Senanayake D M J B, Mandal B
Advanced Centre for Plant Virology, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi, 110012 India.
Virusdisease. 2014;25(3):314-21. doi: 10.1007/s13337-014-0204-1. Epub 2014 Apr 1.
Potato virus Y (PVY) and potato virus X (PVX), the RNA viruses of two different genera results into synergistic interactions on mixed infection. In this study, a N-Wi strain of PVY and a PVX strain that is asymptomatic on potato were used to study their interactions during mixed infection in Nicotiana benthamiana and Nicotiana tabacum with reference to symptom expression, level of coat protein (CP) using ELISA and suppressor gene using real time PCR under high temperature (26-40 °C) and low temperature (5-25 °C) conditions. Both mixed and single infection caused severe necrosis and death of N. benthamiana plants. Single infection of these viruses in N. tabacum showed mild symptoms but mixed infection caused more severe symptoms. Synergistic symptoms were more pronounced under low temperature conditions than at high temperature. In low temperature conditions, the CP level of PVX in N. benthamiana was twofold higher than PVY and both the viruses reached at peak at 28 dpi in single virus infection. When PVY and PVX inoculated together, the CP levels of both the viruses increased and reached to the peak earlier (within 7-14 days) than that in the single virus inoculation. Although, the CP level of PVX was higher than PVY in mixed infection, at later stage (28 dpi) both the CP level declined to the similar level. The level of p25 suppressor gene was higher than HC-Pro in single inoculation. However, under mixed inoculation of PVY and PVX, expression of p25 was declined to the level of HC-Pro when the CP levels of both the virus also were observed to decline. The expression pattern of CP and suppressor gene was different in plants when mixed infection was created by inoculation of one virus followed by the other. This study showed the level of CP and suppressor gene of specific strain of PVY and PVX during their mixed infection in tobacco.
马铃薯Y病毒（PVY）和马铃薯X病毒（PVX）是两个不同属的RNA病毒，它们在混合感染时会产生协同相互作用。在本研究中，使用PVY的N-Wi株系和在马铃薯上无症状的PVX株系，参照症状表现、利用酶联免疫吸附测定法检测外壳蛋白（CP）水平以及利用实时荧光定量PCR检测抑制基因，研究它们在本氏烟草和烟草中混合感染期间，在高温（26 - 40℃）和低温（5 - 25℃）条件下的相互作用。混合感染和单一感染均导致本氏烟草植株严重坏死和死亡。这些病毒在烟草中的单一感染表现出轻微症状，但混合感染导致更严重的症状。协同症状在低温条件下比高温时更明显。在低温条件下，本氏烟草中PVX的CP水平比PVY高两倍，且在单一病毒感染时，两种病毒在接种后28天达到峰值。当PVY和PVX一起接种时，两种病毒的CP水平均升高，且比单一病毒接种更早（在7 - 14天内）达到峰值。尽管在混合感染中PVX的CP水平高于PVY，但在后期（接种后28天），两种病毒的CP水平均下降至相似水平。在单一接种中，p25抑制基因的水平高于HC-Pro。然而，在PVY和PVX混合接种时，当观察到两种病毒的CP水平也下降时，p25的表达下降至HC-Pro的水平。当通过先后接种一种病毒来造成混合感染时，植物中CP和抑制基因的表达模式不同。本研究显示了PVY和PVX特定株系在烟草中混合感染期间的CP和抑制基因水平。
