Fungal canker pathogens trigger carbon starvation by inhibiting carbon metabolism in poplar stems

Ping Li; Wenxin Liu; Yinan Zhang; Junchao Xing; Jinxin Li; Jinxia Feng; Xiaohua Su; Jiaping Zhao

doi:10.1038/s41598-019-46635-5

Scientific Reports (Jul 2019)

Fungal canker pathogens trigger carbon starvation by inhibiting carbon metabolism in poplar stems

Ping Li,
Wenxin Liu,
Yinan Zhang,
Junchao Xing,
Jinxin Li,
Jinxia Feng,
Xiaohua Su,
Jiaping Zhao

Affiliations

Ping Li: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Wenxin Liu: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Yinan Zhang: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Junchao Xing: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Jinxin Li: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Jinxia Feng: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry
Xiaohua Su: State Key Laboratory of Tree Genetics and Breeding, Institute of Forestry, Chinese Academy of Forestry
Jiaping Zhao: State Key Laboratory of Tree Genetics and Breeding, Forestry Institute of New Technology, Chinese Academy of Forestry

DOI: https://doi.org/10.1038/s41598-019-46635-5
Journal volume & issue: Vol. 9, no. 1
pp. 1 – 14

Abstract

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Abstract 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.

Published in Scientific Reports

ISSN: 2045-2322 (Online)
Publisher: Nature Portfolio
Country of publisher: United Kingdom
LCC subjects: Medicine; Science
Website: https://www.nature.com/srep/

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