Grafting is a useful cultivation technology to resist abiotic and biotic stresses and is an integral part of citrus production. However, some widely utilized rootstocks may still exhibit graft incompatibility in the orchard. "Hongmian miyou" (Citrus maxima (Burm.) Merrill) is mutated from "Guanxi miyou", but these two scions showed different compatibility with available Poncirus trifoliata rootstock. Foliage etiolation is an observed symptom of graft incompatibility, but its mechanism remains poorly understood. This study is the first to investigate the morphological, physiological, and anatomical differences between the compatible/incompatible grafts, and perform transcriptome profiling at crucial stages of the foliage etiolation process. Based on the comprehensive analyses, hormonal balance was disordered, and two rate-limiting genes, NCED3 (9-cis-epoxycarotenoid dioxygenases 3) and NCED5, being responsible for ABA (abscisic acid) accumulation, were highlighted. Further correlation analysis indicated that IAA (indole-3-acetic acid) and ABA were the most likely inducers of the expression of stresses-related genes. In addition, excessive starch accumulation was observed in lamina and midribs of incompatible grafts leaves. These results provided a new insight into the role of the hormonal balance and abscisic acid biosynthesis genes in regulation and contribution to the graft incompatibility, and will further define and deploy candidate genes to explore the mechanisms underlying citrus rootstock- scion interactions.

中文翻译：

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柑橘相容/不相容移植物的比较转录组学分析。

嫁接是抵抗非生物和生物胁迫的有用栽培技术，是柑橘生产不可分割的一部分。然而，一些广泛使用的砧木在果园中仍可能表现出嫁接不相容性。“红面蜜优”（Citrus maxima (Burm.) Merrill）是从“关西蜜优”变异而来的，但这两个接穗与现有的红枣砧木表现出不同的相容性。叶子黄化是移植物不相容的观察到的症状，但其机制仍然知之甚少。本研究首次研究了相容/不相容移植物之间的形态、生理和解剖学差异，并在叶子黄化过程的关键阶段进行转录组分析。综合分析，荷尔蒙平衡紊乱，并且突出了两个限速基因，NCED3（9-顺式-环氧类胡萝卜素双加氧酶3）和NCED5，负责ABA（脱落酸）的积累。进一步的相关性分析表明，IAA（吲哚-3-乙酸）和ABA最有可能是应激相关基因表达的诱导剂。此外，在不亲和嫁接叶的叶片和中脉中观察到过多的淀粉积累。这些结果为激素平衡和脱落酸生物合成基因在调节和促进嫁接不相容性中的作用提供了新的见解，并将进一步定义和部署候选基因以探索柑橘砧木-接穗相互作用的机制。进一步的相关性分析表明，IAA（吲哚-3-乙酸）和ABA最有可能是应激相关基因表达的诱导剂。此外，在不亲和嫁接叶的叶片和中脉中观察到过多的淀粉积累。这些结果为激素平衡和脱落酸生物合成基因在调节和促进嫁接不相容性中的作用提供了新的见解，并将进一步定义和部署候选基因以探索柑橘砧木-接穗相互作用的机制。进一步的相关性分析表明，IAA（吲哚-3-乙酸）和ABA最有可能是应激相关基因表达的诱导剂。此外，在不亲和嫁接叶的叶片和中脉中观察到过多的淀粉积累。这些结果为激素平衡和脱落酸生物合成基因在调节和促进嫁接不相容性中的作用提供了新的见解，并将进一步定义和部署候选基因以探索柑橘砧木-接穗相互作用的机制。