Potential Roles for Pattern Molecule of PAMP-triggered Immunity in Improving Crop Cold Tolerance

Abstract Pathogen infection cross-activates cold response and increase cold tolerance of host plants. However it is not possible to use the infection to increase cold tolerance of field plants. Here flagellin 22 (flg22), the most widely-studied PAMP, was used to mimic the pathogen infection to cross-activate cold response. Flg22 treatment alleviated the injury caused by freezing in Arabidopsis, oilseed and tobacco. In Arabidopsis, flg22 activated the expression of immunity and cold-related genes. Moreover the flg22 induced alleviation of cold injury was lost in NahG transgenic line (SA-deficient), sid2-2 and npr1-1 mutant plants, and flg22-induced expression of cold tolerance-related genes, which indicating that salicylic acid signaling pathway is required for the alleviation of cold injury by flg22 treatment. In short flg22 application can be used to enhance cold tolerance in field via a salicylic acid-depended pathway.

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A salivary effector enables whitefly to feed on host plants by eliciting salicylic acid-signaling pathway

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1714990116 ◽

2018 ◽

Vol 116 (2) ◽

pp. 490-495 ◽

Cited By ~ 27

Author(s):

Hong-Xing Xu ◽

Li-Xin Qian ◽

Xing-Wei Wang ◽

Ruo-Xuan Shao ◽

Yue Hong ◽

...

Keyword(s):

Salicylic Acid ◽

Signaling Pathway ◽

Host Plants ◽

Salivary Protein ◽

In Planta ◽

Protein Protein Interaction ◽

Salicylic Acid Signaling ◽

Homeobox Transcription Factor ◽

Phloem Feeding ◽

Sa Signaling

Phloem-feeding insects feed on plant phloem using their stylets. While ingesting phloem sap, these insects secrete saliva to circumvent plant defenses. Previous studies have shown that, to facilitate their feeding, many phloem-feeding insects can elicit the salicylic acid- (SA-) signaling pathway and thus suppress effective jasmonic acid defenses. However, the molecular basis for the regulation of the plant's defense by phloem-feeding insects remains largely unknown. Here, we show that Bt56, a whitefly-secreted low molecular weight salivary protein, is highly expressed in the whitefly primary salivary gland and is delivered into host plants during feeding. Overexpression of the Bt56 gene in planta promotes susceptibility of tobacco to the whitefly and elicits the SA-signaling pathway. In contrast, silencing the whitefly Bt56 gene significantly decreases whitefly performance on host plants and interrupts whitefly phloem feeding with whiteflies losing the ability to activate the SA pathway. Protein-protein interaction assays show that the Bt56 protein directly interacts with a tobacco KNOTTED 1-like homeobox transcription factor that decreases whitefly performance and suppresses whitefly-induced SA accumulation. The Bt56 orthologous genes are highly conserved but differentially expressed in different species of whiteflies. In conclusion, Bt56 is a key salivary effector that promotes whitefly performance by eliciting salicylic acid-signaling pathway.

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