Warren Jaimie M, Covert Sarah F
Department of Genetics, University of Georgia, Athens, Georgia 30602, USA.
Appl Environ Microbiol. 2004 Jan;70(1):441-51. doi: 10.1128/AEM.70.1.441-451.2004.
Cronartium quercuum f. sp. fusiforme is the causative agent of fusiform rust disease of southern pines in the United States. This disease is characterized by the formation of woody branch and stem galls. Differential display was used to identify pine genes whose expression is altered by C. quercuum f. sp. fusiforme infection and to identify C. quercuum f. sp. fusiforme genes that are expressed in fusiform rust galls. Six pine cDNAs that appeared to be differentially expressed in galled and healthy stems and 13 C. quercuum f. sp. fusiforme cDNAs expressed in galled tissues were identified. A probe that hybridizes specifically to C. quercuum f. sp. fusiforme 18S rRNA was used to estimate that 14% of the total RNA in fusiform rust galls was from C. quercuum f. sp. fusiforme. This finding was used to calibrate gene expression levels in galls when comparing them to expression levels in uninfected pines or in isolated C. quercuum f. sp. fusiforme cultures. According to Northern analysis and reverse transcriptase PCR analysis, all six of the pine clones were expressed at lower levels in galls than in healthy tissues. Seven of the nine C. quercuum f. sp. fusiforme clones that were assayed were expressed at higher levels in galls than in axenic culture. A number of the cDNAs encode proteins that are similar to those that play roles in plant development, plant defense, or fungal stress responses.
梭形柄锈菌栎专化型是美国南部松树梭形锈病的病原体。这种病害的特征是形成木质化的枝条和茎干瘿瘤。采用差异显示技术来鉴定其表达因梭形柄锈菌栎专化型感染而改变的松树基因，以及在梭形锈病瘿瘤中表达的梭形柄锈菌栎专化型基因。鉴定出了6个在瘿瘤茎干和健康茎干中似乎差异表达的松树cDNA，以及13个在瘿瘤组织中表达的梭形柄锈菌栎专化型cDNA。使用一种与梭形柄锈菌栎专化型18S rRNA特异性杂交的探针来估计，梭形锈病瘿瘤中总RNA的14%来自梭形柄锈菌栎专化型。在将瘿瘤中的基因表达水平与未感染松树或分离的梭形柄锈菌栎专化型培养物中的表达水平进行比较时，这一发现被用于校准瘿瘤中的基因表达水平。根据Northern分析和逆转录酶PCR分析，所有6个松树克隆在瘿瘤中的表达水平均低于健康组织。在检测的9个梭形柄锈菌栎专化型克隆中，有7个在瘿瘤中的表达水平高于无菌培养。许多cDNA编码的蛋白质与在植物发育、植物防御或真菌应激反应中起作用的蛋白质相似。
