PDF(Pubmed)
Abstract：
Citrus is commercially propagated via grafting, which ensures trees have consistent fruit traits combined with favorable traits from the rootstock such as soil adaptability, vigor, and resistance to soil pathogens. Graft incompatibility can occur when the scion and rootstock are not able to form a permanent, healthy union. Understanding and preventing graft incompatibility is of great importance in the breeding of new fruit cultivars and in the choice of scion and rootstock by growers. The rootstock US-1283, a citrandarin generated from a cross of \"Ninkat\" mandarin (Citrus reticulata) and \"Gotha Road\" #6 trifoliate orange (Poncirus trifoliata), was released after years of field evaluation because of its superior productivity and good fruit quality on \"Hamlin\" sweet orange (C. sinensis) under Florida\'s growing conditions. Subsequently, it was observed that trees of \"Bearss\" lemon (C. limon) and \"Valencia\" sweet orange (C. sinensis) grafted onto US-1283 exhibited unhealthy growth near the graft union. The incompatibility manifested as stem grooving and necrosis underneath the bark on the rootstock side of the graft. Another citrandarin rootstock, US-812 (C. reticulata \"Sunki\" × P. trifoliata \"Benecke\"), is fully graft compatible with the same scions. Transcriptome analysis was performed on the vascular tissues above and below the graft union of US-812 and US-1283 graft combinations with \"Bearss\" and \"Valencia\" to identify expression networks associated with incompatibility and help understand the processes and potential causes of incompatibility. Transcriptional reprogramming was stronger in the incompatible rootstock than in the grafted scions. Differentially expressed genes (DEGs) in US-1283, but not the scions, were associated with oxidative stress and plant defense, among others, similar to a pathogen-induced immune response localized to the rootstock; however, no pathogen infection was detected. Therefore, it is hypothesized that this response could have been triggered by signaling miscommunications between rootstock and scion either through (1) unknown molecules from the scion that were perceived as danger signals by the rootstock, (2) missing signals from the scion or missing receptors in the rootstock necessary for the formation of a healthy graft union, (3) the overall perception of the scion by the rootstock as non-self, or (4) a combination of the above.
摘要：
柑橘通过嫁接进行商业繁殖，这确保树木具有一致的果实性状与砧木的有利性状相结合，如土壤适应性，活力,和对土壤病原体的抗性。当接穗和砧木不能形成永久性的，健康的结合了解和防止嫁接不相容性对于新水果品种的育种以及种植者选择接穗和砧木非常重要。US-1283砧木，是由“Ninkat”普通话（柑桔）和“GothaRoad”＃6三叶橙（Poncirustrifoliata）的杂交产生的柑桔，经过多年的田间评估，由于其在“Hamlin”甜橙上具有出色的生产力和良好的水果品质（C.sinensis)在佛罗里达的生长条件下。随后，据观察，“熊”柠檬树(C.limon)和“瓦伦西亚”甜橙(C.sinensis）嫁接到US-1283上，在移植物结合附近表现出不健康的生长。不相容性表现为移植物砧木侧树皮下方的茎槽和坏死。另一种柑橘砧木，US-812(C.网状\“Sunki\”×P。三叶\“Benecke”)，与相同的接穗完全兼容。对US-812和US-1283与“Bearss”和“Valencia”的移植物结合上方和下方的血管组织进行转录组分析，以确定与不相容性相关的表达网络，并帮助了解过程和潜在原因。不相容砧木的转录重编程比嫁接接穗更强。US-1283中的差异表达基因（DEGs），而不是接穗，与氧化应激和植物防御有关，其中,类似于定位于砧木的病原体诱导的免疫反应；然而，未检测到病原体感染.因此,据推测，这种反应可能是由砧木和接穗之间的信号传递错误触发的，或者通过（1）来自接穗的未知分子，这些分子被砧木视为危险信号，（2）缺失的信号从接穗或缺失的受体在砧木需要形成一个健康的移植物结合，（3）砧木对接穗的整体感知为非自我，或(4)上述的组合。
