Variation in content and composition of lignin in young wood of Norway spruce

Abstract

Abstract Lignin content and composition are important traits in several tree breeding programs, but very little is known about their natural variation. This study compares the lignin content in 1-year-old plants and 9-year-old trees of Norway spruce belonging to the same full-sib families. It is shown that the lignin content, according to the modified acetyl bromide method, does not vary significantly within or among the different full-sib families either as plants or as young trees. There is, however, on average 4.0% higher lignin content (31.4% versus 27.4%) and lower standard error for the trees than for the plants. The number of C9-units g−1 lignin, analyzed by thioacidolysis, ranges from 516 to 1186 μmmol C9-units g−1 lignin in plants and from 716 to 953 μmmol C9-units g−1 lignin in trees, with no significant differences among the families. However, the extent of change in C9-units g−1 lignin varies among the families with age. The ratio of erythro and threo stereoisomers does not vary significantly among the families. However, the ratio changes differently with age among the families similar to the C9-units g−1 lignin. Additionally, the content of p-hydroxyphenyl (H) lignin is 0.6% higher in the trees than in the plants (1.4% versus 0.8%), estimated indirectly from GC-MS data by a novel subtractive technique, indicating a higher degree of compression wood in the young trees. In conclusion, the amount and composition of lignin does not vary within or among the families at the same age. However, the amount of lignin increases with age while the change in lignin composition varies between family and age.