Activity of two lignin biosynthesis enzymes during development of a maize internode

Abstract

To ascertain the temporal relationships of phenylpropanoid and lignin pathway enzymes, phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol-NADPH dehydrogenase (CAD), with lignin concentration, PAL and CAD activities and lignin concentrations were assessed during progressive development of the 10th internode in maize (Zea mays L). Enzyme activities were quantified and lignin concentrations were determined by the detergent system of fiber fractionation from lower, middle, and upper sections of the elongating internode harvested 3, 5, 7, 9, 11, 13, and 15 days after the internode had reached 10 mm in length. Over 15 days, a coordinated, sequential, and basipetal pattern of enzyme activities and lignin accumulation evolved through the internode, spanning the stages of rapid elongation, cellular differentiation, and secondary cell wall formation. PAL activity was initiated first, rising to peak activity in elongating tissue, and falling basipetally in tissues as they matured. CAD activity rose in fully elongated, maturing internode tissue where PAL activity was waning following its peak activity. Lignin accumulated in tissues with high CAD activity. CAD activity and lignin deposition patterns were similar : simultaneously increasing in activity and deposition over time while activity and deposition also shifting basipetally through the internode, keeping pace with secondary cell wall formation. Lignin concentration correlated significantly with CAD, but not with PAL.

Spatial gradients in cell wall composition and transcriptional profiles along elongating maize internodes

“…At this time the internode was actively elongating and would normally elongate to about 15 cm within a couple of days [26]. The basal Section S1 contained intercalary meristem cells.…”

Overexpression of GA20‐OXIDASE1 impacts plant height, biomass allocation and saccharification efficiency in maize

“…We have measured cellulose and lignin levels in the ninth internode of plants from V10 to S + 14d. Consistent with literature (Morrison et al ., ; Zhang et al ., ), we found that the onset of secondary cell wall formation in a developing internode of control plants involved cellulose deposition first (V10 to V14), followed by lignin biosynthesis (V12 to S). The cell wall fraction (CWR/DW) first increased (V10 to V14) and then was stable towards silking (between V14 and S).…”

Maize Stem Tissues: Impact of Development on Cell Wall Degradability

“…While phloroglucinol‐stained thin sections taken from the middle of these elongating internodes did not show the presence of lignin, other than in protoxylem vessels, it would be expected that the older cells closer to the top of the internode may have completed elongation and begun the post‐elongation, secondary wall deposition process by this sampling date. Morrison et al (1994) reported that lignification had begun in the top third of an elongating maize internode by Day 6 of a 13‐d elongation period. The middle third of the maize internode did not contain more acid detergent lignin than the bottom third of the internode until Day 9 of elongation (Morrison et al, 1994).…”