Metabolite fingerprints of maize and sugarcane seedlings: searching for markers after inoculation with plant growth-promoting bacteria in humic acids

Chemical and Biological Technologies in Agriculture

Table 1 List of metabolites that showed significantly higher abundances in both maize and sugarcane extracts from seedlings treated with humic acids and plant growth-promoting bacteria in comparison with respective control

Compounds	Maize	Sugarcane	Remark
Maleic acid	116*	122*	From Krebs tricarboxylic acid cycle (TCA)
Malic acid	1384**	345**
Malonic acid	416**	298**
Fumaric acid	505**	126**
Citric acid	949**	740**
Isocitric acid	2131**	140**
Aconitic acid	6959**	2567**
Aspartic acid	120**	629**	Essential amino acid
Shikimic acid	955**	385**	Precursor of aromatic compounds, key metabolism in the phenyl propanoid pathway
4-Hydroxybenzoate	223**	98**	It is isomeric with 2-hydroxybenzoic acid, known as salicylic acid, a precursor to aspirin
3,4-Dihydroxycinnamic acid	113**	29**	Aromatic compound
Quinic acid	578**	494**	A cyclic polyol
Mucic acid	395**	408**	Is an aldaric acid obtained by oxidation of galactose or galactose
Ribonic acid	136**	155**	Ribonic acid is a product of the enzyme ribose 1-dehydrogenase (NADP+) [EC 1.1.1.115]
Trehalose	25*	133**	Sugar linked to drought-stress plant response
Erythritol	53*	169*	Nutrient for several α-2 Proteobacteria
Oxalic acid	971**	259**	Strong dicarboxylic acid produced by metabolism of glyoxylic acid or ascorbic acid
Threonic acid	216**	211**	Sugar acid derived from threose. The l-isomer is a metabolite of ascorbic acid (vitamin C)
Isothreonic acid	233**	211**	Vitamin C derivative
Tocopherol	38*	49*	Vitamin E
Linolenic acid	29*	495**	Unsaturated fatty acid:octadecatrienoic acids (18:3)
Myristic acid	42*	175*	Saturated fatty acid with the molecular formula CH₃(CH₂)₁₂COOH
2-Monopalmitin	42*	357**	Unsaturated fatty acid

The number represent the percentage of increase in respect to control level followed by the F significance test (p < 0.01** and p < 0.05)