Search

Galena Russet is a potato variety notable for high marketable yields resulting from greater resistance to external tuber defects compared to industry standard Russet Burbank. Galena Russet exhibits long dormancy, cold-sweetening resistance, and higher protein content than standard varieties. In early-season trials conducted over 3 years in the Pacific Northwest, Galena Russet produced total and U.S. No. 1 yields similar to standard varieties. During 4 years of full-season trials in five western states, Galena Russet produced greater total and U.S. No. 1 yields than Russet Burbank and Ranger Russet in most locations, with specific gravities greater than Ranger Russet on average. Galena Russet produced light-colored fries out of storage with temperatures as low as 4.4 °C, demonstrating its cold-sweetening resistance and low reducing sugar concentrations. Moreover, the asparagine concentration of Galena Russet tubers was 42 and 36% lower than Russet Burbank and Ranger Russet tubers, respectively, following 2 months of storage. Low reducing sugar and asparagine concentrations may predict low acrylamide formation during processing. Galena Russet has shown greater resistance to PVY than Russet Burbank and Ranger Russet.

Background Genome-wide single nucleotide polymorphism (SNP) markers coupled with allele dosage information has emerged as a powerful tool for studying complex traits in cultivated autotetraploid potato (Solanum tuberosum L., 2n = 4× = 48). To date, this approach has been effectively applied to the identification of quantitative trait loci (QTLs) underlying highly heritable traits such as disease resistance, but largely unexplored for traits with complex patterns of inheritance. Results In this study, an F1 tetraploid russet mapping population (162 individuals) was evaluated for multiple quantitative traits over two years and two locations to identify QTLs associated with tuber sugar concentration, processing quality, vine maturity, and other high-value agronomic traits. We report the linkage maps for the 12 potato chromosomes and the QTL location with corresponding genetic models and candidate SNPs explaining the highest phenotypic variation for tuber quality and maturity related traits. Significant QTLs for tuber glucose concentration and tuber fry color were detected on chromosomes 4, 5, 6, 10, and 11. Collectively, these QTLs explained between 24 and 46% of the total phenotypic variation for tuber glucose and fry color, respectively. The QTL on chromosome 10 was associated with apoplastic invertases, with ‘Premier Russet’ contributing the favorable allele for fry processing quality. On chromosome 5, minor-effect QTLs for tuber glucose concentration and fry color co-localized with various major-effect QTLs, including vine maturity, growth habit, tuber shape, early blight (Altenaria tenuis), and Verticillium wilt (Verticillium spp.). Conclusions Linkage analysis and QTL mapping in a russet mapping population (A05141) using SNP dosage information successfully identified favorable alleles and candidate SNPs for resistance to the accumulation of tuber reducing sugars. These novel markers have a high potential for the improvement of tuber processing quality. Moreover, the discovery of different genetic models for traits with overlapping QTLs at the maturity locus clearly suggests an independent genetic control.

Pomerelle Russet is an early maturing fresh potato variety, which produces moderately high early-season (95–110 days after planting) yields of long tubers with brown-russet skin. It is notable for its very attractive, smooth tubers and resistances to internal and external defects with a high percentage of U.S. No. 1 tubers. Fresh merit ratings for Pomerelle Russet in trials conducted in Idaho, Oregon and Washington were consistently higher than Russet Burbank and Russet Norkotah. Early harvest yields for Pomerelle Russet are generally comparable to Russet Norkotah with a higher percentage of U.S. No. 1 tubers. Compared to Russet Burbank and Russet Norkotah, Pomerelle Russet has greater resistance to Potato mop-top virus, soft rot, corky ringspot and tuber infections from late blight. It also has higher protein and vitamin C concentrations than Ranger Russet, Russet Burbank and Russet Norkotah, indicating that it can provide an enhanced level of dietary protein and vitamin C relative to these standard potato varieties. Pomerelle Russet has moderate specific gravity and good resistance to sugar ends. It also has moderately long dormancy, about 30 days shorter than Russet Burbank. Average post-harvest processing ratings for Pomerelle Russet were similar to Ranger Russet and greater than Russet Burbank. Pomerelle Russet also has maintained acceptable fry color for about 180–200 days in storage at 8.9 °C, indicating potential for processing out of mid-term storage, with improved fry color uniformity relative to industry standards. However, its primary use appears to be as a high quality, early fresh variety.

