Modification of Monolignol Biosynthetic Pathway in Jute: Different Gene, Different Consequence

Abstract

Lignin, a cross-linked macromolecule of hydrophobic aromatic structure, provides additional rigidity to a plant cell wall. Although it is an integral part of the plant cell, presence of lignin considerably reduces the quality of the fiber of fiber-yielding plants. Decreasing lignin in such plants holds significant commercial and environmental potential. This study aimed at reducing the lignin content in jute-a fiber crop, by introducing hpRNA-based vectors for downregulation of two monolignoid biosynthetic genes- cinnamate 4-hydroxylase (C4H) and caffeic acid O-methyltransferase (COMT). Transgenic generations, analyzed through Southern, RT-PCR and northern assays showed downregulation of the selected genes. Transgenic lines exhibited reduced level of gene expression with ~ 16–25% reduction in acid insoluble lignin for the whole stem and ~13–14% reduction in fiber lignin content compared to the control lines. Among the two transgenic plant types one exhibited an increase in cellulose content and concomitant improvement of glucose release. Composition of the lignin building blocks was found to alter and this alteration resulted in a pattern, different from other plants where the same genes were manipulated. It is expected that successful COMT-hpRNA and C4H-hpRNA transgenesis in jute will have far-reaching commercial implications leading to product diversification and value addition.

A wheat caffeic acid 3-O-methyltransferase TaCOMT-3D positively contributes to both resistance to sharp eyespot disease and stem mechanical strength

“…In previous studies, assays of knock-out/down mutants/transgenic plants indicated that COMT participated predominantly in syringl monolignol biosynthesis and can change lignin content and composition 12 , 36 – 39 . For example, the Brachypodium Bd5139 mutant with a single nucleotide mutation in the caffeic acid O -methyltransferase encoding gene BdCOMT6 displayed a moderately altered lignifiation in mature stems 38 .…”

“…It has been demonstrated that in maize, rice and sorghum ( Sorghum bicolor L.), the O-methyltransferase responsible for the production of syringyl lignin was also involved in the synthesis of lignin-linked tricin 35 . Several groups aimed to improve the production of biofuel and generated transgenic plants with deficit/reduction of syringyl lignin unit through knock-out/down of the lignin-related COMT genes in plants 13 , 36 – 39 . However, no genetic evidence for defense roles of COMT genes has yet been reported in plants.…”

Identification of genic SSRs in jute (Corchorus capsularis, Malvaceae) and development of markers for phenylpropanoid biosynthesis genes and regulatory genes

“…Also, Shafrin et al. () have developed low‐lignin transgenic jute by inactivating caffeic acid O‐methyltransferase ( COMT ). We have developed five SSR markers for these two genes, which may be useful for genetic mapping of lignin content and targeting low‐lignin genotypes in breeding programmes.…”

Lignin provides mechanical support to herbaceous peony (Paeonia lactiflora Pall.) stems

“…The second category is the lignin monomer biosynthesis-related genes, including HCT , C3 ′ H , CCoAOMT , COMT , and F5H , which influence lignin monomer biosynthesis, determine the proportion of various monomers in lignin, and thus affect the total lignin content to some extent 49 . In jute or Arabidopsis , the repression of COMT or F5H expression resulted in significant decreases in S-lignin 50 , 51 . Moreover, downstream of the lignin biosynthetic pathway, some genes involved in lignin monomer biosynthesis and polymerization, such as CCR , CAD , and POD 49 , were significantly positively correlated with lignin content 52 .…”