Phytoene synthase (PSY) has been considered as an important regulatory enzyme in carotenoids biosynthesis pathway. Previous study finds that the yellow fruit in Solanum lycopersicum var. cerasiforme accession PI 114490 is caused by loss-of-function of SlPSY1 due to trans-splicing between SlPsy1 and an unknown gene transcribed from neighbour opposite strand DNA of SlPsy1. The genomic DNA sequences of SlPsy1 between red and yellow-fruited tomato lines have one single-nucleotide polymorphism (SNP) in the fourth intron and one SSR in the intergenic region. In the current study, the cause of trans-splicing event was further investigated. The data showed that the previously defined unknown gene was a putative long non-coding RNA ACoS-AS1 with three variants in many yellow-fruited tomato lines. The intronic SNP and intergenic SSR were tightly associated with trans-splicing event SlPsy1-ACoS-AS1. However, transgenic tomato lines carrying the genomic DNA of SlPsy1 from PI 114490 did not generate transcripts of ACoS-AS1and SlPsy1-ACoS-AS1 suggesting that only the intronic SNP could not cause the trans-splicing event. Over-expression of SlPsy1-ACoS-AS1 in red-fruited tomato line M82 did not have any phenotype change while over-expression of wild type SlPsy1 resulted in altered leaf colour. Sub-cellular localization analysis showed that SlPSY1-ACoS-AS1 could not enter plastids where SlPSY1 has its enzyme activity. Mutation of ACoS-AS1 in PI 114490 generated by CRISPR/Cas9 techniques resulted in red fruits implying that ACoS-AS1 was essential to trans-splicing event SlPsy1-ACoS-AS1. The results obtained here will extend knowledge to understand the mechanism of trans-splicing event SlPsy1-ACoS-AS1 and provide additional information for the regulation of carotenoids biosynthesis.

中文翻译：

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lncRNA ACoS-AS1 的转录对于 SlPsy1 和 ACoS-AS1 之间的反式剪接至关重要，从而导致番茄出现黄色果实。

八氢番茄红素合酶（PSY）被认为是类胡萝卜素生物合成途径中的重要调节酶。先前的研究发现，Solanum lycopersicum var. 的黄色果实。cerasiforme 登录号 PI 114490 是由于 SlPsy1 与从 SlPsy1 的相邻相反链 DNA 转录的未知基因之间的反式剪接而导致 SlPSY1 功能丧失所致。红果番茄品系和黄果番茄品系之间的SlPsy1基因组DNA序列在第四个内含子中具有1个单核苷酸多态性(SNP)，在基因间区域中具有1个SSR。在本研究中，进一步研究了反式剪接事件的原因。数据显示，先前定义的未知基因是一个假定的长非编码RNA ACoS-AS1，在许多黄果番茄品系中具有三个变体。内含子SNP和基因间SSR与反式剪接事件SlPsy1-ACoS-AS1密切相关。然而，携带来自PI 114490的SlPsy1基因组DNA的转基因番茄品系没有产生ACoS-AS1和SlPsy1-ACoS-AS1的转录本，这表明只有内含子SNP不能引起反式剪接事件。SlPsy1-ACoS-AS1 在红果番茄品系 M82 中的过表达没有任何表型变化，而野生型 SlPsy1 的过表达导致叶色改变。亚细胞定位分析表明SlPSY1-ACoS-AS1不能进入SlPSY1具有酶活性的质体。通过 CRISPR/Cas9 技术产生的 PI 114490 中的 ACoS-AS1 突变导致果实呈红色，这表明 ACoS-AS1 对于转拼事件 SlPsy1-ACoS-AS1 至关重要。这里获得的结果将扩展知识以了解反式剪接事件 SlPsy1-ACoS-AS1 的机制，并为类胡萝卜素生物合成的调节提供更多信息。