Graft compatibility is the capacity of two plants to form cohesive vascular connections. Tomato and pepper are incompatible graft partners; however, the underlying cause of graft rejection between these two species remains unknown. We diagnosed graft incompatibility between tomato and diverse pepper varieties based on weakened biophysical stability, decreased growth, and persistent cell death using viability stains. Transcriptomic analysis of the junction was performed using RNA-sequencing, and molecular signatures for incompatible graft response were characterized based on meta-transcriptomic comparisons with other biotic processes. We show that tomato is broadly incompatible with diverse pepper cultivars. These incompatible graft partners activate prolonged transcriptional changes that are highly enriched for defense processes. Amongst these processes was broad nucleotide-binding and leucine-rich repeat receptors (NLR) upregulation and genetic signatures indicative of an immune response. Using transcriptomic datasets for a variety of biotic stress treatments, we identified a significant overlap in the genetic profile of incompatible grafting and plant parasitism. In addition, we found over 1000 genes that are uniquely upregulated in incompatible grafts. Based on NLR overactivity, DNA damage, and prolonged cell death we hypothesize that tomato and pepper graft incompatibility is characterized by an immune response that triggers cell death which interferes with junction formation.

中文翻译：

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辣椒和番茄之间的移植物不相容性会引发免疫反应并引发局部细胞死亡


嫁接相容性是指两种植物形成粘性维管连接的能力。番茄和辣椒是不相容的嫁接伴侣；然而，这两个物种之间移植物排斥的根本原因仍然未知。我们根据活力染色减弱的生物物理稳定性、生长下降和持续的细胞死亡来诊断番茄和不同辣椒品种之间的移植不相容性。使用RNA测序对连接进行转录组分析，并根据与其他生物过程的宏转录组比较来表征不相容移植物反应的分子特征。我们发现番茄与多种辣椒品种普遍不相容。这些不相容的移植物伴侣会激活长期的转录变化，这些变化对于防御过程来说是高度丰富的。这些过程包括广泛的核苷酸结合和富含亮氨酸的重复受体（NLR）上调以及表明免疫反应的遗传特征。使用各种生物胁迫处理的转录组数据集，我们发现不相容嫁接和植物寄生的遗传谱存在显着重叠。此外，我们发现超过 1000 个基因在不相容的移植物中独特地上调。基于 NLR 过度活跃、DNA 损伤和长期细胞死亡，我们假设番茄和辣椒移植物不相容的特点是免疫反应触发细胞死亡，从而干扰连接形成。