School of Agriculture, Ningxia University, Yinchuan 750021, China.
USDA-ARS-NEA, Adaptive Cropping Systems Laboratory, 10300 BARC, Beltsville, MD 20705, USA.
Tree Physiol. 2019 Jun 1;39(6):1032-1045. doi: 10.1093/treephys/tpz014.
Goji berry (Lycium barbarum L.) is one of the important economic crops due to its exceptional nutritional value and medicinal benefits. Although reduced sugar levels in goji berry exposed to long-term elevated carbon dioxide (CO2) have been documented, the underlying molecular mechanisms remain unknown. The objective of this study was to explore the transcriptome of goji berry fruit under ambient and elevated CO2 concentrations and further to screen the differentially expressed genes (DEGs) for functions related to sugar metabolism. Fruit samples from goji berry exposed to ambient (400 μmol mol-1) and elevated (700 μmol mol-1) levels of CO2 for 120 days were analyzed for total sugar, carotenoid and flavone analysis. In this study, a reduction in total sugar and carotenoid levels in the fruits grown under elevated CO2 levels were observed. Fruit samples were also used to construct cDNA libraries using a HiSeqTM2500 platform. Consequently, 81,100 unigenes were assembled, of which 35,111 (43.3%) were annotated using various databases. Through DEGs analysis, it was found that 55 genes were upregulated and 18 were down-regulated in response to elevated CO2 treatment. Genes involved in the sugar metabolism and the related pathways were identified by Gene Ontology and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis. Furthermore, three genes, LBGAE (Lycium barbarum UDP-glucuronate 4-epimerase), LBGALA (Lycium barbarum alpha-galactosidase) and LBMS (Lycium barbarum malate synthase), associated with sugar metabolism were identified and discussed with respect to the reduction in the total sugar levels along with the enzymes acid invertase (AI), sucrose synthase (SS) and sucrose phosphate synthase (SPS) of the sucrose metabolism. This study can provide gene sources for elucidating the molecular mechanisms of sugar metabolism in the fruit of goji berry under elevated CO2.
枸杞（Lycium barbarum L.）是一种重要的经济作物，具有独特的营养价值和药用功效。虽然已经有研究报道了长期暴露在高浓度二氧化碳（CO2）下的枸杞果实中糖分含量降低的现象，但其中的分子机制仍不清楚。本研究旨在探讨在常温和高 CO2 浓度下枸杞果实的转录组，并进一步筛选与糖代谢相关的差异表达基因（DEGs）。将枸杞果实暴露在常温和高 CO2（400 μmol mol-1 和 700 μmol mol-1）浓度下 120 天后，分析其总糖、类胡萝卜素和类黄酮含量。本研究发现，在高 CO2 浓度下生长的果实中总糖和类胡萝卜素水平降低。还使用果实样本通过 HiSeqTM2500 平台构建 cDNA 文库。最终，组装了 81100 个 unigenes，其中 35111 个（43.3%）通过各种数据库进行了注释。通过 DEGs 分析，发现有 55 个基因上调，18 个基因下调，对高 CO2 处理有响应。通过基因本体论和京都基因与基因组百科全书（KEGG）途径富集分析，鉴定出与糖代谢相关的基因和途径。此外，还鉴定出与糖代谢相关的三个基因 LBGAE（Lycium barbarum UDP-葡萄糖酸 4-差向异构酶）、LBGALA（Lycium barbarum alpha-半乳糖苷酶）和 LBMS（Lycium barbarum 苹果酸合酶），并讨论了其与总糖水平降低以及蔗糖代谢中的酸性转化酶（AI）、蔗糖合酶（SS）和蔗糖磷酸合酶（SPS）等酶的关系。本研究可为阐明高 CO2 下枸杞果实糖代谢的分子机制提供基因资源。
