Transcriptome analysis of carbohydrate metabolism during bulblet formation and development in Lilium davidii var. unicolor

Abstract

BackgroundThe formation and development of bulblets are crucial to the Lilium genus since these processes are closely related to carbohydrate metabolism, especially to starch and sucrose metabolism. However, little is known about the transcriptional regulation of both processes. To gain insight into carbohydrate-related genes involved in bulblet formation and development, we conducted comparative transcriptome profiling of Lilium davidii var. unicolor bulblets at 0 d, 15 d (bulblets emerged) and 35 d (bulblets formed a basic shape with three or four scales) after scale propagation.ResultsAnalysis of the transcriptome revealed that a total of 52,901 unigenes with an average sequence size of 630 bp were generated. Based on Clusters of Orthologous Groups (COG) analysis, 8% of the sequences were attributed to carbohydrate transport and metabolism. The results of KEGG pathway enrichment analysis showed that starch and sucrose metabolism constituted the predominant pathway among the three library pairs. The starch content in mother scales and bulblets decreased and increased, respectively, with almost the same trend as sucrose content. Gene expression analysis of the key enzymes in starch and sucrose metabolism suggested that sucrose synthase (SuSy) and invertase (INV), mainly hydrolyzing sucrose, presented higher gene expression in mother scales and bulblets at stages of bulblet appearance and enlargement, while sucrose phosphate synthase (SPS) showed higher expression in bulblets at morphogenesis. The enzymes involved in the starch synthetic direction such as ADPG pyrophosphorylase (AGPase), soluble starch synthase (SSS), starch branching enzyme (SBE) and granule-bound starch synthase (GBSS) showed a decreasing trend in mother scales and higher gene expression in bulblets at bulblet appearance and enlargement stages while the enzyme in the cleavage direction, starch de-branching enzyme (SDBE), showed higher gene expression in mother scales than in bulblets.ConclusionsAn extensive transcriptome analysis of three bulblet development stages contributes considerable novel information to our understanding of carbohydrate metabolism-related genes in Lilium at the transcriptional level, and demonstrates the fundamentality of carbohydrate metabolism in bulblet emergence and development at the molecular level. This could facilitate further investigation into the molecular mechanisms underlying these processes in lily and other related species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0358-4) contains supplementary material, which is available to authorized users.

Somatic embryogenesis and direct as well as indirect organogenesis in Lilium pumilum DC. Fisch., an endangered ornamental and medicinal plant

“…28) In this study, starch and sucrose contents were determined during the preparation of regenerated bulblets in vitro. Results indicate that starch content in mother scales and bulblets stabilized after 45 d, after which bulblets developed with a final and complete shape.…”

Effect of blanching and drying temperatures on the browning‐related enzymes and physicochemical properties of lily bulb flours

“…Lily bulbs are good sources of starches, and its content accounted for 62.33% to 69.07% of the dry weight (Yu, Zhang, Li, Wang, & Xiong, 2015). The starch physicochemical properties, including morphology, amylose, crystal, and thermal properties, were affected by growth periods and cultivars (Li, Gao, Jiang, & Xia, 2012;Li et al, 2014;Takeda, Takeda, & Hizukuri, 1983;Wu, Wu, Jiao, Zhang, & Lv, 2012;Yu, Zhang, Shao, et al, 2015). Huang et al (2017) found that UV-C treatment downregulated the activities of α-amylase and β-amylase resulting in a higher content than that of the control during storage.…”

The proof is in the bulb: glycerol influences key stages of lily development

“…Transcriptome analyses have been performed in several Lilium species, to explore the effect of cold exposure (Wang et al ., ; Villacorta‐Martin et al ., ), carbohydrate metabolism (Li et al ., ), stress (Wang et al ., ), and dormancy release (Wang et al ., ). To the best of our knowledge, no transcriptome analysis was ever performed in the context of bulb size.…”