Lignin is a chemical compound found in which tissue?
Answers
Answer:
ethnic chemical compound
Answer:
Lignin is deposited mainly in tracheids, vessels, fibres of xylem and phloem and sclerenchyma. However, lignin composition varies among species, phylogenetic groups, cell types, developmental stages and even seasonal growth.
Explanation:
Lignin is a polymer resulting from the oxidative coupling of primarily three p-hydroxycinnamyl alcohols (monolignols): p-coumaryl, coniferyl and sinapyl alcohols. Lignin is deposited mainly in tracheids, vessels, fibres of xylem and phloem and sclerenchyma. However, lignin composition varies among species, phylogenetic groups, cell types, developmental stages and even seasonal growth. In recent decades, the number of species where lignins have been detected has notably increased, such as the red alga Calliarthron, some Coleochaetale species and some bryophytes. Moreover, the presence of syringyl lignins, which has been restricted solely to angiosperms, has been confirmed also in most studied phylogenetic groups, from rhodophytes to gymnosperms, including non-vascular plants. The discovery in Selaginella of a novel enzyme analogous to angiosperm ferulate-5-hydroxylase supports the existence of evolutionarily convergent pathways that lead to syringyl lignin biosynthesis. In this review, the role of lignins in the development of vascular system and the presence and composition of lignins in different phylogenetic groups will be discussed, paying special attention to new contributions and the evolutionary development of syringyl lignins.