Duduit James R, Kosentka Pawel Z, Miller Morgan A, Blanco-Ulate Barbara, Lenucci Marcello S, Panthee Dilip R, Perkins-Veazie Penelope, Liu Wusheng
Department of Horticultural Science, North Carolina State University, Raleigh, NC, 27607, USA.
Department of Plant Sciences, University of California, Davis, CA, 95616, USA.
Hortic Res. 2022 Jun 1;9:uhac084. doi: 10.1093/hr/uhac084. eCollection 2022.
Lycopene content in tomato fruit is largely under genetic control and varies greatly among genotypes. Continued improvement of lycopene content in elite varieties with conventional breeding has become challenging, in part because little is known about the underlying molecular mechanisms in high-lycopene tomatoes (HLYs). We collected 42 HLYs with different genetic backgrounds worldwide. High-performance liquid chromatography (HPLC) analysis revealed lycopene contents differed among the positive control wild tomato , HLYs, the normal lycopene cultivar "Moneymaker", and the non-lycopene cultivar NC 1Y at the pink and red ripe stages. Real-time RT-PCR analysis of expression of the 25 carotenoid biosynthesis pathway genes of each genotype showed a significantly higher expression in nine upstream genes (, , , , , , , and but not the well-studied , and ) at the breaker and/or red ripe stages in HLYs compared to Moneymaker, indicating a higher metabolic flux flow into carotenoid biosynthesis pathway in HLYs. Further conversion of lycopene to carotenes may be prevented via the two downstream genes ( and ), which had low-abundance transcripts at either or both stages. Additionally, the significantly higher expression of four downstream genes (, , , and ) at either or both ripeness stages leads to significantly lower fruit lycopene content in HLYs than in the wild tomato. This is the first systematic investigation of the role of the complete pathway genes in regulating fruit lycopene biosynthesis across many HLYs, and enables tomato breeding and gene editing for increased fruit lycopene content.
番茄果实中的番茄红素含量在很大程度上受遗传控制，不同基因型之间差异很大。利用传统育种方法持续提高优良品种中的番茄红素含量已变得具有挑战性，部分原因是对高番茄红素番茄（HLYs）的潜在分子机制了解甚少。我们收集了全球42个具有不同遗传背景的HLYs。高效液相色谱（HPLC）分析表明，在粉红和红熟阶段，阳性对照野生番茄、HLYs、正常番茄红素品种“Money maker”和非番茄红素品种NC 1Y的番茄红素含量存在差异。对每个基因型的25个类胡萝卜素生物合成途径基因的表达进行实时RT-PCR分析，结果显示，与“Money maker”相比，HLYs在破色期和/或红熟期的9个上游基因（、、、、、、、和，但不包括研究较多的、和）表达显著更高，这表明HLYs进入类胡萝卜素生物合成途径的代谢通量更高。通过两个下游基因（和）可能会阻止番茄红素进一步转化为胡萝卜素，这两个基因在任一阶段或两个阶段的转录本丰度都较低。此外，四个下游基因（、、、和）在任一成熟阶段或两个成熟阶段的显著更高表达导致HLYs果实中的番茄红素含量显著低于野生番茄。这是首次对众多HLYs中完整途径基因在调节果实番茄红素生物合成中的作用进行系统研究，有助于番茄育种和基因编辑以提高果实番茄红素含量。
