Wang Cui-Cui, Sulli Maria, Fu Da-Qi
Fruit Biology Laboratory, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
Italian National Agency for New Technologies, Energy and Sustainable Development, Roma, Italy.
PLoS One. 2017 Dec 13;12(12):e0189481. doi: 10.1371/journal.pone.0189481. eCollection 2017.
Glycoalkaloids are toxic compounds that are synthesized by many Solanum species. Glycoalkaloid biosynthesis is influenced by plant genetic and environmental conditions. Although many studies have shown that light is an important factor affecting glycoalkaloid biosynthesis, the specific mechanism is currently unknown. Chlorophyll and carotenoid biosynthesis depend on light signal transduction and share some intermediate metabolites with the glycoalkaloid biosynthetic pathway. Here, we used virus-induced gene silencing to silence genes encoding phytoene desaturase (PDS) and magnesium chelatase (CHLI and CHLH) to reduce chlorophyll and carotenoid levels in eggplant leaves. Quantification of carotenoid and chlorophyll levels is analyzed by LC/PDA/APCI/MS and semipolar metabolite profiling by LC/HESI/MS. Notably, the resulting lines showed decreases in glycoalkaloid production. We further found that the expression of some genes involved in the production of glycoalkaloids and other metabolites were suppressed in these silenced lines. Our results indicate that photosynthetic pigment accumulation affects steroidal glycoalkaloid biosynthesis in eggplant leaves. This finding lays the foundation for reducing the levels of endogenous antinutritional compounds in crops.
糖苷生物碱是许多茄属植物合成的有毒化合物。糖苷生物碱的生物合成受植物遗传和环境条件的影响。尽管许多研究表明光照是影响糖苷生物碱生物合成的重要因素，但具体机制目前尚不清楚。叶绿素和类胡萝卜素的生物合成依赖于光信号转导，并且与糖苷生物碱生物合成途径共享一些中间代谢产物。在此，我们利用病毒诱导的基因沉默技术使编码八氢番茄红素去饱和酶（PDS）和镁螯合酶（CHLI和CHLH）的基因沉默，以降低茄子叶片中的叶绿素和类胡萝卜素水平。通过LC/PDA/APCI/MS分析类胡萝卜素和叶绿素水平的定量，并通过LC/HESI/MS进行半极性代谢物分析。值得注意的是，所得品系的糖苷生物碱产量降低。我们进一步发现，在这些沉默品系中，一些参与糖苷生物碱和其他代谢物生产的基因表达受到抑制。我们的结果表明，光合色素积累影响茄子叶片中甾体糖苷生物碱的生物合成。这一发现为降低作物中内源性抗营养化合物的水平奠定了基础。
