Transcriptome landscape reveals the molecular mechanisms involved in the improvement of fruit traits by the grafting of watermelon and bottle gourd. Grafting has been used as a sustainable alternative for watermelon breeding to control soil-borne pathogens and to increase tolerance to various abiotic stresses. However, some reports have shown that grafting can negatively affect the quality of fruits. Despite several field studies on the effects of grafting on fruit quality, the regulation of this process at the molecular level has not been revealed. The aim of this study was to elucidate various molecular mechanisms involved in different tissues of heterografted watermelon and bottle gourd plants. Grafting with bottle gourd rootstock increased the size and rind thickness of watermelon fruits, whereas that with watermelon rootstock produced bottle gourd fruits with higher total soluble solid content and thinner rinds. Correspondingly, genes related to ripening, softening, cell wall strengthening, stress response and disease resistance were differentially expressed in watermelon fruits. Moreover, genes associated mainly with sugar metabolism were differentially expressed in bottle gourd fruits. RNA-seq revealed more than 400 mobile transcripts across the heterografted sets. More than half of these were validated from PlaMoM, a database for plant mobile macromolecules. In addition, some of these mobile transcripts contained a transfer RNA-like structure. Other RNA motifs were also enriched in these transcripts, most with a biological role based on GO analysis. This transcriptome study provided a comprehensive understanding of various molecular mechanisms underlying grafted tissues in watermelon.

中文翻译：

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涉及西瓜和葫芦的相互移植物的转录组变化揭示了增加果实大小、果皮韧性和可溶性固体的分子机制。

转录组景观揭示了西瓜和葫芦嫁接改善果实性状的分子机制。嫁接已被用作西瓜育种的可持续替代方法，以控制土壤传播的病原体并提高对各种非生物胁迫的耐受性。然而，一些报道表明嫁接会对水果的质量产生负面影响。尽管对嫁接对果实品质的影响进行了多项实地研究，但尚未揭示该过程在分子水平上的调控。本研究的目的是阐明涉及异种嫁接西瓜和葫芦植物不同组织的各种分子机制。用葫芦砧木嫁接增加了西瓜果实的大小和果皮厚度，而用西瓜砧木生产的葫芦果实具有较高的总可溶性固形物含量和较薄的果皮。相应地，与成熟、软化、细胞壁强化、应激反应和抗病性相关的基因在西瓜果实中差异表达。此外，主要与糖代谢相关的基因在葫芦果实中差异表达。RNA-seq 揭示了 400 多个跨异种移植集的移动转录本。其中一半以上是从植物移动大分子数据库 PlaMoM 验证的。此外，其中一些移动转录本包含转移 RNA 样结构。这些转录本中也富含其他 RNA 基序，大多数具有基于 GO 分析的生物学作用。