Two sugar beet chitinase genes,BvSP2andBvSE2, analysed with SNP Amplifluor-like markers, are highly expressed after Fusarium root rot inoculations and field susceptibility trial

Abstract

BackgroundThe pathogens fromFusariumspecies can cause Fusarium root rot (RR) and other diseases in plant species including sugar beet (Beta vulgarisL.), and they have a strong negative impact on sugar beet yield and quality.MethodsA total of 22 sugar beet breeding lines were evaluated for the symptoms of RR after inoculation withFusarium oxysporumSch., isolate No. 5, and growth in a field trial. Two candidate genes for RR resistance,BvSP2andBvSE2, encoding chitinases Class IV and III, respectively, were previously identified in sugar beet, and used for genotyping using modern Amplifluor-like single nucleotide polymorphism (SNP) genotyping approach. The qPCR expression analysis was used to verify responses of the candidate genes for RR infections.ResultsA strong association of two SNP markers forBvSP2andBvSE2with resistance to RR in sugar beet was found in our study. Very highBvSP2expression (100-fold compared to Controls) was observed in three RR resistant accessions (2182, 2236 and KWS2320) 14 days after inoculation which returned to the control level on Day 18. RR sensitive breeding line 2210 showed a delay in mRNA level, reaching maximal expression ofBvSP218 days after inoculation. The geneBvSE2, showed a strong expression level in leaf samples from the infected field trial only in the breeding line 2236, which showed symptoms of RR, and this may be a response to other strains ofF. oxysporum.