have enhanced resistance to M. persicae in leaf disc and whole plant bioassays, demonstrating the potential for extending transgenic plant technology to the control of sap-sucking insect pests.
Nuclear genome analysis using RFLPs and RAPDs has been assessed within different species of the genus Brachypodium P. Beauv. and representatives of other grasses in order to determine the characteristics of the Brachypodium genome and to establish its evolutionary position in relation to other Pooideae. Distinctive features of the Brachypodium genome are its small size, the low amount of repetitive DNA, the lack of restriction fragment length polymorphisms within the genus for the assayed probe/enzyme combinations, and the genomic variability demonstrated at species level by random DNA amplification. These molecular studies confirm Brachypodium as an isolated ancient genus best placed in its own tribe (Brachypodieae). Its relationships to other tribes Bromeae, Triticeae, Poeae are resolved, Brachypodieae being the earliest tribe to diverge from this core of pooids. Within the genus two major Old World clades are distinguishable: an annual clade, represented only by B. distachyon; and a perennial clade, represented by all the other species studied (except B. mexicanum). The perennial American species B. mexicanum appears equally attached to these two clades. RFLP data were found to be useful in obtaining phylogenies at generic and higher rank levels, whereas the highly variable RAPD data were more suitable for resolving interspecific and intraspecific evolutionary pathways.
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