Highlights 1998-1999

• Highly glyphosate-tolerant commercial clones were identified in a field trial. We identified several highly resistant lines of commercially grown clones of diploid hybrid cottonwoods after they were sprayed at herbicide rates several-fold above commercial levels. Some of these lines will be used in large-scale trials to study production value of glyphosate-resistant plantations.

 

• A single-gene strategy for glyphosate tolerance in poplar was superior to use of two genes under high herbicide levels. Use of Monsanto's CP4 gene alone caused less herbicide-related damage and chlorosis, and improved growth, compared with a construct that included both their CP4 and GOX genes. Using a single gene will simplify regulatory approval of transgenic trees, and help to avoid damage when growers opt for high concentrations of glyphosate.

 

• A field trial of BT-cottonwoods showed high levels of resistance to beetle damage and improved tree growth. A rebuilt Bt-Cry3a gene from Mycogen provided virtual immunity to damage from cottonwood leaf beetle under natural infestation in eastern Oregon, and resulted in significantly improved growth. This gene can reduce the need for insecticide use, while improving plantation growth and survival.

 

• Using AFLP genetic markers, we created the first genome map of a poplar leaf , beetle, then used it to identify a gene for resistance to Bt. The genome map was composed of 187 segregating loci and 19 linkage groups. This map and its resistance markers may be useful for monitoring resistance development by beetles when transgenic trees are deployed.

 

• New grants from the USDA Forest Service and the Plant Genome Program of the USDA National Research Initiative (NRI) will support studies of disease resistance genes in poplar. With grants totaling $240,000 we can make considerable progress in sequencing, mapping, and learning how to isolate native resistance genes from poplar for marker-aided breeding and genetic engineering. Diseases continue to greatly limit plantation productivity.

 

• Two APETALA1-like genes useful for engineering sterility were cloned from black cottonwood. The genes show the DNA sequence and expression expected for this class of genes. They are prime candidates for use in engineering male and female sterility because of its early and bisexual expression. Sterility would reduce ecological impacts and simplify regulatory approval for transgenic trees.

 

• Highly polymorphic DNA markers have been used to quantify gene flow from wild populations and plantations. Ten microsatellite markers were used in paternity analysis to demonstrate high levels of gene movement between wild populations. Knowledge of gene flow patterns is essential for gaining regulatory approval of transgenic plantations.

 

• Paternity analysis demonstrated an extremely low rate of fertility in the field for 24-305, a commercially valuable triploid clone being used in a large field trial of glyphosate tolerance. Microsatellite DNA markers showed that 24-305 fathered only 0.08% of progeny surveyed directly adjacent to its plantations. Because of its near-sterility, use of this clone may be encouraged for rotation-length field studies in which flowering is permitted, as well as for possible commercial products.

 

• Two new Members are joining the TGERC for Phase II. We are happy to welcome Aracruz Celulose and Champion International to the TGERC beginning in July 1999. Their expertise, international perspectives, and support will substantially advance TGERC studies.

 

• TGERC will soon become a National Science Foundation Industry/University Cooperative Research Center. This will provide new funding, an independent evaluator of Cooperative affairs, and give added national recognition to the quality of TGERC research.