College of Horticulture, Nanjing Agricultural University, No. 1 Weigang, Nanjing 210095, PR China.
J Plant Physiol. 2017 Nov;218:155-166. doi: 10.1016/j.jplph.2017.08.004. Epub 2017 Aug 12.
Grapevine (Vitis vinifera L.) is considered to be one of the most popular and widespread fruit crops in the world. Numerous value added products are prepared from grape fruit and investments are being made to establish new viticulture region (Hoff et al., 2017; Imran et al., 2017). CPPU [forchlorfenuron N-(2-chloro-4-pyridyl)-N-phenylurea] is a synthetic cytokine-like plant regulator which promotes grape berry set and development. The influence of CPPU [forchlorfenuron N-(2-chloro-4-pyridyl)-N-phenylurea] on berry development of 'Shine Muscat' (Vitis labruscana Bailey×V vinifera L.) grapes was evaluated under field conditions. A concentration response was observed over a range of 0, 5, and 10 mgL CPPU that was applied to fruitlets (mean diameter 6mm) at 2 weeks after full bloom. Gas-chromatography mass-spectrometry (GC-MS) revealed that volatile compounds such as terpenoids and aromatics; especially linalool, geraniol and benzyl alcohols, were greatly reduced in CPPU-treated grapes. In contrast, aliphatics, such as hexanol, were increased in CPPU-treated berries. RNA sequencing (RNA-Seq) was conducted to identify differentially expressed genes (DEGs) that were induced by CPPU, especially those related to volatile biosynthesis. A total of 494, 1237, and 1085 DEGs were detected in CPPU0-vs-CPPU5, CPPU0-vs-CPPU10, and CPPU5-vs-CPPU10 treatments, respectively. The results were compared against two databases (Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG)) to annotate gene descriptions and assign a pathway to each gene. GO covers three domains: biological processes, molecular functions and cellular components. Pathway enrichment annotation demonstrated that highly ranked genes were associated with the fatty acid degradation and biosynthesis, phenylpropanoid metabolism and biosynthesis, carotenoid biosynthesis, and plant hormone signal transduction. Analysis with qRT-PCR of twelve selected transcripts validated the data obtained by RNA-seq. Additionally, we also found that genes such as CCDs (carotenoid cleavage dioxygenase), LOX (lipoxygenase), GGDP reductase (geranylgeranyl diphosphate reductase), PAL (phenylalanine ammonia-lyase) and some hormones related genes, were closely involved in the formation of volatiles compounds in CPPU treated berries. In summary, our results provide the first sequential transcriptomic atlas of CPPU treated grape berries which significantly increases our understanding of volatile metabolites and biosynthesis pathways in grape affected by CPPU.
葡萄（Vitis vinifera L.）被认为是世界上最受欢迎和广泛种植的水果之一。人们用葡萄果实生产出了大量附加值产品，并正在投资建立新的葡萄种植区（Hoff 等人，2017 年；Imran 等人，2017 年）。CPPU[氯苯脲 N-（2-氯-4-吡啶基）-N-苯基脲]是一种合成细胞因子样植物调节剂，可促进葡萄浆果的形成和发育。本研究在田间条件下评估 CPPU[氯苯脲 N-（2-氯-4-吡啶基）-N-苯基脲]对‘Shine Muscat’（Vitis labruscana Bailey×V vinifera L.）葡萄浆果发育的影响。在花后 2 周，对果粒（直径 6mm）施加 0、5 和 10mgL CPPU，观察到浓度反应。气相色谱-质谱联用（GC-MS）显示，在 CPPU 处理的葡萄中，萜类化合物和芳香族化合物等挥发性化合物，特别是芳樟醇、香叶醇和苯甲醇，大大减少。相比之下，CPPU 处理的浆果中的脂肪族化合物，如己醇，则增加。进行 RNA 测序（RNA-Seq）以鉴定 CPPU 诱导的差异表达基因（DEGs），特别是与挥发性生物合成相关的基因。在 CPPU0-vs-CPPU5、CPPU0-vs-CPPU10 和 CPPU5-vs-CPPU10 处理中分别检测到 494、1237 和 1085 个 DEGs。将结果与两个数据库（基因本体论（GO）和京都基因与基因组百科全书（KEGG））进行比较，以注释基因描述并为每个基因分配途径。GO 涵盖三个领域：生物过程、分子功能和细胞成分。途径富集注释表明，高排名基因与脂肪酸降解和生物合成、苯丙素代谢和生物合成、类胡萝卜素生物合成以及植物激素信号转导有关。用 qRT-PCR 对 12 个选定的转录本进行分析验证了 RNA-seq 获得的数据。此外，我们还发现 CCDs（类胡萝卜素裂解双加氧酶）、LOX（脂氧合酶）、GGDP 还原酶（香叶基二磷酸还原酶）、PAL（苯丙氨酸解氨酶）和一些与激素相关的基因等基因，与 CPPU 处理的浆果中挥发性化合物的形成密切相关。总之，我们的研究结果提供了 CPPU 处理葡萄浆果的首个连续转录组图谱，这极大地提高了我们对 CPPU 影响葡萄中挥发性代谢物和生物合成途径的理解。
