Institution of Pomology & Olericulture, Sichuan Agricultural University, No 211 Huimin Road, Wenjiang District, Chengdu, 611130, Sichuan, China.
Sichuan Horticultural Crop Agrotechnical Promotion Workstation, No 4 Wuhou Memorial Temple Street, Wuhou District, Chengdu, 610041, Sichuan, China.
BMC Genomics. 2018 Apr 23;19(1):280. doi: 10.1186/s12864-018-4669-y.
During fresh fruit consumption, sensory texture is one factor that affects the organoleptic qualities. Chemical components of plant cell walls, including pectin, cellulose, hemicellulose and lignin, play central roles in determining the textural qualities. To explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture, we performed mRNA-seq analyses of the segment membranes of two citrus cultivars, Shiranui and Kiyomi, with different organoleptic textures.
Segment membranes were sampled at two developmental stages of citrus fruit, the beginning and end of the expansion period. More than 3000 differentially expressed genes were identified. The gene ontology analysis revealed that more categories were significantly enriched in 'Shiranui' than in 'Kiyomi' at both developmental stages. In total, 108 significantly enriched pathways were obtained, with most belonging to metabolism. A detailed transcriptomic analysis revealed potential critical genes involved in the metabolism of cell wall structures, for example, GAUT4 in pectin synthesis, CESA1, 3 and 6, and SUS4 in cellulose synthesis, CSLC5, XXT1 and XXT2 in hemicellulose synthesis, and CSE in lignin synthesis. Low levels, or no expression, of genes involved in cellulose and hemicellulose, such as CESA4, CESA7, CESA8, IRX9 and IRX14, confirmed that secondary cell walls were negligible or absent in citrus segment membranes. A chemical component analysis of the segment membranes from mature fruit revealed that the pectin, cellulose and lignin contents, and the segment membrane's weight (% of segment) were greater in 'Kiyomi'.
Organoleptic quality of citrus is easily overlooked. It is mainly determined by sensory texture perceived in citrus segment membrane properties. We performed mRNA-seq analyses of citrus segment membranes to explore the genes and regulatory pathways involved in fresh citrus' perceived sensory texture. Transcriptomic data showed high repeatability between two independent biological replicates. The expression levels of genes involved in cell wall structure metabolism, including pectin, cellulose, hemicellulose and lignin, were investigated. Meanwhile, chemical component contents of the segment membranes from mature fruit were analyzed. This study provided detailed transcriptional regulatory profiles of different organoleptic citrus qualities and integrated insights into the mechanisms affecting citrus' sensory texture.
在食用新鲜水果时，感官质地是影响其感官品质的一个因素。植物细胞壁的化学组成，包括果胶、纤维素、半纤维素和木质素，在决定质地方面起着核心作用。为了探索与新鲜柑橘感知感官质地相关的基因和调控途径，我们对两个具有不同感官质地的柑橘品种（Shiranui 和 Kiyomi）的果皮进行了 mRNA-seq 分析。
在柑橘果实的两个发育阶段（扩展期的开始和结束时）采集果皮。鉴定出 3000 多个差异表达基因。GO 分析表明，在两个发育阶段，“Shiranui”中显著富集的类别多于“Kiyomi”。总共获得了 108 个显著富集的途径，其中大部分属于代谢途径。详细的转录组分析揭示了参与细胞壁结构代谢的潜在关键基因，例如果胶合成中的 GAUT4、纤维素合成中的 CESA1、3 和 6 以及 SUS4、半纤维素合成中的 CSLC5、XXT1 和 XXT2 以及木质素合成中的 CSE。参与纤维素和半纤维素合成的基因（如 CESA4、CESA7、CESA8、IRX9 和 IRX14）表达水平较低或不表达，证实了柑橘果皮中的次生细胞壁很少或不存在。对成熟果实果皮的化学成分分析表明，“Kiyomi”果皮的果胶、纤维素和木质素含量以及果皮的重量（果皮占果皮的百分比）更高。
柑橘的感官品质容易被忽视。它主要由柑橘果皮性质感知的感官质地决定。我们对柑橘果皮进行了 mRNA-seq 分析，以探索与新鲜柑橘感知感官质地相关的基因和调控途径。转录组数据显示，两个独立生物学重复之间具有高度的可重复性。研究了参与细胞壁结构代谢的基因的表达水平，包括果胶、纤维素、半纤维素和木质素。同时，分析了成熟果实果皮的化学成分含量。该研究提供了不同感官品质柑橘的详细转录调控谱，并深入了解了影响柑橘感官质地的机制。
