Variation in egg-induced HR is independent of cell death induced by other biotic stresses
To understand whether a B. nigra plant showing absence of egg-induced HR-like cell death was also impaired in the ability to develop cell death against other biotic stresses, we tested two B. nigra accessions that either consistently develop a strong HR-like response (SF48-O1) or no cell death at all (DG1-S1). We treated them with egg wash and extracts of the Gram-negative hemibiotrophic bacteriumXanthomonas campestris pv. Campestris (Xcc) and the necrotrophic fungi Alternaria brassicicola and Rhizoctonia solani . We found that DG1-S1, the accession unable to develop cell death upon egg wash, could still develop a cell death against pathogen extracts (Supporting information: Fig. S1). In other words, egg wash induced different HR-like severity between the two accessions unlike the three pathogen extracts (Kruskal–Wallis test,p  < 0.01) (Fig. 1, Supporting information: Fig. S2).