Momol M T, Norelli J L, Piccioni D E, Momol E A, Gustafson H L, Cummins J N, Aldwinckle H S
Department of Plant Pathology.
Department of Horticultural Sciences.
Plant Dis. 1998 Jun;82(6):646-650. doi: 10.1094/PDIS.1998.82.6.646.
Shoot tips of potted Empire and Golden Delicious trees on the susceptible dwarfing rootstock M.26 in the greenhouse were injected with inoculum containing 5 × 10 CFU/ml Erwinia amylovora. At intervals after inoculation, trees were sampled at increments between the shoot tip and the roots by excising stem segments. Segments were ground in phosphate buffer and assayed for the presence of E. amylovora by plating on semi-selective medium and by a polymerase chain reaction (PCR)-based detection method. Eleven days after inoculation, E. amylovora was detected by PCR in symptomless scion tissue >50 cm below the shoot-tip in Empire and Golden Delicious, and in 2-year-old tissue in Golden Delicious. By 21 days, E. amylovora was detected in the M.26 rootstock of Empire trees, and by 41 days in the M.26 rootstock of Golden Delicious. In a similar experiment the following year, Empire trees on M.26 rootstock were inoculated with E. amylovora at early (16 May), mid- (11 June), and late (6 July) phenophase of shoots. Three weeks after inoculation, E. amylovora was detected by PCR from M.26 rootstocks of five of six plants inoculated at the late phenophase, compared to zero of six plants inoculated at the early or mid-phenophase. Late-season fire blight infections of the scion may be particularly hazardous for the health of the rootstock.
在温室中，将含有5×10 CFU/ml解淀粉欧文氏菌的接种物注射到易感矮化砧木M.26上盆栽的帝国和金冠苹果树的茎尖。接种后每隔一段时间，通过切除茎段，从茎尖到根部按增量对树木进行采样。将茎段在磷酸盐缓冲液中研磨，并通过在半选择性培养基上平板培养和基于聚合酶链反应（PCR）的检测方法来检测解淀粉欧文氏菌的存在。接种11天后，通过PCR在帝国和金冠苹果茎尖以下>50 cm的无症状接穗组织中以及金冠苹果的2年生组织中检测到了解淀粉欧文氏菌。到21天时，在帝国树的M.26砧木中检测到了解淀粉欧文氏菌，到41天时在金冠苹果的M.26砧木中检测到了该菌。在次年的一项类似实验中，在M.26砧木上的帝国树在新梢的早期（5月16日）、中期（6月11日）和晚期（7月6日）物候期接种了解淀粉欧文氏菌。接种三周后，在晚期物候期接种的六株植物中有五株的M.26砧木通过PCR检测到了解淀粉欧文氏菌，而在早期或中期物候期接种的六株植物中无一检测到。接穗在生长季后期感染火疫病可能对砧木的健康特别有害。
