Dataset Information

Fasciclin-like arabinogalactan proteins, PtFLAs, play important roles in GA-mediated tension wood formation in Populus.

ABSTRACT: In Populus, the transcripts of fasciclin-like arabinogalactan proteins (FLAs) are accumulated in tension wood (TW) xylem, however their biological functions in TW formation are largely unknown. In this work, we demonstrated that PtFLA6, one of poplar TW-associated PtFLAs, was abundantly expressed in TW, and mainly localized in differentiating G-fibers. The bended stems of PtFLA6 antisense transgenic poplar showed decreased transcripts of PtFLAs, including PtFLA6, and reduced PtFLA6 like proteins, leading to inhibited TW differentiation and formation. We also showed that gibberellin A3 (GA3) was enriched in the xylem of TW side, accompanied with a lowered level of PtRGA1, a poplar DELLA protein. When GA3 biosynthesis was restrained in the bended poplar stems by a GA biosynthesis inhibitor (daminozide), TW formation was obviously repressed, as a result of restricted PtRGA1 degradation, and reduced PtFLA6 like proteins and PtFLA expression. Further studies indicated that PtFLAs were negatively regulated by PtRGA1. This study suggests that PtFLAs play important roles in the poplar TW formation, possibly regulated by GA signaling.

SUBMITTER: Wang H

PROVIDER: S-EPMC5522414 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Fasciclin-like arabinogalactan proteins, PtFLAs, play important roles in GA-mediated tension wood formation in Populus.

Wang Haihai H Jin Yanli Y Wang Cuiting C Li Bei B Jiang Chunmei C Sun Zhencang Z Zhang Zhiping Z Kong Fanjing F Zhang Hongxia H

Scientific reports 20170721 1

In Populus, the transcripts of fasciclin-like arabinogalactan proteins (FLAs) are accumulated in tension wood (TW) xylem, however their biological functions in TW formation are largely unknown. In this work, we demonstrated that PtFLA6, one of poplar TW-associated PtFLAs, was abundantly expressed in TW, and mainly localized in differentiating G-fibers. The bended stems of PtFLA6 antisense transgenic poplar showed decreased transcripts of PtFLAs, including PtFLA6, and reduced PtFLA6 like proteins ...[more]

PMID: 28733593

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Project description:Fasciclin-like arabinogalactan proteins (FLAs) are a subclass of arabinogalactan proteins (AGPs) involved in plant growth, development and response to abiotic stress. Although many studies have been performed to identify molecular functions of individual family members, little information is available on genome-wide identification and characterization of FLAs in the genus Populus. Based on genome-wide analysis, we have identified 35 Populus FLAs which were distributed on 16 chromosomes and phylogenetically clustered into four major groups. Gene structure and motif composition were relatively conserved in each group. All the members contained N-terminal signal peptide, 23 of which included predicted glycosylphosphatidylinositol (GPI) modification sites and were anchored to plasma membranes. Subcellular localization analysis showed that PtrFLA2/20/26 were localized in cell membrane and cytoplasm of protoplasts from Populus stem-differentiating xylem. The Ka/Ks ratios showed that purifying selection has played a leading role in the long-term evolutionary period which greatly maintained the function of this family. The expression profiles showed that 32 PtrFLAs were differentially expressed in four tissues at four seasons based on publicly available microarray data. 18 FLAs were further verified with qRT-PCR in different tissues, which indicated that PtrFLA1/2/3/7/11/12/20/21/22/24/26/30 were significantly expressed in male and female flowers, suggesting close correlations with the reproductive development. In addition, PtrFLA1/9/10/11/17/21/23/24/26/28 were highly expressed in the stems and differentiating xylem, which may be involved in stem development. To determine salt response of FLAs, qRT-PCR was performed to analyze the expression of 18 genes under salinity stress across two time points. Results demonstrated that all the 18 FLAs were expressed in root tissues; especially, PtrFLA2/12/20/21/24/30 were significantly induced at different time points. In summary, this study may lay the foundation for further investigating the biological functions of FLA genes in Populus trichocarpa.

Project description:BackgroundWood formation affects the chemical and physical properties of wood, and thus affects its utility as a building material or a feedstock for biofuels, pulp and paper. To obtain genome-wide insights on the transcriptome changes and regulatory networks in wood formation, we used high-throughput RNA sequencing to characterize cDNA libraries of mature xylem from tension wood (TW), opposite wood (OW), and normal wood (NW), in the industrial tree species Populus tomentosa.ResultsOur sequencing generated 140,978,316 (TW), 128,972,228 (OW), and 117,672,362 (NW) reads, corresponding to 10,127 (TW), 10,129 (OW), and 10,129 (NW) unique genes. Of these, 361 genes were differentially transcribed between TW and OW (log2FC ≥ 1 or ≤ -1, FDR < 0.05), 2,658 differed between OW and NW, and 2,417 differed between TW and NW. This indicates that NW differs significantly from the wood in branches; GO term analysis also indicated that OW experienced more transcriptome remodeling. The differentially expressed genes included 97 encoding transcription factors (TFs), 40 involved in hormone signal transduction, 33 in lignin biosynthesis, 21 in flavonoid biosynthesis, and 43 in cell wall metabolism, including cellulose synthase, sucrose synthase, and COBRA. More than half of the differentially expressed TF showed more than 4-fold lower transcript levels in NW compared with TW or OW, indicating that TF abundances differed dramatically in different wood types and may have important roles in the formation of reaction wood. In addition, transcripts of most of the genes involved in lignin biosynthesis were more abundant in OW compared with TW, consistent with the higher lignin content of OW. We constructed two transcriptomic networks for the regulation of lignin and cellulose biosynthesis, including TFs, based on the co-expression patterns of different genes. Lastly, we used reverse transcription quantitative PCR to validate the differentially expressed genes identified.ConclusionsHere, we identified the global patterns and differences in gene expression among TW, OW, and NW, and constructed two transcriptomic regulatory networks involved in TW formation in P. tomentosa. We also identified candidate genes for molecular breeding of wood quality, and provided a starting point to decipher the molecular mechanisms of wood formation in Populus.

Dataset Information

Fasciclin-like arabinogalactan proteins, PtFLAs, play important roles in GA-mediated tension wood formation in Populus.

Publications

Fasciclin-like arabinogalactan proteins, PtFLAs, play important roles in GA-mediated tension wood formation in Populus.

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