Transcript abundances of LIM transcription factor, 4CL, CAld5H and CesAs affect wood properties in Eucalyptus globulus

Abstract

Eucalyptus globulusis the main hardwood species grown in pulpwood plantations in temperate regions of the world. We have cloned six genes influencing wood quality including the LIM domain transcription factor (LIM), 4-coumarate-CoA ligase (4CL), coniferaldehyde 5-hydroxylase (CAld5H) and the three catalytic units of cellulose synthase (CesA), fromE. globulus. The transcript abundances of LIM in basal stems of ten independentE. globuluslines showed similar patterns to those of 4CL. We investigated the correlation between gene transcript abundances and wood qualities such as Klason lignin (KL) content, syringaldehyde/vanillin (S/V) ratio and holocellulose (HC) content. Expression of the LIM and 4CL were positively correlated with KL content. A highly significant positive correlation was observed between CAld5H expression and S/V ratio. Furthermore, a ratio of the sum of the transcript abundances of three CesA1, CesA2 and CesA3 to 4CL showed a positive correlation with a ratio of HC/KL content that positively correlated with the chemically extracted fiber content in this woody plant.

Transcript Level Analysis of Lignin and Flavonoid Biosynthesis Related Genes in <i>Eucalyptus globulus</i>

“…We also observed a strong positive correlation between the expression of the individual HCT genes and the KL content (Figure 4). This result concurs with our previous report that HCT plays a role in the determination of lignin content as well as 4CL [16]. The combined coefficient of determination value (R 2 ) of HCT1 and HCT2 in that study was 0.84 and this value was higher than the values determined for the association between the individual HCT gene and the percentage of KL values or 4CL.…”

“…It would be interesting to see if similar results are obtained in the field. Finally, our results provide a strong dataset for selecting elite candidate trees by monitoring transcript levels of several useful genes such as 4CL [16] and HCTs.…”

“…Total RNAs were extracted from basal parts of the stems of 6-month-old plants (about 1 m high) and RT-qPCR was carried out. Relative expression levels of Egl4CL1 (the data were from previous work; [16], EglHCT1, EglHCT2, EglCHS3 and EglCHS4 in ten different lines represented as A-J are shown in Figure 3. The transcript levels of EglHCT1and EglHCT2 were similar to the levels of Egl4CL1, respectively across all lines tested (Figure 3).…”

Transcriptional Profiles of Hybrid Eucalyptus Genotypes with Contrasting Lignin Content Reveal That Monolignol Biosynthesis-related Genes Regulate Wood Composition

“…Another transcription factor, the LIM domain transcription factor, binds specifically to a PAL-box element, which is thought to be an important cis -acting element of lignification-related gene expression ( Kawaoka et al, 2000 ; Kaothien et al, 2002 ). Transgenic tobacco and E. camaldulensis plants with antisense LIM show low concentrations of transcripts of some key genes such as PAL and 4CL that are involved in the lignin biosynthesis pathway ( Kawaoka et al, 2000 , 2006 ; Negishi et al, 2011 ). Thus, LIM seems to play a crucial role in lignification.…”

Isolation and characterization of the 4-coumarate:coenzyme A ligase (4CL1) promoter from Eucalyptus camaldulensis

“…Northern and Western hybridization analyses verified that the Euc4CL1 gene expressed in secondary developing xylem tissues is associated with lignin biosynthesis (Chen et al 2006). Negishi et al (2011) found that the transcript abundances of 4CL were highly correlated with lignin content in the basal part of stems of E. globulus. In E. grandis, there is a single member Egr4CL1 in class I, which is strongly and specifically expressed in developing xylem (Carocha et al 2015).…”