The use of accent lighting in retail stores has focused illumination on potatoes for greater consumer awareness. Unfortunately, this directed light on displayed potatoes may impact the rate or level of tuber greening. The objective of this study was to evaluate the influence of various retail accent light sources on greening and quality of illuminated tubers. Two separate experiments exposed ‘Russet Burbank’ potato tubers to fiber optic, ceramic metal halide, fluorescent, fluorescent with filter lighting (experiment 1) and fiber optic, halogen, and fluorescent lighting (experiment 2). In each experiment, tubers were exposed to a consistent light intensity (1390 lx in experiment 1 and 1300 lx in experiment 2) in addition to a dark control. Tubers were illuminated for 22 h per day at an ambient room temperature of 22 C. Six randomly selected tubers were evaluated for level of greening, chlorophyll concentration, and weight loss at day 0, 2, 4, 7, and 9. Total glycoalkaloid content was analyzed at days 0 and 9. In experiment 1, the fiber optic and fluorescent illuminated tubers showed significantly lower chlorophyll content compared to the ceramic metal halide light source. There was no significant difference in chlorophyll level or greening rating between the fluorescent light source and fluorescent with filter. In experiment 2, the fiber optic illuminated tubers had lower chlorophyll content and less visual greening compared to the halogen illuminated tubers. Total glycoalkaloids were not significantly impacted by light source. The use of fiber optic lighting or a combination of fiber optic lighting with standard fluorescent lighting would retard the progression of greening in the retail store yet potentially highlight the commodity for consumer eye-appeal.

Sage Russet was released in 2009 by Oregon State University, in cooperation with the USDA-ARS and the Agricultural Experiment Stations of Idaho and Washington. It is a product of the Northwest Potato Variety (Tri-State) Development Program. Sage Russet has a medium-early maturity and produces long, somewhat flattened tubers with medium russeting of the skin. Total yields of Sage Russet are similar to those of Russet Burbank and Ranger Russet, but are significantly higher than those of Russet Norkotah. Sage Russet has significantly higher U.S. No.1 yields than Russet Burbank, Russet Norkotah, and Ranger Russet. It can be grown as an early or late crop with high U.S. No.1 yields and minimal internal defects. It achieved very high merit scores in processing and fresh market in Western Regional trials and can be considered for both markets. Sage Russet has a medium to high fertility requirements with high nitrogen use efficiency and medium storage capability. Sage Russet has moderate specific gravity and produces lighter fry color than the industry standard varieties. The color of fried strips following tuber storage at 4.4 °C and 7.2 °C is significantly lighter for Sage Russet than the control varieties, indicating good cold sweetening resistance. Chemical analyses have shown that Sage Russet has higher protein and vitamin C content than control varieties. Sage Russet is moderately resistant to early dying, early blight, and common scab, is resistant to tuber late blight, but susceptible to Fusarium wilt and is prone to shatter bruise.

Payette Russet is a full season, russet-skinned potato cultivar notable for its cold-sweetening resistance and associated low acrylamide formation, making it ideally suited for processing into French fries and other potato products. Low asparagine and reducing sugar concentrations in Payette Russet tubers contribute to an 81 % reduction in acrylamide content in French fries relative to cultivars Ranger Russet and Russet Burbank following eight months storage at 9 °C. In three years of evaluations in the Western Regional Potato Variety Trials, average yield of Payette Russet was intermediate between Ranger Russet and Russet Burbank, but Payette Russet had the highest U.S. No. 1 yield when averaged across all eight trial locations. Acceptably low tuber glucose concentrations (

Russet Burbank is the predominant potato (Solanum tuberosum L.) cultivar grown and stored for fresh market and frozen processing (French fry) use in North America. Multi-year assessments of potato tuber quality under different storage regimes can provide information about a cultivar’s ability to retain process quality when challenged with seasonal variations across multiple years. The objective of a 15-year study initiated in 1999 was to evaluate the quality of Russet Burbank tubers grown and stored at the Kimberly Research and Extension Center. Potatoes were measured for specific gravity at harvest and stored for eight months under three temperatures (5.6, 7.2 and 8.9 °C) and periodically sampled throughout the storage season to determine dormancy length, sugar content, fry color and mottling severity (a quality issue), and weight loss. The year in which the crop was grown significantly (p

