Search Results

You are looking at 1 - 10 of 312 items for :

  • Refine by Access: All x
Clear All
Free access

Wenbin Li, Kelly A. Zarka, David S. Douches, Joseph J. Coombs, Walter L. Pett, and Edward J. Grafius

1 Visiting scholar. 2 Research technician. 3 Professor; to whom reprint requests should be addressed; e-mail douches@pilot.msu.edu . 4 Visiting research associate. 5 Professor. We thank Garst Seed/Zeneca Inc. for providing the codon-modified cryV-Bt

Free access

D.S. Douches, W. Li, K. Zarka, J. Coombs, W. Pett, E. Grafius, and T. El-Nasr

/CAIRO/AGR/A, under grant no. 263-0152-A-00-3036-00, and by the Michigan Agriculture Experiment Station. The authors would like to thank Zeneca for providing the codon-modified Bt-cry5 gene.

Free access

Nazareno Acciarri, Gabriele Vitelli, Salvatore Arpaia, Giuseppe Mennella, Francesco Sunseri, and Giuseppe L. Rotino

Colorado potato beetle (CPB; Leptinotarsa decemlineata-Say) is a serious pest because it has developed resistance against insecticides. Three transgenic eggplant (Solanum melongena L.) lines bearing a mutagenized Bacillus thuringiensis Berl. gene coding for the Cry3B toxin, and the nontransformed control DR2-line were tested in field trials to assess their insect resistance. The transgenic lines 3-2, 6-1, and 9-8 were tested at two different locations in a randomized complete-block design. Samples were taken biweekly to assess the level of CPB and the presence of other insects. At harvest, total yield and fruit number per plot were recorded. Two transgenic lines showed high levels of resistance at both locations, as measured by CPB abundance and yield. Fruit production was almost twice as great in the highly resistant lines (3-2 and 9-8) as in the nontransformed control. The 6-1 transgenic line showed an intermediate level of resistance; it was similar to the control under heavy CPB pressure and was comparable to the other transgenic lines under milder infestations. Analysis by double antibody sandwich–enzyme linked immunosorbent assay (DAS–ELISA), performed on different tissues, revealed a lower amount of Cry3B protein in the 6-1 transgenic line than in lines 3-2 and 9-8. No detrimental effects on nontarget arthropods (including the chrysomelid Altica) were evident. Field observations confirmed that Bt may be able to control CPB infestation in eggplant, representing a potential effective and environmentally safe means of pest control.

Free access

Joseph J. Coombs, David S. Douches, Wenbin Li, Edward J. Grafius, and Walter L. Pett

The Colorado potato beetle [Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae)] is a destructive pest of the cultivated potato (Solanum tuberosum L.) in northern latitudes. Combining resistance mechanisms of leptine glycoalkaloids and glandular trichomes with the synthetic Bacillus thuringiensis Berliner (Bt) cry3A gene in potato may be an effective strategy for controlling the Colorado potato beetle. Bt-cry3A transgenic plants were developed for three potato lines with differing levels of resistance to Colorado potato beetle ['Yukon Gold' (susceptible control), USDA8380-1 (leptine glycoalkaloids), and NYL235-4 (glandular trichomes)]. Polymerase chain reaction, and Southern and northern blot analyses confirmed integration and transcription of the cry3A gene in the transgenic lines. Detached-leaf bioassays of the cry3A engineered transgenic lines demonstrated that resistance effectively controlled feeding by first instar Colorado potato beetles. The susceptible `Yukon Gold' control suffered 32.3% defoliation, the nontransformed high foliar leptine line (USDA8380-1) had 3.0% defoliation, and the nontransformed glandular trichome line (NYL235-4) had 32.9% defoliation. Mean percentage defoliation for all transgenic lines ranged between 0.1% and 1.9%. Mean mortality ranged from 0.0% to 98.9% among the Bt-cry3A transgenic lines, compared to 20% for the susceptible `Yukon Gold' control, 32.2% for USDA8380-1, and 16.4% for NYL235-4. Results indicate that genetic engineering and the availability of natural resistance mechanisms of potato provide the ability to readily combine host plant resistance factors with different mechanisms in potato.

