Expression of Eucalyptus globulus LACCASE48 Restores Lignin Content of Arabidopsis thaliana lac17 Mutant

Author(s)

Araujo, Pedro ^[1] ; Tolentino, Felipe Thadeu ^[2] ; Cesarino, Igor ^[3] ; Gallinari, Rafael Henrique ^[1] ; Steenackers, Ward ^{[4, 5]} ; Sampaio Mayer, Juliana Lischka ^[2] ; Mazzafera, Paulo ^{[2, 6]}

Affiliation

^[1] Univ Estadual Campinas, Dept Genet Evolucao Microbiol & Imunol, Inst Biol, Campinas, SP - Brazil

^[2] Univ Estadual Campinas, Dept Biol Vegetal, Inst Biol, CP 6109, BR-13083970 Campinas, SP - Brazil

^[3] Univ Sao Paulo, Inst Biociencias, Dept Bot, Rua Matao 277, BR-05508090 Sao Paulo, SP - Brazil

^[4] VIB, Dept Plant Syst Biol, B-9052 Ghent - Belgium

^[5] Univ Ghent, Dept Plant Biotechnol & Bioinformat, B-9052 Ghent - Belgium

^[6] Univ Sao Paulo, Dept Crop Sci, Coll Agr Luiz de Queiroz, CP 09, BR-13418900 Piracicaba, SP - Brazil

• Document type: Journal article
• Source: PLANT MOLECULAR BIOLOGY REPORTER; v. 37, n. 5-6, p. 488-498, DEC 2019.
• Web of Science Citations: 0

Abstract

The presence of aromatic polymer lignin is a bottleneck that hampers the efficient processing of Eucalyptus wood into downstream products such as cellulose pulp and biofuels. However, despite the impact of lignin on the economic uses of Eucalyptus wood, little is known regarding the molecular mechanisms underlying lignin deposition in this genus. Here, we report on the identification of a laccase gene potentially involved in lignin polymerization in Eucalyptus globulus by employing a combination of phylogenetic analysis, tissue-specific expression analysis, and genetic complementation assays. EglLAC48 is phylogenetically close to the lignin-related gene AtLAC15 of Arabidopsis thaliana and showed increased expression upon in vitro lignification-promoting conditions. Reverse transcription polymerase chain reaction analysis showed that the expression of EglLAC48 is higher in stems when compared with leaves and roots. In addition, in situ hybridization experiments revealed that EglLAC48 mRNA was mainly localized in developing xylem cells, an important lignification site. In order to provide genetic evidence to support a role for EglLAC48 in lignification, this gene was expressed in the Arabidopsis lac17 mutant background using both the endogenous AtLAC17 promoter and the constitutive CaMV35S promoter. Both strategies were successful in restoring lignin content, but the levels of guaiacyl units were still significantly reduced when compared with those of wild-type plants. The fact that the expression of EglLAC48 was able to restore the lignin levels but not lignin composition of the lac17 mutant suggests that this laccase is potentially involved in lignin polymerization in E. globulus but show different enzyme specificity when compared with AtLAC17. (AU)

• FAPESP's process: 14/23230-4 - Influence of microRNAs in lignification pathways of Eucalyptus grandis and E. globulus
• Grantee: Felipe Thadeu Tolentino
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 15/02527-1 - Development of model systems in sorghum and a systems biology approach to unravel the molecular mechanisms controlling lignin metabolism in grasses
• Grantee: Igor Cesarino
• Support Opportunities: Program for Research on Bioenergy (BIOEN) - Young Investigators Grants