Identification of Tomato Ve1 Homologous Proteins in Flax and Assessment for Race-Specific Resistance in Two Fiber FlaxCultivars against Verticillium dahliae Race 1.

Adrien Blum,Lisa Castel,Azeddine Driouich,Isabelle Trinsoutrot-Gattin,Karine Laval

doi:10.3390/plants10010162

Adrien Blum, Lisa Castel + Show 3 more

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https://doi.org/10.3390/plants10010162

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Abstract

In the last decade, the soil borne fungal pathogen Verticillium dahliae has had an increasingly strong effect on fiber flax (Linum usitatissimum L.), thus causing important yield losses in Normandy, France. Race-specific resistance against V. dahliae race 1 is determined by tomato Ve1, a leucine-rich repeat (LRR) receptor-like protein (RLP). Furthermore, homologous proteins have been found in various plant families. Herein, four homologs of tomato Ve1 were identified in the flax proteome database. The selected proteins were named LuVe11, LuVe12, LuVe13 and LuVe14 and were compared to other Ve1. Sequence alignments and phylogenic analysis were conducted and detected a high similarity in the content of amino acids and that of the Verticillium spp. race 1 resistance protein cluster. Annotations on the primary structure of these homologs reveal several features of tomato Ve1, including numerous copies of a 28 amino acids consensus motif [XXIXNLXXLXXLXLSXNXLSGXIP] in the LRR domain. An in vivo assay was performed using V. dahliae race 1 on susceptible and tolerant fiber flax cultivars. Despite the presence of homologous genes and the stronger expression of LuVe11 compared to controls, both cultivars exhibited symptoms and the pathogen was observed within the stem. Amino acid substitutions within the segments of the LRR domain could likely affect the ligand binding and thus the race-specific resistance. The results of this study indicate that complex approaches including pathogenicity tests, microscopic observations and gene expression should be implemented for assessing race-specific resistance mediated by Ve1 within the large collection of flax genotypes.

Highlights

Flax (Linum usitatissimum L.) is an ancient crop which is currently widely cultivated as a source of fiber, oil and medicine-related compounds [1]
Verticillium wilt is caused by the soil borne fungus Verticillium dahliae Kleb. and is a major threat to over 200 plant species including a large range of plant crops [9,10,11]
Proteins annotated as “Verticillium wilt disease resistance” proteins on Genbank shared between 39.5% and 91.2% aa identity with Ve1 and belonged to the Solanum genus as well as other plant genera

Summary

Introduction

Flax (Linum usitatissimum L.) is an ancient crop which is currently widely cultivated as a source of fiber, oil and medicine-related compounds [1]. More than 50% of the land used for French flax cultivation is located in the region of Normandy because it provides an appropriate pedo-climatic environment for the cultivation of fiber flax (http://www.chambre-agriculture-normandie.fr/panoramalin-normandie/) The importance of this crop has led to whole-genome sequencing of the cultivar CDC Bethune, a linseed cultivar growing on the majority of flax acreage in Canada [4]; this provides substantial resources for the predicted proteome [5]. According to French monitoring organizations, Verticillium wilt, a vascular disease has become a substantial problem for fiber flax cultivation, and it has caused important yield losses during the last decade [7,8]; http://www.fiches.arvalis-infos.fr/). Is a major threat to over 200 plant species including a large range of plant crops [9,10,11] This devastating disease causes significant yield losses and leads to substantial economic losses in different regions of the world [11]. In the oldest shoots, wilting symptoms start in one half of an infected leaf and progress acropetally, from the base to the apex [15]

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