Targhee Russet is a darker-skinned russet potato variety that has shown higher total and marketable yields than Russet Burbank in most yield trials conducted in the western United States. A major strength of Targhee Russet is resistance to tuber soft rot, and it also has moderate resistance to common scab, Verticillium wilt, and net necrosis associated with Potato leafroll virus. Targhee Russet also has exhibited resistance to hollow heart and blackspot bruise. Analyses have shown Targhee Russet to have significantly higher tuber protein and Vitamin C content than Russet Burbank and Ranger Russet. It produces lighter colored fries out of storage than standard processing varieties, indicating its high potential for the production of premium quality frozen and fresh-cut fries. High merit scores for fresh use are also indicative of it having excellent potential as a dual-purpose russet variety, suitable for both processing and fresh-pack operations.

Mountain Gem Russet is a potato variety notable for having both high early and full-season yields of oblong-long, medium-russeted tubers with higher protein content than those of standard potato varieties. Mountain Gem Russet has greater resistance to soft rot, tuber late blight, growth cracks and second growth than Russet Burbank. Mountain Gem Russet produced greater total and U.S. No. 1 yields than Ranger Russet and Russet Norkotah in early-season trials conducted in Idaho, Oregon and Washington over a 3 year period. In full-season trials conducted in five western states over a 4 year period, average total and U.S. No. 1 yields for Mountain Gem Russet were almost always higher than Ranger Russet and Russet Burbank, with specific gravities averaging between these two standard cultivars. It maintains acceptable reducing sugar concentrations and fry quality when stored at 8.9 °C and has displayed a high level of fry color uniformity from tuber stem to bud end providing good potential for early processing. High fresh merit ratings and taste panel sensory scores comparable to Russet Burbank indicate good fresh market potential for Mountain Gem Russet. It was released in 2015 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Teton Russet is an early-maturing, medium-russeted, potato cultivar with high merit for both fresh-pack and processing. In early harvest trials in the Pacific Northwest, Teton Russet had total yields similar to Russet Norkotah, and higher than Ranger Russet and Russet Burbank. Marketable yield of Teton Russet in the early harvest trials was also comparable to or higher than Russet Norkotah in Washington and Oregon, and higher than Ranger Russet and Russet Burbank at these sites, as well as in Idaho. In full-season trials, while total yield of the earlier-maturing Teton Russet tended to be lower than Ranger Russet and Russet Burbank, marketable yield was generally higher than Russet Burbank across the majority of sites due to its higher percentage of U.S. No. 1 tubers. Teton Russet is suitable for processing, with acceptable fry color following up to 8 months of storage at 8.9 °C. Uniformity of fry color was also very consistent. Teton Russet has shown lower levels of the amino acid asparagine relative to Ranger Russet and Russet Burbank which may contribute to lower acrylamide levels in French fries and other processed potato products. Teton Russet is notable for having resistance to common scab (Streptomyces spp.) and Fusarium dry rot, and is moderately resistant to tuber net necrosis. Analyses have also shown Teton Russet to have significantly higher protein levels than Russet Norkotah, Ranger Russet, and Russet Burbank, as well as higher vitamin C content than Russet Norkotah and Russet Burbank. Teton Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Owyhee Russet (AO96160-3) originated from a cross between A89384-10 and A89512-3 in 1996. Owyhee Russet was released in 2009 by Oregon State University, in cooperation with the USDA-ARS and the Agricultural Experiment Stations of Idaho and Washington and is a product of the Northwest Potato Variety (Tri-State) Development Program. Owyhee Russet has semi-erect medium sized vines with medium to late maturity. The tubers are long, with a tan skin, medium russeting, and attractive tuber appearance for fresh market. Owyhee Russet was evaluated in several locations across the Northwest for more than 15 years. Total yield of Owyhee Russet is similar to that of Russet Burbank and Ranger Russet but significantly higher than Russet Norkotah. U.S. No.1 tuber yield of Owyhee Russet is significantly higher than Russet Burbank and Russet Norkotah, resulting in substantially higher marketable yield. Owyhee Russet tubers have significantly higher specific gravity than Russet Burbank and Russet Norkotah. Fry color following tuber storage at 4°C and 9°C is significantly lighter for Owyhee Russet than the comparison varieties. Relative strengths include high yield with a very high proportion of U.S. No.1 tubers, good tuber appearance and excellent processing quality, resistance to cold sweetening, common scab and Fusarium dry rot. Weaknesses include susceptibility to foliar and tuber late blight and susceptibility to metribuzin herbicide injury. Allelic patterns of five SSR markers have shown that Owyhee Russet has a distinctive DNA genetic fingerprint from its russet type reference varieties which are Ranger Russet, Russet Burbank, and Russet Norkotah.

