. 2017 Jul 13;8:1134. doi: 10.3389/fpls.2017.01134

Table 4.

Metabolites enriched at different stages of rice stem internode development.

K-means cluster^a	Enriched sample(s)^b	ESI−^c		ESI+^c
		Metabolite ions^d	Representative metabolite^e	Metabolite ion^d	Representatives metabolite^e
Cluster 1	Elongating stem (ES)	1,021	coniferyl aldehyde	667	Methyl cinnamate
Cluster 2	Elongating stem (ES) and mature stem (MS)	1,426	NCI	1,112	6,7-dihydroxycoumarin, phenylacetaldehyde
Cluster 3	Early mature stem (EMS)	1,222	NCI	440	Demethoxycurcumin, xanthotoxol
Cluster 4	Mature stem (MS)	770	NCI	284	Benzaldehyde, olivetol
Cluster 5	Post mature stem (PMS)	1,899	isoscoparin 2-(6-(E)-p-coumaroylglucoside), isoscoparin 2-(6-(E)-ferulylglucoside)	717	Tricin 7-glucoside

Clusters of metabolites were determined based on abundance within the dataset.

Sample or samples in which metabolites in the cluster are most abundant.

Charge of the electrospray used to ionize metabolites prior to mass spectrometry. ESI−, negative electrospray ionization mode; ESI+, positive electrospray ionization mode.

The number of metabolite ions in the cluster. The retention time and mass-to-charge ratio of detected ions can be found in Tables S10, S11.

Examples of tentatively annotated metabolites. Other annotated metabolites can be found in Tables S10, S11. NCI indicates no confident identifications.