Variation of Glucosinolate Contents in Clubroot-Resistant and -Susceptible Brassica napus Cultivars in Response to Virulence of Plasmodiophora brassicae.

Nazanin Zamani-Noor,Christel Joy Comel,Jutta Papenbrock,Johann Hornbacher

doi:10.3390/pathogens10050563

Nazanin Zamani-Noor, Christel Joy Comel + Show 2 more

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https://doi.org/10.3390/pathogens10050563

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Abstract

The present study investigated the changes in total and individual glucosinolates (GSLs) in roots and leaves of different clubroot-resistant and -susceptible oilseed rape cultivars following artificial inoculation with Plasmodiophora brassicae isolates with different virulence. The results showed significant differences in clubroot incidence and severity as well as in the amount of total and individual glucosinolates between oilseed rape cultivars in response to virulence of the pathogen. Single among with total aliphatic and total indolic glucosinolate contents were significantly lower in leaves of susceptible cultivars compared to resistant ones due to the infection. Similarly, single and total aliphatic as well as indolic glucosinolate contents in roots were lower in susceptible cultivars compared to resistant cultivars analyzed. The different isolates of P. brassicae seem to differ in their ability to reduce gluconasturtiin contents in the host. The more aggressive isolate P1 (+) might be able to suppress gluconasturtiin synthesis of the host in a more pronounced manner compared to the isolate P1. A possible interaction of breakdown products of glucobrassicin with the auxin receptor transport inhibitor response 1 (TIR1) is hypothesized and its possible effects on auxin signaling in roots and leaves of resistant and susceptible cultivars is discussed. A potential interplay between aliphatic and indolic glucosinolates that might be involved in water homeostasis in resistant cultivars is explained.

Highlights

Glucosinolates (GSLs), a known group of constitutive natural plant metabolites, are found in the order Brassicales, mainly in the family of Brassicaceae and in families of Capparaceae, Caricaceae, Resedaceae and Tropaeolaceae [1]
Significant differences in clubroot incidence and severity were observed between oilseed rape cultivars inoculated with different P. brassicae isolates at 35 dpi (Table 1)
While disease incidence (DI) and disease severity index (DSI) in susceptible oilseed rape cultivars inoculated with P. brassicae-Pathotype 1 (P1) were up to 100%, no disease symptoms or very small galls were observed on roots of resistant cultivars and the symptoms were of very low severity (Table 1)

Summary

Introduction

Glucosinolates (GSLs), a known group of constitutive natural plant metabolites, are found in the order Brassicales, mainly in the family of Brassicaceae and in families of Capparaceae, Caricaceae, Resedaceae and Tropaeolaceae [1] Based on their side-chain structure and amino acid precursors, GSLs are divided into three major groups: aliphatic, aromatic and indolic [2]. Plasmodiophora brassicae Woronin, the causal agent of clubroot disease, is one of the most destructive and cosmopolitan of plant pathogens This obligate soil-borne protist attacks over 3700 species of the family Brassicaceae [4] including economically important oilseed rape (Brassica napus L.) cultivars. Several P. brassicae populations were found to be moderately or highly virulent on currently available clubroot-resistant oilseed rape cultivars [7,8,9,10,13]. These new isolates have been informally named as P1 (+), P2 (+) or P3 (+) because they are classified as P1, P2 or P3 on the differentials of Somé et al [11] but (unlike the original P1, P2 or P3) are highly virulent on clubroot resistant oilseed rape cultivars

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