Palisade Russet is a medium-late maturing, lightly russeted potato cultivar notable for its resistance to late blight (Phytophthora infestans) infection of foliage and tuber. Palisade Russet is suitable for processing with low tuber glucose concentrations observed following long-term storage at a temperature as low as 5.6°C with consistently acceptable fry color scores (USDA value ≤2.0) following storage at temperatures of 5.6 to 8.9°C. Reducing sugars are also maintained uniformly throughout the tuber, resulting in a low incidence of sugar ends in French fries relative to standard processing cultivars such as Russet Burbank and Ranger Russet. Palisade Russet has shown high specific gravities in western production regions of the U.S. which may limit its acceptance by the western processing industry. However, in potato production regions with inherently low specific gravities, Palisade Russet could have potential as a processing cultivar. In full-season trials conducted in Idaho, Oregon, and Washington over a 5 year period, the average total yield of Palisade Russet across all three states was very similar to yields observed for Ranger Russet and Russet Burbank. However, the U.S. No. 1 yield of Palisade Russet was 3% and 31% higher relative to Ranger Russet and Russet Burbank, respectively. In addition to late blight, Palisade Russet is also resistant to Verticillium wilt, black dot, and pink rot, and has a moderate level of resistance to net necrosis, PVY, and early blight of both the foliage and tuber. The disease resistances of Palisade Russet make it a good candidate for organic production, or for use by growers seeking reduced pesticide inputs. Palisade Russet displays a low incidence of second growth and growth cracks, especially relative to Russet Burbank, and is intermediate between Ranger Russet and Russet Burbank for incidence of hollow heart/brown center. Blackspot bruise expression for Palisade Russet is less pronounced than for either Ranger Russet or Russet Burbank, however it is slightly more susceptible to shatter bruise. Palisade Russet was released in 2011 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Clearwater Russet is a medium-late maturing, russet-skinned, potato cultivar suitable for processing or fresh pack. It is notable for having a low incidence of external defects that contributes to its high U.S. No 1 yield relative to the dual-purpose industry standard, Russet Burbank. Clearwater Russet also maintains low glucose concentrations in its tubers during long-term storage making it an exceptional processing variety. With its low incidence of sugar ends and cold-induced sweetening resistance, Clearwater Russet can be stored at a temperature of 7.2°C for up to 250 days without the need for reconditioning; fry color from this storage regime is consistently ≤1.0 (USDA Fry Color Scale). This cultivar is also notable for its high tuber protein content, which was 33% greater than that of Russet Burbank. In full-season trials conducted over a 3-year period in California, Colorado, Idaho, Oregon, and Washington, Clearwater Russet had total yields slightly lower than Ranger Russet and Russet Burbank, but averaged 1% and 33% higher U.S. No. 1 yields, respectively, across all states. Average specific gravity of Clearwater Russet is comparable to Ranger Russet and significantly higher than Russet Burbank. Clearwater Russet is resistant to potato virus X (PVX) and tuber late blight and is moderately resistant to Verticillium wilt, common scab, and the common strain of potato virus Y (PVYO). Symptoms of infection with two necrotic strains of PVY were not observed in tubers of Clearwater Russet or Russet Burbank, but were observed in Ranger Russet. Blackspot bruise reaction for Clearwater Russet is less pronounced than for either Ranger Russet or Russet Burbank. The incidence of hollow heart in Clearwater Russet is intermediate between Ranger Russet and Russet Burbank. Internal brown spot has been noted as a problem for Clearwater Russet in the Columbia Basin of Oregon, but has not been observed as problematic in other growing regions. Clearwater Russet was released in 2008 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Pacific Northwest Potato Variety (Tri-State) Development Program.

