Metabolomic and Proteomic Profiles Reveal the Dynamics of Primary Metabolism during Seed Development of Lotus (Nelumbo nucifera)

Lei Wang,Wolfram Weckwerth,Pingfang Yang,Jinlei Fu,Ming Li,Lena Fragner

doi:10.3389/fpls.2016.00750

Lei Wang, Wolfram Weckwerth + Show 4 more

Open Access

https://doi.org/10.3389/fpls.2016.00750

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Abstract

Sacred lotus (Nelumbo nucifera) belongs to the Nelumbonaceae family. Its seeds are widely consumed in Asian countries as snacks or even medicine. Besides the market value, lotus seed also plays a crucial role in the lotus life cycle. Consequently, it is essential to gain a comprehensive understanding of the development of lotus seed. During its development, lotus seed undergoes cell division, expansion, reserve accumulation, desiccation, and maturation phases. We observed morphological and biochemical changes from 10 to 25 days after pollination (DAP) which corresponded to the reserve synthesis and accumulation phase. The volume of the seed expanded until 20 DAP with the color of the seed coat changing from yellow-green to dark green and gradually fading again. Starch and protein rapidly accumulated from 15 to 20 DAP. To further reveal metabolic adaptation, primary metabolites and proteins profiles were obtained using mass spectrometry based platforms. Metabolites and enzymes involved in sugar metabolism, glycolysis, TCA cycle and amino acid metabolism showed sequential dynamics enabling the clear separation of the different metabolic states during lotus seed development. The integration of the data revealed a highly significant metabolic switch at 15 DAP going through a transition of metabolically highly active tissue to the preparation of storage tissue. The results provide a reference data set for the evaluation of primary metabolism during lotus seed development.

Highlights

Sacred lotus (Nelumbo nucifera) belongs to the small plant family of Nelumbonaceae (The Angiosperm Phylogeny Group, 2009), which is found at a basal position of eudicot plants and contains only one genus (Nelumbo) with only two species, sacred lotus and American lotus (Nelumbo lutea) (Pan et al, 2010)
It has been reported that the development of lotus seed could be divided into four phases, phase I cell division and organ formation (1–3 days after pollination, DAP), phase II cell enlargement (4–9 DAP), phase III reserves synthesis and accumulation (10–25 DAP), phase IV desiccation and maturation (Tang et al, 1989)
As mentioned above, sacred lotus seeds can be consumed either freshly or in a mature desiccated form, which is determined by the transition from the stage containing a high content of soluble sugars to a high starch content and desiccated stage

Summary

Introduction

Sacred lotus (Nelumbo nucifera) belongs to the small plant family of Nelumbonaceae (The Angiosperm Phylogeny Group, 2009), which is found at a basal position of eudicot plants and contains only one genus (Nelumbo) with only two species, sacred lotus and American lotus (Nelumbo lutea) (Pan et al, 2010). N. nucifera is distributed in Asia and Northern Australia, Metabolome and Proteome of Developing Lotus Seed whereas N. lutea inhabits the eastern areas of North America and the northern area of South America. In Asia, sacred lotus is an economically important crop with a very long cultivation history. It is widely used as food, medicine, and ornamental plant. Based on its agricultural and horticultural utilization, it can be divided into three groups, namely flower, seed, and rhizome lotus

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