Gene coexpression network analysis combined with metabonomics reveals the resistance responses to powdery mildew in Tibetan hulless barley

Hongjun Yuan,Qiaofeng Yang,Zha Sang,Xingquan Zeng,Qijun Xu,Yulin Wang,Nyima Tashi,Dunzhu Jabu

doi:10.1038/s41598-018-33113-7

Abstract

Powdery mildew is a fungal disease that represents a ubiquitous threat to crop plants. Transcriptomic and metabolomic analyses were used to identify molecular and physiological changes in Tibetan hulless barley in response to powdery mildew. There were 3418 genes and 405 metabolites differentially expressed between the complete resistance cultivar G7 and the sensitive cultivar Z13. Weighted gene coexpression network analysis was carried out, and the differentially expressed genes were enriched in five and four major network modules in G7 and Z13, respectively. Further analyses showed that phytohormones, photosynthesis, phenylpropanoid biosynthesis, and flavonoid biosynthesis pathways were altered during Qingke-Blumeria graminis (DC.) f.sp. hordei (Bgh) interaction. Comparative analyses showed a correspondence between gene expression and metabolite profiles, and the activated defenses resulted in changes of metabolites involved in plant defense response, such as phytohormones, lipids, flavone and flavonoids, phenolamides, and phenylpropanoids. This study enabled the identification of Bgh responsive genes and provided new insights into the dynamic physiological changes that occur in Qingke during response to powdery mildew. These findings greatly improve our understanding of the mechanisms of induced defense response in Qingke and will provide new clues for the development of resistant Tibetan hulless barley varieties.

Highlights

Powdery mildew is a fungal disease that affects more than 10,000 plant species worldwide and significantly reduces the grain yields and quality of agricultural crops[1,2]
The results showed that a great number of metabolites accumulated differentially during the process of Qingke-Blumeria graminis (DC.) f.sp. hordei (Bgh) interaction, which were synchronous with the expression of the differentially expressed genes
The present study reports the first effort to integrate transcriptomic and metabolic techniques for the comparative analyses of the genes and the metabolites involved in responses of Qingke plants to powdery mildew

Summary

Introduction

Powdery mildew is a fungal disease that affects more than 10,000 plant species worldwide and significantly reduces the grain yields and quality of agricultural crops[1,2]. Hordei (Bgh) is a serious disease of wheat crops and can decrease grain yield by up to 30% depending on the severity of infestation Many plant species such as Arabidopsis thaliana[3], wheat (Triticum spp.)[2,4], rice (Oryza sativa)[5], tomato (Solanum lycopersicum)[6] and barley (Hordeum vulgare)[7], have been frequently used for investigating the molecular mechanisms of plant resistance to fungal pathogens including the powdery mildews. Our limited understanding of Tibetan hulless barley genetics seriously hindered the systematical investigation of genes and molecular mechanisms underlying its resistance response to powdery mildew. Connected hub genes are expected to play an important role in biology but not always be significantly associated with the trait of interest[19]. It has been suggested that intramodular hub genes that are highly connected within a module are more likely to be biologically significant if that module is associated with the trait[19,20]

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Conclusion