Classic Russet is a medium maturing potato cultivar with rapid tuber bulking making it suitable for early harvest, as well as full-season production. Classic Russet is notable for its attractive tubers with medium russet skin and excellent culinary characteristics. It resulted from a 1995 cross between Blazer Russet and Summit Russet and was released in 2009 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon and Washington and is a product of the Northwest Potato Variety (Tri-State) Development Program. Classic Russet also shows potential as an early season processing cultivar, with fry color comparable to Russet Burbank and Ranger Russet. Classic Russet total yields were comparable to Russet Norkotah and Ranger Russet in early harvest trials and comparable to Ranger Russet and Russet Burbank in full season trials. When averaged across sites in early harvest or full season trials, U.S. No. 1 yields of Classic Russet were generally greater than those of Russet Norkotah, Ranger Russet, and Russet Burbank. Protein content for Classic Russet is relatively high, averaging 22% higher than Ranger Russet, 32% higher than Russet Burbank and 24% higher than Russet Norkotah. Specific gravity of Classic Russet in early harvest trials was comparable to Russet Norkotah but lower than Ranger Russet and was similar to Russet Burbank in full season trials. The incidence of hollow heart in Classic Russet is low, similar to that of Ranger Russet. It is less susceptible to blackspot bruise than Russet Burbank, Ranger Russet and Russet Norkotah but shatter bruise can be a concern if not matured properly prior to harvest. Classic Russet is moderately resistant to common scab and dry rot and is moderately susceptible to foliar and tuber infections of early blight and symptoms of corky ringspot. It is susceptible to Verticillium wilt, soft rot, foliar and tuber late blight, PLRV and PLRV net necrosis, and the common strain of potato virus Y (PVY°).

Highland Russet is a late-season potato variety with light russet skin notable for its high yield of uniform U.S. No. 1 tubers, and good processing and culinary qualities. It resulted from a 1990 cross between Ranger Russet and Russet Legend and has been evaluated for over 15 years in public and industry trials throughout the western U.S. Highland Russet was released in 2006 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon and Washington and is a product of the Northwest Potato Variety (Tri-State) Development Program. It is suitable for processing into French fries and other frozen potato products and due to its large blocky shape, recovers a high proportion of fries per unit weight of tubers. Fry color and processing ratings for Highland Russet were similar to Ranger Russet and Russet Burbank but fry color uniformity was higher than either of the standard varieties. In full-season trials conducted over a three-year period in the states of Idaho, Oregon, Washington, Colorado, and California; Highland Russet averaged 7% and 9% higher total yields and 21% and 52% higher U.S. No. 1 yields than Ranger Russet and Russet Burbank, respectively. It has moderately high specific gravity, with values similar to Ranger Russet and higher than Russet Burbank. Highland Russet is moderately resistant to Verticillium wilt and powdery scab root galling, as well as to tuber infections of late blight. It is also moderately resistant to common strains of potato virus Y (PVYO) but is susceptible to PVYNTN. It is moderately susceptible to pink rot, common scab, powdery scab of the tuber and early blight of the tuber, as well as to Pectobacterium soft rot and Fusarium dry rot. Highland Russet is susceptible to foliar late blight, PLRV infection, Root-knot nematode and corky ringspot but is moderately resistant to PLRV net necrosis. The incidence of hollow heart in Highland Russet is low, similar to that of Ranger Russet and lower than Russet Burbank, Blackspot bruise reaction of Highland Russet is similar to Russet Burbank but it is less susceptible to shatter bruise.

Premier Russet is a russet-skinned, high yielding potato cultivar suitable for processing or fresh-pack. Premier Russet is notable for its resistance to the accumulation of reducing sugars in its tubers. This characteristic allows tubers of Premier Russet to be stored at temperatures as low as 5.6°C for 250 days without the need for reconditioning prior to processing. The low temperature sweetening resistance of Premier Russet allows for its storage at colder temperatures which contributes to prolonged tuber dormancy and quality, and to a reduction in the incidence and severity of storage diseases associated with the higher storage temperatures typically used for industry-standard cultivars such as Russet Burbank and Ranger Russet. Premier Russet was released in 2006 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest Potato Variety (Tri-State) Development Program. In full-season trials conducted over a 3-year period in the states of Idaho, Oregon, Washington, Colorado, California, New Mexico, and Texas, Premier Russet averaged 5% and 4% higher yields than Ranger Russet and Russet Burbank, respectively, and had a higher percentage of US No. 1 yield than either cultivar. Specific gravity of Premier Russet is consistently greater than that of Ranger Russet or Russet Burbank. Premier Russet is resistant to common and powdery scab, very resistant to the common strain of potato virus Y (PVYO), and moderately resistant to Verticillium wilt, early blight of the foliage and tuber, Pectobacterium (Erwinia) soft rot, and to galling of roots by powdery scab. Blackspot bruise reaction for Premier Russet is similar to that of Ranger Russet. The incidence of hollow heart in Premier Russet is higher than that of Ranger Russet or Russet Burbank. Cultural recommendations to manage hollow heart in Premier Russet are provided.

