Fungus-induced changes in expression of the wheat lignin biosynthesis pathway. A, Schematic of pathways leading to lignin formation in plants. Metabolite analysis of Z. tritici-infected wheat leaves identified increased levels of Phe and ferulate during the late stages of infection. B, Relative expression changes of lignin biosynthetic pathway components in wheat leaves from 1 to 14 dpi with Z. tritici. Green shading indicates significant down-regulation (adjusted P < 0.05), while red shading indicates up-regulation (adjusted P < 0.05). PAL, Phenylalanine ammonia lyase; C4H, cinnamate 4-hydroxylase; C3H, p-coumarate 3-hydroxylase; COMT, caffeic acid O-methyl transferase; F5H, ferulate 5-hydroxylase; 4CL, 4-coumarate:CoA ligase; CCR, cinnamoyl-CoA reductase; CCoA-3H, cinnamyl alcohol dehydrogenase; CCoA-OMT, caffeoyl-CoA O-methyltransferase; CAD, cinnamyl-alcohol dehydrogenase.