Fig. 4.

AM colonization reduces SCW marker gene activity and alters the composition of cell wall phenolics in distinct zones of CRs. (A) Real time RT-PCR–based expression pattern of the SCW marker gene CesA4 in noncolonized (NC) and mycorrhizal (M) crown roots (CRs), large lateral roots (LLRs), and fine lateral roots (FLRs). Means of two technical replicates are shown. (B) pCesA4-GUS expression in old (OCRs) and early emerging (ECRs) noncolonized (NC), and mycorrhizal (M) crown roots and in NC vs. M mature crown roots (MCRs). (Scale bars, 1 cm.) (C) Cell wall phenolic acid (lignin precursor) composition of tips (one-third of root length from apex of CRs) of NC and M root systems as determined by HPLC-multiple reaction monitoring (MRM) after alkaline hydrolysis followed by an acid hydrolysis. Data for each hydrolysis subfraction are displayed. Means ± SE of eight biological replicates consisting each of a pool of five root systems are shown in micrograms per gram of cell wall residues (CWRs). S, H, and G refer to the phenolic acid precursors of S, H, and G lignin. S refers to the sum of syringic and sinapic acid; H refers to the sum of 4-OH-benzaldehyde, 4-OH-benzoic acid, p-coumaric acid, and caffeic acid; and G refers to the sum of vanillic acid, ferulic acid, and coniferaldehyde. (D) Details of the measured extracts shown in C for all conditions where changes between NC and M were significant.