. 2021 Jul 2;12:679966. doi: 10.3389/fpls.2021.679966

TABLE 3.

Abundance of compounds observed in pretreatment liquid fractions obtained from leaf and stem plant material.

	Leaf				Stem
	NP	WRF	ALK	W + K	NP	WRF	ALK	W + K
Coumaric acid	ND	ND	+ +	+ + + +	ND	ND	+ +	+ + +	*Arundo donax*
Hydroxybenzoic acid	ND	ND	Trace	+ + +	ND	ND	+	+ + +
Ferulic acid	+	+ +	+	+	ND	ND	+	ND
Diferulic acid isomers	+ + +	+ + +	ND	+ +	+ + +	ND	ND	ND
Ferulic acid cyclobutane isomers	+ + + +	+ + +	ND	+ +	+ + +	Trace	ND	Trace
Apigenin-C-pentoside-C-pentoside	ND	+	ND	+	+	ND	ND	+
Apigenin-C-hexoside-C-pentoside	+	+	+	+ +	+ +++	+	+ +	+ +
Coumaric acid	ND	ND	+ + +	+ + + +	ND	ND	+ +	+ + + +	*Cortaderia selloana*
Hydroxybenzoic acid	ND	ND	+ +	+ + +	ND	ND	+ + +	+ + +
Ferulic acid	Trace	ND	ND	ND	ND	ND	ND	ND
Diferulic acid isomers	+ +	+ + +	+ + +	+ +	+	+ +	+	+ +
Ferulic acid cyclobutane isomers	+ +	+ + +	+ +	+	+	+	+	+
Apigenin-C-pentoside-C-pentoside	ND	ND	ND	ND	ND	ND	ND	ND
Apigenin-C-hexoside-C-pentoside	+ +	+	+ +	++	+ ++	++ + +	+ +++	++ + +
Compound M_r 436	ND	ND	ND	ND	ND	ND	ND	ND
Coumaric acid	ND	ND	+ + + +	+ +	ND	Trace	+ + + +	+ + + +	*Phragmites australis*
Hydroxybenzoic acid	ND	ND	+	+	Trace	ND	+ + +	+ + +
Ferulic acid	+ + +	+ + +	+	+	Trace	Trace	ND	ND
Diferulic acid isomers	+ + + +	+ + +	+ +	+ +	+ +	+ +	Trace	+
Ferulic acid cyclobutane isomers	+ + + +	+ +	+ +	+ +	Trace	+	+	+
Apigenin-C-pentoside-C-pentoside	ND	+ + + +	ND	+ + +	Trace	+ + +	+	+ +
Apigenin-C-hexoside-C-pentoside	ND	+ + + +	ND	+ + +	ND	+ + + +	ND	+ + + +
Compound M_r 436	ND	ND	ND	ND	ND	ND	ND	ND
Coumaric acid					ND	ND	+ + + +	+ + + +	**Miscanthus × giganteus**
Hydroxybenzoic acid					ND	ND	+ + + +	+ + +
Ferulic acid					Trace	Trace	ND	ND
Diferulic acid isomers					ND	+	Trace	Trace
Ferulic acid cyclobutane isomers					ND	+ +	+	+
Apigenin-C-pentoside-C-pentoside					ND	ND	ND	ND
Apigenin-C-hexoside-C-pentoside					ND	ND	ND	ND
Compound M_r 436					ND	+ + + +	ND	+ + + +

The apigenin-C-hexoside-C-pentoside (AHP) compound schaftoside is commonly reported in grasses, however there are other flavonoids that are also relatively abundant in grasses. Furthermore, there are also reports of flavonoid biosynthesis in white rot fungi (Gąsecka et al., 2015). Pretreatments: NP, non-pretreated control samples (incubated only with water); WRF, samples pretreated with Pleurotus ostreatus; ALK, samples pretreated with 0.1 M NaOH for 24 h at 21°C; W + K, samples pretreated with P. ostreatus followed by 0.1 M NaOH for 24h at 21°C. The symbol “+” indicates levels detected, ND, not detected; Trace, very low levels detected.