Molecular cloning and functional analysis of 4-Coumarate:CoA ligase 4(4CL-like 1)from Fraxinus mandshurica and its role in abiotic stress tolerance and cell wall synthesis

Abstract

Background Four-Coumarate:CoA ligase gene ( 4CL ) plays multiple important roles in plant growth and development by catalyzing the formation of CoA ester. 4CL belongs to the plant phenylpropane derivative, which is related to the synthesis of flavonoids and lignin and is a key enzyme in the biosynthetic pathway. Results In this study, 12 4CL genes of Fraxinus mandschurica were identified and named Fm4CL1 - Fm4CL12 , respectively. The analysis of the expression pattern of Fm4CL genes indicate that Fm4CL-like 1 gene may play a role in the lignin synthesis pathway. Our study indicate that overexpression of Fm4CL-like 1 increases the lignin content of transgenic tobacco by 39.5% compared to WT, and the S/G ratio of transgenic tobacco increased by 19.7% compared with WT. The xylem cell layer of transgenic line is increased by 40% compared to WT, the xylem cell wall thickness increased by 21.6% compared to the WT. Under mannitol-simulated drought stress, the root length of transgenic tobacco is 64% longer than WT, and the seed germination rate of the transgenic lines is 47% higher than that of WT. In addition, the H 2 O 2 content in the transgenic tobacco was 22% lower than that of WT, while the POD and SOD content was higher than WT by 30 and 24% respectively, which showed Fm4CL-like 1 affect the accumulation of reactive oxygen species (ROS). The MDA content and relative conductivity was 25 and 15% lower than WT, respectively. The water loss rate is 16.7% lower than that of WT. The relative expression levels of stress-related genes NtHAK , NtAPX , NtCAT , NtABF2 , and NtZFP were higher than those of WT under stress treatment. The stomatal apertures of OE (Overexpression) were 30% smaller than those of WT, and the photosynthetic rate of OE was 48% higher than that of WT. These results showed that the overexpression line exhibited stronger adaptability to osmotic stress than WT. Conclusions Our results indicate that Fm4CL-like 1 is involved in secondary cell wall development and lignin synthesis. Fm4CL-like 1 play an important role in osmotic stress by affecting cell wall and stomatal development. Electronic supplementary material The online version of this article (10.1186/s12870-019-1812-0) contains supplementary material, which is available to authorized users.

Characterization of the Gh4CL gene family reveals a role of Gh4CL7 in drought tolerance

“…On the other hand, the Gh4CL7 overexpression plants had a lower level of H 2 O 2 and MDA and a higher activity of antioxidant enzymes (SOD, POD, and CAT) compared to WT under the drought stress conditions. These results are consistent with previous finding that Fm4CL had a role in drought tolerance by modulating the level of ROS [24].…”

“…We found that repressing the expression level of Gh4CL7 in G. hirsutum reduced the lignin content and led to a reduction in drought resistance, consistent with the result of rice plants with a decreased lignin content being more prone to drought stress [63]. Studies in Fraxinus mandshurica also showed that decreased lignin content resulted in drought resistance reduction [24]. The hydrophobicity of lignin is thought to have an inhibitory effect on the transpiration of plant tissue under drought conditions [64], that could be the reason for Arabidopsis plants overexpressing Gh4CL7 that had an increased level of lignin content being more resistant to drought.…”

“…In both poplars and Arabidopsis, the expression levels of 4CL genes were induced by salt stress and wounding [7,8]. The 4CL-like genes may also play a role in response to abiotic stresses [23][24]. Overexpression of Fm4CL-like1 in tobacco increased drought tolerance due to increasing lignin accumulation and the activities of antioxidant enzymes, and upregulating the expression levels of stress-related genes [24].…”

Transcriptomic and metabolomic analyses reveal mechanisms of adaptation to salinity in which carbon and nitrogen metabolism is altered in sugar beet roots

“…Moreover, the KEGG annotation analysis revealed that the expression of a large number of genes related to phenylpropane biosynthesis is upregulated. Some studies have indicated that phenylpropane biosynthesis is related to flavonoid and lignin synthesis, which can improve the osmoregulatory effect of Fraxinus mandshurica [48]. Ma et al reported similar conclusions with respect to buckwheat [49].…”

Transcriptome analysis reveals underlying immune response mechanism of fungal (Penicillium oxalicum) disease in Gastrodia elata Bl. f. glauca S. Chow (Orchidaceae)

“…4CL belongs to the plant phenylpropane derivative, which is related to the synthesis of avonoids and lignin and is a key enzyme in the biosynthetic pathway. It was reported that Fm4CL-like 1 is involved in secondary cell wall development and lignin synthesis and it play an important role in osmotic stress by affecting cell wall and stomatal development [88]. This may be a part of fungal disease immune response mechanism in G. elata Bl.…”