RESUMO
Species of the genus Cuphea (family Lythraceae) are being developed as potential domestic sources of medium length fatty acids (lauric and capric) for use in industrial lubricants and detergents. During September 2004, patches of dead plants were observed in test plots of Cuphea sp. cv. PSR-23 (1) (Cuphea viscosissima Jacq. × C. lanceolata W.T. Aiton) near Morris, MN and Prosper, ND, approximately 200 km apart. Seed yield in the diseased Morris field was 78 kg/ha compared with 516 kg/ha in nearby, nonaffected fields of the same variety, for an 85% yield reduction. Stems were split open to reveal long, cylindrical sclerotia as much as 8 mm long. Isolations from diseased stem tissue and sclerotia were identified as Sclerotinia sclerotiorum (Lib.) de Bary and produced typical sized sclerotia (4 to 6 mm in diameter) after 7 days growth on potato dextrose agar (PDA). Cuphea PSR-23 plants were grown in the greenhouse in individual pots for 5 weeks and then inoculated. Three inoculation methods were used. For the first method, ascospores of a sunflower isolate of S. sclerotiorum were sprayed onto blooming flowers and foliage at a rate of 5,000 spores per ml. The inoculated plants were kept in a dark, 18°C mist chamber for 48 h and then returned to a greenhouse maintained at 24/20°C, day/night temperatures. All 20 inoculated plants were visibly colonized by Sclerotinia sp. after 3 days, and all plants were dead by 7 days. The second inoculation used the petiole inoculation technique employed by canola researchers (2). The blade from the third leaf was excised and a micropipette tip containing an agar disk of mycelia of the Cuphea isolate was placed over the cut end of the petiole. Five days after inoculation, all 30 inoculated plants were dead, while none of the 10 control plants (using sterile agar disks on the cut petiole) were affected. Isolations were made from diseased plants inoculated by all methods, and S. sclerotiorum colonies were observed on PDA medium with typical sclerotia from 4 to 6 mm in diameter. The third inoculation method tested root infection. S. sclerotiorum was grown on autoclaved proso millet (Panicum miliaceum L.) seed for 7 days, and 5 g of colonized millet seed was placed in a hole 6 cm from the base of a Cuphea plant, with one plant per 3.7 liter pot. Sunflower (Helianthus annuus L.; oilseed hybrid Cargill 270) plants served as inoculated controls. None of the 20 Cuphea plants were infected via soil inoculations compared with 70% of 30 sunflower plants that developed basal stalk rot and wilt within 2 weeks after inoculation. To our knowledge, this is the first report of S. sclerotiorum infection on Cuphea sp., and is believed to be the first report of infection on any genus within the Lythraceae (loosestrife family). With over 100 annual and perennial species in the genus Cuphea, the possibility of Sclerotinia spp. resistance needs to be investigated to further develop this potential oilseed crop. References: (1) S. J. Knapp and J. M. Crane. Crop Sci. 40:299, 2000. (2) J. Zhao et al. Plant Dis. 88:1033, 2004.
RESUMO
Multiparameter flow cytometry (FCM) measurements were made on acridine orange (AO)-stained mouse testicular cells and epididymal sperm cells to determine the effects of varying dosages of thiotepa (0-5 mg/kg ip daily X 5 days) on spermatogenesis at 7, 28, and 67 days after the last exposure (ALE). FCM multiparameter measurements included DNA stainability vs RNA content, peak amplitude vs integrated area of DNA fluorescent signal, and double-stranded DNA vs single-stranded DNA. Thiotepa exhibited dramatic damaging effects on the kinetics and/or cell kill of seven testicular cell types measured by dual-parameter flow cytometry. At 7 days ALE, one 4N cell type, likely the pachytene spermatocyte, was absent from the testes, and another was reduced by about 70%. By 28 days ALE, most of the germ cells were absent from the seminiferous tubules, and by 67 days ALE the testes were undergoing recovery of spermatogenesis with only half of the seminiferous tubules repopulated after treatment with 5.0 mg/kg. The dual parameters of DNA stainability vs RNA content provided better resolution of testicular cell types into distinct populations than the peak vs area processing of the green fluorescent signal of AO-stained cells. Dosage of thiotepa was significantly related to percentage of sperm head morphological abnormalities assayed by light microscopy. Utilizing the metachromatic properties of acridine orange, FCM measurements of the amount of single-stranded DNA induced within acid-stressed whole sperm or heat-stressed nuclei detected alterations of chromatin structure at the same minimal effective dose required to increase abnormal sperm head morphology. Epididymal sperm isolated from mice exposed to some concentrations of thiotepa had an increased percentage of free heads and tails. DNA in free heads denatured in situ to a greater extent than DNA in intact sperm.
