Liu Guang, Yang Xingping, Xu Jinhua, Zhang Man, Hou Qian, Zhu Lingli, Huang Ying, Xiong Aisheng
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
Acta Biochim Biophys Sin (Shanghai). 2017 Mar 1;49(3):216-227. doi: 10.1093/abbs/gmw132.
Watermelon is an important and economical horticultural crop in China, where ~20% of the plants are grafted. The development of grafted watermelon fruit involves a diverse range of gene interactions that results in dynamic changes in fruit. However, the molecular mechanisms underlying grafting-induced fruit quality change are unclear. In the present study, we measured the lycopene content by high-performance liquid chromatography and used RNA-Seq (quantification) to perform a genome-wide transcript analysis of fruits from watermelon grafted onto pumpkin rootstock (pumpkin-grafted watermelon, PGW), self-grafted watermelon (SGW), and non-grafted watermelon (NGW). The results showed variation in the lycopene content in the flesh of PGW fruits, first increasing and then decreasing in the four stages, which was different from the trend in the flesh of NGW and SGW fruits. The transcriptome profiling data provided new information on the grafting-induced gene regulation of lycopene biosynthesis during fruit growth and development. The expression levels of 33 genes from 8 gene families (GGPS, PSY, PDS, ZDS, CRTISO, LCYb, LCYe, and CHY) related to lycopene biosynthesis, which play critical roles in fruit coloration and contribute significantly to fruit phytonutrient values, were monitored during the four periods of fruit development in watermelon. Compared with those of NGW and SGW, 14 genes were differentially expressed in PGW during fruit development, suggesting that these genes possibly help to mediate lycopene biosynthesis in grafted watermelon fruit. Our work provides some novel insights into grafting-responsive carotenoid metabolism and its potential roles during PGW fruit development and ripening.
西瓜是中国一种重要且经济的园艺作物，约20%的植株采用嫁接种植。嫁接西瓜果实的发育涉及多种基因相互作用，导致果实发生动态变化。然而，嫁接诱导果实品质变化的分子机制尚不清楚。在本研究中，我们通过高效液相色谱法测定了番茄红素含量，并使用RNA测序（定量）对嫁接在南瓜砧木上的西瓜（南瓜嫁接西瓜，PGW）、自嫁接西瓜（SGW）和未嫁接西瓜（NGW）的果实进行全基因组转录分析。结果表明，PGW果实果肉中番茄红素含量存在差异，在四个阶段先增加后减少，这与NGW和SGW果实果肉中的趋势不同。转录组分析数据为果实生长发育过程中嫁接诱导的番茄红素生物合成基因调控提供了新信息。在西瓜果实发育的四个时期，监测了与番茄红素生物合成相关的8个基因家族（GGPS、PSY、PDS、ZDS、CRTISO、LCYb、LCYe和CHY）中33个基因的表达水平，这些基因在果实着色中起关键作用，并对果实植物营养素价值有显著贡献。与NGW和SGW相比，14个基因在PGW果实发育过程中差异表达，表明这些基因可能有助于介导嫁接西瓜果实中的番茄红素生物合成。我们的工作为嫁接响应类胡萝卜素代谢及其在PGW果实发育和成熟过程中的潜在作用提供了一些新见解。
