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Proteomics and metabolomics analyses reveal the cucurbit sieve tube system as a complex metabolic space
Author(s) -
Hu Chaoyang,
Ham ByungKook,
Elshabrawi Hattem M.,
Alexander Danny,
Zhang Dabing,
Ryals John,
Lucas William J.
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13209
Subject(s) - phloem , metabolite , metabolomics , metabolic pathway , sieve tube element , biology , biochemistry , botany , enzyme , microbiology and biotechnology , bioinformatics
Summary The plant vascular system, and specifically the phloem, plays a pivotal role in allocation of fixed carbon to developing sink organs. Although the processes involved in loading and unloading of sugars and amino acids are well characterized, little information is available regarding the nature of other metabolites in the sieve tube system ( STS ) at specific sites along the pathway. Here, we elucidate spatial features of metabolite composition mapped with phloem enzymes along the cucurbit STS . Phloem sap ( PS ) was collected from the loading (source), unloading (apical sink region) and shoot–root junction regions of cucumber, watermelon and pumpkin. Our PS analyses revealed significant differences in the metabolic and proteomic profiles both along the source–sink pathway and between the STS s of these three cucurbits. In addition, metabolite profiles established for PS and vascular tissue indicated the presence of distinct compositions, consistent with the operation of the STS as a unique symplasmic domain. In this regard, at various locations along the STS we could map metabolites and their related enzymes to specific metabolic pathways. These findings are discussed with regard to the function of the STS as a unique and highly complex metabolic space within the plant vascular system.