Trehalose promotes the formation of Lanzhou lily bulblets by increasing carbohydrate content

Recent studies have shown that trehalose plays an important and pervasive role in plants, which actively regulates seed germination, flowering, and stress tolerance. However, whether trehalose promotes bulblet formation in Lanzhou lily (Lilium davidii) scale cutting propagation has not been reported. In the current study, the regulatory roles of trehalose during the formation of bulblets in lily-scale cutting were investigated. The results show that trehalose significantly increased the number and diameter of bulblets with an optimal concentration at 50 mM. Moreover, trehalose increased the content of sucrose, starch, soluble sugar and endogenous trehalose in the scales and bulblets. These results indicate that trehalose might promote the formation of Lanzhou lily bulblets by increasing the carbohydrate content in the scales. Further, trehalose improved trehalose 6-phosphate synthase (TPS) and ADP glucose pyrophosphorylase (AGP) activity, reduced Sucrose synthase (SuSy) activity in scales, up-regulated SSS1, SBE, AGP1, TPS6, TPS7, TPS9 expression level in scales on day 50, and down-regulated SuSy1 and INV2 expression level in scales. Therefore, trehalose might increase carbohydrates content in scales and bulblets by regulating the activity and gene expression of key enzymes in carbohydrate synthesis and hydrolysis pathways, thereby promoting bulblet formation in Lanzhou lily-scale cutting.