Arabidopsis late blight: infection of a nonhost plant byAlbugo laibachiienables full colonization byPhytophthora infestans

Abstract

SummaryThe oomycete pathogen Phytophthora infestans causes potato late blight, and as a potato and tomato specialist pathogen, is seemingly poorly adapted to infect plants outside the Solanaceae. Here, we report the unexpected finding that P. infestans can infect Arabidopsis thaliana when another oomycete pathogen, Albugo laibachii, has colonized the host plant. The behaviour and speed of P. infestans infection in Arabidopsis pre‐infected with A. laibachii resemble P. infestans infection of susceptible potato plants. Transcriptional profiling of P. infestans genes during infection revealed a significant overlap in the sets of secreted‐protein genes that are induced in P. infestans upon colonization of potato and susceptible Arabidopsis, suggesting major similarities in P. infestans gene expression dynamics on the two plant species. Furthermore, we found haustoria of A. laibachii and P. infestans within the same Arabidopsis cells. This Arabidopsis—A. laibachii—P. infestans tripartite interaction opens up various possibilities to dissect the molecular mechanisms of P. infestans infection and the processes occurring in co‐infected Arabidopsis cells.

Evolution of host range inColeosporium ipomoeae, a plant pathogen with multiple hosts

“…Studies on other pathogens have documented Table S2 shows that pathogen genotypes derived from these by recombination are also all virulent on at most one host species. priority effects, in which, for example, inoculation by a virulent pathogen facilitates infection in a subsequent inoculation by a normally avirulent pathogen (41)(42)(43). However, when a virulent and an avirulent pathogen are simultaneously inoculated, such priority effects are generally absent (44)(45)(46).…”

Albugo-imposed changes to tryptophan-derived antimicrobial metabolite biosynthesis may contribute to suppression of non-host resistance to Phytophthora infestans in Arabidopsis thaliana

“…We recently reported that A. laibachii Nc14 (AlNc14) [47] suppresses Arabidopsis NHR to P. infestans ([12], Fig. 1a, b, d and e).…”

“…Arabidopsis ( Arabidopsis thaliana ) plants were grown as previously described [12]. Seeds were sown on Scotts Levington F2 compost (Scotts, Ipswich, UK) and vernalized for one week at 5–6 °C.…”

“…Sequential infection of plants with Albugo and then P. infestans were carried out with appropriate controls as previously described [12]. …”

“…We recently found that A. laibachii suppresses Arabidopsis non-host resistance to Phytophthora infestans [12]. P. infestans is a hemibiotrophic oomycete that causes late blight disease in potato and tomato, leading to global yield losses [13], and is adapted to a few solanaceous plant species [14], but not to Arabidopsis [15].…”