A Century-Old Mystery Unveiled: Sekizaisou is a Natural Lignin Mutant

Abstract

prepared the samples for metabolomic analysis. R.V. and G.G. analyzed the metabolites in different mulberry cultivars and interpreted the data. N.T. and T.I. contributed to histochemical analysis and pulp preparation, respectively. M.Y. and N. prepared milled wood samples and M.Y. analyzed lignin structure by thioacidolysis. S.L., H.K., and J.R. prepared samples for NMR and performed NMR analysis and interpretation of the data. S.S. and N.M. analyzed the monomeric composition of cell wall polysaccharides. N and M.U. managed cultivated plants. S.K. wrote the

Importance of Lignin Coniferaldehyde Residues for Plant Properties and Sustainable Uses

“…In fact, natural mutants in CAD s thrive in the wild and have been readily identified, such as the CAD ‐null mutant of pine . Natural mutants in CAD have also been selected and preferentially used in agriculture more than 100‐years ago, like the Sekizaisou variety of mulberry trees, which improved both silkworm growth and silk quality when used for feed . The far reaching effects of aldehyde concentration on biomass properties suggest that these residues, despite being considered minor lignin constituents, have a determining role in diversifying the biological functions and industrial uses of lignin in plants.…”

“…The use of Arabidopsis represents an ideal model to quickly investigate multiple genetic engineering strategies and validate analytical method-ologies, both transposable to agronomically relevant lignocellulosic feedstock species. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In contrast to total G CHOH and S CHOH residue levels which could only be reduced or annulled compared to WT plants, total G CHO residue content varied by roughly threefold changes in either direction in Arabidopsis with specific genetic changes, namely increasing in the cad4xcad5 mutant and decreasing in the 4cl1x4cl2 mutant ( Figure 2A). Arabidopsis natural ecotype variant Wassilewskija (WS) presented~60 % more G CHO residues than the Columbia-0 (Col-0) ecotype, although their G CHOH and S CHOH residue amounts did not differ ( Figure S2).…”

“…[19,20] Natural mutants in CAD have also been selected and preferentially used in agriculture more than 100-years ago, like the Sekizaisou variety of mulberry trees, which improved both silkworm growth and silk quality when used for feed. [21] The far reaching effects of aldehyde concentration on biomass properties suggest that these residues, despite being considered minor lignin constituents, have a determining role in diversifying the biological functions and industrial uses of lignin in plants. However, although different methods have been previously used to quantify coniferaldehyde residues in lignin, their position, amount and linkage have never been compared to obtain a full picture of how these less abundant residues are accumulated.…”

Simultaneous manipulation of lignin structure and secondary cell wall formation in transgenic poplar

“…CAD downregulation via expression of antisense and sense RNA constructs also induces structural modification of lignin [9,10]. In addition, CAD suppression by a hairpin RNA construct and a nonsense mutation of CAD lead to reduced lignin content with an altered structure [11][12][13]. CAD reductions in woody species result in the incorporation of substantial amounts of p-hydroxycinnamaldehyde units, especially sinapaldehyde units, into lignin [11,12,14].…”

“…In addition, CAD suppression by a hairpin RNA construct and a nonsense mutation of CAD lead to reduced lignin content with an altered structure [11][12][13]. CAD reductions in woody species result in the incorporation of substantial amounts of p-hydroxycinnamaldehyde units, especially sinapaldehyde units, into lignin [11,12,14]. CAD suppression also results in an increase in the number of free phenolic groups in the lignin, which enhance the reactivity of lignin under alkaline conditions.…”