Introduction of US-8 genotypes of Phytophthora infestans has coincided with an increase in severity of potato late blight in North America. As alternatives to chemical fungicides, 18 bacterial strains patented as biological control agents (BCA) of both sprouting and Fusarium dry rot were cultivated in three liquid media and screened in wounded potato bioassays for their ability to suppress late blight incited by P. infestans (US-8, mating type A2). Washed or unwashed stationary-phase bacteria were mixed with fungal zoospores to inoculate potato wounds with 5µL containing ∼108 bacterial CFU/mL and 2×104 zoospore count/mL. Disease suppressiveness was evaluated after tubers were stored a week at 15°C, 90% relative humidity. One-fifth of the 108 BCA treatments screened, reduced late blight by 25–60%, including among other strains Pseudomonas fluorescens S22:T:04 (showing most consistency), P22:Y:05, S11:P:12 and Enterobacter cloacae S11:T:07. Small-scale pilot testing of these four strains, alone and...

Residue concentrations of chlorpropham (CIPC) on stored Russet Burbank potatoes were evaluated after thermal aerosol treatment at maximum labeled rates. The aerosol was applied after the potatoes had been placed in the storage structure and the wound healing process was complete. Average residue concentrations four days after the initial application ranged from 6 to 8 mg/kg fresh tuber weight depending on the storage temperature and the application rates. A second aerosol treatment applied 90 days after the first treatment kept the residue concentrations above 5 mg/kg for the duration of the storage period. A direct spray application to the tubers at various times during the study raised the average CIPC concentration an additional 2 to 3 mg/kg. All CIPC residue concentrations measured on tubers in this study were below the EPA established (1996) tolerance of 30 mg/kg. Residue concentrations of CIPC were greater on potatoes near the bottom of the pile than near the top of the pile. These variations in CIPC residue concentrations (3–8 mg/kg between top and bottom of the bulk pile) are appropriate justification for the development of improved application methodology.

The cytotoxic efficacy of antitumor drugs targeted at DNA topoisomerase II (topo II) in many cases varies in direct proportion to cellular topo II content. To investigate the transcriptional control of the predominant alpha form of topo II, the 5' flanking region of the human topo II alpha gene (positions -562 to +90) was subcloned into a firefly luciferase reporter plasmid and transiently transfected into HL-60 human leukemia cells, a line capable of monocytic differentiation after treatment with various agents. Early in phorbol-12-myristate-13-acetate (30 nM)-induced differentiation (18-24 hr after treatment), an unexpected 3-5-fold activation of topo II alpha gene promoter activity was observed. Activation was observed in HL-60 cells and U-937 cells, but not in HeLa human cervical carcinoma cells. Sodium butyrate (NaB) (0.4 mM) also led to activation (4-17-fold) of the topo II alpha promoter in HL-60 and U-937 cells. Promoter sequences between position -90 and position +90 mediated the inducing effects of NaB. This NaB-dependent promoter-reporter induction was partly mirrored by a transient approximately 2-fold increase in endogenous topo II alpha enzyme. The stimulus for promoter activation could be partly attributed to a 2-fold increase in DNA synthesis at 16 hr for NaB, but not phorbol-12-myristate-13-acetate. Regardless of the primary stimulus for topo II alpha promoter trans-activation, it could be bypassed by treatment of HL-60 cells with NaB for 48 hr before transfection, revealing the expected 60-70% suppression of topo II alpha promoter activity. Further study of topo II alpha promoter down-regulation later in monocytic differentiation may serve as a model for elucidating the transcriptional mechanisms that may also be exploited by tumor cells expressing intrinsic or acquired resistance to topo II-directed drugs.