We introduced a synthetic gene encoding a truncated version of the CryIA(b) protein derived from Bacillus thuringiensis into immature embryos of an elite line of maize using microprojectile bombardment. This gene was expressed using either the CaMV 35S promoter or a combination of two tissue specific promoters derived from maize. High levels of CryIA(b) protein were obtained using both promoter configurations. Hybrid maize plants resulting from crosses of transgenic elite inbred plants with commercial inbred lines were evaluated for resistance to European corn borer under field conditions. Plants expressing high levels of the insecticidal protein exhibited excellent resistance to repeated heavy infestations of this pest.

Field Performance of Elite Transgenic Maize Plants Expressing an Insecticidal Protein Derived from Bacillus thuringiensis

Metabolism and roles of stilbenes in plants

There were no significant differences in the percent mortality and weight of earthworms (Lumbricus terrestris) after 40 days in soil planted with Bt (NK4640Bt) or non-Bt corn or after 45 days in soil amended with biomass of Bt or non-Bt corn. The toxin was present in the guts and casts of earthworms in soil planted with Bt corn or amended with biomass of Bt corn, but it was cleared within 2‐3 days from the guts after placing in fresh soil. There were no significant differences in the colony-forming units of culturable bacteria (including actinomycetes) and fungi and in the numbers of protozoa and nematodes between rhizosphere soil of Bt and non-Bt corn or between soil amended with biomass of Bt and non-Bt corn. The Cry1Ab protein in root exudates and biomass of Bt corn appears not to be toxic to earthworms, nematodes, protozoa, bacteria, and fungi. The presence of the toxin in the guts and casts of earthworms confirmed that the toxin released in root exudates and from transgenic biomass was bound on surface-active particles in soil, which protected the toxin from biodegradation, as has been observed in this laboratory with purified toxin. q 2001 Elsevier Science Ltd. All rights reserved.

Bacillus thuringiensis (Bt) toxin released from root exudates and biomass of Bt corn has no apparent effect on earthworms, nematodes, protozoa, bacteria, and fungi in soil

The Bacillus thuringiensis (Bt) crystal toxins are safe biological insecticides, but have short persistance and are poorly effective against pests that feed inside plant tissues. Production of effective levels of these proteins in plants has required resynthesis of the genes encoding them. We report that amplification of an unmodified crylA(c) coding sequence in chloroplasts up to approximately 10,000 copies per cell resulted in the accumulation of an unprecedented 3-5% of the soluble protein in tobacco leaves as protoxin. The plants were extremely toxic to larvae of Heliothis virescens, Helicoverpa zea, and Spodoptera exigua. Since the plastid transgenes are not transmitted by pollen, this report has implications for containment of Bt genes in crop plants. Furthermore, accumulation of insecticidal protein at a high level will facilitate improvement in the management of Bt resistant insect populations.

Amplification of a Chimeric Bacillus Gene in Chloroplasts Leads to an Extraordinary Level of an Insecticidal Protein in Tobacco

A fundamental but unanswered biological question asks how much energy, on average, Earth's different life forms spend per unit mass per unit time to remain alive. Here, using the largest database to date, for 3,006 species that includes most of the range of biological diversity on the planet-from bacteria to elephants, and algae to sapling trees-we show that metabolism displays a striking degree of homeostasis across all of life. We demonstrate that, despite the enormous biochemical, physiological, and ecological differences between the surveyed species that vary over 10(20)-fold in body mass, mean metabolic rates of major taxonomic groups displayed at physiological rest converge on a narrow range from 0.3 to 9 W kg(-1). This 30-fold variation among life's disparate forms represents a remarkably small range compared with the 4,000- to 65,000-fold difference between the mean metabolic rates of the smallest and largest organisms that would be observed if life as a whole conformed to universal quarter-power or third-power allometric scaling laws. The observed broad convergence on a narrow range of basal metabolic rates suggests that organismal designs that fit in this physiological window have been favored by natural selection across all of life's major kingdoms, and that this range might therefore be considered as optimal for living matter as a whole.

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Mean mass-specific metabolic rates are strikingly similar across life's major domains: Evidence for life's metabolic optimum

Losses in yield due to damage by Ostrinia nubilalis (Hubner) at different stages of plant development and different levels of infestation were ascertained for 4 corn hybrids, Zea mays L., commonly grown in the Midwest. Yield losses resulted primarily from physiological damage due to the corn borer infestation rather than losses due to unharvestable ears. During the whorl stage (stage 2) of plant development, yield losses per unit of infestation were greater for the susceptible, long-season hybrid than for the mid-season hybrid with an intermediate level of resistance to corn borer leaf feeding. However, the yield potential of the long-season hybrid, especially B73 × Mo 17, was great enough to compensate for the greater loss. During the pretassel (stage 4) and pollen-shedding (stage 5) stages, losses tended to be greater for the long-season than for the mid-season hybrids. B37 × Oh 43 was more tolerant to damage than the other hybrids as expressed by yield loss during these stages. Physiological yield losses tended to be lower when an infestation was initiated in stage 6 (kernels blistered), but losses due to unharvestable ears were greater.

European Corn Borer: Yield Losses in Relation to Hybrid and Stage of Corn Development

In peanuts, a mechanism of resistance to fungal infection is reportedly due to the synthesis of stilbene phytoalexins, which are antibiotic, low molecular weight metabolites. The phytoalexin-associated response of different peanut genotypes to exogenous invasion in the field has not been investigated and may be useful for breeding resistant peanut cultivars. Five peanut genotypes, Georgia Green, Tifton 8, C-99R, GK-7 High Oleic, and MARC I, which differ in resistance to major peanut diseases, were investigated for their ability to produce phytoalexins under field conditions in South Georgia in 2001 and 2002. Five known peanut phytoalexins, trans-resveratrol, trans-arachidin-1, trans-arachidin-2, trans-arachidin-3, and trans-3‘-isopentadienyl-3,5,4‘-trihydroxystilbene, were quantitated. The phytoalexins were measured in peanuts of different pod maturity (yellow, orange, brown, and black) with or without insect pod damage (externally scarified or penetrated). Kernels from insect-damaged pods of C-99R and Ti...

Interrelationship of phytoalexin production and disease resistance in selected peanut genotypes.

A method of producing a Poisson distribution of egg masses over plants and time was developed for artificial infestation of field corn that simulates natural oviposition by Ostrinia nubilalis (Hubner). Data were collected for 2 yr on the length of cavities (cm) and subsequent yield losses by using different levels of infestation in a Poisson distribution. Yield losses and damage were greater during stage 5 (pollen-shedding) than during stage 2 (early whorl) of plant development. Statistically, significant correlations were obtained between shelled weight and ear weight (0.986), shelled weight and total cavities (-0.323 and -0.112), ear weight and total cavities (-0.321), shelled weight and entrance holes (-0.075), and entrance holes and total cavities (0.906).

R. E. Lynch

Papers

European Corn Borer: Yield Losses in Relation to Hybrid and Stage of Corn Development

Interrelationship of phytoalexin production and disease resistance in selected peanut genotypes.

European Corn Borer: Yield Losses and Damage Resulting from a Simulated Natural Infestation

Interaction of larval age and antibiotic on the susceptibility of three insect species to Bacillus thuringiensis

Fungi associated with eggs and first-instar larvae of the European corn borer