Free access

Qi Chen, Gojko Jelenkovic, Chee-Kok Chin, Sharon Billings, Jodi Eherhardt, Joseph C. Goffreda, and Peter Day

Three constructs of a coleopteran toxic cryIIIB Bacillus thuringiensis gene were engineered and incorporated into eggplant (Solanum melongena L.). Southern blot analysis of the eight primary transformants and segregational analysis of their R, progenies indicated that the chimeric cryIIIB constructs in each of the transgenic plants were stably incorporated at a single locus or at multiple sites within the same linkage group and that they were regularly transmissible to the progeny. The results of Northern blot and RNase protection analyses demonstrated that transcription of the cryIIIB mRNA takes place in plant cells, but only a small amount of the expected entire length transcripts were produced. The amount of the 5' end mRNA fragment produced was at least 30 to 40 times more abundant than the amount of the 3' end mRNA fragment. This could be interpreted to mean that either the two ends of the mRNA are of different stability or that the transcription process is often interrupted and only a few mRNAs complete the entire process to the end. When the transgenic plant mRNA was reverse-transcribed, amplified by polymerase chain reaction, and hybridized to the cryIIIB probe, two smaller molecular weight mRNA species were identified. Thus, the preponderance of the cryIIIB mRNA in transgenic plants exists as a truncated species, a situation similar to that of cryI genes when expressed in transgenic plants. Seedlings from the eight independent transgenic plants were tested for Coleopteran insect resistance. However, they did not demonstrate any significant resistance to the first and second instar larvae of the Colorado potato beetle (Leptinotarsa decemlineata Say).

Free access

B.T. Scully and D.H. Wallace

A diverse set of 112 common bean (Paseolus vulgaris L.) accessions were evaluated for variation in eight traits related to yield over a 2-year period. Days to flower, days of pod fill, and days to maturity ranged from 25 to 66, 44 to 83, and 70 to 133, respectively, in upstate New York: Yield and biomass ranged from 81 to 387 and 270 to 1087 g•m-2, respectively. Harvest index ranged from 12% to 65%. The biomass (biomass/days to maturity) and seed (yield/days of pod fill) growth rates ranged from 3.2 to 9.3 and 1.2 to 9.5 g•m-2 -day-1, respectively. The economic growth rate (yield/days to maturity) extended from 0.6 to 5.7 g•m-2 -day-1. The growth rates, biomass, and days of pod fill were linearly and positively related to yield. Biomass and the growth rates explained a large amount of the variation in yield, with r 2 values between 0.71 and 0.84; days of pod fill explained the least, with r 2 = 0.09. Yield followed a curvilinear relationship with days to flower and days to maturity; yield was maximized at 48.5 days to flower and 112.2 days to maturity. Yield was a quadratic function of harvest index and maximized at 57.2%. Among these three curvilinear traits, days to flower explained 80% of the variation in yield, while days to maturity and harvest index accounted for 25% and 12.5%, respectively. The “ideal” genotype for New York was defined at these maximum values for harvest index, days to maturity, days to flower, and at 63.7 days of pod fill. Additionally, a simple equation is proposed to aid breeders in the selection of common bean accessions with strong sink strength. It is defined as “relative sink strength”: RSS = seed growth rate/biomass growth rate. Values > 1.0 implied strong sink capacity in common beans.

Free access

Maria A. Estrada, Kelly Zarka, Susannah Cooper, Joseph Coombs, David S. Douches, and Edward J. Grafius

crops. Potato has been genetically transformed to express genes of various subspecies of Bacillus thuringiensis Berliner ( Bt ) ( Douches and Grafius, 2005 ). The delta endotoxins of B. thuringiensis are the most widely researched genes among the

Free access

Martin M. Williams II, Carl A. Bradley, Stephen O. Duke, Jude E. Maul, and Krishna N. Reddy

Lepidoptera larvae, commonly known as the Bt trait. Largely, because the GR+Bt combination appeared to simplify weed and insect management and at an economical advantage to pest management in non-Bt glyphosate-sensitive (GS) corn, transgenic cultivars were

Free access

C. Catanzaro, S. Bhatti, and B.T. Jordan III

The U.S. Environmental Protection Agency limits the amount of nitrate and phosphate, yet these nutrients are applied in relatively large amounts during crop production. The objective of greenhouse studies conducted in 2002–05 was to determine the effects of calcined, attapulgite-type clays used as substrate amendments during production of containerized poinsettias, chrysanthemums, and ornamental grasses. Crops were grown with recommended rates of controlled-release fertilizers and irrigation volumes set to achieve a leaching fraction around 0.2. Results with poinsettias grown in substrates amended with clays were as follows: EC of leachate from poinsettia was reduced by up to 39% in the first few weeks after potting; orthophosphate concentration in leachate was reduced by up to 74% in peat-based substrate; cumulative irrigation volume required to produce plants in 16.5-cm containers was reduced by 11%. With two chrysanthemum cultivars, clays reduced EC of leachate and increased plant growth. A non-calcined clay reduced growth of poinsettia and `Oborozuki' Japanese sweetflag grass, but not `Karl Foerster' feather reed grass. Results from these studies suggest that, with controlled irrigation volumes, calcined clays added to a peat-based substrate can reduce leachate nutrient concentrations and reduce crop water requirements without negatively affecting crop growth or quality.

Free access

B.T. Scully, R.L. Beiriger, and E.A. Wolf