Dynamics and Transcriptome Analysis of Starch and Sucrose Metabolism During Corm Development in Freesia Hybrida

Abstract

Background Starch and sucrose metabolism plays a crucial role in the formation and development of bulbs in bulbous plants, which, however, remains unclear and unexplored in the corms of Freesia hybrida, one kind of famous bulbous flower. Herein, we investigated the dynamics of the major form of carbohydrates and related enzyme activities and profiled the transcriptome of freesia corms at four developmental stages with the aim to reveal the relation of starch and sucrose metabolism to corm development and the transcriptional regulation of this metabolic process.Results The content of starch, sucrose and soluble sugars followed an overall upward trend across the corm developmental stages. Activities of the adenosine diphosphoglucose pyrophosphorylase, starch branching enzyme and β-amylase generally followed the pattern of the starch and sucrose level. Activities of sucrose phosphate synthase increased from corm formation till the initial swelling stage and subsequently reached a plateau. Activities of invertase and sucrose synthase peaked at the later rapid swelling stage. Transcriptome analysis revealed a total of 100,999 unigenes, out of which 44,405 unigenes were annotated. Analysis based on Clusters of Orthologous Groups suggested that carbohydrate transport and metabolism (9.34% of the sequences) was prominent across the corm developmental process. Totally 3427 differentially expressed genes were identified and the enrichment analysis directed starch and sucrose metabolism a critical pathway in corm development especially at the rapid swelling stage. Genes encoding key carbohydrate-metabolizing enzymes were identified and their differential expression related to corm development was explored.Conclusions The comparative transcriptome analysis discloses essential roles of starch and sucrose metabolism and the genetic mechanism related to the corm development. The results construct a valuable resource pool for further molecular-level studies, which are helpful for metabolic regulation of carbohydrates and improvement in molecular breeding of Freesia hybrida.

Insights into the regulation of energy metabolism during the seed-to-seedling transition in marine angiosperm Zostera marina L.: Integrated metabolomic and transcriptomic analysis

“…Starch and sucrose regulatory pathway is crucial in maintaining the dynamic balance of sugar substances and energy homeostasis in plant growth and development by regulating the interconversion of starch and sugar (Zhao et al, 2022). Some studies have suggested that sucrose serves as a substrate for the formation of storage reserves and as a main nutrient and energy source for plant development (Yu et al, 2016;Ma et al, 2020). In the metabolic pathways of Nelumbo nucifera, sucrose is mainly produced in leaves by photosynthesis, transported to seeds, and then accumulated as energy reserves for seed maturation (Wang et al, 2016a).…”

“…Previous studies have shown that energy metabolism plays a dominant role in regulating seed development; it provides the material and energy basis for seed development by regulating the synthesis, hydrolysis, and conversion of storage compounds, such as starch, storage proteins, and lipids (Liu et al, 2015;Ali and Elozeiri, 2017;Ma et al, 2017). Starch is the major form of carbohydrates and energy carriers in plant storage organs (Ma et al, 2020). The amylolytic breakdown of stored starch in seeds during germination is an important biochemical event that provides reducing sugars as energy sources to support the early stages of seed germination in angiosperm plants (Chen et al, 2019).…”