Browsing by Author "Krebs, Stephen L."
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Item Armut ve ayvada nişasta jel elektroforez tekniğine göre peroksidaz izoenzim analizleri için en uygun yöntemin belirlenmesi(Uludağ Üniversitesi, 2002) Küden, Ali; Krebs, Stephen L.; Arora, Rajeev; Gülen, Hatice; Uludağ Üniversitesi/Ziraat Fakültesi/Bahçe Bitkileri Bölümü.Bu çalışma, armut çeşitleri ile ayva anaçlarında çeşitli amaçlarla kullanılabilecek peroksidaz (PRX) izoenzim analizleri için en uygun nişasta jel elektroforez (SGE) yönteminin belirlenmesi üzerine kurulmuştur. Denemede, Bartlett (BT= Williams) ve Beurre Hardy (BH) armut çeşitleri ile QA ayva anacının yıllık sürgünlerinden alınan kabuk dokusu örnekleri kullanılmıştır. SGE için Krebs (1996), modifiye edilmiş Krebs (1996) ve modifiye edilmiş Santamour ve ark (1986) olmak üzere 3 farklı ekstraksiyon solüsyonu; Histidine-citrate, pH 5.7, Morpholine-citrate pH 6.25 ve Lithium Borate/Tris-citrate pH 8.3 olmak üzere 3 farklı jel ve elektrot sistemi ve Wendel ve Weeden (1989), modifiye edilen Santamour ve ark. (1986) ve Santamour ve ark (1986) Guaiacol yöntemi olmak üzere 3 farklı boyama sistemi denenmiştir. Sonuç olarak, armut ve ayvada SGE ile peroksidaz izoenzim analizlerinde Santamour ve ark. (1986) yöntemine göre ekstrakte edilen örneklerin Lithium borate/Tris citrate pH 8.3 jel ve elektrot sistemine göre elektroforezden geçirilip Wendel ve Weeden (1989) yöntemine göre boyandığı kombinasyon en iyi sonucu vermiştir.Item Environmental regulation of a 25 kDa dehydrin in relation to Rhododendron cold acclimation(American Society for Horticultural Science, 2004-05) Marian, Calin Ovidiu; Krebs, Stephen L.; Arora, Rajeev; Eriş, Atilla; Uludağ Üniversitesi/Ziraat Fakültesi/Bahçe Bitkileri Bölümü.; 6602612385The influence of photoperiod and temperature on the seasonal (fall to winter) cold acclimation and accumulation of a 25 kDa dehydrin,in Rhododendron 'Chionoides' was studied by exposing two groups of plants each in the greenhouse or outdoors to either a natural photoperiod (or short days) or an extended photoperiod (or long days) regime. Results suggest that the shortening daylength alone is sufficient to trigger both the first stage of cold acclimation and concomitant 25 kDa dehydrin induction. Exposure of the plants to natural photoperiod and temperatures induced the greatest cold hardiness and 25 kDa accumulation, while exposure to extended photoperiods (long days) and warmer temperatures (in the greenhouse) failed to induce any significant freezing tolerance in leaves. Whereas short days trigger the cold acclimation process initially, low inductive temperatures can eventually replace the photoperiod stimulus. Seasonal accumulation of 25 kDa dehydrin, on the other hand, appears to be predominantly effected by short photoperiods. Data indicated that the leaf water content of outdoor plants maintained under natural photoperiod was lower than that of plants grown under extended photoperiod. This was also true for the greenhouse plants at the first (September) and the last (January) sampling. It is hypothesized that early 25 kDa dehydrin accumulation may be due to short-day-induced cellular dehydration. Accumulation of two other dehydrins of 26 kDa and 32 kDa molecular masses does not appear to be associated with short day (SD)-induced first stage of cold acclimation. Results show that their accumulation may be regulated by low, subfreezing temperatures and may be associated with the second and/or third stage of cold acclimation of 'Chionoides' rhododendron leaves.Item Peroxidase isozyme profiles in compatible and incompatible pear-quince graft combinations(Amer Soc Horticultural Science, 2002-03) Arora, Rajeev; Kuden, Ali; Krebs, Stephen L.; Postman, Joseph; Gülen, Hatice; Uludağ Üniversitesi/Ziraat Fakültesi/Bahçe Bitkileri Bölümü.; 6603211102The similarity or differences of peroxidase isozymes in rootstocks and scions may influence their graft compatibility. This study was conducted to identify peroxidase isozymes that may be used as markers to predict compatibility between pear (Pyrus communis L.) and various quince (Cydonia oblonga Mill.) clones. 'Bartlett' (BT) and 'Beurre Hardy' (BH) pear cultivars are known to form incompatible and compatible grafts, respectively, with quince rootstocks. The two pear scion cultivars were budded on 'quince A' (QA), 'quince BA-29% and 15 selected quince clones from Turkey. Bark and cambial tissues were taken from nonbudded rootstocks and scions, and 4 cm above and below the graft union for peroxidase isozyme analysis performed by starch gel electrophoresis. Isoperoxidase analyses were also performed on samples from the graft unions collected 12 months after grafting. Many isozyme bands were observed commonly in the two scions; however, one anodal peroxidase A was detected in BH (compatible scion) but not in BT (incompatible scion) samples. This isoperoxidase was also detected in QA, Quince BA-29, and nine of the Turkish quince clones. Another isoperoxidase, band B, was detected in BH but not in BT or any of the rootstocks. However, the compatible (BH/QA) and moderately compatible (BT/BA-29) graft union tissues contained bands A and B whereas incompatible graft union tissues (BT/QA) lacked both. Graft union samples involving BT and five Turkish quince clones (705, 609-2, 702, 804, and 806) had both 'A' and 'B' isoperoxidases while one or both of these bands were absent in nonbudded graft partners. Field observations of 3.5 year-old grafts of BT and Turkish quince clones revealed that the vegetative growth (vigor) of BT scion was significantly greater, when grafted on these five clones, than that in graft combinations with other clones. We suggest that matching of isoperoxidase 'A' in quince rootstocks and BH pear scion may be associated with a compatible graft combination. Additionally, presence of isoperoxidases 'A' and 'B' in the graft union tissues may be used as an indicator to predict a compatible graft between BT and quince rootstocks.