Non-Specific Lipid Transfer Proteins in Triticum kiharae Dorof. et Migush.: Identification, Characterization and Expression Profiling in Response to Pathogens and Resistance Inducers.

Odintsova Odintsova,Korostyleva Korostyleva,Kasianov Kasianov,Kudryavtsev Kudryavtsev,Slezina Slezina,Shcherbakova Shcherbakova,Istomina Istomina,Kovtun Kovtun

doi:10.3390/pathogens8040221

Abstract

Non-specific lipid-transfer proteins (nsLTPs) represent a family of plant antimicrobial peptides (AMPs) implicated in diverse physiological processes. However, their role in induced resistance (IR) triggered by non-pathogenic fungal strains and their metabolites is poorly understood. In this work, using RNA-seq data and our AMP search pipeline, we analyzed the repertoire of nsLTP genes in the wheat Triticum kiharae and studied their expression in response to Fusarium oxysporum infection and treatment with the intracellular metabolites of Fusarium sambucinum FS-94. A total of 243 putative nsLTPs were identified, which were classified into five structural types and characterized. Expression analysis showed that 121 TkLTPs including sets of paralogs with identical mature peptides displayed specific expression patters in response to different treatments pointing to their diverse roles in resistance development. We speculate that upregulated nsLTP genes are involved in protection due to their antimicrobial activity or signaling functions. Furthermore, we discovered that in IR-displaying plants, a vast majority of nsLTP genes were downregulated, suggesting their role as negative regulators of immune mechanisms activated by the FS-94 elicitors. The results obtained add to our knowledge of the role of nsLTPs in IR and provide candidate molecules for genetic engineering of crops to enhance disease resistance.

Highlights

Non-specific lipid-transfer proteins are low-molecular-weight cysteine-rich proteins discovered in all land plants [1,2,3,4,5]
We showed that treatment of T. kiharae seeds with the elicitor metabolites of F. sambucinum effectively protects wheat seedlings from F. oxysporum infection
To investigate the role of Non-specific lipid-transfer proteins (nsLTPs) in induced resistance, we first studied the repertoire of nsLTPs in four transcriptomes: from untreated, infected, elicitor-treated, and IR-displaying wheat seedlings

Summary

Introduction

Non-specific lipid-transfer proteins (nsLTPs) are low-molecular-weight cysteine-rich proteins discovered in all land plants [1,2,3,4,5]. They possess a conserved eight-cysteine motif (ECM): Pathogens 2019, 8, 221; doi:10.3390/pathogens8040221 www.mdpi.com/journal/pathogens. Several classification systems were suggested for plant nsLTPs that take into account their molecular weight, sequence similarity, the number of amino acid residues between cysteine residues and the position of intron(s) in the corresponding genes [6,19,20,21]. In addition to important physiological functions mentioned above that make nsLTP genes promising candidates for genetic transformation of plants to increase resistance to pathogenic microorganisms, nsLTPs show potential as templates for drug development in medicine displaying antimicrobial activity against human bacterial pathogens and inhibiting clinical sepsis [24]

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