Identifying new lignin bioengineering targets: 1. Monolignol-substitute impacts on lignin formation and cell wall fermentability

Table 1 Klason lignin, in-vitro ruminal fermentation kinetics^a, nonfermentable polysaccharides (NP), gas reduction per unit lignin (GRL)^b, and nonfermentable polysaccharide accumulation per unit lignin (NPAL)^c for nonlignified and artificially lignified cell walls of maize.

Monolignols	Lignin mg/g	L₁ (h)	k₁ (h^-1)	A(mL/g)	L₂ (h)	k₂ (h^-1)	B(mL/g)	AB(mL/g)	NP (mg/g)	GRL	NPAL
Nonlignified	--	2.0	0.217	290	2.4	0.044	53	343	22	--	--
CA:SA	153	3.4	0.097	243	19.9	0.067	17	259	114	0.545	0.604
CA:SA:DHCA	154	3.0	0.094	241	17.6	0.068	23	265	113	0.508	0.594
CA:SA:GG	152	2.6	0.099	243	13.6	0.053	28	271	94	0.473	0.474
CA:SA:MC	111	2.1	0.124	265	9.1	0.049	33	298	59	0.406	0.343
CA:SA:CQA	92	2.1	0.160	272	5.3	0.050	42	315	28	0.308	0.071
CA:SA:MF	159	3.2	0.080	211	15.6	0.067	23	235	166	0.680	0.911
CA:SA:FQA	117	2.8	0.130	265	10.7	0.048	30	295	52	0.410	0.258
CA:SA:EC	170	2.9	0.060	238	31.6	0.118	6	244	155	0.578	0.779
CA:SA:EGC	160	3.1	0.094	259	23.3	0.089	11	270	87	0.455	0.413
CA:SA:EGCG	167	3.1	0.098	246	16.6	0.057	23	269	88	0.443	0.399
LSD^d	12	0.7	0.015	16	9.9	0.036	17	14	21	0.115	0.120

^aKinetic parameters: lag time (L₁), rate constant (k₁), and volume (A) of gas produced from a rapidly digested pool; lag time (L₂), rate constant (k₂), and volume (B) of gas produced from a slowly digested pool; and total gas volume (AB)
^bGRL calculated as (AB_nonlignified - AB_lignified)/Klason lignin
^cNPAL calculated as (NP_lignified - NP_nonlignified)/Klason lignin
^dLSD, least significant difference (P = 0.05).
Cell walls were lignified with a binary mixture of coniferyl alcohol (CA) and sinapyl alcohol (SA) or trinary mixtures of CA and SA with dihydroconiferyl alcohol (DHCA), guaiacylglycerol (GG), methyl caffeate (MC), caffeoylquinic acid, (CQA), methyl ferulate (MF), feruloylquinic acid (FQA), epicatechin (EC), epigallocatechin (EGC), or epigallocatechin gallate (EGCG).

ISSN: 1471-2229