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SummarySnowdrop lectin (Galanthus nivalis agglutinin; GNA) has been shown previously to be toxic towards rice brown planthopper (Nilaparvata lugens; BPH) when administered in artificial diet. BPH feeds by phloem abstraction, and causes 'hopper burn', as well as being an important virus vector. To evaluate the potential of the gna gene to confer resistance towards BPH, transgenic rice (Oryza sativa L.) plants were produced, containing the gna gene in constructs where its expression was driven by a phloemspecific promoter (from the rice sucrose synthase RSs1 gene) and by a constitutive promoter (from the maize ubiquitin ubi1 gene). PCR and Southern analyses on DNA from these plants confirmed their transgenic status, and that the transgenes were transmitted to progeny after selffertilization. Western blot analyses revealed expression of GNA at levels of up to 2.0% of total protein in some of the transgenic plants. GNA expression driven by the RSs1 promoter was tissue-specific, as shown by immunohistochemical localization of the protein in the non-lignified vascular tissue of transgenic plants. Insect bioassays and feeding studies showed that GNA expressed in the transgenic rice plants decreased survival and overall fecundity (production of offspring) of the insects, retarded insect development, and had a deterrent effect on BPH feeding. gna is the first transgene to exhibit insecticidal activity towards sap-sucking insects in an important cereal crop plant.

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A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg++ and that is stimulated by monovalent ions has been purified 7-to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots.Absorption of inorganic ions bylplant-root cells is an energyrequiring process dependent on aerobic respiration (1, 2). Furthermore, adenosine triphosphate (ATP) appears to be the energy source, since ion absorption by plant roots is inhibited by dinitrophenol (3,4), arsenate (4), and oligomycin (5-7). The mechanism of energy transfer from ATP to the ion-transport system is unknown, however, and this phenomenon represents one of the major unresolved aspects of the ion-absorption process in plants.We have suggested (8, 9) that the energy transduction process involved in ion transport of plant cells involves an adenosine triphosphatase (ATPase; EC 3.6.1.3) similar to the "transport" ATPase of animal cells (10). Plant ATPase is associated with membranes, requires MIg++, and is further activated by monovalent ions (8, 9, 11). A high correlation exists between the KCl-or RbCl-activated component of the ATPase and K+ or Rb+ absorption by root tissue (9). Also, the kinetics of monovalent-ion transport into roots and the kinetics of monovalent ion-stimulated ATPase are similar (8, 9). However, in order for this ATPase to be involved in energy transduction for ion transport, it should be associated with one or both of the membranes involved in active ion transport (i.e., either the plasma membrane or tonoplast), and this has not been demonstrated.It is difficult to isolate and identify the membrane system containing the ion-stimulated ATPase because of the ubiquity of membrane-associated ATPases in plants (12)(13)(14) and the paucity of known membrane "markers" for plant cells (14). We have recently found, however, that the membrane system containing the monovalent ion-stimulated ATPase can be separated from nearly all the other membranes on either continuous or discontinuous sucrose gradients (14). In this paper, we show that this membrane system has a high ste...

Based on high correlations between membrane-bound ATPase activities and ion absorption rates of several plant species (9-11, 29), it was suggested that an ATPase mediates energy transfer to the ion transport system. This proposal was strengthened by the demonstration that the monovalent ionstimulated ATPase is associated with the plasma membrane of oat roots (19,20).The purified plasma membrane ATPase is specific for ATP, requires Mg" and is further activated by monovalent ions 'This research was supported by a grant from the National Science Foundation (GB-31052X (19,20,28). In this paper the enzyme is further characterized with respect to its requirements for ATP, Mg2+, and KCI. The kinetics of KCl stimulation of the plasma membrane ATPase of oat roots were virtually identical to the kinetics of K+ influx into oat roots, both of which are best described by a single isotherm with continually changing kinetic parameters. MATERIALS AND METHODSPlasma membranes were isolated from oat (Avena sativa L. cv. Goodfield) roots as previously described (19,20). Briefly, about 50 g of 6-day-old roots were excised, washed in cold deionized water, and ground (mortar and pestle) in 200 ml of a medium consisting of 0.25 M sucrose, 0.003 M EDTA, 2.5 mm dithiothreitol, and 0.025 M tris-MES, pH 7.2. The homogenate was strained through cheesecloth and successively centrifuged at 13,000g for 15 min and 80,000g for 30 min. The 13,000 to 80,000g pellet was suspended in 30 ml of fresh grinding medium, pelleted. suspended in 2.5 ml of 20% (w/w) sucrose containing 1 mM MgSO4 and 1 mm tris-MES, pH 7.2, and 2 ml were layered onto a 36-ml discontinuous gradient consisting of 28 ml of 45%4o (w/w) and 8 ml of 34% sucrose in 1 mM MgSO, and 1 mm tris-MES, pH 7.2 (Mg2+ was omitted from the gradient for experiments involving Mg2+ as a variable). The gradient was centrifuged for 2 hr at 95,000g in a Spinco SW 27 rotor. The membranes collecting at the 34 to 45% sucrose interface are more than 75% plasma membranes (20).ATPase activity was measured at 38 C in a 1-ml volume containing 3 mm ATP (tris salt) at desired pH, 33 mm tris-MES at desired pH and variable amounts of mono-and divalent ions