Dataset Information

Accumulation of Catechin and Proanthocyanidins in Black Poplar Stems After Infection by Plectosphaerella populi: Hormonal Regulation, Biosynthesis and Antifungal Activity.

ABSTRACT: Flavan-3-ols including the monomeric catechin and the polymeric proanthocyanidins (PAs) are abundant phenolic metabolites in poplar (Populus spp.) previously described to protect leaves against pathogen infection. However, it is not known whether stems are also defended in this way. Here we investigated flavan-3-ol accumulation, activity, and the regulation of formation in black poplar (P. nigra) stems after infection by a newly described fungal stem pathogen, Plectosphaerella populi, which forms canker-like lesions in stems. We showed that flavan-3-ol contents increased in P. populi-infected black poplar stems over the course of infection compared to non-infected controls. Transcripts of leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) genes involved in the last steps of flavan-3-ol biosynthesis were also upregulated upon fungal infection indicating de novo biosynthesis. Amending culture medium with catechin and PAs reduced the mycelial growth of P. populi, suggesting that these metabolites act as anti-pathogen defenses in poplar in vivo. Among the hormones, salicylic acid (SA) was higher in P. populi-infected tissues compared to the non-infected controls over the course of infection studied, while jasmonic acid (JA) and JA-isoleucine (JA-Ile) levels were higher than controls only at the early stages of infection. Interestingly, cytokinins (CKs) were also upregulated in P. populi-infected stems. Poplar saplings treated with CK showed decreased levels of flavan-3-ols and SA in stems suggesting a negative association between CK and flavan-3-ol accumulation. Taken together, the sustained upregulation of SA in correlation with catechin and PA accumulation suggests that this is the dominant hormone inducing the formation of antifungal flavan-3-ols during P. populi infection of poplar stems.

SUBMITTER: Ullah C

PROVIDER: S-EPMC6873352 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Accumulation of Catechin and Proanthocyanidins in Black Poplar Stems After Infection by Plectosphaerella populi: Hormonal Regulation, Biosynthesis and Antifungal Activity.

Ullah Chhana C Unsicker Sybille B SB Reichelt Michael M Gershenzon Jonathan J Hammerbacher Almuth A

Frontiers in plant science 20191115

Flavan-3-ols including the monomeric catechin and the polymeric proanthocyanidins (PAs) are abundant phenolic metabolites in poplar (Populus spp.) previously described to protect leaves against pathogen infection. However, it is not known whether stems are also defended in this way. Here we investigated flavan-3-ol accumulation, activity, and the regulation of formation in black poplar (P. nigra) stems after infection by a newly described fungal stem pathogen, Plectosphaerella p ...[more]

PMID: 31803202

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Project description:Boron (B) is an essential nutrient for normal growth of plants. Despite its low abundance in soils, B pollution and toxicity have been reported to increase in especially arid and semi-arid environments. Poplars are known to be tolerant species to B toxicity and accumulation. In the current study, physiological, transcriptomic and hormonal regulations behind B toxicity response were investigated comparatively in poplar species. Previously identified clones of Populus nigra (P.n) and Populus alba (P.a) having contrasting B accumulation and leaf B toxicity symptoms were treated with elevated soil B supply in a pot trial. The physiological results of treatment indicated better biomass growth, higher leaf chlorophyll content and more than three folds lower B accumulation in leaves of P.a compared to P.n. Microarray based transcriptomic analysis revealed 1902 and 1006 differentially regulated transcripts for the leaves and roots of P.a, respectively. Several transcripts responsible in salicylic acid (SA) production (salicylic acid binding protein 2) and SA dependent gene regulation (chitinases, proteases, lipases and protease inhibitors) were strongly upregulated specifically in P.a tissues under B toxicity. Furthermore, endogenous SA content in the roots and leaves of P.a increased with a soil B concentration-dependent manner while there was no significant alteration in the same hormone for P.n tissues under B toxicity. Therefore, increase in endogenous SA concentration was strongly attributed to lower B uptake and B toxicity tolerance in P.a. In addition to SA mediated gene regulation, genes responsible in external excretion process was also supposed to be functional in P.a for reduction of tissue B content under toxic conditions. On the other hand, transcriptome profiling of P.n under B toxicity revealed 1624 and 1419 altered transcripts for the leaves and roots, respectively. Specific induction in transcripts annotated to ATP binding cassette B type transporters, glutathione S transferases and metallochaperones in P.n were linked to internal excretion of excess B in the species that could be related with much higher B uptake from the roots, directional transport to the leaves and detoxification under toxic B conditions.

Project description:Carbon starvation is the current leading hypothesis of plant mortality mechanisms under drought stress; recently, it is also used to explain tree die-off in plant diseases. However, the molecular biology of the carbon starvation pathway is unclear. Here, using a punch inoculation system, we conducted transcriptome and physiological assays to investigate pathogen response in poplar stems at the early stages of Botryosphaeria and Valsa canker diseases. Transcriptome assays showed that the majority of differentially expressed genes (DEGs) in stem phloem and xylem, such as genes involved in carbon metabolism and transportation, aquaporin genes (in xylem) and genes related to the biosynthesis of secondary metabolites and the phenylpropanoid pathway (related to lignin synthesis), were downregulated at 7 days after inoculation (DAI). Results also showed that the expression of the majority of disease-resistance genes upregulated in poplar stems, which may be connected with the downregulation expression of the majority of WRKY family genes. Physiological assays showed that transpiration rate decreased but WUE (water use efficiency) increased the 3 and 7 DAI, while the net photosynthetic rate decreased at 11 DAI in Botryosphaeria infected poplars (ANOVA, P < 0.05). The NSC (non-structural carbohydrates) content assays showed that the soluble sugar content of stem phloem samples increased at 3, 7, and 11 DAI that might due to the impede of pathogen infection. However, soluble sugar content of stem xylem and root samples decreased at 11 DAI; in contrast, the starch content unchanged. Therefore, results revealed a chronological order of carbon related molecular and physiological performance: declination of genes involved in carbon and starch metabolism first (at least at 7 DAI), declination of assimilation and carbon reserve (at 11 DAI) second. Results implied a potential mechanism that affects the host carbon reserve, by directly inhibiting the expression of genes involved in carbon metabolism and transport.

Dataset Information

Accumulation of Catechin and Proanthocyanidins in Black Poplar Stems After Infection by Plectosphaerella populi: Hormonal Regulation, Biosynthesis and Antifungal Activity.

Publications

Accumulation of Catechin and Proanthocyanidins in Black Poplar Stems After Infection by <i>Plectosphaerella populi</i>: Hormonal Regulation, Biosynthesis and Antifungal Activity.

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