Wang Haojie, Jian Liru, Wang Zhipeng, Jiao Yu, Wang Yuzhu, Ma Fengwang, Li Pengmin
State Key Laboratory for Crop Stress Resistance and High-Efficiency/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
Plant Cell Environ. 2024 Nov;47(11):4398-4415. doi: 10.1111/pce.15031. Epub 2024 Jul 12.
Phloretin has different glycosylation modes in plants. Phlorizin (phloretin 2'-O-glucoside) is one of the glycosylation products of phloretin, and accumulates abundantly in apple plants. However, it is still unclear whether phlorizin is more beneficial for apple plants compared with other glycosylation products of phloretin. We created transgenic apple plants with different glycosylation modes of phloretin. In transgenic plants, the accumulation of phlorizin was partly replaced by that of trilobatin (phloretin 4'-O-glucoside) or phloretin 3',5'-di-C-glycoside. Compared with wild type, transgenic plants with less phlorizin showed dwarf phenotype, larger stomatal size, higher stomatal density and less tolerance to drought stress. Transcriptome and phytohormones assay indicate that phlorizin might regulate stomatal development and behaviour via controlling auxin and abscisic acid signalling pathways as well as carbonic anhydrase expressions. Transgenic apple plants with less phlorizin also showed less resistance to spider mites. Apple plants may hydrolyse phlorizin to produce phloretin, but cannot hydrolyse trilobatin or phloretin 3',5'-di-C-glycoside. Compared with its glycosylation products, phloretin is more toxic to spider mites. These results suggest that the glycosylation of phloretin to produce phlorizin is the optimal glycosylation mode in apple plants, and plays an important role in apple resistance to stresses.
根皮素在植物中有不同的糖基化模式。根皮苷（根皮素2'-O-葡萄糖苷）是根皮素的糖基化产物之一，在苹果植株中大量积累。然而，与根皮素的其他糖基化产物相比，根皮苷是否对苹果植株更有益仍不清楚。我们培育了具有不同根皮素糖基化模式的转基因苹果植株。在转基因植株中，根皮苷的积累部分被三叶苷（根皮素4'-O-葡萄糖苷）或根皮素3',5'-二-C-糖苷所取代。与野生型相比，根皮苷含量较低的转基因植株表现出矮化表型、气孔尺寸更大、气孔密度更高以及对干旱胁迫的耐受性更低。转录组和植物激素分析表明，根皮苷可能通过控制生长素和脱落酸信号通路以及碳酸酐酶表达来调节气孔发育和行为。根皮苷含量较低的转基因苹果植株对叶螨的抗性也较低。苹果植株可能将根皮苷水解产生根皮素，但不能水解三叶苷或根皮素3',5'-二-C-糖苷。与其糖基化产物相比，根皮素对叶螨的毒性更大。这些结果表明，根皮素糖基化生成根皮苷是苹果植株中的最佳糖基化模式，并且在苹果抗逆性中发挥重要作用。
