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Lignin is present in all vascular plants, but not in bryophytes, supporting the idea that the original function of lignin was restricted to water transport. It is covalently linked to hemicellulose and therefore cross-links different plant polysaccharides , conferring mechanical strength to the cell wall and by extension the plant as a whole ...
The inclusion of lignin makes the secondary cell wall less flexible and less permeable to water than the primary cell wall. [4] In addition to making the walls more resistant to degradation, the hydrophobic nature of lignin within these tissues is essential for containing water within the vascular tissues that carry it throughout the plant.
The basic function of the xylem is to transport water upward from the roots to parts of the plants such as stems and leaves, but it also transports nutrients. [1] [2] The word xylem is derived from the Ancient Greek word, ξύλον (xylon), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. [3]
In the first 140–150 million years of vascular plant evolution, tracheids were the only type of conductive cells found in fossils of plant xylem tissues. [5] Ancestral tracheids did not contribute significantly to structural support, as can be seen in extant ferns. [6]
Casbury pointed out that this structure may be composed of lignin or suberin. Later scholars mostly thought it was suberin. [21] It was not until the 1990s that after analyzing the Casparian strip of several plants, it was found that lignin was the main component, but many textbooks have not been updated. [4]
The presence of vessels in xylem has been considered to be one of the key innovations that led to the success of the flowering plants. It was once thought that vessel elements were an evolutionary innovation of flowering plants, but their absence from some basal angiosperms and their presence in some members of the Gnetales suggest that this hypothesis must be re-examined; vessel elements in ...
Lignin-modifying enzymes benefit industry as they can break down lignin; a common waste product of the paper and pulp industry. These enzymes have been used in the refinement of poplar as lignin inhibits the enzymatic hydrolysis of treated poplar and Lignin-modifying enzymes can efficiently degrade the lignin thus fixing this problem. [4]
There was a belief that plants were healthy under sterile conditions and it was not until 1887 that Victor Galippe discovered bacteria normally occurring inside plant tissues. [2] Though, most of the endophytic studies reports the mutualistic relationship of bacteria and fungus, Das et al., (2019) reported about endophytic virome and their ...